U.S. patent application number 13/256270 was filed with the patent office on 2012-01-05 for heat pump system.
This patent application is currently assigned to DAIKIN INDUSTRIES, LTD.. Invention is credited to Shuji Fujimoto, Noriyuki Okuda, Takuro Yamada, Atsushi Yoshimi.
Application Number | 20120000237 13/256270 |
Document ID | / |
Family ID | 42728121 |
Filed Date | 2012-01-05 |
United States Patent
Application |
20120000237 |
Kind Code |
A1 |
Yamada; Takuro ; et
al. |
January 5, 2012 |
HEAT PUMP SYSTEM
Abstract
A heat pump system includes a heat pump circuit, a heat load
circuit, first and second heat exchangers, a flow rate adjustment
element, and a controller. The heat pump circuit circulates primary
refrigerant through a low and high stage-side compression elements,
an expansion element and an evaporator. The heat load circuit
circulates a first fluid and has a first and second branching
portions, first and second branching channels, and a
heat-load-processing section. The first and second heat exchangers
perform heat exchange between the primary refrigerant and the first
fluid. Flow rate of the first fluid in the first and/or second
branching channel is adjustable. The controller performs flow rate
adjustment control so as to maintain a state in which a
predetermined temperature condition is satisfied, or to reduce a
difference between the temperature of the first fluid flowing
through portions of the first and second branching channels.
Inventors: |
Yamada; Takuro; (Osaka,
JP) ; Okuda; Noriyuki; (Osaka, JP) ; Fujimoto;
Shuji; (Osaka, JP) ; Yoshimi; Atsushi; (Osaka,
JP) |
Assignee: |
DAIKIN INDUSTRIES, LTD.
Osaka-shi, Osaka
JP
|
Family ID: |
42728121 |
Appl. No.: |
13/256270 |
Filed: |
March 10, 2010 |
PCT Filed: |
March 10, 2010 |
PCT NO: |
PCT/JP2010/001698 |
371 Date: |
September 13, 2011 |
Current U.S.
Class: |
62/324.6 |
Current CPC
Class: |
F25B 2309/061 20130101;
F25B 2400/13 20130101; F25B 2700/21152 20130101; F25B 2700/1933
20130101; F25B 2700/21151 20130101; F25B 2339/047 20130101; F25B
1/10 20130101; F25B 2700/1931 20130101; F25B 9/008 20130101; F25B
2400/072 20130101; F25B 40/00 20130101 |
Class at
Publication: |
62/324.6 |
International
Class: |
F25B 30/00 20060101
F25B030/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 13, 2009 |
JP |
2009-061902 |
Claims
1. A heat pump system comprising: a heat pump circuit configured to
have a primary refrigerant circulated therethrough, the heat pump
circuit including at least a low-stage-side compression element, a
high-stage-side compression element, an expansion element, and an
evaporator; a first heat load circuit configured to have a first
fluid circulated therethrough, the first heat load circuit having a
first branching portion, a second branching portion, a first
branching channel arranged to connect the first branching portion
and the second branching portion, a second branching channel
arranged to connect the first branching portion and the second
branching portion without merging with the first branching channel,
and a first heat-load-processing section; a first heat exchanger
arranged and configured to perform heat exchange between the
primary refrigerant flowing from a discharge side of the
low-stage-side compression element toward an intake side of the
high-stage-side compression element and the first fluid flowing
through the first branching channel; a second heat exchanger
arranged and configured to perform heat exchange between the
primary refrigerant flowing from the high-stage-side compression
element toward the expansion element and the first fluid flowing
through the second branching channel; a first flow rate adjustment
element arranged and configured to adjust at least one of a flow
rate of the first fluid in the first branching channel and the a
flow rate of the first fluid in the second branching channel; and a
controller configured to perform flow rate adjustment control of
the first flow rate adjustment element so as to maintain a state in
which a predetermined temperature condition is satisfied, including
a case in which a ratio between temperature of the first fluid
flowing through a portion of the first branching channel that has
passed through the first heat exchanger and temperature of the
first fluid flowing through a portion of the second branching
channel that has passed through the second heat exchanger is 1, or
reduce a difference between the temperature of the first fluid
flowing through a portion of the first branching channel that has
passed through the first heat exchanger and the temperature of the
first fluid flowing through a portion of the second branching
channel that has passed through the second heat exchanger, the heat
pump circuit, the first heat load circuit, the first heat
exchanger, the second heat exchanger, the first flow rate
adjustment element and the controller being configured and arranged
such that the first fluid cooled in the first heat load circuit and
not yet warmed can be fed to the first heat exchanger and the
second heat exchanger.
2. The heat pump system according to claim 1, wherein the
controller is further configured to control output of the
low-stage-side compression element and the high-stage-side
compression element so that temperature of the primary refrigerant
that flows into the first heat exchanger and temperature of the
primary refrigerant that flows into the second heat exchanger both
become a temperature equal to or greater than a first
heat-load-corresponding temperature requested in the first
heat-load-processing section, while causing the temperature of the
primary refrigerant flowing to the first heat exchanger to become a
temperature equal to or greater than the first fluid flowing to the
first heat exchanger, and the temperature of the primary
refrigerant flowing to the second heat exchanger to become a
temperature equal to or greater than the first fluid flowing to the
second heat exchanger.
3. The heat pump system according to claim 2, wherein the first
heat load circuit further includes a first heat load bypass circuit
arranged to connect a portion between the first
heat-load-processing section and the first branching portion, and a
portion between the first heat-load-processing section and the
second branching portion; and a first heat-load-bypass
flow-rate-adjustment element arranged and configured to adjust a
flow rate of the first fluid that passes through the first heat
load bypass circuit; the controller is further configured to
perform a control in the flow rate adjustment control so that a
target value of the temperature of the first fluid flowing through
the portion of the first branching channel that has passed through
the first heat exchanger and a target value of the temperature of
the first fluid flowing through the portion of the second branching
channel that has passed through the second heat exchanger become a
temperature that exceeds the first heat-load-corresponding
temperature; and the controller is further configured to operate
the first heat-load-bypass flow-rate-adjustment element and adjust
the flow rate of the first fluid flowing through the first heat
load bypass circuit so that the temperature of the first fluid fed
to the first heat-load-processing section becomes the first
heat-load-corresponding temperature.
4. The heat pump system according to claim 2, wherein the
controller is further configured to perform a control in the flow
rate adjustment control so that a target value of the temperature
of the first fluid flowing through the portion of the first
branching channel that has passed through the first heat exchanger
and a target value of the temperature of the first fluid flowing
through the portion of the second branching channel that has passed
through the second heat exchanger become the first
heat-load-corresponding temperature.
5. The heat pump system according to claim 2, wherein the
controller is further configured to control at least one of the
low-stage-side compression element, the high-stage-side compression
element, and the expansion element in the flow rate adjustment
control so as to: maintain a state in which a predetermined
compression ratio condition is satisfied, including a case in which
a ratio between compression ratio in the low-stage-side compression
element and compression ratio in the high-stage-side compression
element is 1, or reduce a difference between the compression ratio
in the low-stage-side compression element and the compression ratio
in the high-stage-side compression element.
6. The heat pump system according to claim 5, wherein the
controller is further configured to perform a low-stage intake
degree-of-superheat control in order to increase a degree of
superheat of the primary refrigerant taken in by the low-stage-side
compression element in a case where the discharge temperature of
the primary refrigerant of the low-stage-side compression element
increases when the flow rate adjustment control is performed.
7. The heat pump system according to claim 6, wherein the heat pump
circuit further includes a
primary-refrigerant-to-primary-refrigerant heat exchanger arranged
and configured to cause heat exchange to be performed between the
primary refrigerant taken in by the low-stage-side compression
element and the primary refrigerant that has passed through the
second heat exchanger and then flows toward the expansion element;
and the controller is further configured to perform a the low-stage
intake degree-of-superheat control using the
primary-refrigerant-to-primary-refrigerant heat exchanger.
8. The heat pump system according to claim 5, wherein the
controller is further configured to perform a control during load
reduction in order to reduce a degree of superheat of the primary
refrigerant taken in by the low-stage-side compression element
while reducing a target value of the discharge temperature of the
primary refrigerant of the low-stage-side compression element in a
case where the temperature of the first fluid flowing from the
first heat-load-processing section toward the first heat exchanger
and the second heat exchanger has increased when the flow rate
adjustment control is performed.
9. The heat pump system according to claim 8, further comprising: a
second heat load circuit configured to have a second fluid
circulated therethrough, the second heat load circuit having a
second heat load section; and a third heat exchanger arranged and
configured to cause heat exchange to be performed between the
second fluid circulating through the second heat load circuit and
the primary refrigerant flowing from the high-stage-side
compression element toward the second heat exchanger.
10. The heat pump system according to claim 9, further comprising a
fourth heat exchanger arranged and configured to cause heat
exchange to be performed between the second fluid flowing from the
second heat-load-processing section toward the third heat
exchanger, among the second fluid that passes through the second
heat load circuit, and the primary refrigerant which has passed
through the second heat exchanger and is thereafter flowing toward
the expansion element.
11. The heat pump system according to claim 9, wherein the
controller is further configured to adjust a circulation amount of
the second fluid circulating through the second heat load circuit
so that the temperature of the primary refrigerant that passes
through the third heat exchanger approximates a target value of the
temperature of the primary refrigerant discharged by the
low-stage-side compression element in a case where the target value
of the temperature of the primary refrigerant discharged by the
low-stage-side compression element is less than the target value of
the temperature of the primary refrigerant discharged by the
high-stage-side compression element.
12. The heat pump system according to claim 9, wherein the second
heat load processing section is a hot-water-supply tank; and the
second fluid is water used for hot-water supply.
13. The heat pump system according to claim 2, wherein the
controller is further configured to operate the first flow rate
adjustment element in the flow rate adjustment control in order to
reduce flow rate of the first fluid having a lower temperature of
the first fluid flowing through the portion of the first branching
channel that has passed through the first heat exchanger; and the
first fluid flowing through the portion of the second branching
channel that has passed through the second heat exchanger.
14. The heat pump system according to claim 13, wherein the first
flow rate adjustment element arranged and configure to adjust a
ratio between a flow rate of the first fluid flowing through the
first branching channel and a flow rate of the first fluid flowing
through the second branching channel; and the controller is further
configured to operate the first flow rate adjustment element in the
flow rate adjustment control in order to reduce the flow rate ratio
of the first fluid having a lower temperature of the first fluid
flowing through the portion of the first branching channel that has
passed through the first heat exchanger; and the first fluid
flowing through the portion of the second branching channel that
has passed through the second heat exchanger, while keeping
constant a flow rate of the first fluid fed to the first
heat-load-processing section.
15. The heat pump system according to claim 13, wherein the first
flow rate adjustment element is further arranged and configured to
adjust a flow rate of the first fluid fed to the first
heat-load-processing section; and the controller is further
configured, in the flow rate adjustment control, to reduce the flow
rate of the first fluid fed to the first heat-load-processing
section by operating the first flow rate adjustment element in a
case where a flow rate ratio is low for the first fluid having a
lower temperature of the first fluid flowing through the portion of
the first branching channel that has passed through the first heat
exchanger; and the first fluid flowing through the portion of the
second branching channel that has passed through the second heat
exchanger.
16. The heat pump system according to claim 13, wherein the first
flow rate adjustment element includes a ratio adjustment section
configured to adjust a ratio between a flow rate of the first fluid
flowing through the first branching channel and a flow rate of the
first fluid flowing through the second branching channel, and a
flow rate adjustment section configured to adjust a flow rate of
the first fluid fed to the first heat-load-processing section; the
controller is further configured to operate the first flow rate
adjustment element in the flow rate adjustment control in order to
increase the flow rate of the first fluid having a temperature that
exceeds the first heat-load-corresponding temperature and/or reduce
the flow rate of the first fluid having a temperature that is less
than the first heat-load-corresponding temperature, as determined
from among the temperature of the first fluid flowing through the
portion of the first branching channel that has passed through the
first heat exchanger and the temperature of the first fluid flowing
through the portion of the second branching channel that has passed
through the second heat exchanger; and the controller is further
configured to reduce the flow rate of the first fluid fed to the
first heat-load-processing section in proportion to the increase of
the temperature of the first fluid fed to the first
heat-load-processing section in a case where the temperature of the
first fluid fed to the first heat-load-processing section has
exceeded the first heat-load-corresponding temperature.
17. The heat pump system according to claim 1, further comprising:
a first branching channel temperature detector arranged and
configured to ascertain temperature of the first fluid flowing
through the portion of the first branching channel that has passed
through the first heat exchanger; and a second branching channel
temperature detector arranged and configured to ascertain
temperature of the first fluid flowing through the portion of the
second branching channel that has passed through the second heat
exchanger.
18. The heat pump system according to claim 1, further comprising:
a branching portion temperature detector arranged and configured to
ascertain at least one of a temperature of the first fluid flowing
through the portion of the first branching channel that has passed
through the first heat exchanger and a temperature of the first
fluid flowing through the portion of the second branching channel
that has passed through the second heat exchanger; and a merging
portion temperature detector arranged and configured to ascertain a
temperature of the first fluid flowing toward the first
heat-load-processing section after the first fluid which has passed
through the first branching channel has merged with the first fluid
which has passed through the second branching channel.
19. The heat pump system according to claim 1, further comprising:
a first branching channel flow rate detector arranged and
configured to ascertain a flow rate of the first fluid flowing
through the first branching channel; and a second branching channel
flow rate detector arranged and configured to ascertain a flow rate
of the first fluid flowing through the second branching
channel.
20. The heat pump system according to claim 1, further comprising:
a branching portion flow rate detector arranged and configured to
ascertain at least one of a flow rate of the first fluid flowing
through the first branching channel and a flow rate of the first
fluid flowing through the second branching channel; and a merging
portion flow rate detector arranged and configured to ascertain a
flow rate of the first fluid flowing toward the first
heat-load-processing section after the first fluid flowing through
the first branching channel and the first fluid flowing through the
second branching channel have merged.
21. The heat pump system according to claim 1, wherein the primary
refrigerant flowing from the discharge side of the low-stage-side
compression element toward the intake side of the high-stage-side
compression element and the first fluid flowing through the first
branching channel are in an opposing-flow relationship in the first
heat exchanger; and the primary refrigerant flowing from the
high-stage-side compression element toward the expansion element
and the first fluid flowing through the second branching channel
are in an opposing-flow relationship in the second heat
exchanger.
22. The heat pump system according to claim 1, wherein the first
heat-load-processing section is an air-warming heat exchanger used
to warm air in a disposed target space; and the first fluid is a
secondary refrigerant.
23. The heat pump system according to claim 1, wherein the
low-stage-side compression element and the high-stage-side
compression element utilize have a shared rotating shaft, which is
rotatably driven such that compression work is performed.
24. The heat pump system according to claim 1, wherein the
controller is further configured to keep a discharge pressure of
the high-stage-side compression element at a pressure that is equal
to or greater than a critical pressure of the primary refrigerant
in the flow rate adjustment control; and the heat pump system is
configured to be used in an environment in which ambient
temperature of the first heat-load-processing section is a
temperature equal to or less than a critical temperature of the
primary refrigerant.
25. The heat pump system according to claim 1, wherein the primary
refrigerant is carbon dioxide.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heat pump system.
BACKGROUND ART
[0002] There are known conventional systems that perform an
air-warming operation using a heat pump cycle through which a
primary refrigerant circulates, and a secondary-side cycle through
which a secondary refrigerant circulates.
[0003] For example, with the heat pump-type air conditioner
described in Patent Document 1 (Japanese Laid-open Patent
Application Publication No. 2004-177067), high pressure-side
primary refrigerant and low pressure-side primary refrigerant are
made to undergo heat exchange, and the heating of the secondary
refrigerant for air warming is aided using the heat of the low
pressure-side primary refrigerant thus warmed, whereby an
improvement in efficiency is ensured.
SUMMARY OF THE INVENTION
Technical Problem
[0004] The heat pump-type air conditioner described in Patent
Document 1 (Japanese Laid-open Patent Application Publication No.
2004-177067) described above envisions a single-stage compression
type having a single compression mechanism, and the drive force
required in the compression mechanism is high.
[0005] An object of the present invention is to provide a heat pump
system that can improve cycle efficiency in heat load processing
performed by the secondary refrigerant.
Solution to Problem
[0006] A heat pump system of a first aspect of the present
invention comprises a heat pump circuit, a first heat load circuit,
a first heat exchanger, a second heat exchanger, a first flow rate
adjustment mechanism, and a controller. The heat pump circuit has
at least a low-stage-side compression mechanism, a high-stage-side
compression mechanism, an expansion mechanism, and an evaporator.
The heat pump circuit circulates a primary refrigerant. The first
heat load circuit has a first branching portion, a second branching
portion, a first branching channel, a second branching channel, and
a first heat-load-processing section. The first branching channel
connects the first branching portion and the second branching
portion. The second branching channel connects the first branching
portion and the second branching portion without merging with the
first branching channel. The first heat load circuit circulates a
first fluid. The first heat exchanger performs heat exchange
between the primary refrigerant flowing from a discharge side of
the low-stage-side compression mechanism toward an intake side of
the high-stage-side compression mechanism and the first fluid
flowing through the first branching channel. The second heat
exchanger performs heat exchange between the primary refrigerant
flowing from the high-stage-side compression mechanism toward the
expansion mechanism and the first fluid flowing through the second
branching channel. The first flow rate adjustment mechanism is
capable of adjusting at least one flow rate among the flow rate of
the first fluid in the first branching channel and the flow rate of
the first fluid in the second branching channel. The controller
performs flow rate adjustment control for operating the first flow
rate adjustment mechanism. In the flow rate adjustment control, the
first flow rate adjustment mechanism is operated so as to maintain
a state in which predetermined temperature conditions are
satisfied, including a case in which the ratio between the
temperature of the first fluid flowing through a portion of the
first branching channel that has passed through the first heat
exchanger and the temperature of the first fluid flowing through a
portion of the second branching channel that has passed through the
second heat exchanger is 1; or to reduce the difference between the
temperature of the first fluid flowing through a portion of the
first branching channel that has passed through the first heat
exchanger and the temperature of the first fluid flowing through a
portion of the second branching channel that has passed through the
second heat exchanger. A compression mechanism may be further
provided apart from the high-stage-side compression mechanism and
the low-stage-side compression mechanism, and it is apparent that
multistage compression systems are also included in the scope of
the present invention.
[0007] According to the heat pump system of the aspect of the
present invention described above, the difference between the
ambient temperature and the temperature of the first fluid heated
in the first heat exchanger, and the difference between the ambient
temperature and the temperature of the first fluid heated in the
second heat exchanger can be prevented from increasing in the case
that the heat amount of the secondary refrigerant fed to the first
heat-load-processing section is the same. It is therefore possible
to minimize the total of the radiation loss by release from the
first fluid, which has been heated in the first heat exchanger,
prior to arriving at the first heat-load-processing section and the
radiation loss by release from the first fluid, which has been
heated in the second heat exchanger, prior to arriving at the first
heat-load-processing section. It is thereby possible to improve the
efficiency of the heat pump system in terms of processing the heat
load in the first heat load heat exchanger.
[0008] The heat pump system of the second aspect of the present
invention is the heat pump system of the first aspect, wherein the
controller controls output of the low-stage-side compression
mechanism and the high-stage-side compression mechanism so that the
temperature of the primary refrigerant that flows into the first
heat exchanger and the temperature of the primary refrigerant that
flows into the second heat exchanger both become a temperature
equal to or greater than a first heat-load-corresponding
temperature requested in the first heat-load-processing section,
while causing the temperature of the primary refrigerant flowing to
the first heat exchanger to become a temperature equal to or
greater than the first fluid flowing to the first heat exchanger,
and while causing the temperature of the primary refrigerant
flowing to the second heat exchanger to become a temperature equal
to or greater than the first fluid flowing to the second heat
exchanger.
[0009] According to the heat pump system of the aspect described
above, it is possible to reliably increase the temperature of the
first fluid by using the primary refrigerant that flows into the
first heat exchanger, without a reduction in the temperature of the
first fluid that flows into the first heat exchanger. The discharge
refrigerant temperature of the high-stage-side compression
mechanism can be prevented from increasing abnormally. Similarly,
it is possible to reliably increase the temperature of the first
fluid by using the primary refrigerant that flows into the second
heat exchanger, without a reduction in the temperature of the first
fluid that flows into the second heat exchanger. It is possible to
adapt to the heat load in the first heat load heat exchanger by
using only the heat amount obtained by the first fluid in the first
heat exchanger and the second heat exchanger.
[0010] The heat pump system of the third aspect of the present
invention is the heat pump system of the second aspect, wherein the
first heat load circuit further comprises a first heat load bypass
circuit for connecting the portion between the first
heat-load-processing section and the first branching portion, and
the portion between the first heat-load-processing section and the
second branching portion; and a first heat-load-bypass
flow-rate-adjustment mechanism capable of adjusting the flow rate
of the first fluid that passes through the first heat load bypass
circuit. The controller performs a control in the flow rate
adjustment control so that a target value of the temperature of the
first fluid flowing through the portion of the first branching
channel that has passed through the first heat exchanger and a
target value of the temperature of the first fluid flowing through
the portion of the second branching channel that has passed through
the second heat exchanger become a temperature that exceeds the
first heat-load-corresponding temperature. The controller operates
the first heat-load-bypass flow-rate-adjustment mechanism and
adjusts the flow rate of the first fluid flowing through the first
heat load bypass circuit so that the temperature of the first fluid
fed to the first heat-load-processing section becomes the first
heat-load-corresponding temperature.
[0011] According to the heat pump system of the aspect described
above, the temperature of the first fluid fed to the first
heat-load-processing section can be adjusted by the first heat load
bypass flow rate adjustment mechanism by adjusting the flow rate of
the first fluid that passes through the first heat load bypass
circuit, even in an operating condition in which the temperature of
the first fluid flowing through the portion of the first branching
channel that has passed through the first heat exchanger as well as
the temperature of the first fluid flowing through the portion of
the second branching channel that has passed through the second
heat exchanger have become a temperature that exceeds the first
heat load-corresponding temperature required in the first
heat-load-processing section. It is thereby possible to bring the
temperature of the first fluid fed to the first
heat-load-corresponding section close to the first heat
load-processing temperature in order to increase the efficiency of
the heat pump circuit, even when the temperature of the first fluid
flowing through the portion of the first branching channel that has
passed through the first heat exchanger and the temperature of the
first fluid flowing through the portion of the second branching
channel that has passed through the second heat exchanger have
exceeded the first heat load-corresponding temperature.
[0012] The heat pump system of the fourth aspect of the present
invention is the heat pump system of the second aspect, wherein the
controller performs a control in the flow rate adjustment control
so that a target value of the temperature of the first fluid
flowing through the portion of the first branching channel that has
passed through the first heat exchanger and a target value of the
temperature of the first fluid flowing through the portion of the
second branching channel that has passed through the second heat
exchanger become the first heat-load-corresponding temperature.
[0013] According to the heat pump system of the aspect described
above, the temperature of the first fluid flowing through the
portion of the first branching channel that has passed through the
first heat exchanger and the temperature of the first fluid flowing
through the portion of the second branching channel that has passed
through the second heat exchanger are brought close to the first
heat-load-corresponding temperature required in the first
heat-load-processing section. It is thereby possible to avoid a
state in which the temperature of the first fluid flowing through
the first heat load circuit has considerably exceeded the first
heat-load-corresponding temperature, and to effectively reduce
radiation loss.
