U.S. patent application number 15/076649 was filed with the patent office on 2016-12-15 for heat exchange apparatus and heat pump apparatus.
The applicant listed for this patent is Panasonic Intellectual Property Management Co., Ltd.. Invention is credited to BUNKI KAWANO, TOMOICHIRO TAMURA.
Application Number | 20160363351 15/076649 |
Document ID | / |
Family ID | 55745676 |
Filed Date | 2016-12-15 |
United States Patent
Application |
20160363351 |
Kind Code |
A1 |
KAWANO; BUNKI ; et
al. |
December 15, 2016 |
HEAT EXCHANGE APPARATUS AND HEAT PUMP APPARATUS
Abstract
A heat exchange apparatus according to the present disclosure
includes a refrigerant supply source, an ejector, an extractor, a
first pump, a second pump, a cooler, and a liquid passage. The
first pump is a dynamic pump and disposed on the liquid passage
between the extractor and the cooler. The second pump is a positive
displacement pump and disposed on the liquid passage between an
outlet of the first pump and an inlet of refrigerant liquid of the
ejector.
Inventors: |
KAWANO; BUNKI; (Osaka,
JP) ; TAMURA; TOMOICHIRO; (Kyoto, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Intellectual Property Management Co., Ltd. |
Osaka |
|
JP |
|
|
Family ID: |
55745676 |
Appl. No.: |
15/076649 |
Filed: |
March 22, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 1/08 20130101; F25B
43/006 20130101; F25B 2341/0014 20130101; F25B 31/00 20130101; F25B
2341/001 20130101; F25B 2400/16 20130101; F25B 41/003 20130101;
F25B 45/00 20130101; F25B 30/02 20130101 |
International
Class: |
F25B 1/08 20060101
F25B001/08; F25B 45/00 20060101 F25B045/00; F25B 43/00 20060101
F25B043/00; F25B 30/02 20060101 F25B030/02; F25B 31/00 20060101
F25B031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 9, 2015 |
JP |
2015-116413 |
Claims
1. A heat exchange apparatus comprising: a refrigerant supply
source that supplies a refrigerant vapor, the refrigerant vapor
being a refrigerant in a vapor phase; a cooler that cools a
refrigerant liquid and that supplies the cooled refrigerant liquid,
the refrigerant liquid being the refrigerant in a liquid phase; an
ejector that produces a refrigerant mixed flow using the
refrigerant vapor supplied from the refrigerant supply source and
the cooled refrigerant liquid supplied from the cooler; an
extractor that receives the refrigerant mixed flow from the ejector
and extracts the refrigerant liquid from the refrigerant mixed
flow; a liquid passage that constitutes a loop on which the
extractor, the cooler and the ejector are disposed in this order
and that circulates the refrigerant liquid flowing therein; a first
pump that is a dynamic pump, that is disposed on the liquid passage
between the an outlet of the extractor and an inlet of the cooler,
and that pumps the liquid refrigerant from the extractor to the
cooler; and a second pump that is a positive displacement pump and
that is disposed on the liquid passage between an outlet of the
first pump and an inlet of the ejector.
2. The heat exchange apparatus according to claim 1, further
comprising: a third pump that is a dynamic pump and that is
disposed on the liquid passage between the outlet of the first pump
and inlet of the second pump.
3. The heat exchange apparatus according to claim 1, wherein the
second pump is disposed on the liquid passage between the outlet of
the first pump and an inlet of the cooler.
4. The heat exchange apparatus according to claim 1, wherein the
first pump is located at a lowest level in a vertical direction on
the liquid passage.
5. The heat exchange apparatus according to claim 1, wherein the
first pump and the second pump are located at an identical level in
a vertical direction.
6. The heat exchange apparatus according to claim 1, wherein the
first pump has a required net positive suction head smaller than a
required net positive suction head of the second pump, and the
first pump has a width of pressure increase larger than the
required net positive suction head of the second pump.
7. The heat exchange apparatus according to claim 1, wherein the
second pump has a pump efficiency higher than a pump efficiency of
the first pump.
8. The heat exchange apparatus according to claim 1, wherein a
saturation vapor pressure at a temperature of 20.degree.
C.+-.15.degree. C. of the refrigerant is lower than an atmospheric
pressure.