[0014] In the case that the first flow rate adjustment mechanism is
controlled so as to obtain the first heat-load-corresponding
temperature, it is possible to eliminate the need to provide to the
first heat load circuit a function for adjusting the temperature of
the first fluid moving toward the first heat-load-processing
section.
[0015] The heat pump system of the fifth aspect of the present
invention is the heat pump system of any of the second to fourth
aspects, wherein the controller controls at least one of the
low-stage-side compression mechanism, the high-stage-side
compression mechanism, and the expansion mechanism in the flow rate
adjustment control so as to: maintain a state in which
predetermined compression ratio conditions are satisfied, including
a case in which the ratio between the compression ratio in the
low-stage-side compression mechanism and the compression ratio in
the high-stage-side compression mechanism is 1, or reduce the
difference between the compression ratio in the low-stage-side
compression mechanism and the compression ratio in the
high-stage-side compression mechanism.
[0016] According to the heat pump system of the aspect described
above, the compressor drive force required in the high-stage-side
compression mechanism and the low-stage-side compression mechanism
can be minimized in the case that flow rate adjustment control is
performed so that the temperature of the primary refrigerant
flowing to the first heat exchanger and the temperature of the
primary refrigerant flowing to the second heat exchanger both
become a temperature equal to or greater than the first
heat-load-corresponding temperature, while ensuring that the
temperature of the primary refrigerant flowing to the first heat
exchanger becomes a temperature equal to or greater than the
temperature of the first fluid flowing to the first heat exchanger,
and while ensuring that the temperature of the primary refrigerant
flowing to the second heat exchanger becomes a temperature equal to
or greater than the temperature of the first fluid flowing to the
second heat exchanger. Not only is it thereby possible to reduce
radiation loss by the first fluid, but it is also possible to
handle the heat load in the first heat-load-processing section
using a low drive force and to further improve efficiency.
[0017] The heat pump system of the sixth aspect of the present
invention is the heat pump system of the fifth aspect, wherein the
controller performs low-stage intake degree-of-superheat control
for increasing the degree of superheat of the primary refrigerant
taken in by the low-stage-side compression mechanism in the case
that the discharge temperature of the primary refrigerant of the
low-stage-side compression mechanism increases when the flow rate
adjustment control is performed.
[0018] Generally, the compression ratio of the low-stage-side
compression mechanism tends to increase in the case that the target
value of the discharge temperature of the primary refrigerant in
the low-stage-side compression mechanism is high. The compression
ratio of the high-stage-side compression mechanism also increases
as a result. Therefore, the drive force required by the compression
mechanism increases and energy consumption increases.
[0019] In contrast, with this heat pump system, low-stage intake
degree-of-superheat control for increasing the target value of the
degree of superheat of the primary refrigerant taken in by the
low-stage-side compression mechanism is performed in the case that
the target value of the discharge temperature of the primary
refrigerant in the low-stage-side compression mechanism is to be
increased. It is therefore possible to minimize the compression
ratio of the low-stage-side compression mechanism required for
discharge temperature of the primary refrigerant in the
low-stage-side compression mechanism to reach the target value. In
addition, the compression ratio of the high-stage-side compression
mechanism can also be minimized. The required drive force of the
compression mechanism can thereby be further minimized. In the
converse case that the target value of the discharge temperature of
the primary refrigerant in the low-stage-side compression mechanism
becomes low, the degree of superheat of the primary refrigerant
taken in by the low-stage-side compression mechanism is reduced to
thereby enable to reduce the specific volume of the primary
refrigerant taken in by the low-stage-side compression mechanism,
while an increase in the compression ratio of the high-stage-side
compression mechanism is also suppressed by reducing the increase
in the compression ratio of the low-stage-side compression
mechanism. A circulation amount can thereby be ensured and capacity
can be increased while suppressing an increase in the compression
ratio.
[0020] The heat pump system of the seventh aspect of the present
invention is the heat pump system of the sixth aspect, wherein the
heat pump circuit furthermore has a
primary-refrigerant-to-primary-refrigerant heat exchanger for
causing heat exchange to be performed between the primary
refrigerant taken in by the low-stage-side compression mechanism
and the primary refrigerant that has passed through the second heat
exchanger and then flows toward the expansion mechanism. The
controller performs low-stage intake degree-of-superheat control
using the primary-refrigerant-to-primary-refrigerant heat
exchanger.
[0021] According to the heat pump system of the aspect of the
present invention described above, heat for cooling the primary
refrigerant prior to being taken into the expansion mechanism can
be recovered as heat for increasing the degree of superheat of the
primary refrigerant taken in by the low-stage-side compression
mechanism. It is thereby possible not only to increase the degree
of superheat of the primary refrigerant taken in by the
low-stage-side compression mechanism, but it is also possible
suppress a reduction in the through-rate of the primary refrigerant
in the expansion mechanism and to improve capacity.
[0022] The heat pump system of the eighth aspect of the present
invention is the heat pump system of any of the fifth to seventh
aspects, wherein the controller performs a control during load
reduction for reducing the degree of superheat of the primary
refrigerant taken in by the low-stage-side compression mechanism
while reducing the target value of the discharge temperature of the
primary refrigerant of the low-stage-side compression mechanism in
the case that the temperature of the first fluid flowing from the
first heat-load-processing section toward the first heat exchanger
and the second heat exchanger has increased when flow rate
adjustment control is performed.
[0023] According to the heat pump system of the aspect described
above, the heat load in the first heat-load-processing section is
low in the case that temperature of the first fluid flowing from
the first heat load circuit toward the first heat exchanger and the
second heat exchanger has increased, and it is therefore possible
to handle the load even in the case that a change has been made to
the efficient operating state described above. The density of the
primary refrigerant taken in by the low-stage-side compression
mechanism can also be increased, and the circulation amount of the
primary refrigerant can be increased. It is thereby possible to
increase the capacity of the heat pump circuit while adapting to
load fluctuations.
[0024] The heat pump system of the ninth aspect of the present
invention is the heat pump system of the eighth aspect, further
comprising a second heat load circuit through which a second fluid
circulates, the second heat load circuit having a second heat load
section; and a third heat exchanger for causing heat exchange to be
performed between the second fluid circulating through the second
heat load circuit and the primary refrigerant flowing from the
high-stage-side compression mechanism toward the second heat
exchanger.
[0025] According to the heat pump system of the aspect described
above, not only can the heat of the primary refrigerant discharged
by the high-stage-side compression mechanism be used for both heat
load processing in the first heat load circuit and heat load
processing in the second heat load circuit, but a temperature range
beyond what is required in the first heat load circuit can be used
in the second heat load circuit.
[0026] The heat pump system of the tenth aspect of the present
invention is the heat pump system of the ninth aspect, further
comprising a fourth heat exchanger for causing heat exchange to be
performed between the second fluid flowing from the second
heat-load-processing section toward the third heat exchanger, among
the second fluid that passes through the second heat load circuit,
and the primary refrigerant which has passed through the second
heat exchanger and is thereafter flowing toward the expansion
mechanism.
[0027] According to the heat pump system of the aspect described
above, in the case that the temperature variation range of the
first fluid in the first heat-load-processing section is included
in the temperature variation range of the second fluid in the
second heat-load-processing section, heat exchange with the primary
refrigerant in a low-temperature state and heat exchange with the
primary refrigerant in a high-temperature state among the primary
refrigerant discharged by the high-stage-side compression mechanism
can be used for heat exchange with the second fluid, and the
primary refrigerant in an intermediate-temperature state can be
used for heat exchange with the first fluid. It is thereby possible
to improve heat exchange efficiency because heat exchange can be
performed in the second heat exchanger, the third heat exchanger,
and the fourth heat exchanger while the temperature difference
between the primary refrigerant and the first and second fluids is
kept minimized.
[0028] The heat pump system of the eleventh aspect of the present
invention is the heat pump system of the ninth and tenth aspects,
wherein the controller adjusts the circulation amount of the second
fluid circulating through the second heat load circuit so that the
temperature of the primary refrigerant that passes through the
third heat exchanger approximates a target value of the temperature
of the primary refrigerant discharged by the low-stage-side
compression mechanism in the case that the target value of the
temperature of the primary refrigerant discharged by the
low-stage-side compression mechanism is less than the target value
of the temperature of the primary refrigerant discharged by the
high-stage-side compression mechanism.
[0029] According to the heat pump system of the aspect described
above, the maximum temperature of the primary refrigerant flowing
through the first heat exchanger and the maximum temperature of the
primary refrigerant flowing through the second heat exchanger are
brought close together, whereby the temperature of the first fluid
flowing through the portion of the first branching channel that has
passed through the first heat exchanger and the temperature of the
first fluid flowing through portion of the second branching channel
that has passed through the second heat exchanger are more readily
brought close together.
[0030] For example, if it is desired to keep the flow rate of the
first fluid fed to the first heat-load-processing section low, the
temperature of the primary refrigerant flowing through the first
heat exchanger and the temperature of the primary refrigerant
flowing through second heat exchanger come close to each other even
if the time for the first fluid to pass through the first heat
exchanger and/or pass through the second heat exchanger is
increased. Accordingly, the temperature of the first fluid flowing
through the portion of the first branching channel that has passed
through the first heat exchanger and the temperature of the first
fluid flowing through the portion of the second branching channel
that has passed through the second heat exchanger can be made to
converge at a value near the temperature of the primary refrigerant
flowing through the first heat exchanger (the temperature of the
primary refrigerant flowing through the second heat exchanger).
[0031] The heat pump system of the twelfth aspect of the present
invention is the heat pump system of any of the ninth to eleventh
aspects, wherein the second heat load processing unit is a
hot-water-supply tank. The second fluid is water for hot-water
supply.
[0032] According to the heat pump system of the aspect described
above, hot water can be made using the temperature of the primary
refrigerant discharged from the high-stage-side compression
mechanism.
[0033] The heat pump system of the thirteenth aspect of the present
invention is the heat pump system of any of the second to twelfth
aspects, wherein the controller operates the first flow rate
adjustment mechanism in the flow rate adjustment control to thereby
reduce the flow rate of the first fluid having a lower temperature
among: the temperature of the first fluid flowing through the
portion of the first branching channel that has passed through the
first heat exchanger; and the temperature of the first fluid
flowing through the portion of the second branching channel that
has passed through the second heat exchanger.
[0034] According to the heat pump system of the aspect described
above, the flow rate of the first fluid having a lower temperature
among the temperature of the first fluid flowing through the
section of the first branching channel that has passed through the
first heat exchanger and the temperature of the first fluid flowing
through the portion of the second branching channel that has passed
through the second heat exchanger is reduced, whereby flow speed of
the first fluid having a lower temperature can be reduced and the
heating time can be increased. It is possible to increase the
amount of heat recovered from the primary refrigerant in the heat
exchanger having the reduced flow rate among the first heat
exchanger and the second heat exchanger.
[0035] For example, the amount of recovered heat can be increased
by reducing the through speed to extend the time available for heat
exchange in the case that the first fluid has passed through the
first heat exchanger or the second heat exchanger at a high flow
speed without being heated to the inlet temperature of the primary
refrigerant.
[0036] The heat pump system of the fourteenth aspect of the present
invention is the heat pump system of the thirteenth aspect, wherein
the first flow rate adjustment mechanism is capable of adjusting
the ratio between the flow rate of the first fluid flowing through
the first branching channel and the flow rate of the first fluid
flowing through the second branching channel. The controller
operates the first flow rate adjustment mechanism in the flow rate
adjustment control to thereby reduce the flow rate ratio of the
first fluid having a lower temperature among: the temperature of
the first fluid flowing through the portion of the first branching
channel that has passed through the first heat exchanger; and the
temperature of the first fluid flowing through the portion of the
second branching channel that has passed through the second heat
exchanger, while keeping constant the flow rate of the first fluid
fed to the first heat-load-processing section.
[0037] According to the heat pump system of the aspect described
above, using the temperature of the first fluid flowing through the
portion of the first branching channel that has passed through the
first heat exchanger and the temperature of the first fluid flowing
through the portion of the second branching channel that has passed
through the second heat exchanger, the flow speed of the first
fluid having the higher temperature is increased and the heating
time is reduced, and the flow speed of the first fluid having the
lower temperature is reduced and the heating time is extended, by
adjusting the flow rate ratio. The temperature of the first fluid
flowing through the portion of the first branching channel that has
passed through the first heat exchanger and the temperature of the
first fluid flowing through the portion of the second branching
channel that has passed through the second heat exchanger can be
varied so as the reduce temperature difference. In the case that
the heat load has not changed in the first heat-load-processing
section, not only can the temperature difference be reduced, but it
is also possible to adapt to the heat load of the first
heat-load-processing section by keeping the flow rate of the first
fluid fed to the first heat-load-processing section.
[0038] The heat pump system of the fifteenth aspect of the present
invention is the heat pump system of the thirteenth aspect, wherein
the first flow rate adjustment mechanism is capable of adjusting
the flow rate of the first fluid fed to the first
heat-load-processing section. In the flow rate adjustment control,
the controller reduces the flow rate of the first fluid fed to the
first heat-load-processing section by operating the first flow rate
adjustment mechanism in the case that the flow rate ratio is low
for the first fluid having a lower temperature among: the
temperature of the first fluid flowing through the portion of the
first branching channel that has passed through the first heat
exchanger; and the temperature of the first fluid flowing through
the portion of the second branching channel that has passed through
the second heat exchanger.
[0039] According to the heat pump system of the aspect described
above, when the flow rate of the first fluid fed to the first
heat-load-processing section is reduced, the temperature increase
of the first fluid having a lower temperature is made greater than
the temperature increase of the first fluid having a higher
temperature, in the case that the flow rate ratio is low for the
first fluid having a lower temperature among: the temperature of
the first fluid flowing through the portion of the first branching
channel that has passed through the first heat exchanger; and the
temperature of the first fluid flowing through the portion of the
second branching channel that has passed through the second heat
exchanger. It is thereby possible to vary the flow rate so that the
temperature difference is reduced. Also, in the case that the heat
load is reduced in the first heat-load-processing section, not only
can the temperature difference be reduced, but it is also possible
to adapt to the heat load in the first heat-load-processing
section.
[0040] The heat pump system of the sixteenth aspect of the present
invention is the heat pump system of the thirteenth aspect, wherein
the first flow rate adjustment mechanism includes a ratio
adjustment section for adjusting the ratio between the flow rate of
the first fluid flowing through the first branching channel and the
flow rate of the first fluid flowing through the second branching
channel, and a flow rate adjustment section for adjusting the flow
rate of the first fluid fed to the first heat-load-processing
section. The controller operates the first flow rate adjustment
mechanism in the flow rate adjustment control to thereby increase
the flow rate of the first fluid having a temperature that exceeds
the first heat-load-corresponding temperature and/or reduce the
flow rate of the first fluid having a temperature that is less than
the first heat-load-corresponding temperature, as determined from
among the temperature of the first fluid flowing through the
portion of the first branching channel that has passed through the
first heat exchanger and the temperature of the first fluid flowing
through the portion of the second branching channel that has passed
through the second heat exchanger; and the controller reduces the
flow rate of the first fluid fed to the first heat-load-processing
section in proportion to the increase of the temperature of the
first fluid fed to the first heat-load-processing section in the
case that the temperature of the first fluid fed to the first
heat-load-processing section has exceeded the first
heat-load-corresponding temperature.
[0041] According to the heat pump system of the aspect described
above, the flow rate of the first fluid flowing through the first
heat load circuit can be set to a rate adapted to the heat load in
the first heat-load-processing section while the difference between
the temperature of the first fluid flowing through section of the
first branching channel that has passed through the first heat
exchanger and the temperature of the first fluid flowing through
the portion of the second branching channel that has passed through
the second heat exchanger is reduced.
[0042] The heat pump system of the seventeenth aspect of the
present invention is the heat pump system of any of the first to
sixteenth aspects, further comprising: first branching channel
temperature detector for ascertaining the temperature of the first
fluid flowing through the portion of the first branching channel
that has passed through the first heat exchanger; and second
branching channel temperature detector for ascertaining the
temperature of the first fluid flowing through the portion of the
second branching channel that has passed through the second heat
exchanger.
[0043] According to the heat pump system of the aspect described
above, the precision of flow rate adjustment control can be
improved because it is possible to directly ascertain the
temperature of the first fluid flowing through the portion of the
first branching channel that has passed through the first heat
exchanger, and the temperature of the first fluid flowing through
the portion of the second branching channel that has passed through
the second heat exchanger.
[0044] The heat pump system of the eighteenth aspect of the present
invention is the heat pump system of any of the first to sixteenth
aspects, further comprising: branching portion temperature detector
and merging portion temperature detector. The branching portion
temperature detector ascertains at least one of the temperature of
the first fluid flowing through the portion of the first branching
channel that has passed through the first heat exchanger and the
temperature of the first fluid flowing through the portion of the
second branching channel that has passed through the second heat
exchanger. The merging portion temperature detector for ascertains
the temperature of the first fluid flowing toward the first
heat-load-processing section after the first fluid which has passed
through the first branching channel has merged with the first fluid
which has passed through the second branching channel.
[0045] According to the heat pump system of the aspect described
above, it is possible to directly ascertain at least either of the
temperature of the first fluid flowing through the portion of the
first branching channel that has passed through the first heat
exchanger and the temperature of the first fluid flowing through
the portion of the second branching channel that has passed through
the second heat exchanger by using the branching portion
temperature detector and to directly ascertain the temperature of
the first fluid after merging by using the merging portion
temperature detector. The precision of flow rate adjustment control
can thereby be improved by performing control so as to reduce the
difference between the temperature ascertained by the branching
portion temperature detector and the temperature ascertained by the
merging portion temperature detector.
[0046] The heat pump system of the nineteenth aspect of the present
invention is the heat pump system of any of the first to sixteenth
aspects, further comprising: first branching channel flow rate
detector for ascertaining the flow rate of the first fluid flowing
through the first branching channel; and second branching channel
flow rate detector for ascertaining the flow rate of the first
fluid flowing through the second branching channel.
[0047] According to the heat pump system of the aspect described
above, the precision of flow rate adjustment control can be
improved because the flow rate of the first fluid flowing through
the first branching channel and the flow rate of the first fluid
flowing through the second branching channel can be directly
ascertained.
[0048] The heat pump system of the twentieth aspect of the present
invention is the heat pump system of any of the first to sixteenth
aspects, further comprising: branching portion flow rate detector
for ascertaining at least one among the flow rate of the first
fluid flowing through the first branching channel and the flow rate
of the first fluid flowing through the second branching channel;
and merging portion flow rate detector for ascertaining the flow
rate of the first fluid flowing toward the first
heat-load-processing section after the first fluid flowing through
the first branching channel and the first fluid flowing through the
second branching channel have merged.
[0049] According to the heat pump system of the aspect described
above, it is possible to directly ascertain at least either of the
flow rate of the first fluid flowing through the first branching
channel and the flow rate of the first fluid flowing through the
second branching channel by using the branching portion flow rate
detector and to directly ascertain the flow rate of the first fluid
after merging by using the merging portion flow rate detector. It
is thereby possible to ascertain the flow rate of the first
branching channel or the second branching channel, whichever is not
provided with the branching portion flow rate detector, as the
difference between the flow rate ascertained by the branching
portion flow rate detector and the flow rate ascertained by the
merging portion flow rate detector. The precision of flow rate
adjustment control can thereby be improved.
[0050] The heat pump system of the twenty-first aspect of the
present invention is the heat pump system of any of the first to
twentieth aspects, wherein the primary refrigerant flowing from the
discharge side of the low-stage-side compression mechanism toward
the intake side of the high-stage-side compression mechanism and
the first fluid flowing through the first branching channel are in
an opposing-flow relationship in the first heat exchanger. The
primary refrigerant flowing from the high-stage-side compression
mechanism toward the expansion mechanism and the first fluid
flowing through the second branching channel are in an
opposing-flow relationship in the second heat exchanger.
[0051] According to the heat pump system of the aspect described
above, it is possible to minimize the temperature required as the
temperature of the primary refrigerant discharged from the
low-stage-side compression mechanism and the temperature of the
primary refrigerant discharged from the high-stage-side compression
mechanism. The drive force of the compression mechanism can thereby
be minimized.
[0052] The heat pump system of the twenty-second aspect of the
present invention is the heat pump system of any of the first to
twenty-first aspects, wherein the first heat-load-processing
section is an air-warming heat exchanger for warming air in a
disposed target space. The first fluid is a secondary
refrigerant.
[0053] According to the heat pump system of the aspect described
above, it is possible to warm the space in which the first
heat-load-processing section is disposed.
[0054] The heat pump system of the twenty-third aspect of the
present invention is the heat pump system of any of the first to
twenty-second aspects, wherein the low-stage-side compression
mechanism and the high-stage-side compression mechanism have a
shared rotating shaft that is rotatably driven, whereby compression
work is performed.
[0055] According to the heat pump system of the aspect described
above, a rotating shaft is shared in an arrangement having a
180.degree. phase difference, whereby drive efficiency can be
improved.
[0056] The heat pump system of the twenty-fourth aspect of the
present invention is the heat pump system of any of the first to
twenty-third aspects, wherein the controller keeps the discharge
pressure of the high-stage-side compression mechanism at a pressure
that is equal to or greater than a critical pressure of the primary
refrigerant in the flow rate adjustment control. The heat pump is
used in an environment in which the ambient temperature of the
first heat-load-processing section is a temperature equal to or
less than the critical temperature of the primary refrigerant.
[0057] According to the heat pump system of the aspect described
above, primary refrigerant in a state exceeding critical pressure
is fed to a heat load having a temperature that is lower than the
critical temperature of the primary refrigerant, whereby heat
release can be carried out in an area in which the slope of the
isotherm of the primary refrigerant is smooth on a Mollier graph.
It is therefore possible to perform operation that increases the
enthalpy difference between the start and end of the primary
refrigerant heat release step.
[0058] The heat pump system of the twenty-fifth aspect of the
present invention is the heat pump system of any of the first to
twenty-fourth aspects, wherein the primary refrigerant is carbon
dioxide.
[0059] According to the heat pump system of the aspect described
above, it is possible to implement a refrigeration cycle of a heat
pump circuit using a natural refrigerant.
Effects of Invention
[0060] As noted in the description above, the following effects are
obtained in accordance with the present invention.
[0061] In the first aspect, it is possible to improve the
efficiency of the heat pump system in terms of processing the heat
load in the first heat load heat exchanger.
[0062] In the second aspect, it is possible to adapt to the heat
load in the first heat load heat exchanger by using only the heat
amount obtained by the first fluid in the first heat exchanger and
the second heat exchanger.
[0063] In the third aspect, it is possible to bring the temperature
of the first fluid fed to the first heat-load-processing section
close to the first heat load-corresponding temperature even when in
order to increase the efficiency of the heat pump circuit, the
temperature of the first fluid flowing through the portion of the
first branching channel that has passed through the first heat
exchanger and the temperature of the first fluid flowing through
the portion of the second branching channel that has passed through
the second heat exchanger have exceeded the first heat
load-corresponding temperature.