9. A heat pump apparatus comprising: the heat exchange apparatus
according to claim 1, wherein the refrigerant supply source is a
compressor that compresses a refrigerant vapor input to the
refrigerant supply source and that outputs the compressed
refrigerant vapor to the ejector.
10. The heat pump apparatus according to claim 9, further
comprising: an evaporator that generates the refrigerant vapor to
be supplied to the compressor; and a liquid back passage that
connects the extractor and the evaporator and that flows a
refrigerant liquid that has an amount equal to the refrigerant that
was output from the evaporator and that was supplied to the
extractor via the compressor and the ejector.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present disclosure relates to a heat exchange apparatus
and a heat pump apparatus.
[0003] 2. Description of the Related Art
[0004] Conventional heat exchange apparatus has been used for
refrigeration cycle apparatus applied to equipment such as an air
conditioner, a refrigerator freezer, and a water heater. Japanese
Patent No. 4454456 describes a refrigeration cycle apparatus using
water as a refrigerant having an extremely small load on the global
environment. FIG. 6 illustrates a refrigeration cycle apparatus
described in Japanese Patent No. 4454456.
[0005] As illustrated in FIG. 6, a refrigeration cycle apparatus
100 includes an evaporator 110, a condenser 120, a connection pipe
130, and a connection pipe 150. An upper portion of the evaporator
110 is connected to an upper portion of the condenser 120 by the
connection pipe 130. The connection pipe 130 is provided with a
compressor 140. A lower portion of the evaporator 110 is connected
to a lower portion of the condenser 120 by the connection pipe 150.
The evaporator 110 is connected to an evaporator-side liquid
passage 160. The evaporator-side liquid passage 160 is provided
with a load 180 and a cold water pump 220. The condenser 120 is
connected to a condenser-side liquid passage 170. The
condenser-side liquid passage 170 is provided with a cooling tower
210 and a coolant pump 230.
SUMMARY
[0006] In one general aspect, the techniques disclosed here feature
a heat exchange apparatus including: a refrigerant supply source
that supplies a refrigerant vapor, the refrigerant vapor being a
refrigerant in a vapor phase; a cooler that cools a refrigerant
liquid and that supplies the cooled refrigerant liquid, the
refrigerant liquid being the refrigerant in a liquid phase; an
ejector that produces a refrigerant mixed flow using the
refrigerant vapor supplied from the refrigerant supply source and
the cooled refrigerant liquid supplied from the cooler; an
extractor that receives the refrigerant mixed flow from the ejector
and extracts the refrigerant liquid from the refrigerant mixed
flow; a liquid passage that constitutes a loop on which the
extractor, the cooler and the ejector are disposed in this order
and that circulates the refrigerant liquid flowing therein; a first
pump that is a dynamic pump, that is disposed on the liquid passage
between the an outlet of the extractor and an inlet of the cooler,
and that pumps the liquid refrigerant from the extractor to the
cooler; and a second pump that is a positive displacement pump and
that is disposed on the liquid passage between an outlet of the
first pump and an inlet of the ejector.
[0007] With the technique described above, a height from the first
pump (dynamic pump) to the extractor can be reduced so that the
size of the heat exchange apparatus can be reduced. Thus,
performance of the heat exchange apparatus can be reduced with a
suppressed increase in the size of the heat exchange apparatus.
[0008] Additional benefits and advantages of the disclosed
embodiments will become apparent from the specification and
drawings. The benefits and/or advantages may be individually
obtained by the various embodiments and features of the
specification and drawings, which need not all be provided in order
to obtain one or more of such benefits and/or advantages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 illustrates a configuration of a heat exchange
apparatus according to a first embodiment;
[0010] FIG. 2 is a sectional view of an ejector;
[0011] FIG. 3 illustrates a configuration of a heat exchange
apparatus according to a second embodiment;
[0012] FIG. 4 illustrates a configuration of a heat exchange
apparatus according to a third embodiment;
[0013] FIG. 5 illustrates a configuration of a heat exchange
apparatus according to a fourth embodiment; and
[0014] FIG. 6 illustrates a configuration of a conventional
refrigeration cycle apparatus.
DETAILED DESCRIPTION
(Underlying Knowledge Forming Basis of the Present Disclosure)
[0015] With an increased awareness of environments such as global
warming, further enhancement of performance has been required for a
heat exchange apparatus or a heat pump apparatus. However, a
technique for enhancing performance of the heat exchange apparatus
or the heat pump apparatus often causes an increase in size of a
system.
[0016] To enhance performance of a heat exchange apparatus or a
heat pump apparatus, a technique for efficiency increasing the
pressure of refrigerant is needed. In view of this, inventors of
the present invention have developed a technique of replacing a
condenser with a condensation ejector and an extractor, as a
technique for efficiency increasing the pressure of refrigerant.
The extractor extracts only refrigerant liquid from a refrigerant
flow in two phases discharged from the condensation ejector. The
pressure of refrigerant discharged from the compressor is
efficiently increased with the condensation ejector so that the
refrigerant is condensed, thereby reducing work on the compressor.
Accordingly, a coefficient of performance (COP) of a system can be
enhanced.
[0017] However, the inventors found that a system employing the
above-described technique requires a pump discharge pressure ten
times as high as that of a conventional system. That is, to enhance
the COP of a system, a pressure increase efficiency obtained by a
pump and an ejector needs to exceed a pressure increase efficiency
of a compressor. However, to increase the pump discharge pressure
while maintaining a high pump efficiency, the head required for
suppressing cavitation of the pump (required net positive suction
head: NPSHr) significantly increases. If the required pump
discharge pressure decuples, the required net positive suction head
also decuples. This NPSHr needs to be obtained with a height
(water-level head) from the inlet of the pump to an internal liquid
level of the extractor. In the conventional refrigeration cycle
apparatus described in Japanese Patent No. 4454456, for example, a
water-level head of 1 m is obtained. In the conventional
refrigeration cycle apparatus described in Japanese Patent No.
4454456, in a case where the condenser 120 is replaced with an
ejector and an extractor, a water-level head of 10 m is required.
This causes an increase in size of the system.
[0018] As described above, the inventors of the present invention
found difficulty, as a new problem, in obtaining both maintenance
of a high pump efficiency and prevention of a system size increase
in fabricating a heat exchange apparatus in which a condenser is
replaced with a condensation ejector and an extractor and a
refrigerant vapor from a refrigerant supply source is efficiently
increased in pressure and condensed by pump power. Based on the
finding of the new problem, the inventors have reached the
following aspects of the invention.
[0019] In a first aspect of the present disclosure, a heat exchange
apparatus includes:
[0020] a refrigerant supply source that supplies a refrigerant
vapor, the refrigerant vapor being a refrigerant in a vapor
phase;
[0021] a cooler that cools a refrigerant liquid and that supplies
the cooled refrigerant liquid, the refrigerant liquid being the
refrigerant in a liquid phase;
[0022] an ejector that produces a refrigerant mixed flow using the
refrigerant vapor supplied from the refrigerant supply source and
the cooled refrigerant liquid supplied from the cooler;
[0023] an extractor that receives the refrigerant mixed flow from
the ejector and extracts the refrigerant liquid from the
refrigerant mixed flow;
[0024] a liquid passage that constitutes a loop on which the
extractor, the cooler and the ejector are disposed in this order
and that circulates the refrigerant liquid flowing therein;
[0025] a first pump that is a dynamic pump, that is disposed on the
liquid passage between the an outlet of the extractor and an inlet
of the cooler, and that pumps the liquid refrigerant from the
extractor to the cooler; and
[0026] a second pump that is a positive displacement pump and that
is disposed on the liquid passage between an outlet of the first
pump and an inlet of the ejector.
[0027] In the first aspect, a width of pressure increase (a pump up
width or range) by the first pump can be set at a width
corresponding to the NPSHr of the second pump. Since the NPSHr of
the second pump is sufficiently smaller than a required pressure of
the ejector, the width of pressure increase required for the first
pump is small, and the NPSHr of the first pump is also small. Thus,
the use of a dynamic pump as the first pump can efficiently
increase the pressure with a small NPSHr. In addition, the second
pump sucks refrigerant liquid whose pressure has been increased in
a width corresponding to the NPSHr of the second pump, and thus,
the risk of performance degradation due to cavitation in the second
pump can be reduced. Accordingly, the pressure of an efficient
positive displacement pump as the second pump can efficiently
increase the pressure of refrigerant liquid to a required pressure
of the ejector. Thus, in this configuration, the height from the
first pump to the extractor is reduced so that the size of the heat
exchange apparatus can be reduced and the pressure of refrigerant
liquid can be efficiently increased to a required pressure of the
ejector.