[0064] In the fourth aspect, it is possible to avoid a state in
which the temperature of the first fluid flowing through the first
heat load circuit has considerably exceeded the first
heat-load-corresponding temperature, and to effectively reduce
radiation loss.
[0065] In the fifth aspect, not only is it possible to reduce
radiation loss, but it is also possible to handle the heat load in
the first heat-load-processing section using a low drive force and
to further improve efficiency.
[0066] In the sixth aspect, a circulation amount can be ensured and
capacity can be increased while suppressing an increase in the
compression ratio.
[0067] In the seventh aspect, it is possible to not only increase
the degree of superheat of the primary refrigerant taken in by the
low-stage-side compression mechanism, but it is also possible to
suppress a reduction in the through-rate of the primary refrigerant
in the expansion mechanism and to improve capacity.
[0068] In the eighth aspect, it is possible to increase the
capacity of the heat pump circuit while adapting to load
fluctuations.
[0069] In the ninth aspect, not only can the heat of the primary
refrigerant discharged by the high-stage-side compression mechanism
be used for both heat load processing in the first heat load
circuit and heat load processing in the second heat load circuit,
but also a temperature range beyond what is required in the first
heat load circuit can be used in the second heat load circuit.
[0070] In the tenth aspect, it is possible to improve heat exchange
efficiency because heat exchange can be performed in the second
heat exchanger, the third heat exchanger, and the fourth heat
exchanger while the temperature difference between the primary
refrigerant and the first and second fluids is kept minimized.
[0071] In the eleventh aspect, the temperature of the first fluid
flowing through the portion of the first branching channel that has
passed through the first heat exchanger and the temperature of the
first fluid flowing through portion of the second branching channel
that has passed through the second heat exchanger are more readily
brought close together.
[0072] In the twelfth aspect, hot water can be made using the
temperature of the primary refrigerant discharged from the
high-stage-side compression mechanism
[0073] In the thirteenth aspect, it is possible to increase the
amount of heat recovered from the primary refrigerant in the heat
exchanger having the reduced flow rate among the first heat
exchanger and the second heat exchanger.
[0074] In the fourteenth aspect, the temperature of the first fluid
flowing through the portion of the first branching channel that has
passed through the first heat exchanger and the temperature of the
first fluid flowing through the portion of the second branching
channel that has passed through the second heat exchanger can be
varied so as to reduce the temperature difference, and in the case
that the heat load has not changed in the first
heat-load-processing section, not only can the temperature
difference be reduced, but it is also possible to adapt to the heat
load of the first heat-load-processing section by keeping the flow
rate of the first fluid fed to the first heat-load-processing
section.
[0075] In the fifteenth aspect, it is possible to vary the flow
rate so that the temperature difference is reduced. Also, in the
case that the heat load is reduced in the first
heat-load-processing section, not only can the temperature
difference be reduced, but it is also possible to adapt to the heat
load in the first heat-load-processing section.
[0076] In the sixteenth aspect, the flow rate of the first fluid
flowing through the first heat load circuit can be set to a rate
adapted to the heat load in the first heat-load-processing section
while the difference between the temperature of the first fluid
flowing through section of the first branching channel that has
passed through the first heat exchanger and the temperature of the
first fluid flowing through the portion of the second branching
channel that has passed through the second heat exchanger is
reduced.
[0077] In the seventeenth aspect, the precision of flow rate
adjustment control can be improved.
[0078] In the eighteenth aspect; the precision of flow rate
adjustment control can be improved by performing control so as to
reduce the difference between the temperature ascertained by the
branching portion temperature detector and the temperature
ascertained by the merging portion temperature detector.
[0079] In the nineteenth aspect, the precision of flow rate
adjustment control can be improved.
[0080] In the twentieth aspect, the precision of flow rate
adjustment control can be improved.
[0081] In the twenty-first aspect, the drive force of the
compression mechanism can be minimized.
[0082] In the twenty-second aspect, it is possible to warm the
space in which the first heat-load-processing section is
disposed.
[0083] In the twenty-third aspect, a rotating shaft is shared and a
180.degree. phase difference is provided, whereby drive efficiency
can be improved.
[0084] In the twenty-fourth aspect, it is possible to perform
operation that increases the enthalpy difference between the start
and end of the primary refrigerant heat release step.
[0085] In the twenty-fifth aspect, it is possible to implement a
refrigeration cycle of a heat pump circuit using a natural
refrigerant.
BRIEF DESCRIPTION OF THE DRAWINGS
[0086] FIG. 1 is a schematic structural diagram of a heat pump
system according to the first embodiment of the present
invention.
[0087] FIG. 2 is a pressure-enthalpy graph of a heat pump circuit
according to the first embodiment.
[0088] FIG. 3 is a temperature-entropy graph of the heat pump
circuit according to the first embodiment.
[0089] FIG. 4 is a schematic structural diagram of a heat pump
system according to the second embodiment.
[0090] FIG. 5 is a schematic structural diagram of a heat pump
system according to the third embodiment.
[0091] FIG. 6 is a schematic structural diagram of a heat pump
system according to the fourth embodiment.
[0092] FIG. 7 is a schematic structural diagram of a heat pump
system according to the fifth embodiment.
[0093] FIG. 8 is a schematic structural diagram of a heat pump
system according to Modification A of the fifth embodiment.
[0094] FIG. 9 is a schematic structural diagram of a heat pump
system according to Modification B of the fifth embodiment.
[0095] FIG. 10 is a schematic structural diagram of a heat pump
system according to Modification C of the fifth embodiment.
[0096] FIG. 11 is a schematic structural diagram of a heat pump
system according to the sixth embodiment.
[0097] FIG. 12 is a schematic structural diagram of a heat pump
system according to Modification A of the sixth embodiment.
[0098] FIG. 13 is a schematic structural diagram of a heat pump
system according to the seventh embodiment.
[0099] FIG. 14 is a schematic structural diagram of a heat pump
system according to the eighth embodiment.
[0100] FIG. 15 is a schematic structural diagram of a heat pump
system according to the ninth embodiment.
[0101] FIG. 16 is a schematic structural diagram of a heat pump
system according to the tenth embodiment.
[0102] FIG. 17 is a schematic structural diagram of a heat pump
system according to the eleventh embodiment.
[0103] FIG. 18 is a schematic structural diagram of a heat pump
system according to the twelfth embodiment.
[0104] FIG. 19 is a schematic structural diagram of a heat pump
system according to the thirteenth embodiment.
[0105] FIG. 20 is a schematic structural diagram of a heat pump
system according to Modification <14-5> of the
embodiments.
[0106] FIG. 21 is a schematic structural diagram of a heat pump
system according to Modification <14-5> of each of the
embodiments.
[0107] FIG. 22 is a Mollier graph of Modification <14-8> of
the embodiments.
[0108] FIG. 23 is a Mollier graph of Modification <14-9> of
the embodiments.
[0109] FIG. 24 is a schematic structural diagram of a heat pump
system according to Modification <14-11> of the
embodiments.
[0110] FIG. 25 is a schematic structural diagram of a heat pump
system according to Modification <14-12> of the
embodiments.
[0111] FIG. 26 is a schematic structural diagram of a heat pump
system according to Modification <14-13> of the
embodiments.
[0112] FIG. 27 shows a comparative example of the Mollier graph of
Modification <14-17> of the embodiments.
[0113] FIG. 28 is a Mollier graph of Modification <14-17> of
the embodiments.
[0114] FIG. 29 is a Mollier graph of Modification <14-18> of
the embodiments.
DESCRIPTION OF EMBODIMENTS
<1> First Embodiment
<1-1> Configuration of the Heat Pump System 1
[0115] FIG. 1 is a schematic structural diagram of a heat pump
system 1 according to the first embodiment, which is an embodiment
of the present invention.
[0116] The heat pump system 1 is provided with a heat pump circuit
10, an air-warming circuit 60, a hot-water supply circuit 90, an
intermediate-pressure water heat exchanger 40, and a high-pressure
water heat exchanger 50. The heat pump system 1 is a system that
uses the heat obtained by the heat pump circuit 10 not only as heat
for air warming via the air-warming circuit 60, but also as heat
for hot-water supply via the hot-water supply circuit 90.
(Intermediate-pressure water heat exchanger 40)
[0117] The intermediate-pressure water heat exchanger 40 causes
heat exchange to be performed between carbon dioxide as the primary
refrigerant circulating through the heat pump circuit 10 and water
as the secondary refrigerant circulating through the air-warming
circuit 60.
(High-Pressure Water Heat Exchanger 50)
[0118] The high-pressure water heat exchanger 50 has a first
high-pressure water heat exchanger 51, a second high-pressure water
heat exchanger 52, and a third high-pressure water heat exchanger
53. The first high-pressure water heat exchanger 51 causes heat
exchange to be performed between carbon dioxide as the primary
refrigerant circulating through the heat pump circuit 10 and water
for hot-water supply that circulates through the hot-water supply
circuit 90. The second high-pressure water heat exchanger 52 causes
heat exchange to be performed between carbon dioxide as the primary
refrigerant circulating through the heat pump circuit 10 and water
as the secondary refrigerant circulating through the air-warming
circuit 60. The third high-pressure water heat exchanger 53 causes
heat exchange to be performed between carbon dioxide as the primary
refrigerant circulating through the heat pump circuit 10 and water
for hot-water supply that circulates through the hot-water supply
circuit 90.
(Heat Pump Circuit 10)
[0119] The heat pump circuit 10 is a circuit that uses a natural
refrigerant and is a circuit through which carbon dioxide is
circulated as a primary refrigerant. The heat pump circuit 10 is
provided with a low-stage-side compressor 21, a high-stage-side
compressor 25, an economizer heat exchanger 7, an injection channel
70, a primary-refrigerant-to-primary-refrigerant heat exchanger 8,
a primary bypass 80, an expansion valve 5a, an evaporator 4, an
intermediate-pressure tube 23, a high-pressure tube 27, a
low-pressure tube 20, a fan 4f, and a controller 11. The evaporator
4 is disposed, e.g., outdoors.
[0120] The intermediate-pressure tube 23 connects the discharge
side of the low-stage-side compressor 21 and the intake side of the
high-stage-side compressor 25. The intermediate-pressure tube 23
has a first intermediate-pressure tube 23a, a second
intermediate-pressure tube 23b, a third intermediate-pressure tube
23c, and a fourth intermediate-pressure tube 23d.
[0121] The first intermediate-pressure tube 23a connects the
discharge side of the low-stage-side compressor 21 and the
upstream-side end section of the intermediate-pressure water heat
exchanger 40 via a low-stage-discharge point B. An
intermediate-pressure temperature sensor 23T for detecting the
temperature of the passing primary refrigerant is mounted in the
first intermediate-pressure tube 23a. The second
intermediate-pressure tube 23b passes through the interior of the
intermediate-pressure water heat exchanger 40 while carbon dioxide
as the primary refrigerant is allowed to flow therein so that there
is no mixing with the water for air warming as the secondary
refrigerant. The third intermediate-pressure tube 23c connects the
downstream-side end section of the intermediate-pressure water heat
exchanger 40 and an injection merging point D via an
intermediate-pressure water heat exchanger passage point C. The
fourth intermediate-pressure tube 23d connects the injection
merging point D and the intake side of the high-stage-side
compressor 25. A high-stage intake pressure sensor 24P for
detecting the pressure of the passing primary refrigerant and a
high-stage intake temperature sensor 24T for detecting the
temperature of the passing primary refrigerant are mounted in the
fourth intermediate-pressure tube 23d.
[0122] The high-pressure tube 27 connects the discharge side of the
high-stage-side compressor 25 and the expansion valve 5 or a
primary bypass expansion valve 5b. The high-pressure tube 27 has a
first high-pressure tube 27a, a second high-pressure tube 27b, a
third high-pressure tube 27c, a fourth high-pressure tube 27d, a
fifth high-pressure tube 27e, a sixth high-pressure tube 27f, a
seventh high-pressure tube 27g, an eighth high-pressure tube 27h, a
ninth high-pressure tube 27i, a tenth high-pressure tube 27j, an
eleventh high-pressure tube 27k, a twelfth high-pressure tube 27l,
and a thirteenth high-pressure tube 27m.
[0123] The first high-pressure tube 27a connects the discharge side
of the high-stage-side compressor 25 and a first high-pressure
water heat exchanger 51 via a high-stage discharge point E. A
high-pressure pressure sensor 27P for detecting the pressure of the
passing primary refrigerant, and a high-pressure temperature sensor
27T for detecting the temperature of the passing primary
refrigerant are mounted in the first high-pressure tube 27a. The
second high-pressure tube 27b passes through the interior of the
first high-pressure water heat exchanger 51 while carbon dioxide as
the primary refrigerant is allowed to flow therein so that there is
no mixing with the water for hot-water supply. The third
high-pressure tube 27c connects the downstream-side end section of
the first high-pressure water heat exchanger 51 and the
upstream-side end section of the second high-pressure water heat
exchanger 52 via a first high-pressure point F. The fourth
high-pressure tube 27d passes through the interior of the second
high-pressure-water heat exchanger 52 while carbon dioxide as the
primary refrigerant is allowed to flow therein so that there is no
mixing with the water as secondary refrigerant for air warming. The
fifth high-pressure tube 27e connects the downstream-side end
section of the second high-pressure water heat exchanger 52 and the
upstream-side end section of the third high-pressure-water heat
exchanger 53 via a second high-pressure point G The sixth
high-pressure tube 27f passes through the interior of the third
high-pressure-water heat exchanger 53 while carbon dioxide as the
primary refrigerant is allowed to flow therein so that there is no
mixing with the water as secondary refrigerant for air warming. The
seventh high-pressure tube 27g connects the downstream-side end
section of the third high-pressure-water heat exchanger 53 and a
third high-pressure point H. The eighth high-pressure tube 27h
connects the third high-pressure point H and the upstream-side end
section in the flow direction of the primary refrigerant toward the
expansion valve 5a side in the economizer heat exchanger 7. The
ninth high-pressure tube 27i passes through the economizer heat
exchanger 7 while primary refrigerant is allowed to flow therein so
that there is no mixing with the primary refrigerant flowing
through the injection channel 70. The tenth high-pressure tube 27j
connects a fourth high-pressure point I and the downstream-side end
section in the flow direction of the primary refrigerant toward the
expansion valve 5a side in the economizer heat exchanger 7. The
eleventh high-pressure tube 27k connects the fourth high-pressure
point I and the upstream-side end section in the flow direction of
the primary refrigerant toward the expansion valve 5a side in the
primary-refrigerant-to-primary-refrigerant heat exchanger 8. The
twelfth high-pressure tube 27l passes through the
primary-refrigerant-to-primary-refrigerant heat exchanger 8 while
primary refrigerant is allowed to flow therein so that there is no
mixing between the primary refrigerant flowing through the
low-pressure tube 20. The thirteenth high-pressure tube 27m
connects the expansion valve 5a and the downstream-side end section
in the flow direction of the primary refrigerant toward the
expansion valve 5a side in the
primary-refrigerant-to-primary-refrigerant heat exchanger 8 via a
fifth high-pressure point J.
[0124] The low-pressure tube 20 has a first low-pressure tube 20a,
a second low-pressure tube 20b, a third low-pressure tube 20c, a
fourth low-pressure tube 20d, and a fifth low-pressure tube 20e.
The first low-pressure tube 20a connects the expansion valve 5a and
a third low-pressure point M via a first low-pressure point K. The
second low-pressure tube 20b connects the third low-pressure point
M and the upstream-side end section of the evaporator 4. The third
low-pressure tube 20c connects the downstream-side end section of
the evaporator 4 and the upstream-side end section of the
primary-refrigerant-to-primary-refrigerant heat exchanger 8 in
terms of the flow direction of the primary refrigerant in the
low-pressure tube 20 via a fourth low-pressure point N. The fourth
low-pressure tube 20d passes through the
primary-refrigerant-to-primary-refrigerant heat exchanger 8 while
the primary refrigerant is allowed to flow therein so that there is
no mixing with the primary refrigerant flowing through the twelfth
high-pressure tube 27l. The fifth low-pressure tube 20e connects
the downstream-side end section of the
primary-refrigerant-to-primary-refrigerant heat exchanger 8 in
terms of the flow direction of the primary refrigerant in the
low-pressure tube 20 and an intake point A, which is the intake
side of the low-stage-side compressor 21. A low-pressure pressure
sensor 20P for detecting the pressure of the passing primary
refrigerant and a low-pressure temperature sensor 20T for detecting
the temperature of the passing primary refrigerant are mounted in
the fifth low-pressure tube 20e.
[0125] The injection channel 70 has an injection expansion valve
73, a first injection tube 72, a second injection tube 74, a third
injection tube 75, and a fourth injection tube 76.
[0126] The first injection tube 72 connects the third high-pressure
point H and the injection expansion valve 73. The second injection
tube 74 connects the injection expansion valve 73 and the
upstream-side end section in terms of the flow direction of the
primary refrigerant flowing through the injection channel 70 in the
economizer heat exchanger 7 via an injection intermediate-pressure
point Q. The third injection tube 75 passes through the economizer
heat exchanger 7 while primary refrigerant is allowed to flow
therein so that there is no mixing with the primary refrigerant
flowing through the ninth high-pressure tube 27i. The fourth
injection tube 76 connects the injection merging point D and the
downstream-side end section in the flow direction of the primary
refrigerant flowing through the injection channel 70 in the
economizer heat exchanger 7 via an economizer post-heat-exchange
point R.
[0127] In the heat pump circuit 10, the coefficient of performance
the heat pump circuit is thus improved because the injection
channel 70 is used. For example, in the case that, among other
things, the air-warming load is low, operating efficiency can be
improved by increasing the injection amount that passes through the
injection channel 70, even when the cooling effect of the primary
refrigerant cannot be sufficiently obtained in the
intermediate-pressure water heat exchanger 40, which is used for
improving the efficiency of the heat pump circuit 10. In the heat
pump circuit 10, the injection merging point D is provided between
the intermediate-pressure water heat exchanger 40 and the
high-stage-side compressor 25. Accordingly, high-temperature
primary refrigerant discharged from the low-stage-side compressor
21 can be fed to the intermediate-pressure water heat exchanger 40
while being kept in a high-temperature state without being cooled
prior to arriving in the intermediate-pressure water heat exchanger
40. For this reason, the water for air warming that passes through
the intermediate-pressure water heat exchanger 40 can be brought to
a sufficiently high temperature. Furthermore, the third
high-pressure point H is provided in a position that allows a
portion of the primary refrigerant in the upstream side of the
economizer heat exchanger 7 to be branched to the injection channel
70. Therefore, it is possible to avoid a reduction in capacity due
to overcooling of the primary refrigerant moving from the
low-stage-side compressor 21 toward the high-stage-side compressor
25. The primary bypass 80 has a fourteenth high-pressure tube 27n,
a sixth low-pressure tube 20f, and the primary bypass expansion
valve 5b. The fourteenth high-pressure tube 27n connects the fourth
high-pressure point I and the primary bypass expansion valve 5b.
The sixth low-pressure tube 20f connects primary bypass expansion
valve 5b and the third low-pressure point M via the second
low-pressure point L. Since the primary bypass expansion valve 5b
is provided to the primary bypass 80, the controller 11 can adjust
the amount of primary refrigerant that passes through the
primary-refrigerant-to-primary-refrigerant heat exchanger 8 side.
It is therefore possible to make adjustment so that the primary
refrigerant taken in by the low-stage-side compressor 21 is at a
suitable degree of superheat. Specifically, the controller 11 can
increase the flow rate of the primary refrigerant that passes
through the primary-refrigerant-to-primary-refrigerant heat
exchanger 8 and increase the degree of superheat of the primary
refrigerant taken in by the low-stage-side compressor 21 in the
case that the valve opening degree of the primary bypass expansion
valve 5b is reduced, whereby the compression ratio required for the
discharge refrigerant temperature of the low-stage-side compressor
21 to reach a target temperature can be minimized. Also, the
controller 11 can reduce the flow rate of the primary refrigerant
that passes through the primary-refrigerant-to-primary-refrigerant
heat exchanger 8 and reduce the degree of superheat of the primary
refrigerant taken in by the low-stage-side compressor 21 in the
case that the opening degree of the primary bypass expansion valve
5b is increased, thereby making it possible to avoid a situation in
which the intake refrigerant density of the low-stage-side
compressor 21 is dramatically reduced and a circulation amount
cannot be obtained.
[0128] The controller 11 controls the low-stage-side compressor 21,
the high-stage-side compressor 25, the injection expansion valve
73, the expansion valve 5a, the primary bypass expansion valve 5b,
the fan 4f, and other components on the basis of values detected by
the above-described intermediate-pressure temperature sensor 23T,
the high-stage intake pressure sensor 24P, the high-stage intake
temperature sensor 24T, the high-pressure pressure sensor 27P, the
high-pressure temperature sensor 27T, the low-pressure pressure
sensor 20P, the low-pressure temperature sensor 20T, and the
like.
(Air-Warming Circuit 60)
[0129] The air-warming circuit 60 circulates water as a secondary
refrigerant. The air-warming circuit 60 has a radiator 61, a branch
flow mechanism 62, an air-warming feed tube 65, an air-warming
return tube 66, an intermediate-pressure-side branching channel 67,
and a high-pressure-side branching channel 68. The branch flow
mechanism 62 includes an air-warming mixing valve 64 and an
air-warming pump 63. The radiator 61 is disposed in a space where
air warming will be performed, and warm water as the secondary
refrigerant flows therein, whereby the air of the target space is
warmed to perform air warming. A radiator temperature sensor 61T is
provided to the radiator 61 in order to detect the temperature of
the water for air warming flowing inside the radiator. Although not
shown in the drawings, the radiator 61 has a feed port for
receiving warm water sent from the air-warming pump 63 and a return
port for feeding out water releasing heat in the radiator 61 to the
intermediate-pressure-water heat exchanger 40 and the second
high-pressure-water heat exchanger 52. The air-warming return tube
66 connects the return port of the radiator 61 and an air-warming
branching point X. In the air-warming branching point X, the water
after releasing heat in the radiator 61 is branched to the
intermediate-pressure-side branching channel 67, which sends the
water to the intermediate-pressure-water heat exchanger 40 side,
and the high-pressure-side branching channel 68, which sends the
heated water to the second high-pressure-water heat exchanger 52.
An air-warming-return temperature sensor 66T is provided to the
air-warming-return tube 66 in order to detect the temperature of
the passing secondary refrigerant for air warming.
[0130] The intermediate-pressure-side branching channel 67 has a
first intermediate-pressure-side branching channel 67a, a second
intermediate-pressure-side branching channel 67b, and a third
intermediate-pressure-side branching channel 67c. The first
intermediate-pressure-side branching channel 67a connects the
branching point X and the upstream-side end section of the
intermediate-pressure-water heat exchanger 40 in the flow direction
of the water in the intermediate-pressure-side branching channel
67. The second intermediate-pressure-side branching channel 67b
passes through the interior of the intermediate-pressure-water heat
exchanger 40 while water for air warming as the secondary
refrigerant is allowed to flow therein so that there is no mixing
with the carbon dioxide as the primary refrigerant flowing through
the second intermediate-pressure tube 23b. Here, an opposing-flow
arrangement is used in the intermediate-pressure-water heat
exchanger 40 in which the carbon dioxide as the primary refrigerant
flowing through the second intermediate-pressure tube 23b and the
water for air warming as the secondary refrigerant flowing through
the second intermediate-pressure-side branching channel 67b flow in
mutually opposite directions. The third intermediate-pressure-side
branching channel 67c connects an air-warming merging point Y and
the downstream-side end section of the intermediate-pressure-water
heat exchanger 40 in the flow direction of the water in the
intermediate-pressure-side branching channel 67. An
intermediate-pressure-side branching channel temperature sensor 67T
is provided to the third intermediate-pressure-side branching
channel 67c in order to detect the temperature of the passing water
for air warming.
[0131] The high-pressure-side branching channel 68 has a first
high-pressure-side branching channel 68a, a second
high-pressure-side branching channel 68b, and a third
high-pressure-side branching channel 68c. The first
high-pressure-side branching channel 68a connects the air-warming
branching point X and the upstream-side end section of the second
high-pressure-water heat exchanger 52 in the flow direction of the
water in the high-pressure-side branching channel 68. The second
high-pressure-side branching channel 68b passes through the
interior of the second high-pressure-water heat exchanger 52 while
water for air warming as the secondary refrigerant is allowed to
flow therein so that there is no mixing with the carbon dioxide as
the primary refrigerant flowing through the fourth high-pressure
tube 27d. In the second high-pressure-water heat exchanger 52, an
opposing-flow arrangement is used in which the carbon dioxide as
the primary refrigerant flowing through the fourth high-pressure
tube 27d and the water for air warming as the secondary refrigerant
flowing through the second high-pressure-side branching channel 68b
flow in mutually opposite directions. The third high-pressure-side
branching channel 68c connects the air-warming merging point Y and
the downstream-side end section of the second high-pressure-water
heat exchanger 52 in the flow direction of the water in the
high-pressure-side branching channel 68. A high-pressure-side
branching channel temperature sensor 68T is provided to the third
high-pressure-side branching channel 68c in order to detect the
temperature of the passing water for air warming.
[0132] The temperature of the water for air warming that is flowing
through the first intermediate-pressure-side branching channel 67a
and the temperature of the water for air warming that is flowing
through the first high-pressure-side branching channel 68a have the
same temperature distribution because these waters for air warming
remain branched by the air-warming branching point X and there is
no interchange of heat with the exterior. In contrast, the
temperature of the water for air warming that flows through the
third intermediate-pressure-side branching channel 67c becomes a
temperature that corresponds to the heat amount obtained by heat
exchange with the primary refrigerant flowing through the second
intermediate-pressure tube 23b in the intermediate-pressure-water
heat exchanger 40. The temperature of the water for air warming
flowing through the third high-pressure-side branching channel 68c
becomes a temperature that corresponds to the heat amount obtained
by heat exchange with the primary refrigerant flowing through the
fourth high-pressure tube 27d in the second high-pressure-water
heat exchanger 52. Therefore, there are cases in which the
temperature of the water for air warming flowing through the third
intermediate-pressure-side branching channel 67c and the
temperature of the water for air warming flowing through the third
high-pressure-side branching channel 68c are different.
[0133] The air-warming feed tube 65 connects the air-warming
merging point Y and the feed port of the radiator 61. The
air-warming pump 63 for adjusting the flow rate of the water for
air warming that passes through the air-warming feed tube 65 is
provided at a midway point of the air-warming feed tube 65. The
air-warming mixing valve 64 is provided at the air-warming merging
point Y for merging the water for air warming that has passed
through the third intermediate-pressure-side branching channel 67c
and the water for air warming that has passed through the third
high-pressure-side branching channel 68c. The air-warming mixing
valve 64 adjusts the opening degree of the portion connected to the
third intermediate-pressure-side branching channel 67c side and the
opening degree of the portion connected to the third
high-pressure-side branching channel 68c side to thereby adjust the
ratio of the flow rate of the water for air warming flowing to the
intermediate-pressure-side branching channel 67 and the flow rate
of the water for air warming flowing to the third
high-pressure-side branching channel 68c.
[0134] The controller 11 controls the branch flow ratio in the
air-warming mixing valve 64 and the flow rate through the
air-warming pump 63 so that the secondary refrigerant having a
required temperature in the radiator 61 can be fed on the basis of,
among other things, the temperature detected by the above-described
radiator temperature sensor 61T, the intermediate-pressure-side
branching temperature sensor 67T, and the high-pressure-side
branching temperature sensor 68T.
(Hot-Water Supply Circuit 90)
[0135] The hot-water supply circuit 90 circulates water for
hot-water supply. The hot-water supply circuit 90 has a hot-water
storage tank 91, a water supply tube 94, a hot-water supply tube
98, a hot-water supply bypass tube 99, a hot-water supply mixing
valve 93, a hot-water supply heat pump tube 95, and a hot-water
supply pump 92.
[0136] Although not shown in the drawings, a circulation feed port
and a circulation return port are provided to the hot-water storage
tank 91. Normal-temperature water is fed into the hot-water storage
tank 91 from near the lower-end section of the hot-water storage
tank 91 via the water supply tube 94 after having passed through
external city water (not shown). The hot-water supply heat pump
tube 95 has a first hot-water supply heat pump tube 95a, a second
hot-water supply heat pump tube 95b, a third hot-water supply heat
pump tube 95c, a fourth hot-water supply heat pump tube 95d, a
fifth hot-water supply heat pump tube 95e, and a sixth hot-water
supply heat pump tube 95f.
[0137] The first hot-water supply heat pump tube 95a connects the
circulation feed port of the hot-water storage tank 91 and the
hot-water supply pump 92. A hot-water supply water-intake
temperature sensor 94T is provided to the first hot-water supply
heat pump tube 95a in order to detect the temperature of the
passing water for hot-water supply. The second hot-water supply
heat pump tube 95b connects the hot-water supply pump 92 and the
upstream-side end section of the third high-pressure-water heat
exchanger 53 in the flow direction of the water in the hot-water
supply heat pump tube 95. The third hot-water supply heat pump tube
95c passes through the interior of the third high-pressure-water
heat exchanger 53 while water for hot-water supply is allowed to
flow therein so that there is no mixing with the carbon dioxide as
the primary refrigerant flowing through the sixth high-pressure
tube 27f. Here, an opposing-flow arrangement is used in the third
high-pressure-water heat exchanger 53 in which the carbon dioxide
as the primary refrigerant flowing through the sixth high-pressure
tube 27f and the water for hot-water supply flowing through the
third hot-water supply heat pump tube 95c flow in mutually opposite
directions. The fourth hot-water supply heat pump tube 95d connects
the downstream-side end section of the third high-pressure-water
heat exchanger 53 in the flow direction of the water in the
hot-water supply heat pump tube 95, and the upstream-side end
section of the first high-pressure water heat exchanger 51 in the
flow direction of the water in the hot-water supply heat pump tube
95. A hot-water supply intermediate temperature sensor 95T for
detecting the temperature of the passing water for hot-water supply
is provided in the fourth hot-water supply heat pump tube 95d. Heat
exchange is not performed in the second high-pressure-water heat
exchanger 52 between the water for hot-water supply and the carbon
dioxide as the primary refrigerant. The fifth hot-water supply heat
pump tube 95e passes through the interior of the first
high-pressure water heat exchanger 51 while water for hot-water
supply is allowed to flow therein so that there is no mixing with
the carbon dioxide as the primary refrigerant flowing through the
second high-pressure tube 27b. Here, an opposing-flow arrangement
is used in the first high-pressure water heat exchanger 51 in which
the carbon dioxide as the primary refrigerant flowing through the
second high-pressure tube 27b and the water for hot-water supply
flowing through the fifth hot-water supply heat pump tube 95eflow
in mutually opposite directions. The sixth hot-water supply heat
pump tube 95f connects the circulation return port of the hot-water
storage tank 91 and the downstream-side end section of the first
high-pressure water heat exchanger 51 in the flow direction of the
water in the hot-water supply heat pump tube 95. A hot-water supply
hot-water outlet temperature sensor 98T is provided to the sixth
hot-water supply heat pump tube 95f in order to detect the
temperature of the passing water for hot-water supply.
[0138] The hot-water supply tube 98 directs hot water accumulated
in the hot-water storage tank 91 from the vicinity of the
upstream-side end section of the hot-water storage tank 91 to a
location (not shown) in which the hot water is to be used. The
water supply tube 94 is provided with a water supply branching
point W, which is a branching portion for branching from the flow
that moves toward the hot-water storage tank 91 side. The hot-water
supply tube 98 is provided with a hot-water supply merging point Z
for merging with the flow that moves from the hot-water storage
tank 91 toward a location in which the hot water is to be used. The
hot-water supply bypass tube 99 connects the water supply branching
point W and the hot-water supply merging point Z. The hot-water
supply mixing valve 93 is provided at the hot-water supply merging
point Z and is capable of adjusting the mixing ratio of the hot
water sent from the hot-water storage tank 91 via the hot-water
supply tube 98 and the normal-temperature water fed from city water
via the hot-water supply bypass tube 99. The mixing ratio in the
hot-water supply mixing valve 93 is adjusted to thereby adjust the
temperature of the water sent to the location in which it is to be
used.
[0139] The controller 11 controls the flow rate through the
hot-water supply pump 92 on the basis of the temperatures and the
like detected by the above-described hot-water supply water-intake
temperature sensor 94T, the hot-water supply intermediate
temperature sensor 95T, the hot-water supply hot-water outlet
temperature sensor 98T, and the like.
<1-2> Operation of the Heat Pump Circuit 10
[0140] FIG. 2 is a pressure-enthalpy graph of the case in which the
heat pump system 1 is operated. FIG. 3 is a temperature-entropy
graph of the case in which the heat pump system 1 is operated.
[0141] The state of temperature distribution of the primary
refrigerant is described below using a specific example.
[0142] The low-stage-side compressor 21 compresses (point B) the
primary refrigerant (point A) at about 22.degree. C. flowing from
the low-pressure tube 20, so that the target discharge temperature
reaches about 90.degree. C. The pressure of the primary refrigerant
flowing through the low-pressure tube 20 is adjusted by the
controller 11 so as to become a reduced pressure (evaporative
pressure) capable of causing the carbon dioxide as the primary
refrigerant to evaporate using the ambient temperature in the
location where the evaporator 4 is disposed.
[0143] The primary refrigerant discharged from the low-stage-side
compressor 21 flows into the second intermediate-pressure tube 23b
inside the intermediate-pressure-water heat exchanger 40 via the
first intermediate-pressure tube 23a. The primary refrigerant which
has flowed into the intermediate-pressure-water heat exchanger 40
is cooled (point C) to about 35.degree. C. by heat exchange with
the water as secondary refrigerant for air warming which is passing
through the second intermediate-pressure-side branching channel
67b. Here, the primary refrigerant and the secondary refrigerant in
the intermediate-pressure-water heat exchanger 40 are flowing in an
opposing-flow arrangement, and the primary refrigerant is therefore
effectively cooled by the secondary refrigerant, which is in a
state cooled to about 30.degree. C. by heat release in the radiator
61, in the vicinity of the outlet of the second
intermediate-pressure tube 23b inside the
intermediate-pressure-water heat exchanger 40.
[0144] The primary refrigerant which has passed through the
intermediate-pressure-water heat exchanger 40 is further cooled to
about 30.degree. C. at the injection merging point D of the third
intermediate-pressure tube 23c by merging with the primary
refrigerant at about 27.degree. C. flowing in via the injection
channel 70. Here, the controller 11 performs a control such that to
achieves the primary refrigerant merged at the injection merging
point D has a degree of superheat or a supercritical state.
Furthermore, at this point, the controller 11 performs a control so
that the target temperature of the primary refrigerant discharged
from the high-stage-side compressor 25 is brought to 90.degree. C.,
which is the same as the target temperature of the primary
refrigerant discharged from the low-stage-side compressor 21, while
the high-stage-side compressor 25 is driven with the primary
refrigerant merged in the injection merging point D being at the
same compression ratio as the compression ratio in the
low-stage-side compressor 21. The controller 11 performs a control
so as to adjust the heat balance in the intermediate-pressure-water
heat exchanger 40 and the injection channel 70 in relation to the
primary refrigerant to be taken into the high-stage-side compressor
25.
[0145] The primary refrigerant merged in the injection merging
point D is taken into the high-stage-side compressor 25, and the
primary refrigerant is further compressed so that the target
discharge temperature reaches about 90.degree. C., which is the
same temperature as the target temperature of the discharge
refrigerant of the low-stage-side compressor 21. At this point, the
high-stage-side compressor 25 is controlled by the controller 11 so
as to compress the primary refrigerant and bring the discharge
refrigerant pressure to a pressure that exceeds the critical
pressure of the primary refrigerant (point E).
[0146] The primary refrigerant discharged by the high-stage-side
compressor 25 flows into the second high-pressure tube 27b inside
the first high-pressure water heat exchanger 51 via the first
high-pressure tube 27a. The primary refrigerant that has flowed
into the first high-pressure water heat exchanger 51 undergoes heat
exchange with the water for hot-water supply passing through the
fifth hot-water supply heat pump tube 95e and is thereby cooled to
about 85.degree. C. (point F). The temperature continuously changes
because the primary refrigerant releases heat while being kept in a
state of having exceeded critical pressure. Here, the primary
refrigerant and the secondary refrigerant in the first
high-pressure water heat exchanger 51 are flowing in an
opposing-flow arrangement, and the primary refrigerant is therefore
effectively cooled by the water for hot-water supply, which is at
about 30.degree. C. and not yet sufficiently heated, in the
vicinity of the outlet of the second high-pressure tube 27b inside
the first high-pressure water heat exchanger 51.
[0147] The primary refrigerant which has passed through the first
high-pressure water heat exchanger 51 flows into the fourth
high-pressure tube 27d inside the second high-pressure-water heat
exchanger 52 via the third high-pressure tube 27c. The primary
refrigerant which has flowed into the second high-pressure-water
heat exchanger 52 is cooled to about 35.degree. C. (point G) by
undergoing heat exchange with the water as the secondary
refrigerant for air warming that is passed through the second
high-pressure-side branching channel 68b. Here, the primary
refrigerant and the secondary refrigerant in the second
high-pressure-water heat exchanger 52 are flowing in an
opposing-flow arrangement, and the primary refrigerant is therefore
effectively cooled by the secondary refrigerant, which is in a
cooled state of about 30.degree. C. having released heat in the
radiator 61, in the vicinity of the outlet of the fourth
high-pressure tube 27d inside the second high-pressure-water heat
exchanger 52.
[0148] The primary refrigerant which has passed through the second
high-pressure-water heat exchanger 52 flows into the sixth
high-pressure tube 27f inside the third high-pressure-water heat
exchanger 53 via the fifth high-pressure tube 27e. The primary
refrigerant which has flowed into the third high-pressure-water
heat exchanger 53 undergoes heat exchange with the water for
hot-water supply that is passing through the third hot-water supply
heat pump tube 95c and is further cooled to about 30.degree. C.
(point H). Here, the primary refrigerant and the secondary
refrigerant in the third high-pressure-water heat exchanger 53 are
flowing in an opposing flow arrangement, and the primary
refrigerant is therefore effectively cooled by the water for
hot-water supply at about 20.degree. C., which is slightly
increased from the temperature of the municipal water due to mixing
in the hot-water storage tank 91, in the vicinity of the outlet of
the sixth high-pressure tube 27f inside the third
high-pressure-water heat exchanger 53. The primary refrigerant
which has passed through the third high-pressure-water heat
exchanger 53 reaches the third high-pressure point H via the
seventh high-pressure tube 27g.
[0149] Here, the high-pressure water heat exchanger 50 is divided
into three heat exchangers, and temperature changes occur in the
heat release process because the primary refrigerant flowing
through the high-pressure water heat exchanger 50 is in a
supercritical state, and the range of temperature variation
(30.degree. C. to 65.degree. C.) of the water as the secondary
refrigerant circulating through the air-warming circuit 60 is
included in the range of temperature variation (20.degree. C. to
90.degree. C.) of the water for hot-water supply in the hot-water
supply circuit 90. Heat exchange with the primary refrigerant in a
relatively low-temperature state and heat exchange with the primary
refrigerant in a relatively high-temperature state among the
primary refrigerant discharged from the high-stage-side compressor
25 is used for heat exchange for hot-water supply, and the heat
exchange with the primary refrigerant in an
intermediate-temperature state is used for heat exchange with the
secondary refrigerant for air warming so as to adapt to this
temperature distribution. It is thereby possible to improve heat
exchange efficiency because the temperature difference between the
fluids for carrying out heat exchange can be minimized in not only
heat exchange between the primary refrigerant and the water for
hot-water supply, but also in heat exchange between the primary
refrigerant and the water for air warming.
[0150] The primary refrigerant which has reached the third
high-pressure point H is branched into a flow that moves toward the
expansion valve 5a side via the eighth high-pressure tube 27h and a
flow that moves toward the injection channel 70 side. The amount of
branching at this point is controlled by the controller 11 by
adjusting the opening degree of the injection expansion valve 73.
The primary refrigerant branched to the injection channel 70 side
passes through the first injection tube 72 and is depressurized in
the injection expansion valve 73; and the temperature of the
primary refrigerant is reduced to about 23.degree. C. (point
Q).
[0151] The primary refrigerant depressurized in the injection
expansion valve 73 flows into the third injection tube 75 inside
the economizer heat exchanger 7 via the second injection tube 74.
The primary refrigerant which has flowed into the economizer heat
exchanger 7 undergoes heat exchange with the primary refrigerant
flowing through the ninth high-pressure tube 27i at about
30.degree. C. and is heated to about 27.degree. C. (point R).
[0152] The primary refrigerant at about 27.degree. C. that has
passed through the third injection tube 75 inside the economizer
heat exchanger 7 merges with the primary refrigerant flowing
through the intermediate-pressure tube 23 at the above-described
injection merging point D via the fourth injection tube 76.
[0153] Of the primary refrigerant that has arrived at the third
high-pressure point H, the primary refrigerant at about 30.degree.
C. which has not flowed to the injection channel 70 side flows into
the ninth high-pressure tube 27i inside the economizer heat
exchanger 7 via the eighth high-pressure tube 27h. The primary
refrigerant at about 30.degree. C. which has flowed into the ninth
high-pressure tube 27i inside the economizer heat exchanger 7
undergoes heat exchange with the primary refrigerant at about
27.degree. C. that is flowing through the third injection tube 75,
as described above, and is thereby further cooled to about
25.degree. C. (point I). The primary refrigerant which has passed
through the ninth high-pressure tube 27i inside the economizer heat
exchanger 7 arrives at the fourth high-pressure point I via the
tenth high-pressure tube 27j.
[0154] The primary refrigerant which has reached the fourth
high-pressure point I is branched into a flow that moves toward the
primary bypass 80 side and a flow that moves toward the eleventh
high-pressure tube 27k side. The amount of branching at this point
is adjusted by the controller 11 which controls the opening degree
of the primary bypass expansion valve 5b. The primary refrigerant
that has flowed through the eleventh high-pressure tube 27k flows
into the twelfth high-pressure tube 27l inside the
primary-refrigerant-to-primary-refrigerant heat exchanger 8. The
primary refrigerant at about 25.degree. C. having flowed into the
twelfth high-pressure tube 27l inside the
primary-refrigerant-to-primary-refrigerant heat exchanger 8
undergoes heat exchange with the primary refrigerant at about
-3.degree. C. that flows through the fourth low-pressure tube 20d
and is cooled to about 20.degree. C. (point J).
[0155] The primary refrigerant that has passed through the twelfth
high-pressure tube 27l inside the
primary-refrigerant-to-primary-refrigerant heat exchanger 8 flows
to the expansion valve 5a via the thirteenth high-pressure tube
27m. In the expansion valve 5a, the opening degree is adjusted by
the controller 11, whereby the amount of depressurization of the
passing primary refrigerant is adjusted, the refrigerant pressure
of the primary refrigerant that has passed by is reduced, and the
refrigerant temperature is also reduced to about -3.degree. C.
(point K). Here, the amount of depressurization of the primary
refrigerant is adjusted by the controller 11, whereby the pressure
is reduced to a pressure that is equal to or less than the critical
pressure to achieve a gas-liquid two-phase state.
[0156] In the heat pump circuit 10, not only can the primary
refrigerant be cooled by the economizer heat exchanger 7; it can
also be further cooled by the
primary-refrigerant-to-primary-refrigerant heat exchanger 8. In the
heat pump circuit 10 it is possible to use the primary refrigerant
of the intake side of the low-stage-side compressor 21 through
which primary refrigerant at the lowest temperature flows in the
cooling of the primary refrigerant flowing through the
primary-refrigerant-to-primary-refrigerant heat exchanger 8. The
density of the primary refrigerant passing through the expansion
valve 5a can thereby be increased, and the circulation amount of
the primary refrigerant in the heat pump circuit 10 can be
increased.
[0157] The primary refrigerant that has passed through the
expansion valve 5a flows to the third low-pressure point M via the
first low-pressure tube 20a and merges with the primary refrigerant
flowing in through the sixth low-pressure tube 20f (point M).
[0158] Of the primary refrigerant that has arrived at the fourth
high-pressure point I, the primary refrigerant at about 25.degree.
C. which has not flowed to the eleventh high-pressure tube 27k side
flows to the primary bypass 80 side and flows to the primary bypass
expansion valve 5b via the fourteenth high-pressure tube 27n. The
opening degree of the primary bypass expansion valve 5b is adjusted
by the controller 11, whereby the amount of depressurization of the
primary refrigerant passing through is adjusted, the refrigerant
pressure of the primary refrigerant that has passed through is
reduced, and the refrigerant temperature is also reduced to about
-3.degree. C. (point L). In this case as well, the amount of
depressurization of the primary refrigerant is adjusted by the
controller 11 in similar fashion to point K, whereby the pressure
is reduced to a pressure that is equal to or less than the critical
pressure to achieve a gas-liquid two-phase state.
[0159] The primary refrigerant that has passed through the primary
bypass expansion valve 5b flows to the third low-pressure point M
via the sixth low-pressure tube 20f and merges with the primary
refrigerant that has flowed in via the first low-pressure tube 20a
described above (point M).
[0160] The primary refrigerant at about -3.degree. C. which has
merged at the third low-pressure point M flows into the evaporator
4 via the second low-pressure tube 20b. The primary refrigerant
which has flowed into the evaporator 4 undergoes heat exchange with
air actively fed by the fan 4f to the evaporator 4. The primary
refrigerant at about -3.degree. C. in a gas-liquid two-phase state
evaporates while the temperature is kept constant by heat exchange
in the evaporator 4 (latent heat variation) to increase dryness and
to achieve a nearly saturated state (point N).
[0161] The primary refrigerant that has passed through the
evaporator 4 flows into the fourth low-pressure tube 20d inside the
primary-refrigerant-to-primary-refrigerant heat exchanger 8 via the
third low-pressure tube 20c . The primary refrigerant at about
-3.degree. C. which flows through the fourth low-pressure tube 20d
of the primary-refrigerant-to-primary-refrigerant heat exchanger 8
undergoes heat exchange with the primary refrigerant at about
25.degree. C. that flows through the twelfth high-pressure tube
27l, as described above, and is thereby heated to about 22.degree.