[0028] In a second aspect of the present disclosure, the heat
exchange apparatus in the first aspect may further include: a third
pump that is a dynamic pump and that is disposed on the liquid
passage between the outlet of the first pump and an inlet of the
second pump. In the second aspect, the width of pressure increase
by the first pump can be further reduced so that the NPSHr of the
first pump can be further reduced and the size of the heat exchange
apparatus can be further reduced.
[0029] In a third aspect of the present disclosure, the second pump
of the heat exchange apparatus of the first or second aspect may be
disposed on the liquid passage between the outlet of the first pump
and an inlet of the cooler.
[0030] In a fourth aspect of the present disclosure, the first pump
of the heat exchange apparatus in one of the first to third aspects
may be located at a lowest level in a vertical direction on the
liquid passage.
[0031] In a fifth aspect of the present disclosure, the first pump
and the second pump of the heat exchange apparatus in one of the
first to fourth aspects may be located at an identical level in a
vertical direction.
[0032] In a sixth aspect of the present disclosure, in the heat
exchange apparatus in one of the first to fifth aspects, the first
pump may have a required net positive suction head smaller than a
required net positive suction head of the second pump, and the
first pump may have a width of pressure increase larger than the
required net positive suction head of the second pump.
[0033] In a seventh aspect of the present disclosure, the second
pump of the heat exchange apparatus in one of the first to sixth
aspects may have a pump efficiency higher than a pump efficiency of
the first pump. The phrase of "the second pump has a pump
efficiency higher than a pump efficiency of the first pump" means
that the maximum efficiency of the second pump is higher than the
maximum efficiency of the first pump.
[0034] In an eighth aspect of the present disclosure, a saturation
vapor pressure at a temperature of 20.degree. C..+-.15.degree. C.
of the refrigerant of the heat exchange apparatus in one of the
first to seventh aspects may be lower than an atmospheric
pressure.
[0035] A heat pump apparatus in a ninth aspect of the present
disclosure includes the heat exchange apparatus according to any
one of the first to eighth aspects, and the refrigerant supply
source is a compressor that compresses a refrigerant vapor input to
the refrigerant supply source and that outputs the compressed
refrigerant vapor to the ejector. In the ninth aspect, advantages
as those of the first aspect can be obtained.
[0036] In a tenth aspect of the present disclosure, the heat pump
apparatus in the ninth aspect may further include an evaporator
that generates the refrigerant vapor to be supplied to the
compressor; and a liquid back passage that connects the extractor
and the evaporator and that flows a refrigerant liquid that has an
amount equal to the refrigerant that was output from the evaporator
and that was supplied to the extractor via the compressor and the
ejector. With the configuration in which the amount of the
refrigerant liquid in the evaporator and the amount of the
refrigerant liquid in the extractor are balanced by the liquid back
passage, the heat pump apparatus can be stably operated.
[0037] Embodiments of the present disclosure will be described
hereinafter with reference to the drawings. The present disclosure
is not limited to the following embodiments.
FIRST EMBODIMENT
[0038] As illustrated in FIG. 1, a heat exchange apparatus 200
according to a first embodiment includes a refrigerant supply
source 11, an ejector 12, an extractor 13, a first pump 14, a
second pump 15, a cooler 16, and a first liquid passage 17. The
first liquid passage 17 constitutes a loop and includes pipes 17a
to 17e. On the loop constituted by the first liquid passage 17, the
ejector 12, the extractor 13, the first pump 14, the second pump
15, and the cooler 16 are connected to one another in this order by
the pipes 17a to 17e.
[0039] The refrigerant supply source 11 is not specifically limited
as long as the refrigerant supply source 11 can supply a
refrigerant vapor (a refrigerant in a gas phase) to the ejector 12.
The refrigerant supply source 11 is, for example, a compressor that
is a component of a heat pump apparatus. The refrigerant supply
source 11 may be an evaporator that vaporizes a refrigerant (e.g.,
water) by using exhaust heat from factories and outputs the
vaporized refrigerant as a refrigerant vapor.