C. to achieve a state with a degree of superheat (point A).
[0162] The primary refrigerant which has passed through the fourth
low-pressure tube 20d inside the
primary-refrigerant-to-primary-refrigerant heat exchanger 8 becomes
superheated state and is taken into the low-stage-side compressor
21.
[0163] The primary refrigerant circulates in the heat pump circuit
10 in the manner described above.
<1-3> Operation of the Air-Warming Circuit 60
[0164] The controller 11 performs a control so that water as the
secondary refrigerant at about 65.degree. C. is fed to the radiator
61 in order to warm the space in which the radiator 61 is
disposed.
[0165] The state of temperature distribution of the secondary
refrigerant for air warming is described below using a specific
example.
[0166] The water as the secondary refrigerant for air warming which
released heat while passing through the interior of the radiator 61
falls to a temperature of about 35.degree. C. (although this
depends on the performance of the radiator 61 and level of the
air-warming load) and flows to the air-warming branching point X
via the air-warming-return tube 66.
[0167] The flow toward the intermediate-pressure-side branching
channel 67 and the flow toward the high-pressure-side branching
channel 68 side are branching at the air-warming branching point
X.
[0168] The secondary refrigerant which has flowed from the
air-warming branching point X toward the intermediate-pressure-side
branching channel 67 side flows into the second
intermediate-pressure-side branching channel 67b inside the
intermediate-pressure-water heat exchanger 40 via the first
intermediate-pressure-side branching channel 67a. The secondary
refrigerant flowing through the second intermediate-pressure-side
branching channel 67b inside the intermediate-pressure-water heat
exchanger 40 is heated by the primary refrigerant passing through
the second intermediate-pressure tube 23b, as described above,
whereby the temperature of the secondary refrigerant at about
30.degree. C. is increased to about 65.degree. C. As described
above, the primary refrigerant and the secondary refrigerant in the
intermediate-pressure-water heat exchanger 40 are flowing in an
opposing-flow arrangement, and the secondary refrigerant is
therefore effectively heated by the primary refrigerant at about
90.degree. C., which is a relatively high temperature, in the
vicinity of the outlet of the second intermediate-pressure-side
branching channel 67b inside the intermediate-pressure-water heat
exchanger 40. The secondary refrigerant which passed through the
second intermediate-pressure-side branching channel 67b inside the
intermediate-pressure-water heat exchanger 40 and was warmed to
about 65.degree. C. passes through the third
intermediate-pressure-side branching channel 67c and flows to the
air-warming merging point Y.
[0169] The secondary refrigerant that flows from the air-warming
branching point X toward the high-pressure-side branching channel
68 side flows into the second high-pressure-side branching channel
68b inside the second high-pressure-water heat exchanger 52 by way
of the first high-pressure-side branching channel 68a. The
secondary refrigerant flowing through the second high-pressure-side
branching channel 68b inside the second high-pressure-water heat
exchanger 52 is heated by the primary refrigerant passing through
the fourth high-pressure tube 27d, as described above, whereby the
temperature of the secondary refrigerant at about 30.degree. C. is
increased to about 65.degree. C. As described above, the primary
refrigerant and the secondary refrigerant in the second
high-pressure-water heat exchanger 52 are flowing in an
opposing-flow arrangement, and the secondary refrigerant is
therefore effectively heated by the primary refrigerant at about
85.degree. C., which is a relatively high temperature, in the
vicinity of the outlet of the second high-pressure-side branching
channel 68b inside the second high-pressure-water heat exchanger
52. The secondary refrigerant which passed through the second
high-pressure-side branching channel 68b inside the second
high-pressure-water heat exchanger 52 and was warmed to about
65.degree. C. passes through the third high-pressure-side branching
channel 68c and flows to the air-warming merging point Y
[0170] The secondary refrigerant which has passed through the third
intermediate-pressure-side branching channel 67c and the secondary
refrigerant which has passed through the third high-pressure-side
branching channel 68c are merged at the air-warming merging point
Y. The controller 11 adjusts the opening degree of the
intermediate-pressure-side branching channel 67 side of the
air-warming mixing valve 64t and the opening degree of the
high-pressure-side branching channel 68 side of the air-warming
mixing valve 64 to thereby adjust the flow rate of the secondary
refrigerant flowing through the intermediate-pressure-side
branching channel 67 side and the flow rate of the secondary
refrigerant flowing through the high-pressure-side branching
channel 68 side. The controller 11 can thereby perform a control so
that the temperature of the secondary refrigerant merged in the
air-warming merging point Y becomes the temperature requested in
the radiator 61, by adjusting the flow rate of the secondary
refrigerant that passes through the air-warming pump 63 while
adjusting the ratio of the amount by which the secondary
refrigerant circulating through the air-warming circuit 60 is
heated in the intermediate-pressure-water heat exchanger 40 side
and the amount by which the secondary refrigerant is heated in the
second high-pressure-water heat exchanger 52 side.
[0171] In this manner, the secondary refrigerant merged at the
air-warming merging point Y and heated to about 65.degree. C. is
fed to the radiator 61 via the air-warming feed tube 65. The
secondary refrigerant circulates in the air-warming circuit 60 in
the manner described above.
<1-4> Operation of the Hot-Water Supply Circuit 90
[0172] The controller 11 controls the flow rate of the hot-water
supply pump 92 so that hot water at about 90.degree. C. can be
stored in the hot-water storage tank 91.
[0173] The state of temperature distribution of the water for
hot-water supply is described below using a specific example.
[0174] Water including inflowing city water at a relatively low
temperature in the lower part of the hot-water storage tank 91
flows toward the hot-water supply heat pump tube 95 at a
temperature of about 20.degree. C.
[0175] Water for hot-water supply at about 20.degree. C. which has
passed through the first hot-water supply heat pump tube 95a and
the second hot-water supply heat pump tube 95b flows into the third
hot-water supply heat pump tube 95c inside the third
high-pressure-water heat exchanger 53. The water for hot-water
supply that flows through the third hot-water supply heat pump tube
95c inside the third high-pressure-water heat exchanger 53 is
heated by the primary refrigerant at about 35.degree. C. that
passes through the sixth high-pressure tube 27f inside the third
high-pressure-water heat exchanger 53, as described above, whereby
the temperature of the water for hot-water supply at about
20.degree. C. is increased to about 30.degree. C. As described
above, an opposing-flow arrangement is used in the third
high-pressure-water heat exchanger 53 in which the primary
refrigerant and the secondary refrigerant flow in mutually opposite
directions, and the secondary refrigerant is thereby effectively
heated by the primary refrigerant at about 35.degree. C., which is
a relatively high temperature, in the vicinity of the outlet of the
third hot-water supply heat pump tube 95c inside the third
high-pressure-water heat exchanger 53.
[0176] The water for hot-water supply warmed to about 30.degree. C.
in the third high-pressure-water heat exchanger 53 flows through
the fourth hot-water supply heat pump tube 95d into the fifth
hot-water supply heat pump tube 95e inside the first high-pressure
water heat exchanger 51. The water for hot-water supply flowing
through the fifth hot-water supply heat pump tube 95e inside the
first high-pressure water heat exchanger 51 is heated by the
primary refrigerant at about 90.degree. C. passing through the
second high-pressure tube 27b inside the first high-pressure water
heat exchanger 51, as described above, whereby the temperature of
the water for hot-water supply at about 30.degree. C. is increased
to about 90.degree. C. As described above, the primary refrigerant
and the secondary refrigerant in the first high-pressure water heat
exchanger 51 are flowing in an opposing-flow arrangement, and the
secondary refrigerant is therefore effectively heated by the
primary refrigerant at about 90.degree. C., which is a relatively
high temperature, in the vicinity of the outlet of the fifth
hot-water supply heat pump tube 95e inside the first high-pressure
water heat exchanger 51.
[0177] The water for hot-water supply heated to about 90.degree. C.
in the first high-pressure water heat exchanger 51 flows through
the sixth hot-water supply heat pump tube 95f to the upper part of
the hot-water storage tank 91.
[0178] In this manner, water for hot-water supply circulates
through the hot-water supply circuit 90, whereby the temperature of
the water for hot-water supply stored inside the hot-water storage
tank 91 can be increased.
<1-5> Secondary Refrigerant-Temperature Equalization
Control
[0179] As described above, the controller 11 operates the heat pump
circuit 10 so that cycle efficiency can be kept as optimal as
possible while making it possible to feed to each of the circuits a
heat amount that can adapt to not only the air warming load of the
air-warming circuit 60, but also to the hot-water supply load of
the hot-water supply circuit 90. Specifically, in relation to the
air-warming circuit 60, the controller 11 controls the
low-stage-side compressor 21, the high-stage-side compressor 25,
the expansion valve 5a, and the like so that the temperature of the
primary refrigerant flowing into the intermediate-pressure-water
heat exchanger 40 and the temperature of the primary refrigerant
flowing into the second high-pressure-water heat exchanger 52 are
both higher temperatures than the temperature required in the
radiator 61, while the temperature of the primary refrigerant
flowing into the intermediate-pressure-water heat exchanger 40 is
made to be a higher temperature than the temperature of the
secondary refrigerant for air warming that flows into the
intermediate-pressure-water heat exchanger 40, and while the
temperature of the primary refrigerant flowing into the second
high-pressure-water heat exchanger 52 is made to be a higher
temperature than the temperature of the secondary refrigerant for
air warming that flows into the second high-pressure-water heat
exchanger 52.
[0180] The controller 11 performs a control so that the temperature
obtained after the heat released during passage through the first
high-pressure water heat exchanger 51 has been subtracted from the
target discharge temperature of the high-stage-side compressor 25
becomes greater than the temperature requested by the radiator 61,
while the target discharge temperature of the low-stage-side
compressor 21 is made to be greater than the temperature requested
by the radiator 61. Also, the controller 11 performs a control so
that the compression ratio of the low-stage-side compressor 21 and
the compression ratio of the high-stage-side compressor 25 are
equal and are made as low as possible with the evaporation
temperature having been established based on the installation
environment of the evaporator 4. In order to achieve these objects,
the controller 11 specifically controls the low-stage-side
compressor 21, the high-stage-side compressor 25, the expansion
valve 5a, the injection expansion valve 73, the primary bypass
expansion valve 5b, and the fan 4f of the heat pump circuit 10. The
temperature of the primary refrigerant is controlled by the
controller 11 so as to be equal to or less than a predetermined
high-temperature limit value because when the temperature of the
primary refrigerant is excessively high, scale (scale or the like)
is liable to form on the inner surface of the tubes through which
flows the secondary refrigerant for air warming performing heat
exchange and/or the inner surfaces of the tubes of the water for
hot-water supply performing heat exchange.
[0181] The controller 11 performs secondary refrigerant-temperature
equalization control so that the temperature of the secondary
refrigerant flowing through the third intermediate-pressure-side
branching channel 67c of the air-warming circuit 60 and the
temperature of the secondary refrigerant flowing through third
high-pressure-side branching channel 68c become the same
temperature, while making it possible to maintain to the extent
possible an operating state having optimal cycle efficiency in the
heat pump circuit 10 side described above. The controller 11 not
only merely performs a control so that the temperature of the
secondary refrigerant flowing through the third
intermediate-pressure-side branching channel 67c and the
temperature of the secondary refrigerant flowing through the third
high-pressure-side branching channel 68c are equalized, but also
performs a control so that the equalized temperature matches the
temperature requested by the radiator 61. The controller 11
specifically controls to thereby bring the temperature into
conformity with the temperature requested by the radiator 61, by
performing: mixing-ratio control for controlling the mixing ratio
of the air warming mixing value 64 to thereby adjust the ratio of
the flow rate of the secondary refrigerant for air warming flowing
through the intermediate-pressure-side branching channel 67 and the
flow rate of the secondary refrigerant for air warming flowing
through the high-pressure-side branching channel 68; and flow-rate
control for controlling the flow rate through the air-warming pump
63 to adjust the flow rate of the secondary refrigerant for air
warming fed to the radiator 61.
[0182] In order to set the temperature of the secondary refrigerant
for air warming flowing through the third
intermediate-pressure-side branching channel 67c and the
temperature of the secondary refrigerant for air warming flowing
through the third high-pressure-side branching channel 68c to the
same temperature, the controller 11 controls the air-warming mixing
valve 64 so that the flow rate of the secondary refrigerant having
a lower temperature is reduced and the flow rate of the secondary
refrigerant having a higher temperature is increased on the basis
of the temperature detected by the intermediate-pressure-side
branching temperature sensor 67T and the temperature detected by
the high-pressure-side branching temperature sensor 68T. The flow
speed of the secondary refrigerant having a lower temperature is
thereby reduced when the flow rate is reduced, and the time for the
secondary refrigerant to receive heat from the primary refrigerant
in the heat exchange with the primary refrigerant can be extended,
and the temperature is increased as a result. Conversely, the flow
speed of the secondary refrigerant having a higher temperature is
thereby increased when the flow rate is increased, and the time for
the secondary refrigerant to receive heat from the primary
refrigerant in the heat exchange with the primary refrigerant can
be shortened, and the temperature is reduced as a result. In this
manner, the difference between the temperature of the secondary
refrigerant for air warming flowing through the third
intermediate-pressure-side branching channel 67c and the
temperature of the secondary refrigerant for air warming flowing
through the third high-pressure-side branching channel 68c is
reduced.
[0183] As used herein, the temperature requested by the radiator 61
is the value of a temperature having a constant width, which is
described below.
[0184] In the air-warming circuit 60, the required heat release
amount in the radiator 61 by the secondary refrigerant for air
warming can be set by input by the user. The controller 11 controls
the air-warming mixing valve 64 and the air-warming pump 63 so as
to ensure the heat release amount in the radiator 61 requested by
the user. Specifically, control for ensuring the heat release
amount requested by the radiator 61 includes the case in which the
temperature of the secondary refrigerant for air warming is kept
low while the flow rate of the secondary refrigerant for air
warming passing through the air-warming pump 63 is increased, the
case in which the temperature of the secondary refrigerant for air
warming is set high while the flow rate of the secondary
refrigerant for air warming passing through the air-warming pump 63
is reduced, and other cases. In other words, in the case that the
same heat amount is to be ensured, the temperature required as the
temperature of the secondary refrigerant for air warming in the
case that the flow rate through the air-warming pump 63 has been
increased to a designated value is a lower temperature than the
temperature required as the temperature of the secondary
refrigerant for air warming in the case that the flow rate of
through the air-warming pump 63 has been made less than the
designated value. Conversely, in the case that the same heat amount
is to be ensured, the temperature required as the temperature of
the secondary refrigerant for air warming in the case that the flow
rate through the air-warming pump 63 has been reduced to another
value is a higher temperature than the temperature required as the
temperature of the secondary refrigerant for air warming in the
case that the flow rate has been increased above the other value.
Furthermore, the temperature of the secondary refrigerant fed to
the radiator 61 must be a higher temperature than the ambient
temperature of the radiator 61 (the temperature detected by the
radiator temperature sensor 61T) because an object is to warm the
air of the surrounding space in which the radiator 61 is disposed.
The temperature requested by the radiator 61 is a higher
temperature than that detected by the radiator temperature sensor
61T and has a temperature width that corresponds to a flow rate
range capable of ensuring the heat release amount requested by the
radiator 61. It is furthermore possible to cause the heat release
performance of the radiator 61 itself to be reflected to limit the
temperature width.
[0185] The temperature of the secondary refrigerant for air warming
flowing through the air-warming feed tube 65 toward the radiator 61
is the temperature obtained after the merging of the secondary
refrigerant for air warming that has flowed in through the
intermediate-pressure-side branching channel 67 and the secondary
refrigerant for air warming that has flowed in through the
high-pressure-side branching channel 68 in the air-warming merging
point Y.
[0186] Therefore, in the case that the temperature of the secondary
refrigerant flowing through the third intermediate-pressure-side
branching channel 67c and the temperature of the secondary
refrigerant flowing through the third high-pressure-side branching
channel 68c are the same temperature, the temperature of the
secondary refrigerant after merging in the air-warming merging
point Y is the same temperature as that prior to merging, and is
the temperature of the secondary refrigerant for air warming fed
toward the radiator 61.
(Processing for Increasing the Heat Amount)
[0187] In the case that the secondary refrigerant-temperature
equalization control described above is performed and the
temperature equalized by the secondary refrigerant-temperature
equalization control are lower than the temperature requested by
the radiator 61, the controller 11 performs a control for reducing
the flow rate through air-warming pump 63 in order to increase the
heat amount.
[0188] The flow speed of the secondary refrigerant flowing through
the intermediate-pressure-side branching channel 67 and the flow
speed of the secondary refrigerant flowing through the
high-pressure-side branching channel 68 can both be reduced
thereby. As a result, the time available for the secondary
refrigerant flowing through the intermediate-pressure-side
branching channel 67 to receive heat from the primary refrigerant
and the time for the secondary refrigerant flowing through the
high-pressure-side branching channel 68 to receive heat from the
primary refrigerant can both be extended. The temperature of the
secondary refrigerant for air warming flowing through the third
intermediate-pressure-side branching channel 67c and the
temperature of the secondary refrigerant for air warming flowing
through the third high-pressure-side branching channel 68c can be
equalized thereby at the temperature requested by the radiator 61,
and it is possible to adapt to the heat load in the radiator
61.
(Processing for Reducing the Heat Amount)
[0189] In the case that the secondary refrigerant-temperature
equalization control described above is performed and the
temperature equalized by the secondary refrigerant-temperature
equalization control exceed the temperature requested by the
radiator 61, the controller 11 performs a control for increasing
the flow rate through air-warming pump 63 in order to reduce the
heat amount.
[0190] The flow speed of the secondary refrigerant flowing through
the intermediate-pressure-side branching channel 67 and the flow
speed of the secondary refrigerant flowing through the
high-pressure-side branching channel 68 can both be increased
thereby. As a result, the time available for the secondary
refrigerant flowing through the intermediate-pressure-side
branching channel 67 to receive heat from the primary refrigerant
and the time for the secondary refrigerant flowing through the
high-pressure-side branching channel 68 to receive heat from the
primary refrigerant can both be shortened. The temperature of the
secondary refrigerant for air warming flowing through the third
intermediate-pressure-side branching channel 67c and the
temperature of the secondary refrigerant for air warming flowing
through the third high-pressure-side branching channel 68c can be
equalized thereby at the temperature requested by the radiator 61,
and it is possible to adapt to the heat load in the radiator
61.
<1-6> Characteristics of the First Embodiment
[0191] In the heat pump system 1 of the first embodiment, the
controller 11 performs a control so that the temperature of the
secondary refrigerant flowing through the third
intermediate-pressure-side branching channel 67c and the
temperature of the secondary refrigerant flowing through the third
high-pressure-side branching channel 68c are equalized. Here, the
secondary refrigerant flowing through the third
intermediate-pressure-side branching channel 67c and the secondary
refrigerant flowing through the third high-pressure-side branching
channel 68c both release heat to the lower temperature surroundings
and undergo heat loss before arriving at the radiator 61. However,
in the heat pump system 1 of the first embodiment, the temperature
of the secondary refrigerant flowing through the third
intermediate-pressure-side branching channel 67c as well as the
temperature of the secondary refrigerant flowing through the third
high-pressure-side branching channel 68c can be set to temperature
that is not excessively high, and it is possible to minimize the
difference from the ambient temperature. Therefore, it is possible
to minimize heat loss to the surroundings in relation to the
temperature of the secondary refrigerant flowing through the third
intermediate-pressure-side branching channel 67c as well as the
temperature of the secondary refrigerant flowing through the third
high-pressure-side branching channel 68c.
[0192] The controller 11 furthermore performs a control so that the
temperature of the secondary refrigerant flowing through the third
intermediate-pressure-side branching channel 67c and the
temperature of the secondary refrigerant flowing through the third
high-pressure-side branching channel 68c are equalized with the
temperature requested by the radiator 61. Therefore, the
temperature does not need to be adjusted by heating or cooling so
that the temperature of the secondary refrigerant for air warming
that has merged at the air-warming merging point Y becomes the
temperature requested by the radiator 61. It is thereby possible to
dispense with a temperature adjustment heater or cooler.
[0193] In the heat pump circuit 10 in the heat pump system 1 of the
first embodiment, the primary refrigerant taken in by the
high-stage-side compressor 25 is cooled by the secondary
refrigerant for air warming during passage through the
intermediate-pressure-water heat exchanger 40 and is further cooled
by the primary refrigerant flowing in through the injection channel
70. Accordingly, the density of the primary refrigerant taken in by
the high-stage-side compressor 25 can be increased and the
efficiency of the heat pump circuit 10 can be improved.
[0194] The heat obtained by the secondary refrigerant for air
warming by cooling the primary refrigerant taken in by the
high-stage-side compressor 25 can be used for an air-warming heat
load in the radiator 61.
[0195] The temperature of the primary refrigerant flowing through
the high-pressure water heat exchanger 50 is in a temperature range
capable of heating the secondary refrigerant for air warming, even
when the heat required for increasing the temperature of water for
hot-water supply to the requested water temperature is obtained
from the primary refrigerant flowing through the high-pressure
water heat exchanger 50. Accordingly, the heat of the primary
refrigerant flowing through the second high-pressure-water heat
exchanger 52, which is a part of the high-pressure water heat
exchanger 50, can be effectively used for heating the secondary
refrigerant for air warming in a range that allows operating
efficiency of the heat pump circuit 10 to be optimized. The heat of
the primary refrigerant flowing through the high-pressure water
heat exchanger 50 can be effectively used while the operating
efficiency of the heat pump circuit 10 is optimized.
[0196] In the case that, e.g., the secondary refrigerant for air
warming or the water for hot-water supply is to be further warmed
in the high-pressure water heat exchanger 50 after having been
warmed in the intermediate-pressure-water heat exchanger 40, the
heat in the primary refrigerant flowing through the high-pressure
water heat exchanger 50 cannot be sufficiently used in an effective
manner because the secondary refrigerant for air warming or the
water for hot-water supply that is to flow into the high-pressure
water heat exchanger 50 has already been warmed. In other words,
enthalpy variation of the primary refrigerant in the heat release
step cannot be sufficiently used in terms of a Mollier graph. In
the similar case that an attempt is made to heat the secondary
refrigerant for air warming or the water for hot-water supply in
the intermediate-pressure-water heat exchanger 40 after having been
heated in the high-pressure water heat exchanger 50, the secondary
refrigerant for air warming or the water for hot-water supply that
is to flow into the intermediate-pressure-water heat exchanger 40
has already been warmed. Accordingly, there are cases in which the
heat of the primary refrigerant flowing through the
intermediate-pressure-water heat exchanger 40 cannot be
sufficiently used and it is difficult to improve the operating
efficiency of a multistage compression-type heat pump circuit
10.
[0197] In contrast, in the heat pump system 1 of the first
embodiment, the secondary refrigerant cooled in the radiator 61 is
divided in the heat pump circuit 10 and used for being heated in
the intermediate-pressure-water heat exchanger 40 while being made
to pass through the intermediate-pressure-side branching channel 67
and for being heated in the second high-pressure-water heat
exchanger 52 while being made to pass through the
high-pressure-side branching channel 68. Secondary refrigerant
cooled in the radiator 61 and not yet warmed can be fed to the
intermediate-pressure-water heat exchanger 40 and the second
high-pressure-water heat exchanger 52. It is thereby possible to
sufficiently use the heat of the primary refrigerant flowing
through the intermediate-pressure tube 23 in an effective manner
while improving the cooling effect of the primary refrigerant taken
in by the high-stage-side compressor 25.