[0040] As illustrated in FIG. 2, the ejector 12 includes a first
nozzle 23, a second nozzle 25, a mixing portion 27, and a diffuser
portion 28. The first nozzle 23 is connected to the cooler 16 by
the pipe 17e. The refrigerant liquid (refrigerant in a liquid
phase) flowed from the cooler 16 is supplied as a motive flow to
the first nozzle 23 through the pipe 17e. The second nozzle 25 is
connected to the refrigerant supply source 11 by the pipe 26b
(vapor passage). The temperature of liquid refrigerant ejected from
the first nozzle 23 is reduced by the cooler 16. The refrigerant
liquid ejected from the first nozzle 23 with acceleration and the
expanded refrigerant vapor ejected from the second nozzle 25 with
acceleration are mixed in the mixing portion 27. Then, there occur
first condensation due to a temperature difference between the
refrigerant liquid and the refrigerant vapor and second
condensation due to a pressure increase based on energy
transportation between the refrigerant liquid and the refrigerant
vapor and momentum transportation between the refrigerant liquid
and the refrigerant vapor. The refrigerant vapor supplied from the
refrigerant supply source 11 is continuously sucked into the second
nozzle 25 through the pipe 26b. Through the two condensation
stages, a refrigerant mixed flow having a small quality (dryness
fraction) is generated. The diffuser portion 28 restores a static
pressure by decelerating the refrigerant mixed flow. In the ejector
12 having such a configuration, the temperature and pressure of
refrigerant increase.
[0041] The ejector 12 includes a needle pipe 29 and a servo
actuator 30. The needle pipe 29 and the servo actuator 30 are flow
controllers for controlling the flow rate of refrigerant liquid as
a motive flow. The cross section of the orifice of the first nozzle
23 at a tip thereof can be changed by using the needle pipe 29. The
servo actuator 30 can adjust the location of the needle pipe 29.
With this configuration, the flow rate of the refrigerant liquid
flowing in the first nozzle 23 can be controlled.
[0042] The extractor 13 receives the refrigerant mixed flow from
the ejector 12, extracts refrigerant liquid from the refrigerant
mixed flow, and stores the refrigerant liquid. That is, the
extractor 13 separates the refrigerant liquid and the refrigerant
vapor from each other. The extractor 13 basically extracts only the
refrigerant liquid. The extractor 13 is, for example, a
pressure-resistant container having heat insulating properties. The
configuration of the extractor 13 is not specifically limited as
long as the extractor 13 can extract refrigerant liquid.
[0043] The first liquid passage 17 is a passage through which
refrigerant liquid flowed from the extractor 13 returns to the
extractor 13 via the cooler 16 and the ejector 12. The first
passage 17 constitutes a loop. On the first passage 17, the
extractor 13, the cooler 16, and the ejector 12 are arranged in
this order. The refrigerant liquid circulates in the first passage
17.
[0044] The first pump 14 is disposed on the first liquid passage 17
between the extractor 13 and the cooler 16 (specifically between an
outlet of the extractor 13 and an inlet of the cooler 16). The
first pump 14 pumps the refrigerant liquid received from the
extractor 13 to the cooler 16.
[0045] In the first embodiment, the first pump 14 is a dynamic
pump. The dynamic pump is a pump that gives a speed to received
fluid (refrigerant liquid), increases the pressure thereof by
performing static pressure recovery on the given speed, and sends
the fluid. Examples of the dynamic pump include a centrifugal pump,
a diagonal pump, and an axial flow pump. The first pump 14 is
disposed at a location at which a height H from an inlet of the
first pump 14 to the liquid level of refrigerant liquid in the
extractor 13 is larger than the NPSHr of the first pump 14.
[0046] The second pump 15 is disposed on the first liquid passage
17 between an outlet of the first pump 14 to a liquid inlet (inlet
of refrigerant liquid, inlet of a motive flow) of the ejector 12.
In the first embodiment, the second pump 15 is disposed on the
first liquid passage 17 between the outlet of the first pump 14 and
the inlet of the cooler 16. In a case where the second pump 15 is
disposed at such a location, a pressure loss in a section between
the outlet of the first pump 14 and an inlet of the second pump 15
can be minimized. Consequently, the possibility of cavitation in
the second pump 15 further decreases. In addition, the possibility
that the second pump 15 sucks a refrigerant in a gas phase in a
period of transition such as a start time also decreases.
Alternatively, the second pump 15 may be disposed on the first
liquid passage 17 between an outlet of the cooler 16 and the liquid
inlet of the ejector 12. That is, the second pump 15 may be
disposed downstream of the cooler 16.
[0047] In the first embodiment, the second pump 15 is a positive
displacement pump. The positive displacement pump is a pump that
increases the pressure of received fluid (refrigerant liquid) by
changing the volume thereof and sends the fluid. Examples of the
positive displacement pump include a piston pump, a plunger pump, a
gear pump, a roots pump, a vane pump, and a rotary pump.