<2> Second Embodiment
[0198] A heat pump system 201 of the second embodiment is not
provided with the primary bypass 80 (the fourteenth high-pressure
tube 27n, the primary bypass expansion valve 5b, and the sixth
low-pressure tube 20f) in the heat pump system 1 of the first
embodiment, and is a system in which all of the circulating primary
refrigerant passes through the
primary-refrigerant-to-primary-refrigerant heat exchanger 8, as
shown in FIG. 4. The configuration is otherwise the same as the
configuration in the first embodiment described above, and a
description is therefore omitted.
[0199] It is not only possible to reduce the number of components,
but it is also possible to dispense with control of the primary
bypass expansion valve 5b, in the case of a service environment in
which capacity and efficiency problems are less liable to occur
when all of the primary refrigerant circulating through the heat
pump circuit 10 is made to undergo heat exchange in the
primary-refrigerant-to-primary-refrigerant heat exchanger 8.
<3> Third Embodiment
[0200] A heat pump system 301 of the third embodiment is a system
in which the cooling of the primary refrigerant flowing through the
intermediate-pressure tube 23 is entirely carried out in the
intermediate-pressure-water heat exchanger 40 without injection of
primary refrigerant into the intermediate-pressure tube 23, as
shown in FIG. 5. In other words, the heat pump system 301 of the
third embodiment is a system provided with a 33.sup.rd
intermediate-pressure tube 323c and a 38.sup.th high-pressure tube
327g in place of the economizer heat exchanger 7, the injection
channel 70 (injection expansion valve 73, first injection tube 72,
second injection tube 74, third injection tube 75, and fourth
injection tube 76), the eighth high-pressure tube 27h, the ninth
high-pressure tube 27i, the tenth high-pressure tube 27j, the third
intermediate-pressure tube 23c, and the fourth
intermediate-pressure tube 23d, which are provided to the heat pump
system 1 of the first embodiment. The 33.sup.rd
intermediate-pressure tube 323c connects the second
intermediate-pressure tube 23b inside the
intermediate-pressure-water heat exchanger 40 and the intake side
of the high-stage-side compressor 25. The 38.sup.th high-pressure
tube 327g connects the sixth high-pressure tube 27f inside the
third high-pressure-water heat exchanger 53 and the fourth
high-pressure point I. The configuration is otherwise the same as
the configuration in the first embodiment described above, and a
description is therefore omitted.
[0201] In the heat pump system 301, it is possible to avoid a state
in which the refrigerant taken in by the high-stage-side compressor
25 is cooled more as the wet state increases, and it is possible to
minimize the number of components and simplify the circuit
configuration.
[0202] With the heat pump system 301, the injection channel 70 is
not provided, and the amount of primary refrigerant moving toward
the high-pressure water heat exchanger 50 can therefore be
increased in a range in which the primary refrigerant taken in by
the high-stage-side compressor 25 does not enter a wet state, even
if the temperature of the primary refrigerant passing through the
intermediate-pressure-water heat exchanger 40 has been excessively
reduced by secondary refrigerant-temperature equalization
control.
<4> Fourth Embodiment
[0203] The heat pump system 401 of the fourth embodiment is a
system in which the branching to the injection channel 70 side is
disposed in the downstream side of the economizer heat exchanger 7,
as shown in FIG. 6. In other words, the heat pump system 401 of the
fourth embodiment is a system, in the heat pump system 1 of the
first embodiment, provided with a 43.sup.rd high-pressure point 4H
in place of the third high-pressure point H, a 47.sup.th
high-pressure tube 427g in place of the seventh high-pressure tube
27g, a 48.sup.th high-pressure tube 427h in place of the eighth
high-pressure tube 27h, a 49.sup.th high-pressure tube 427i in
place of the ninth high-pressure tube 27i, and a 410.sup.th
high-pressure tube 427j in place of the tenth high-pressure tube
27j. The 43rd high-pressure point 4H is provided on the downstream
side of the economizer heat exchanger 7 and in the upstream side of
the fourth high-pressure point I, in the flow direction of the
primary refrigerant in the heat pump circuit 10, and branches to
the injection channel 470. The 47th high-pressure tube 427g
connects the sixth high-pressure tube 27f inside the third
high-pressure-water heat exchanger 53 and the 48th high-pressure
tube 427h inside the economizer heat exchanger 7. The 49.sup.th
high-pressure tube 427i connects the 43rd high-pressure point 4H
and the 48th high-pressure tube 427h inside the economizer heat
exchanger 7. The 410.sup.th high-pressure tube 427j connects the
43rd high-pressure point 4H and the fourth high-pressure point I.
The configuration is otherwise the same as the configuration in the
first embodiment described above, and a description is therefore
omitted.
[0204] With this heat pump system 401, the cooling effect at the
injection merging point D can be improved because the temperature
of the primary refrigerant flowing through the injection channel
470 can be reduced in comparison with the primary refrigerant
flowing through the injection channel 70 of the heat pump system 1
of the first embodiment.
<5-1> Fifth Embodiment
[0205] The heat pump system 501 of the fifth embodiment is a system
that excludes the third high-pressure-water heat exchanger 53 in
the heat pump system 1 of the first embodiment, as shown in FIG. 7.
In other words, the heat pump system 501 of the fifth embodiment is
a system provided with a 52.sup.nd hot-water supply heat pump tube
595b in place of the second hot-water supply heat pump tube 95b,
third hot-water supply heat pump tube 95c, and fourth hot-water
supply heat pump tube 95d; and a 55.sup.th high-pressure tube 527e
in place of the fifth high-pressure tube 27e, the sixth
high-pressure tube 27f, and the seventh high-pressure tube 27g in
the heat pump system 1 of the first embodiment. Here, the hot-water
supply intermediate temperature sensor 95T used in the heat pump
system 1 of the first embodiment is not required. The 52.sup.rd
hot-water supply heat pump tube 595b connects the hot-water supply
pump 92 and the upstream-side end section of the fifth hot-water
supply heat pump tube 95e inside the first high-pressure water heat
exchanger 51 in the flow direction of the water for hot-water
supply. The 55.sup.th high-pressure tube 527e connects the third
high-pressure point H and the downstream-side end section of the
fourth high-pressure tube 27d inside the second high-pressure-water
heat exchanger 52 in the flow direction of the primary refrigerant.
The configuration is otherwise the same as the configuration in the
first embodiment described above, and a description is therefore
omitted.
[0206] With this heat pump system 501, the primary refrigerant
moving toward the third high-pressure point H is not warmed and the
water for hot-water supply is not cooled, even when, e.g., the
temperature of the water for hot-water supply stored in the
hot-water storage tank 91 has increased and the temperature of the
water for hot-water supply detected by the hot-water supply
water-intake temperature sensor 94T is higher than the temperature
of the primary refrigerant passing through the outlet of the fourth
high-pressure tube 27d inside the second high-pressure-water heat
exchanger 52. Therefore, operation with good efficiency can be
obtained even in a state of low heat load for hot-water supply.
<5-2> Modification of the Fifth Embodiment
(A)
[0207] The heat pump system 501 of the fifth embodiment described
above may be a heat pump system 501A in which the 55.sup.th
high-pressure tube 527e described above is used in place of the
47.sup.th high-pressure tube 427g while the injection channel 470
described in the fourth embodiment is used, as shown in FIG. 8.
[0208] In this case, an effect similar to that of the heat pump
system 401 of the fourth embodiment can also be obtained.
(B)
[0209] The heat pump system 501 of the fifth embodiment may be a
heat pump system 501B in which the connection to the 55.sup.th
high-pressure tube 527e described above is the fourth high-pressure
point I while the injection channel 70 described in the third
embodiment is eliminated, as shown in FIG. 9.
[0210] In this case, an effect similar to that of the heat pump
system 301 of the third embodiment can be further obtained.
(C)
[0211] The heat pump system 501B of the modification (B) of the
fifth embodiment may be a heat pump system 501C in which the
primary bypass 80 is eliminated as described in the second
embodiment, as shown in FIG. 10.
[0212] In this case, an effect similar to that of the heat pump
system 201 of the second embodiment can be further obtained.
<6-1> Sixth Embodiment
[0213] The heat pump system 601 of the sixth embodiment is a system
provided with a gas-liquid separation injection channel 630, as
shown in FIG. 11, in the heat pump system 301 of the third
embodiment, which does not have the injection channel 70. The
gas-liquid separation injection channel 630 has a pre-separation
gas-liquid tube 631, a gas-liquid separator 632, a post-separation
liquid tube 633, a post-separation gas tube 634, a post-separation
gas tube on-off valve 635, and a gas-liquid separation expansion
valve 605. The pre-separation gas-liquid tube 631 extends from the
third low-pressure point M to the gas-phase space in the upper part
of the gas-liquid separator 632. The gas-liquid separator 632
separates the primary refrigerant flowing in from the
pre-separation gas-liquid tube 631 into a gas-phase region in the
upper space and a liquid-phase region in the lower space. The
post-separation liquid tube 633 directs the primary refrigerant
present in the liquid-phase region of the gas-liquid separator 632
to the gas-liquid separation expansion valve 605. The pressure of
the passing primary refrigerant is further reduced in the
gas-liquid separation expansion valve 605. The post-separation gas
tube 634 directs the primary refrigerant present in the gas-phase
region of the gas-liquid separator 632 to the injection merging
point D. The post-separation gas tube on-off valve 635 is capable
of switching between a state that permits and a state that does not
permit the passage of the primary refrigerant in the
post-separation gas tube 634. The configuration is otherwise the
same as the configuration in the first embodiment described above,
and a description is therefore omitted.
[0214] With the heat pump system 601, pressure of the primary
refrigerant in the expansion valve 5a and/or the primary bypass
expansion valve 5b is reduced to a pressure that is lower than a
critical pressure that is the same as the primary refrigerant
flowing through the intermediate-pressure tube 23 to thereby
achieve a gas-liquid two-phase state. The primary refrigerant in a
liquid state is reduced to the pressure of the primary refrigerant
flowing through the low-pressure tube 20 in the gas-liquid
separation expansion valve 605. The post-separation gas tube 634
extends from the gas-phase region of the gas-liquid separator 632,
and the primary refrigerant in a gas state therefore flows to the
post-separation gas tube 634 because the primary refrigerant in a
liquid state is not liable to become mixed therein. The primary
refrigerant taken in by the high-stage-side compressor 25 is
thereby made less likely to enter a wet state after merging with
the primary refrigerant flowing through the intermediate-pressure
tube 23 at the injection merging point D. Liquid compression in the
high-stage-side compressor 25 can thereby be prevented while the
refrigerant density taken in by the high-stage-side compressor 25
is increased and efficiency is improved. In the depressurization of
the primary refrigerant in the expansion valve 5a, the pressure is
not reduced to the pressure of the primary refrigerant flowing
through the low-pressure tube 20 and the pressure is only reduced
to nearly the pressure of the primary refrigerant flowing through
the intermediate-pressure tube 23. Therefore, it is possible to
minimize the occurrence of liquid compression in the
high-stage-side compressor 25, which can occur when the temperature
of the primary refrigerant flowing through the post-separation gas
tube 634 is excessively reduced. Also, the amount of primary
refrigerant moving toward the high-pressure water heat exchanger 50
can be increased in a range in which the primary refrigerant taken
in by the high-stage-side compressor 25 does not enter a wet state,
even when the temperature of the primary refrigerant passing
through the intermediate-pressure-water heat exchanger 40 has
dropped excessively due to secondary refrigerant-temperature
equalization control.
<6-2> Modification of the Sixth Embodiment
(A)
[0215] The heat pump system 601 of the sixth embodiment described
above may be a heat pump system 601A which does not have the third
high-pressure-water heat exchanger 53 as described in the fifth
embodiment, as shown in FIG. 12. The configuration is otherwise the
same as the configuration in the first embodiment described above,
and a description is therefore omitted.
<7> Seventh Embodiment
[0216] A heat pump system 701 of the seventh embodiment may be a
system in which the position of the injection merging point D in
the heat pump system 1 of the first embodiment is an injection
merging point 7D, which is located at a midway point in the first
intermediate-pressure tube 23a for connecting the discharge side of
the low-stage-side compressor 21 and the downstream-side end
section of the second intermediate-pressure tube 23b inside the
intermediate-pressure-water heat exchanger 40, as shown in FIG. 13.
The configuration is otherwise the same as the configuration in the
first embodiment described above, and a description is therefore
omitted.
[0217] In the heat pump system 701, there are cases in which the
discharge refrigerant temperature of the low-stage-side compressor
21 becomes excessively high for the secondary refrigerant for air
warming heated in the intermediate-pressure-water heat exchanger
40, in the case that, e.g., the low-stage-side compressor 21 is
operated to increase drive efficiency using the same compression
ratio as the compression ratio of the high-stage-side compressor 25
while the compression ratio of the high-stage-side compressor 25 is
increased so that a target temperature can be obtained as the
discharge refrigerant temperature of the high-stage-side compressor
25. Even in such cases, it is possible to keep the temperature of
the secondary refrigerant for air warming from becoming too high by
providing the injection merging point 7D at a midway point in the
first intermediate-pressure tube 23a.
[0218] In the heat pump system 701 as well, the temperature and
pressure of the primary refrigerant to be taken in by the
high-stage-side compressor 25 after the primary refrigerant passing
in through the injection channel 70 has merged in the injection
merging point 7D and after having passed through the
intermediate-pressure-water heat exchanger 40 are values detected
by the high-stage intake pressure sensor 24P and the high-stage
intake temperature sensor 24T, and the controller 11 can ascertain
the values and perform control for inhibiting the primary
refrigerant taken in by the high-stage-side compressor 25 from
entering a wet state.
<8> Eighth Embodiment
[0219] A heat pump system 801 of the eighth embodiment is a system
in which the order of the economizer heat exchanger 7 and the
primary-refrigerant-to-primary-refrigerant heat exchanger 8 in the
heat pump system 1 of the first embodiment is reversed, as shown in
FIG. 14. In other words, the heat pump system 801 of the eighth
embodiment is a system in which an 83.sup.rd intermediate-pressure
point 8H in the downstream side of the third low-pressure point M
is provided in place of the third high-pressure point H in the heat
pump system 1 of the first embodiment, and an injection channel 870
branches from the 83.sup.rd intermediate-pressure point 8H. An
810.sup.th high-pressure tube 827j connects the fourth
high-pressure point I and the downstream-side end section of the
sixth high-pressure tube 27f inside the third high-pressure-water
heat exchanger 53. An 87.sup.th high-pressure tube 827g connects
the third low-pressure point M and the 83.sup.rd
intermediate-pressure point 8H. An 88.sup.th high-pressure tube
827h connects the 83.sup.rd intermediate -pressure point 8H and the
upstream-side end section of an 89.sup.th high-pressure tube 827i
inside the economizer heat exchanger 7. The configuration is
otherwise the same as the configuration in the first embodiment
described above, and a description is therefore omitted.
[0220] In this heat pump system 801, the primary refrigerant taken
by the low-stage-side compressor 21 can be warmed in the
primary-refrigerant-to-primary-refrigerant heat exchanger 8 by the
relatively warm primary refrigerant before it is cooled in the
economizer heat exchanger 7. The amount of primary refrigerant
moving toward the high-pressure water heat exchanger 50 can be
thereby increased in a range in which the primary refrigerant to be
taken in by the high-stage-side compressor 25 does not enter a wet
state, even when the temperature of the primary refrigerant passing
through the intermediate-pressure-water heat exchanger 40 becomes
excessively reduced by secondary refrigerant-temperature
equalization control.
<9> Ninth Embodiment
[0221] A heat pump system 901 of the ninth embodiment is a system
for warming water for hot-water supply in the second
high-pressure-water heat exchanger 52 as well in the heat pump
system 1 of the first embodiment, as shown in FIG. 15. In other
words, the heat pump system 901 of the ninth embodiment is a system
provided with a 95.sup.th upstream connection tube 995x, a
95.sup.th hot-water supply heat pump tube 995d, and a 95.sup.th
downstream connection tube 995y in place of the fourth hot-water
supply heat pump tube 95d in the heat pump system 1 of the first
embodiment; and provided with an upstream-connection temperature
sensor 95Tx for detecting the temperature of the water for
hot-water supply passing through the 95.sup.th upstream connection
tube 995x, and a downstream-connection temperature sensor 95Ty for
detecting the temperature of the water for hot-water supply passing
through the 95.sup.th downstream connection tube 995y. The
configuration is otherwise the same as the configuration in the
first embodiment described above, and a description is therefore
omitted.
[0222] In this heat pump system 901, the loss of heat released from
the fourth high-pressure tube 27d can be minimized and effectively
used in the second high-pressure-water heat exchanger 52 because,
e.g., the water for hot-water supply flowing through the 95.sup.th
hot-water supply heat pump tube 995d can absorb the heat that
cannot be absorbed by the secondary refrigerant for air warming
flowing through the second high-pressure-side branching channel 68b
among the heat released from the fourth high-pressure tube 27d.
Also, the size of the heat exchanger required for heating the water
for hot-water supply to a required water temperature can be made
compact because a portion is provided in which both the secondary
refrigerant for air warming and the water for hot-water supply
simultaneously receive the heat of the primary refrigerant.
<10> Tenth Embodiment
[0223] A heat pump system 1x of the tenth embodiment is a system
configured so that the hot-water supply circuit 90 in the heat pump
system 1 of the first embodiment is removed, as shown in FIG. 16.
In other words, the heat pump system 1x of the tenth embodiment is
a system in which the first high-pressure water heat exchanger 51,
the third high-pressure-water heat exchanger 53, and the hot-water
supply circuit 90 in the heat pump system 1 of the first embodiment
are removed; a fourteenth upstream high-pressure tube 127a is
provided in place of the first high-pressure tube 27a, the second
high-pressure tube 27b, and the third high-pressure tube 27c; and a
fourteenth downstream high-pressure tube 127e is provided in place
of the fifth high-pressure tube 27e, the sixth high-pressure tube
27f, and the seventh high-pressure tube 27g. The fourteenth
upstream high-pressure tube 127a connects the discharge side of the
high-stage-side compressor 25 and the upstream-side end section of
the fourth high-pressure tube 27d inside the second
high-pressure-water heat exchanger 52. The fourteenth downstream
high-pressure tube 127e connects the third high-pressure point H
and the downstream-side end section of the fourth high-pressure
tube 27d inside the second high-pressure-water heat exchanger 52.
The configuration is otherwise the same as the configuration in the
first embodiment described above, and a description is therefore
omitted.
[0224] With this heat pump system 1x, it is possible to obtain the
same effects as those of the first embodiment, even when the
hot-water supply circuit 90 is not provided.
<11-1> Eleventh Embodiment
[0225] A heat pump system 2x of the eleventh embodiment is a system
in which the water for hot-water supply flowing through the
hot-water supply circuit 90 in the heat pump system 1 of the first
embodiment undergoes heat exchange with the primary refrigerant in
the intermediate-pressure-water heat exchanger 40 as well as the
high-pressure water heat exchanger 50 side in the same manner as
the secondary refrigerant for air warming, as shown in FIG. 17. In
other words, the heat pump system 2x of the eleventh embodiment is
provided with a second intermediate-pressure-water heat exchanger
153 for performing heat exchange between the primary refrigerant
passing through the intermediate-pressure-water heat exchanger 40
and the water for hot-water supply. A second branching hot-water
supply heat pump tube 195b branches away at a midway point of the
second hot-water supply heat pump tube 95b and then extends to the
downstream-side end section of the second
intermediate-pressure-water heat exchanger 153. The second
intermediate-pressure-water heat exchanger 153 causes heat exchange
to be performed between the water for hot-water supply flowing into
a third branching hot-water supply heat pump tube 195c via the
second branching hot-water supply heat pump tube 195b and the
primary refrigerant flowing into the eleventh intermediate-pressure
tube 123c, which is a part of the third intermediate-pressure tube
23c, after having passed through the intermediate-pressure-water
heat exchanger 40.
[0226] The water for hot-water supply which has passed through the
third branching hot-water supply heat pump tube 195c inside the
second intermediate-pressure-water heat exchanger 153 flows to a
branching hot-water supply mixing valve 193 via a fourth branching
hot-water supply heat pump tube 195d, and merges with the water for
hot-water supply that has flowed in through the fourth hot-water
supply heat pump tube 95d. The water for hot-water supply which has
merged in the branching hot-water supply mixing valve 193 flows
into the fifth hot-water supply heat pump tube 95e inside the first
high-pressure water heat exchanger 51 via a merging hot-water
supply communication tube 196. The configuration is otherwise the
same as the configuration in the first embodiment described above,
and a description is therefore omitted.
[0227] With this heat pump system 2x, in the case that, e.g., the
temperature of the water for hot-water supply flowing out from the
hot-water storage tank 91 to the heat pump circuit 10 side is at a
normal temperature, which is the temperature of city water, there
may be cases in which it is more efficient to cool the water for
hot-water supply in a range in which liquid-compression does not
occur in the high-stage-side compressor 25, even with the primary
refrigerant that has been cooled while passing through the second
intermediate-pressure tube 23b inside the
intermediate-pressure-water heat exchanger 40. In such a case, in
the heat pump system 2x of the eleventh embodiment, cold water for
hot-water supply can be heated using the heat of the primary
refrigerant flowing not only in the high-pressure water heat
exchanger 50 side, but also between the downstream side of the
intermediate-pressure-water heat exchanger 40 and the intake side
of the high-stage-side compressor 25.
[0228] With such a configuration, the controller 11 furthermore
controls the branching hot-water supply mixing valve 193 to thereby
adjust the flow rate of the fourth branching hot-water supply heat
pump tube 195d and the flow rate of the fourth hot-water supply
heat pump tube 95d, whereby degradation of cycle efficiency of the
heat pump circuit 10 can be minimized, even in the case that the
cycle efficiency of the heat pump circuit 10 is slightly degraded
by the secondary refrigerant-temperature equalization control
described above.
[0229] For example, the controller 11 can control the branching
hot-water supply mixing valve 193 to thereby increase the flow rate
through the fourth branching hot-water supply heat pump tube 195d
and to minimize degradation of the cycle efficiency of the heat
pump circuit 10, in the case that the cycle efficiency of the heat
pump circuit 10 is slightly degraded by a reduction in the flow
rate through the intermediate-pressure-side branching channel 67 of
the air-warming circuit 60 by the secondary refrigerant-temperature
equalization control described above.
<11-2> Modification of the Eleventh Embodiment
(A)
[0230] In the heat pump system 2x of the eleventh embodiment, an
example was described in which not only is heat exchange
(intermediate-pressure-water heat exchanger 40) performed with the
secondary refrigerant for air warming, but heat exchange (second
intermediate-pressure-water heat exchanger 153) is also performed
with the water for hot-water supply, in the intermediate-pressure
tube 23 through which the primary refrigerant is flowing from the
low-stage-side compressor 21 toward the high-stage-side compressor
25.
[0231] However, the present invention is not limited thereto, and
it is also possible to use a heat pump system capable of the
following heat exchange in a range that does not depart from the
spirit of the present invention.
[0232] For example, heat exchange can be performed in three
locations so that heat exchange is performed between the water for
hot-water supply, the secondary refrigerant for air warming, and
the primary refrigerant in the high-pressure water heat exchanger
50 of the first embodiment in the intermediate-pressure tube 23 in
which the primary refrigerant is flowing from the low-stage-side
compressor 21 toward the high-stage-side compressor 25. In this
case as well, heat exchange between the water for hot-water supply
and the primary refrigerant flowing through the
intermediate-pressure tube 23 is preferably performed in two
separate locations, i.e., in the upstream side and the downstream
side, where heat exchange is performed between the primary
refrigerant and the secondary refrigerant for air warming, in the
same manner as the high-pressure water heat exchanger 50.
(B)
[0233] The water for hot-water supply may undergo heat exchange in
the intermediate-pressure tube 23 in which the primary refrigerant
flows from the low-stage-side compressor 21 toward the
high-stage-side compressor 25 without being made to undergo heat
exchange with the primary refrigerant in the high-pressure water
heat exchanger 50.
<12> Twelfth Embodiment
[0234] A heat pump system 3x of the twelfth embodiment is a system
in which a bypass channel is provided in the air-warming circuit 60
in the heat pump system 1 of the first embodiment, as shown in FIG.
18. In other words, the heat pump system 3x of the twelfth
embodiment is a system in which an air-warming bypass channel 69
for connecting the air-warming merging point Y and the hot-water
supply merging point Z at a midway point of the air-warming-return
tube 66 is further provided in the air-warming circuit 60 in the
heat pump system 1 of the first embodiment, and a twelfth
air-warming mixing valve 164 is provided in place of the
air-warming mixing valve 64 in the first embodiment. In the twelfth
air-warming mixing valve 164, an adjustment is made by instruction
from the controller 11 to the mixing ratio between the cool
secondary refrigerant for air warming which flows in from the
air-warming bypass circuit 69 and which has just finished releasing
heat in the radiator 61, the warmed secondary refrigerant for air
warming flowing in via the intermediate-pressure-side branching
channel 67, and the warmed secondary refrigerant for air warming
flowing in via the high-pressure-side branching channel 68. The
configuration is otherwise the same as the configuration in the
first embodiment described above, and a description is therefore
omitted.
[0235] In the heat pump system 1 of the first embodiment described
above, there are cases in which a heat amount that exceeds the heat
amount requested by the radiator 61 flows to the radiator 61, even
when processing has been performed to reduce the heat amount while
secondary refrigerant-temperature equalization control as described
above has been performed. With this heat pump system 3x of the
twelfth embodiment, the controller 11 operates the twelfth
air-warming mixing valve 164 and is capable of adjusting the flow
rate of the secondary refrigerant for air warming flowing in
through the air-warming bypass channel 69 toward the air-warming
merging point Y when the heat amount to the radiator 61 is on the
verge of becoming excessive as described above. The secondary
refrigerant having a temperature that exceeds the temperature
requested by the radiator 61 and the secondary refrigerant having a
temperature that is less than that requested by the radiator 61
after heat release has ended in the radiator 61 are mixed. The
controller 11 adjusts these mixing ratios in the twelfth
air-warming mixing valve 164, whereby the temperature of the
secondary refrigerant after mixing is adjusted to the temperature
requested by the radiator 61.
[0236] The secondary refrigerant having the temperature requested
by the radiator 61 can thereby be fed to the radiator 61 while the
occurrence of liquid compression in the high-stage-side compressor
25 is minimized.
<13> Thirteenth Embodiment
[0237] A heat pump system 4x of the thirteenth embodiment is a
system configured so that the economizer heat exchanger 7 and the
third high-pressure point H are positioned between the third
low-pressure point and the portion that branches the flow toward
the primary-refrigerant-to-primary-refrigerant heat exchanger 8 and
the flow toward the primary bypass 80, as shown in FIG. 19. In
other words, the heat pump system 4x of the thirteenth embodiment
is a system in which the fourth high-pressure point I of the heat
pump system 1 of the first embodiment is modified to be a
thirteenth high-pressure point 131 that is on the upstream side of
the third high-pressure point H and is on the downstream side of
the third high-pressure-water heat exchanger 53, and in which a
thirteenth primary bypass 80x and a thirteenth injection channel
70x are provided. A seventh high-pressure tube 127g connects the
thirteenth high-pressure point 131 and the downstream-side end
section of the sixth high-pressure tube 27f inside the third
high-pressure-water heat exchanger 53. A bypass upstream-economizer
high-pressure tube 127n connects the thirteenth high-pressure point
131 and the third high-pressure point H. A bypass
downstream-economizer high-pressure tube 127j connects the primary
bypass expansion valve 5b and the downstream-side end section of
the ninth high-pressure tube 27i inside the economizer heat
exchanger 7. The configuration is otherwise the same as the
configuration in the first embodiment described above, and a
description is therefore omitted.
[0238] With this heat pump system 4x, the primary refrigerant
moving toward the expansion valve 5a is divided into a channel for
cooling by the economizer heat exchanger 7 and a channel for
cooling by the primary-refrigerant-to-primary-refrigerant heat
exchanger 8, and it is therefore possible to adjust the amount of
primary refrigerant that is cooled by either of the channels.
<14> Applicable Modifications of the Embodiments Described
Above
[0239] Heat pump systems were described in detail above in the
first to thirteenth embodiments. However, the present invention is
not limited thereto; modes such as those described below of the
heat pump systems of the embodiments are also included in the
present invention in a range that does not depart from the spirit
of the invention.
<14-1>
[0240] In the embodiments described above, examples were described
for the case in which carbon dioxide is used as the primary
refrigerant.
[0241] However, ethylene, ethane, and/or nitrogen oxide or the
like, which are refrigerants other than carbon dioxide, may also be
used as the primary refrigerant in any of the embodiments described
above. In this case, the refrigerant to be used is preferably one
that can be used with the discharge refrigerant pressure of the
high-stage-side compressor 25 above critical pressure, and that can
minimize the drive force of the compressors.
<14-2>
[0242] In the embodiments described above, examples were described
for the case in which water circulates as the secondary refrigerant
in the air-warming circuit 60.
[0243] However, in any of the embodiments described above, brine or
the like may be used as another heat medium with no limitation
being given to water as the secondary refrigerant.
<14-3>
[0244] In the embodiments described above, examples were described
for the case in which the low-stage-side compressor 21 and the
high-stage-side compressor 25 are provided.
[0245] However, in any of the embodiments described above, it is
possible to provide a so-called single-shaft two-stage or a
single-shaft multistage-type compression mechanism in which a
shared drive shaft is used in the low-stage-side compressor 21 and
the high-stage-side compressor 25. In this case, it is possible to
increase drive efficiency by providing a 180-degree phase
difference in the compression mechanisms.
<14-4>
[0246] In the embodiments described above, examples were described
for the case in which the low-stage-side compressor 21 and the
high-stage-side compressor 25 are connected in series.
[0247] However, in any of the embodiments described above, it is
also possible to use a mode in which three or more compression
mechanisms are connected in series. In such a case, heat load
processing may be performed using the heat of the primary
refrigerant flowing between each compression mechanism. Also, if
the compression mechanisms are provided with two or more
series-connection circuits, another compression mechanism may be
further provided in parallel or in series.
<14-5>
[0248] In the embodiments described above, examples were described
for the case in which control is performed to bring the temperature
of the secondary refrigerant flowing through the
intermediate-pressure-side branching channel 67 and
high-pressure-side branching channel 68 of the air-warming circuit
60 into conformity with the temperature requested by the radiator
61.
[0249] However, in any of the embodiments described above, it is
also possible to make the optimization of the cycle efficiency in
the heat pump circuit 10 an absolute priority over feeding the heat
amount requested by the radiator 61. In this case, there may be
situations in which the heat amount fed to the radiator 61 is
insufficient for maintaining optimal cycle efficiency of the heat
pump circuit 10. In this case, it is possible to use a heat pump
system 5x in which an external heat source section 60A for heating
the passing secondary refrigerant for air warming is provided in
the downstream side of air-warming circuit 60, including the third
high-pressure-side branching channel 68c or the third
intermediate-pressure-side branching channel 67c from downstream
side to prior to arriving at the radiator 61, as shown in FIG. 20.
In this case, it is possible to adapt to the air-warming heat load
while the cycle efficiency of the heat pump circuit 10 is kept in
an optimal state, even when a situation occurs in which it is not
possible to adapt to the air-warming heat load in order to kept the
cycle efficiency of the heat pump circuit 10 optimal due to change
in the environment in which the evaporator 4 is disposed, change in
the air-warming load, or change in the hot-water supply load. A
heat-supply section similar to the external heat source section 60A
may be provided only to the hot-water supply circuit 90, or may be
provided to both the air-warming circuit 60 and the hot-water
supply circuit 90.
[0250] There may be cases in which an excessive heat amount is fed
to the radiator 61 in order to keep the cycle efficiency of the
heat pump circuit 10 optimal. In this case, it is possible to use a
heat pump system 6x in which an external cooling source section 60B
for cooling the passing secondary refrigerant for air warming is
provided in the downstream side of air-warming circuit 60,
including the third high-pressure-side branching channel 68c or the
third intermediate-pressure-side branching channel 67c from
downstream side to prior to arriving at the radiator 61, as shown
in FIG. 21. The external cooling source section 60B may be one in
which a portion of the water supply tube 94 through which external
normal-temperature city water is flowing is bypassed by a water
supply branching valve 94B and a water supply branching tube 194,
and the normal-temperature city water and the secondary refrigerant
for air warming flowing through the air-warming feed tube 65 are
made to undergo heat exchange to thereby cool the secondary
refrigerant for air warming flowing through the air-warming feed
tube 65. In this case, it is possible adapt to the air-warming heat
load while the cycle efficiency of the heat pump circuit 10 is kept
in an optimal state, even when a situation occurs in which it is
not possible to adapt to the air-warming heat load in order to keep
the cycle efficiency of the heat pump circuit 10 optimal due to
change in the environment in which the evaporator 4 is disposed,
change in the air-warming load, or change in the hot-water supply
load. In the case that the water supply branching valve 94B is
used, the heat provided in excess by the heat pump circuit 10 to
the secondary refrigerant of the air-warming circuit 60 is
recovered as heat for hot-water supply, whereby the efficiency of
the heat pump system can also be increased. A heat-supply section
similar to the external heat source section 60B may be provided
only to the hot-water supply circuit 90, or may be provided to both
the air-warming circuit 60 and the hot-water supply circuit 90.
<14-6>
[0251] In the embodiments described above, examples were described
for the case in which there is no particular limitation to the
relationship between the temperature requested by the radiator 61
of the air-warming circuit 60 and the temperature requested for the
water for hot-water supply flowing through the sixth hot-water
supply heat pump tube 95f and then into the hot-water storage tank
91 in the hot-water supply circuit 90, and the temperature of the
primary refrigerant flowing through the intermediate-pressure-water
heat exchanger 40 and/or the high-pressure water heat exchanger 50
of the heat pump circuit 10.
[0252] However, in any of the embodiments described above, it is
possible to improve the cycle efficiency of the heat pump circuit
10 under the presumed condition that the controller 11 controls the
opening degree of the expansion valve 5a, the drive frequency of
the low-stage-side compressor 21, the drive frequency of the
high-stage-side compressor 25, and the like so that the temperature
of the primary refrigerant flowing through the
intermediate-pressure-water heat exchanger 40 exceeds the
temperature requested by the radiator 61 of the air-warming circuit
60. In this case, the air-warming circuit 60 can produce secondary
refrigerant at the temperature requested by the radiator 61 by
using only the heat obtained by the secondary refrigerant flowing
through the intermediate-pressure-side branching channel 67 side,
which is the intermediate-pressure-water heat exchanger 40
side.
<14-7>
[0253] In the embodiments described above, examples were described
for the case in which the compression ratio of the low-stage-side
compressor 21 and the compression ratio of the high-stage-side
compressor 25 are made equal in order to increase the cycle
efficiency of the heat pump circuit 10.
[0254] However, in any of the embodiments described above, there is
no limitation to the case in which the compression ratio of the
low-stage-side compressor 21 and the compression ratio of the
high-stage-side compressor 25 are made to be the same, and, for
example, it is also possible to perform control so that the
difference between the two compression ratios is reduced.
<14-8>
[0255] For example, in the case that the secondary
refrigerant-temperature equalization control described in the
embodiments above is carried out, the controller 11 performs a
control to increase the flow rate through the air-warming pump 63
so as to shorten the time allowed for heat exchange in the case
that the temperatures to be equalized exceed the temperature
requested by the radiator 61. However, when control is performed to
increase the flow rate through the air-warming pump 63 in this
manner, the degree of superheat of the primary refrigerant taken in
by the high-stage-side compressor 25 is liable to be reduced and a
wet state is liable to form because the primary refrigerant in the
intermediate-pressure-water heat exchanger 40 is cooled
further.
[0256] In such a case, the controller 11 may perform low-stage
intake degree-of-superheat control for increasing the degree of
superheat of the primary refrigerant taken in by the low-stage-side
compressor 21 without, e.g., modifying the target discharge
temperature of the low-stage-side compressor 21 and without
modifying the target discharge temperature of the high-stage-side
compressor 25.
[0257] For example, the cycle of the heat pump circuit 10 is
carried out and the flow rate through the air-warming pump 63 is
increased, as shown by the dotted lines in the Mollier graph of
FIG. 22. Here, the controller 11 increases the degree of superheat
of the primary refrigerant taken in by the low-stage-side
compressor 21 without modifying the target discharge temperature of
the low-stage-side compressor 21 and without modifying the target
discharge temperature of the high-stage-side compressor 25 by
performing low-stage intake degree-of-superheat control. The cycle
of the heat pump circuit 10 is carried out as shown by the solid
lines in the Mollier graph of FIG. 22. Here, in a comparison of the
cycle of the dotted lines and the cycle of the solid lines in
relation to the point at which the high-stage-side compressor 25
takes in the primary refrigerant, the cycle of the solid lines
moves in the direction away from the saturated vapor line, and the
degree of superheat increases in the Mollier graph of FIG. 22. The
state of the primary refrigerant taken in by the high-stage-side
compressor 25 is a state in which the degree of superheat is
increased in progression away from the saturated vapor line, even
when the degree of superheat of the primary refrigerant taken in by
the high-stage-side compressor 25 is reduced by an increase in the
air-warming load or by another change in the ambient conditions,
albeit with a slight reduction in the intake refrigerant density of
the low-stage-side compressor 21. Liquid compression in the
high-stage-side compressor 25 is therefore less liable to occur.
The target discharge temperature of the low-stage-side compressor
21 and the target discharge temperature of the high-stage-side
compressor 25 are not modified even when the cycle shown by the
solid lines in the Mollier graph of the FIG. 22 is carried out.
Therefore, heating of the secondary refrigerant for air warming by
heat exchange in the intermediate-pressure-water heat exchanger 40
and heating of the secondary refrigerant for air warming by heat
exchange in the high-pressure water heat exchanger 50 can be
sufficiently carried out. The efficiency of the heat pump circuit
10 can be improved because the compression ratio of the
low-stage-side compressor 21 and the compression ratio of the
high-stage-side compressor 25 can both be reduced.
[0258] The controller 11 controls the opening degree of the primary
bypass expansion valve 5b in the heat pump circuit 10 having the
primary bypass 80 and the primary bypass expansion valve 5b among
the heat pump systems described in the embodiments and
modifications above, making it possible for the above-described
low-stage intake degree-of-superheat control to adjust the amount
of heat exchange in the primary-refrigerant-to-primary-refrigerant
heat exchanger 8. Thus, the degree of superheat of the primary
refrigerant taken in by the low-stage-side compressor 21 can be
adjusted.
<14-9>
[0259] In the embodiments described above, examples were described
for cases in which the target discharge temperature of the
low-stage-side compressor 21 and the target discharge temperature
of the high-stage-side compressor 25 are the same.
[0260] However, in any of the embodiments described above, the
controller 11 may control the drive frequency of the low-stage-side
compressor 21, the drive frequency of the high-stage-side
compressor 25, the opening degree of the expansion valve 5a, and
other factors so that the target discharge temperature of the
low-stage-side compressor 21 and the target discharge temperature
of the high-stage-side compressor 25 are different. In this case,
low-stage discharge temperature reduction control can be performed
in order to reduce the target discharge temperature of the
low-stage-side compressor 21.
[0261] For example, the cycle of the heat pump circuit 10 is
carried out and the flow rate through the air-warming pump 63 is
increased, as shown by the dotted lines in the Mollier graph of
FIG. 23. Here, the controller 11 performs a control for reducing
low-stage discharge temperature to thereby reduce the target
discharge temperature of the low-stage-side compressor 21 and to
increase the flow rate of the secondary refrigerant for air warming
flowing through the second high-pressure-water heat exchanger 52
while the flow rate of the secondary refrigerant for air warming
flowing through the intermediate-pressure-water heat exchanger 40
is reduced without modification of the target discharge temperature
of the high-stage-side compressor 25. Here, the target discharge
temperature of the low-stage-side compressor 21 is set to, e.g.,
65.degree. C. so as to not become equal to or less than the
temperature requested by the radiator 61 of the air-warming circuit
60. The cycle of the heat pump circuit 10 is thereby carried out as
shown by the solid lines in the Mollier graph of FIG. 23. When a
comparison is made of the dotted-lines cycle and the solid-lines
cycle in relation to the point at which the high-stage-side
compressor 25 takes in the primary refrigerant, the solid-lines
cycle moves in the direction away from the saturated vapor line,
and the degree of superheat increases in the Mollier graph of FIG.
23. Liquid compression in the high-stage-side compressor 25 is
thereby made less likely to occur because the state of the primary
refrigerant taken in by the high-stage-side compressor 25 is one
that moves away from the saturated vapor line, whereby the degree
of superheat increases, even when the flow rate through the
air-warming pump 63 is increased and the degree of superheat of the
primary refrigerant taken in by the high-stage-side compressor 25
is reduced. The target discharge temperature of the high-stage-side
compressor 25 is not modified even when the cycle shown by the
solid lines in the Mollier graph of FIG. 23 is carried out in this
manner. Although the target discharge temperature of the
low-stage-side compressor 21 is reduced, it is possible to maintain
a state in which it is possible to adapt to the heat load because
the flow rate of the secondary refrigerant for air warming passing
through the intermediate-pressure-water heat exchanger 40 is
similarly reduced. Also, the efficiency of the heat pump circuit 10
can be improved because the compression ratio of the low-stage-side
compressor 21 and the compression ratio of the high-stage-side
compressor 25 can both be reduced.
[0262] For example, the controller 11 controls the opening degree
of the expansion valve 5a, the drive frequency of the
low-stage-side compressor 21, the drive frequency of the
high-stage-side compressor 25, and other factors, whereby the
low-stage discharge temperature reduction control described above
can be carried out.
<14-10>
[0263] In the embodiments described above, examples were described
for cases in which the conditions of the ambient temperature
environment of the radiator 61 in which the heat pump system is
used are not particularly limited.
[0264] However, in any of the embodiments described above, it is
possible to provide a limiting condition that the temperature of
the secondary refrigerant, which has released heat in the radiator
61, be in a temperature range between the critical temperature of
the carbon dioxide as the primary refrigerant and a temperature
about five degrees lower than the critical temperature, as the
service environment conditions of the heat pump system.
[0265] In the case that the heat pump system is used under such
service conditions, the secondary refrigerant is used for heat
loads having a temperature that is less than the critical
temperature of carbon dioxide as the primary refrigerant.
Therefore, heat exchange in the high-pressure water heat exchanger
50 can be carried out between the primary refrigerant in a state
exceeding the critical pressure and the secondary refrigerant
having a temperature that is less than the critical temperature;
and heat release can be carried out in an area in which the slope
of the isotherm of the primary refrigerant is smooth on a Mollier
graph. It is therefore possible to perform operation that increases
the enthalpy difference between the start and end of the primary
refrigerant heat release step.
<14-11>
[0266] In the embodiments described above, examples were described
for a system in which the controller 11 controls the air-warming
mixing valve 64 and the flow rate through the air-warming pump 63
on the basis of the temperatures detected by the
intermediate-pressure-side branching temperature sensor 67T and the
high-pressure-side branching temperature sensor 68T, and it is not
required that the flow rate of the secondary refrigerant in the
third intermediate-pressure-side branching channel 67c and third
high-pressure-side branching channel 68c of the air-warming circuit
60 be ascertained.
[0267] However, in any of the embodiments described above, it is
possible to use a heat pump system 7x in which an
intermediate-pressure-side branching channel flow rate meter 67Q
for ascertaining the flow rate of the secondary refrigerant for air
warming flowing through the intermediate-pressure-side branching
channel 67, and a high-pressure-side branching channel flow rate
meter 68Q for ascertaining the flow rate of the secondary
refrigerant for air warming flowing through the high-pressure-side
branching channel 68, in place of the intermediate-pressure-side
branching temperature sensor 67T and the high-pressure-side
branching temperature sensor 68T, are provided respectively, as
shown in FIG. 24.
[0268] In this heat pump system 7x, the controller 11 controls the
flow rate through the air-warming mixing valve 64 and/or the
air-warming pump 63 on the basis of the flow rate ascertained by
the intermediate-pressure-side branching channel flow rate meter
67Q and the flow rate ascertained by the high-pressure-side
branching channel flow rate meter 68Q, so that the difference
between the temperature of the secondary refrigerant for air
warming flowing through the third intermediate-pressure-side
branching channel 67c and the temperature of the secondary
refrigerant for air warming flowing through the third
high-pressure-side branching channel 68c is reduced. The controller
11 may perform control so that the temperature of the secondary
refrigerant for air warming flowing through the third
intermediate-pressure-side branching channel 67c and the
temperature of the secondary refrigerant for air warming flowing
through the third high-pressure-side branching channel 68c are the
same temperature.
[0269] The controller 11 ascertains the temperature of the primary
refrigerant flowing through the intermediate-pressure-water heat
exchanger 40 by using the intermediate-pressure temperature sensor
23T, and ascertains the flow rate of the primary refrigerant
flowing through the intermediate-pressure-water heat exchanger 40
by drive frequency of the low-stage-side compressor 21, the
temperature detected by the intermediate-pressure temperature
sensor 23T, and the pressure detected by the high-stage intake
pressure sensor 24P. The controller 11 ascertains the temperature
of the secondary refrigerant for air warming passing through the
first intermediate-pressure-side branching channel 67a by using the
temperature detecting by an air-warming return temperature sensor
66T. The controller 11 furthermore ascertains the flow rate of the
secondary refrigerant for air warming flowing through the
intermediate-pressure-side branching channel 67 by using the
intermediate-pressure-side branching channel flow rate meter 67Q.
The controller 11 thereby calculates the heat amount obtained by
the secondary refrigerant for air warming and calculates a
predicted value as the temperature of the secondary refrigerant for
air warming passing through the third intermediate-pressure-side
branching channel 67c, on the basis of the temperature difference
and the flow rates of the primary refrigerant and secondary
refrigerant for air warming in the intermediate-pressure-water heat
exchanger 40.
[0270] The controller 11 ascertains the temperature and flow rate
of the primary refrigerant flowing through the second
high-pressure-water heat exchanger 52 on the basis of the
high-pressure temperature sensor 27T, the high-pressure pressure
sensor 27P, the drive frequency or other parameters of the
high-stage-side compressor 25, the hot-water supply intermediate
temperature sensor 95T, the flow rate through the hot-water supply
pump 92, and other factors. The controller 11 ascertains the
temperature of the secondary refrigerant for air warming passing
through the first high-pressure-side branching channel 68a by using
the temperature detected by the air-warming return temperature
sensor 66T. The controller 11 furthermore ascertains the flow rate
of the secondary refrigerant flowing through the high-pressure-side
branching channel 68 by using the high-pressure-side branching
channel flow rate meter 68Q. The controller 11 thereby calculates
the heat amount obtained by the secondary refrigerant for air
warming and calculates a predicted value as the temperature of the
secondary refrigerant for air warming passing through the third
high-pressure-side branching channel 68c, on the basis of the
temperature difference and the flow rates of the primary
refrigerant and the secondary refrigerant for air warming in the
second high-pressure-water heat exchanger 52.
[0271] The controller 11 controls the air-warming mixing valve 64
and/or the air-warming pump 63 so that the difference between the
temperature of the secondary refrigerant for air warming passing
through the third intermediate-pressure-side branching channel 67c
and the temperature of the secondary refrigerant for air warming
passing through the third high-pressure-side branching channel 68c
thus calculated in the manner described above is reduced. The
specific details of control using the temperature of the secondary
refrigerant for air warming that passes through the third
intermediate-pressure-side branching channel 67c and the
temperature of the secondary refrigerant for air warming that
passes through the third high-pressure-side branching channel 68c
thus calculated herein are the same as the details described in the
embodiments above.
[0272] In this manner, it is possible to reduce the difference
between the temperature of the secondary refrigerant for air
warming that passes through the third intermediate-pressure-side
branching channel 67c and the temperature of the secondary
refrigerant for air warming that passes through the third
high-pressure-side branching channel 68c, even with the heat pump
system 7x in which the intermediate-pressure-side branching
temperature sensor 67T and the high-pressure-side branching
temperature sensor 68T are not provided.
<14-12>
[0273] It is also possible to use a heat pump system 8x provided
with a feed tube flow rate meter 65Q in place of the
high-pressure-side branching channel flow rate meter 68Q provided
in the manner described above in Modification <14-11>, as
shown in FIG. 25.
[0274] The feed tube flow rate meter 65Q is capable of ascertaining
the flow rate of the secondary refrigerant for air warming that
passes through the air-warming feed tube 65. The flow rate of the
secondary refrigerant for air warming that flows through the
high-pressure-side branching channel 68 can be obtained by
subtracting the flow rate ascertained by the
intermediate-pressure-side branching channel flow rate meter 67Q
from the flow rate of the air-warming feed tube 65, which can be
ascertained by the feed tube flow rate meter 65Q, by using the
intermediate-pressure-side branching channel flow rate meter 67Q
and the feed tube flow rate meter 65Q. The control method and
calculation method can otherwise be carried out in the same manner
as Modification <14-11>.
[0275] The feed tube flow rate meter 65Q may also be provided in
place of the intermediate-pressure-side branching channel flow rate
meter 67Q rather than as a substitute for the high-pressure-side
branching channel flow rate meter 68Q.
<14-13>
[0276] It is also possible to use a heat pump system 9x in which a
feed tube temperature sensor 65T is provided in place of the
high-pressure-side branching temperature sensor 68T described above
in the embodiments, as shown in FIG. 26.
[0277] The feed tube temperature sensor 65T is capable of
ascertaining the temperature of the secondary refrigerant for air
warming that passes through the air-warming feed tube 65. The heat
amount of the secondary refrigerant for air warming that flows
through the high-pressure-side branching channel 68 can be
ascertained by calculating the heat amount of the secondary
refrigerant for air warming that flows through the air-warming feed
tube 65, from the temperature of the air-warming feed tube 65,
which can be ascertained by the feed tube temperature sensor 65T,
and subtracting therefrom the heat amount of the secondary
refrigerant for air warming flowing through the
intermediate-pressure-side branching channel 67 as obtained from
the temperature ascertained by the intermediate-pressure-side
branching temperature sensor 67T, by using the
intermediate-pressure-side branching temperature sensor 67T and the
feed tube temperature sensor 65T. In the case that the flow rate of
the secondary refrigerant for air warming flowing through the
high-pressure-side branching channel 68 can be ascertained, it is
possible to ascertain the temperature of the secondary refrigerant
flowing through the high-pressure-side branching channel 68 from
the thus-ascertained heat amount of the secondary refrigerant for
air warming that flows through the high-pressure-side branching
channel 68. Thus, control after the temperature of the secondary
refrigerant for air warming flowing through the
intermediate-pressure-side branching channel 67 and the temperature
of the secondary refrigerant for air warming flowing through the
high-pressure-side branching channel 68 are thus-ascertained can be
the same as that described in the embodiments above.
[0278] The feed tube temperature sensor 65T may be provided in
place of the intermediate-pressure-side branching tube temperature
sensor 67T rather than in place of the high-pressure-side branching
temperature sensor 68T.
[0279] As described above, in the case that the feed tube
temperature sensor 65T is provided, the controller 11 may control
the air-warming mixing valve 64 and the air-warming pump 63 so as
to reduce the difference between the temperature of the secondary
refrigerant for air warming detected by the feed tube temperature
sensor 65T and the temperature of the secondary refrigerant for air
warming ascertained by another temperature sensor (e.g., the
intermediate-pressure-side branching temperature sensor 67T). In
this case as well, the same effects as the embodiments described
above can be obtained.
<14-14>
[0280] In the embodiments described above, examples were described
for the case in which the temperatures of the secondary refrigerant
flowing through the third intermediate-pressure-side branching
channel 67c and the third high-pressure-side branching channel 68c
are equalized in the secondary refrigerant-temperature equalization
control.
[0281] However, no limit is imposed by the case in which the
temperatures are made perfectly identical; in any of the
embodiments described above, it is also possible to use control in
which the difference between the temperature of the secondary
refrigerant flowing through the third intermediate-pressure-side
branching channel 67c and the temperature of the secondary
refrigerant flowing through the third high-pressure-side branching
channel 68c is merely reduced.
[0282] It is furthermore possible to perform control so as to
satisfy a condition that the difference be equal to or less than a
predetermined value, rather than making a reduction in the
difference between the temperature of the secondary refrigerant
flowing through the third intermediate-pressure-side branching
channel 67c and the temperature of the secondary refrigerant
flowing through the third high-pressure-side branching channel
68c.
<14-15>
[0283] In the embodiments described above, examples were described
for the case in which the flow rate ratio in the air-warming mixing
valve 64 is controlled when the secondary refrigerant-temperature
equalization control is carried out.
[0284] However, in any of the embodiments described above, no
limitation is imposed by control in which the difference between
the temperature of the secondary refrigerant for air warming
flowing through the third intermediate-pressure-side branching
channel 67c and the temperature of the secondary refrigerant for
air warming flowing through the third high-pressure-side branching
channel 68c is reduced by controlling the flow rate ratio in the
air-warming mixing valve 64. For example, also included in the
present invention is the case in which the controller 11 performs a
control for increasing the flow rate through the air-warming pump
63 or reducing the flow rate through the air-warming pump 63 to
thereby reduce the difference between the temperature of the
secondary refrigerant for air warming flowing through the third
intermediate-pressure-side branching channel 67c and the
temperature of the secondary refrigerant for air warming flowing
through the third high-pressure-side branching channel 68c.
[0285] For example, in the case that the temperature of the
secondary refrigerant flowing through the third high-pressure-side
branching channel 68c is less than the temperature of the secondary
refrigerant flowing through the third intermediate-pressure-side
branching channel 67c, the controller 11 performs a control to
reduce the flow rate through the air-warming pump 63 to thereby
make it possible to reduce the temperature difference in a state in
which the temperature difference between the secondary refrigerant
for air warming and the primary refrigerant undergoing heat
exchange in the second high-pressure-water heat exchanger 52 is
greater than the temperature difference between the secondary
refrigerant for air warming and the primary refrigerant undergoing
heat exchange in the intermediate-pressure-water heat exchanger 40.
In this case, the time for receiving heat from the primary
refrigerant in either of the heat exchangers is extended by
reducing the flow rate through the air-warming pump 63, but the
reason for the considerable effect of increasing the temperature by
increasing the time duration is due to the secondary refrigerant
for air warming that passes through the second high-pressure-water
heat exchanger 52 side in which the temperature difference between
the primary refrigerant and the secondary refrigerant is
considerable.
[0286] In the case that the temperature of the secondary
refrigerant flowing through the third high-pressure-side branching
channel 68c is higher than the temperature of the secondary
refrigerant flowing through the third intermediate-pressure-side
branching channel 67c, the controller 11 performs a control to
increase the flow rate through the air-warming pump 63 to thereby
make it possible to reduce the temperature difference in a state in
which the temperature difference between the secondary refrigerant
for air warming and the primary refrigerant undergoing heat
exchange in the second high-pressure-water heat exchanger 52 is
greater than the temperature difference between the secondary
refrigerant for air warming and the primary refrigerant undergoing
heat exchange in the intermediate-pressure-water heat exchanger 40.
In this case, the time for receiving heat from the primary
refrigerant in either of the heat exchangers is reduced by
increasing the flow rate through the air-warming pump 63, but the
reason for the considerable effect of reducing the temperature by
reducing the time duration is due to the secondary refrigerant for
air warming that passes through the second high-pressure-water heat
exchanger 52 side in which the temperature difference between the
primary refrigerant and the secondary refrigerant is
considerable.
[0287] In the case that the temperature of the secondary
refrigerant flowing through the third high-pressure-side branching
channel 68c is less than the temperature of the secondary
refrigerant flowing through the third intermediate-pressure-side
branching channel 67c, the controller 11 performs a control to
increase the flow rate through the air-warming pump 63 to thereby
make it possible to reduce the temperature difference in a state in
which the temperature difference between the secondary refrigerant
for air warming and the primary refrigerant undergoing heat
exchange in the second high-pressure-water heat exchanger 52 is
less than the temperature difference between the secondary
refrigerant for air warming and the primary refrigerant undergoing
heat exchange in the intermediate-pressure-water heat exchanger 40.
In this case, the time for receiving heat from the primary
refrigerant in either of the heat exchangers is reduced by
increasing the flow rate through the air-warming pump 63, but the
reason for the considerable effect of reducing the temperature by
reducing the time duration is due to the secondary refrigerant for
air warming that passes through the intermediate-pressure-water
heat exchanger 40 side in which the temperature difference between
the primary refrigerant and the secondary refrigerant is
considerable.
[0288] In the case that the temperature of the secondary
refrigerant flowing through the third high-pressure-side branching
channel 68c is greater than the temperature of the secondary
refrigerant flowing through the third intermediate-pressure-side
branching channel 67c, the controller 11 performs a control to
reduce the flow rate through the air-warming pump 63 to thereby
make it possible to reduce the temperature difference in a state in
which the temperature difference between the secondary refrigerant
for air warming and the primary refrigerant undergoing heat
exchange in the second high-pressure-water heat exchanger 52 is
less than the temperature difference between the secondary
refrigerant for air warming and the primary refrigerant undergoing
heat exchange in the intermediate-pressure-water heat exchanger 40.
In this case, the time for receiving heat from the primary
refrigerant in either of the heat exchangers is increased by
reducing the flow rate through the air-warming pump 63, but the
reason for the considerable effect of increasing the temperature by
extending the time duration is due to the secondary refrigerant for
air warming that passes through the intermediate-pressure-water
heat exchanger 40 side in which the temperature difference between
the primary refrigerant and the secondary refrigerant is
considerable.
<14-16>
[0289] In the embodiments described above, examples were described
for the case in which no particular control is performed in terms
of the relationship between the temperature of the primary
refrigerant flowing through the intermediate-pressure-water heat
exchanger 40 and the temperature of the primary refrigerant flowing
through the second high-pressure-water heat exchanger 52.
[0290] However, in any of the embodiments described above, it is
also possible for the controller 11 to control the hot-water supply
pump 92 so as to, e.g., adjust and bring the temperature of the
primary refrigerant flowing into the second high-pressure-water
heat exchanger 52 close to the temperature of the primary
refrigerant flowing into the intermediate-pressure-water heat
exchanger 40 by adjusting the flow rate of the water for hot-water
supply that is passing through the first high-pressure water heat
exchanger 51.
[0291] For example, in the case that the target discharge
temperature of the high-stage-side compressor 25 is set higher than
the target discharge temperature of the low-stage-side compressor
21, it is not possible bring the inlet temperature of the primary
refrigerant of the intermediate-pressure-water heat exchanger 40
and the inlet temperature of the primary refrigerant of the second
high-pressure-water heat exchanger 52 close together unless the
temperature of the primary refrigerant discharged from the
high-stage-side compressor 25 is reduced. In such a case, the
controller 11 may control the hot-water supply pump 92 on the basis
of the temperature detected by the hot-water supply intermediate
temperature sensor 95T so that the water for hot-water supply
required for cooling the primary refrigerant in the first
high-pressure water heat exchanger 51 is fed.
[0292] In this case, the temperature of the secondary refrigerant
for air warming flowing through the third
intermediate-pressure-side branching channel 67c and the
temperature of the secondary refrigerant for air warming flowing
through the third high-pressure-side branching channel 68c are more
readily brought close together because the temperature near the
primary-refrigerant inlet of the intermediate-pressure-water heat
exchanger 40 corresponding to the outlet side of the secondary
refrigerant for air warming and the temperature near the
primary-refrigerant inlet of the second high-pressure-water heat
exchanger 52 corresponding to the outlet of the secondary
refrigerant for air warming are proximate values. For example, the
temperature is more readily equalized when the flow rate through
the air-warming pump 63 is reduced. Since the temperature of the
secondary refrigerant for air warming flowing through the third
intermediate-pressure-side branching channel 67c and the
temperature of the secondary refrigerant for air warming flowing
through the third high-pressure-side branching channel 68c are more
readily brought close together, it is possible to minimize the
amount of degradation of the cycle efficiency in the heat pump
circuit 10 caused by secondary refrigerant-temperature equalization
control.
<14-17>
[0293] In the embodiments described above, examples were described
for the case in which the control of the heat pump circuit 10 side
is not particularly specified.
[0294] However, the operating conditions are changed by carrying
out secondary refrigerant-temperature equalization control in the
air-warming circuit 60, and there are cases in which degradation of
the cycle efficiency of the heat pump circuit 10 can be reduced or
improved.
[0295] Here, the compression ratio in the low-stage-side compressor
21 tends to increase in the case that, e.g., the target discharge
temperature of the low-stage-side compressor 21 is increased in
order to handle the air-warming heat load, as shown in the Mollier
graph of FIG. 27 (see the change from the dotted lines to the
dot-dash lines). In accordance with the preceding, there is also an
increase in the compression ratio of the high-stage-side compressor
25 with which alignment is being attempted. Therefore, the required
drive force is increased and energy consumption is also
increased.
[0296] In contrast, the controller 11 may, e.g., modify the
operating conditions from the cycle of the dotted lines to the
cycle of the solid lines (see the change from the dotted lines to
the solid lines), as shown in the Mollier graph of FIG. 28. In
other words, it is possible to perform low-stage intake
degree-of-superheat control for increasing the degree of superheat
of the primary refrigerant taken in by the low-stage-side
compressor 21 in the case that the target discharge temperature of
the low-stage-side compressor 21 is increased. The compression
ratio of the low-stage-side compressor 21 required for achieving
the target discharge temperature of the low-stage-side compressor
21 can be minimized thereby. In association therewith, it is also
possible to minimize the compression ratio of the high-stage-side
compressor 25. The required drive force can be further minimized
thereby.
[0297] It is conversely possible to perform low-stage intake
degree-of-superheat control for reducing the degree of superheat of
the primary refrigerant taken in by the low-stage-side compressor
21 in the case that the cycle state is modified so that the target
discharge temperature of the low-stage-side compressor 21 is
reduced. The specific volume of the primary refrigerant taken in by
the low-stage-side compressor 21 can be reduced while an increase
in the compression ratio of the high-stage-side compressor 25 is
suppressed by minimizing an increase in the compression ratio of
the low-stage-side compressor 21. It is therefore possible to
ensure a circulation amount and to increase capacity while
suppressing an increase in the compression ratio.
[0298] For example, in the control described above, the controller
11 controls the opening degree of the primary bypass expansion
valve 5b, making it possible to adjust the amount of heat exchange
in the primary-refrigerant-to-primary-refrigerant heat exchanger 8
in the heat pump circuit 10 having the primary bypass 80 and the
primary bypass expansion valve 5b among the heat pump systems
described in the embodiments and modifications above. Thus, the
superheat degree of the primary refrigerant taken in by the
low-stage-side compressor 21 can be adjusted.
<14-18>
[0299] In the embodiments described above, examples were described
for the case in which the control of the heat pump circuit 10 side
is not particularly specified.
[0300] However, the operating conditions are changed by carrying
out secondary refrigerant-temperature equalization control in the
air-warming circuit 60, and there are cases in which degradation of
the cycle efficiency of the heat pump circuit 10 can be reduced or
improved.
[0301] Here, there may be cases in which a high temperature is not
required as the temperature of the primary refrigerant flowing
through the intermediate-pressure-water heat exchanger 40 in the
case that the temperature of the secondary refrigerant for air
warming is not significantly reduced in the radiator 61 due to,
among other factors, a lower air-warming heat load.
[0302] In contrast, the controller 11 may, e.g., modify the
operating conditions from the cycle of the dotted lines to the
cycle of the solid lines (see the change from the dotted lines to
the solid lines), as shown in the Mollier graph of FIG. 29. In
other words, it is possible to perform control so that the degree
of superheat of the primary refrigerant taken in by the
low-stage-side compressor 21 is also reduced while the target
discharge temperature of the low-stage-side compressor 21 is
reduced. The compression ratio of the high-stage-side compressor 25
and the compression ratio of the low-stage-side compressor 21
become substantially the same, and it is possible to achieve
efficient operation in which the drive forces of the low-stage-side
compressor 21 and the high-stage-side compressor 25 are minimized.
It is possible to adapt to the load even when the target discharge
temperature of the low-stage-side compressor 21 is reduced in this
manner, because the heat load requested by the radiator 61 is
reduced. The compression drive force can thereby be further reduced
while adapting to load fluctuations.
[0303] For example, in the control described above, the controller
11 controls the opening degree of the primary bypass expansion
valve 5b, making it possible to adjust the amount of heat exchange
in the primary-refrigerant-to-primary-refrigerant heat exchanger 8
in the heat pump circuit 10 having the primary bypass 80 and the
primary bypass expansion valve 5b among the heat pump systems
described in the embodiments and modifications above. Thus, the
superheat degree of the primary refrigerant taken in by the
low-stage-side compressor 21 can be adjusted.
INDUSTRIAL APPLICABILITY
[0304] The refrigeration apparatus of the present invention is
capable of improving cycle efficiency in the processing of the heat
load performed by the secondary refrigerant, and is therefore
particularly useful in the case that application is made to a heat
pump system for processing a heat load using a heat pump circuit
provided with a multistage compression-type compression
element.
REFERENCE SIGNS LIST
[0305] 1 Heat pump system [0306] 4 Evaporator [0307] 4f Fan [0308]
5a Expansion valve [0309] 5b Primary bypass expansion valve [0310]
7 Economizer heat exchanger [0311] 8
Primary-refrigerant-to-primary-refrigerant heat exchanger [0312] 10
Heat pump circuit [0313] 20 Low-pressure tube [0314] 20a to f First
to sixth low-pressure tube [0315] 20P Low-pressure pressure sensor
[0316] 20T Low-pressure temperature sensor [0317] 21 Low-stage-side
compressor [0318] 23 Intermediate pressure tube [0319] 23a to d
First to fourth intermediate pressure tube [0320] 23T
Intermediate-pressure temperature sensor [0321] 24P High-stage
intake pressure sensor [0322] 24T High-stage intake temperature
sensor [0323] 25 High-stage-side compressor [0324] 27 High-pressure
tube [0325] 27a to n First to fourteenth high-pressure tube [0326]
27P High-pressure pressure sensor [0327] 27T High-pressure
temperature sensor [0328] 40 Intermediate-pressure water heat
exchanger [0329] 50 High-pressure water heat exchanger [0330] 51 to
53 First to third high-pressure water heat exchanger [0331] 60
Air-warming circuit [0332] 61 Radiator [0333] 61T Radiator
temperature sensor [0334] 62 Branch flow mechanism (first flow rate
adjustment mechanism) [0335] 63 Air-warming pump (flow rate
adjustment section) [0336] 64 Air-warming mixing valve [0337] 65
Air-warming feed tube [0338] 65T Feed tube temperature sensor
[0339] 65Q Feed tube flow rate meter [0340] 66 Air-warming return
tube [0341] 66T Air-warming return temperature sensor [0342] 67
Intermediate-pressure-side branching channel [0343] 67T
Intermediate-pressure-side branching channel temperature sensor
[0344] 67Q Intermediate-pressure-side branching channel flow rate
meter [0345] 67a to c First to third intermediate-pressure-side
branching channel [0346] 68 High-pressure-side branching channel
[0347] 68T High-pressure-side branching channel temperature sensor
[0348] 68Q High-pressure-side branching channel flow rate meter
[0349] 69 Air-warming bypass channel (first heat load bypass
channel) [0350] 70 Injection channel [0351] 72 First injection tube
[0352] 74 Second injection tube [0353] 75 Third injection tube
[0354] 76 Fourth injection tube [0355] 73 Injection expansion valve
[0356] 90 Primary bypass [0357] 90 Hot-water supply circuit [0358]
91 Hot-water storage tank [0359] 92 Hot-water supply pump [0360] 93
Hot-water supply mixing valve [0361] 94 Water supply tube [0362]
94T Hot-water supply water-intake temperature sensor [0363] 95
Hot-water supply heat pump tube [0364] 95a to f First to sixth
hot-water supply heat pump tube [0365] 95T Hot-water supply
intermediate temperature sensor [0366] 98 Hot-water supply tube
[0367] 98T Hot-water supply hot-water outlet temperature sensor
[0368] 99 Hot-water supply bypass tube [0369] 164 Twelfth
air-warming mixing valve (first heat load bypass flow rate
adjustment mechanism) [0370] A Intake point [0371] B Low-stage
discharge point [0372] C Intermediate-pressure water heat exchanger
passage point [0373] D Injection merge point [0374] E High-stage
discharge point [0375] F First high-pressure point [0376] G Second
high-pressure point [0377] H Third high-pressure point [0378] I
Fourth high-pressure point [0379] J Fifth high-pressure point
[0380] K First low-pressure point [0381] L Second low-pressure
point [0382] M Third low-pressure point [0383] N Fourth
low-pressure point [0384] Q Injection intermediate-pressure point
[0385] R Economizer post-heat-exchange point [0386] X Air-warming
branching point [0387] Y Air-warming merging point [0388] W Water
supply branching point [0389] Z Hot-water supply merging point
CITATION LIST
Patent Literature
[0389] [0390] <Patent Literature 1> Japanese Laid-open Patent
Application Publication No. 2004-177067
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