[0048] In the first embodiment, the first pump 14 is located at a
lowest level in a vertical direction in the first liquid passage
17. The positional relationship between the first pump 14 and the
second pump 15 in the vertical direction is not specifically
limited. However, the second pump 15 and the first pump 14 are
preferably disposed at an identical level in the vertical
direction.
[0049] In the first embodiment, in the first pump 14, the pressure
of refrigerant liquid is increased to a pressure at which the
second pump 15 does not cause cavitation. A most important
performance required for the first pump 14 is unlikeliness of
cavitation with a small NPSHr. That is, a dynamic pump is more
preferably used as the first pump 14 than a positive displacement
pump is. The dynamic pump has difficulty in increasing the pressure
of refrigerant liquid to a high pressure but is not likely to cause
cavitation with a small NPSHr. On the other hand, most important
performances for the second pump 15 are high efficiency and
capability of increasing the pressure of refrigerant liquid to a
high pressure. That is, a positive displacement pump is more
preferably used as the second pump 15 than a dynamic pump is. The
NPSHr of the first pump 14 is smaller than the NPSHr of the second
pump 15. The ratio of (NPSHr of first pump 14)/(NPSHr of second
pump 15) is about 0.1, for example.
[0050] The cooler 16 is constituted by a known heat exchanger such
as a fin-and-tube heat exchanger, a shell-and-tube heat exchanger,
and a cooling tower.
[0051] An operation of the heat exchange apparatus 200 will now be
described.
[0052] First, the ejector 12 receives a refrigerant vapor
discharged from the refrigerant supply source 11 and a refrigerant
liquid supplied from the cooler 16 and generates a refrigerant
mixed flow. The refrigerant mixed flow generated by the ejector 12
is input to the extractor 13. The extractor 13 extracts refrigerant
liquid and stores the refrigerant liquid therein. The refrigerant
liquid stored in the extractor 13 is supplied to the ejector 12 via
the first pump 14, the second pump 15, and the cooler 16. To reduce
a loss of an effective head by a pressure loss of the pipe, the
first pump 14 is disposed on the first liquid passage 17 between
the outlet of the extractor 13 and the inlet of the cooler 16. The
refrigerant liquid stored in the extractor 13 is first sucked into
the first pump 14 and is then increased in pressure in the first
pump 14. The pressure of the refrigerant liquid that has been
increased by the first pump 14 is further increased by the second
pump 15 disposed on the first liquid passage 17 between the outlet
of the first pump 14 and the liquid inlet of the ejector 12. The
second pump 15 may be disposed on the first liquid passage 17
between the outlet of the cooler 16 and the liquid inlet of the
ejector 12.
[0053] In the first embodiment, the pressure of the refrigerant
liquid extracted by the extractor 13 is increased by the first pump
14 and then is further increased by the second pump 15. The width
of the pressure increase by the first pump 14 can be set at a width
corresponding to the NPSHr of the second pump 15. Since the NPSHr
of the second pump 15 is sufficiently smaller than a required
pressure of the ejector 12, a required width of pressure increase
by the first pump 14 is small, and the NPSHr of the first pump 14
is also small. Thus, the use of the dynamic pump as the first pump
14 can efficiently increase the pressure with a small NPSHr. In
addition, since the second pump 15 sucks refrigerant liquid whose
pressure has been increased in a width corresponding to the NPSHr
of the second pump 15, the risk of performance degradation due to
cavitation in the second pump 15 can be reduced. Thus, the use of
an efficient positive displacement pump as the second pump 15 can
efficiently increase refrigerant liquid to a required pressure of
the ejector 12. Accordingly, in the first embodiment, the height
from the first pump 14 to the extractor 13 is reduced so that the
size of the heat exchange apparatus 200 can be reduced and the
pressure of refrigerant liquid can be efficiently increased to a
required pressure of the ejector 12.
SECOND EMBODIMENT
[0054] As illustrated in FIG. 3, a heat exchange apparatus 300
according to a second embodiment additionally includes a third pump
18 in addition to the configuration of the heat exchange apparatus
200 described with reference to FIG. 1. In the second embodiment, a
first liquid passage 17 constitutes a loop and includes pipes 17a
to 17f. On the loop constituted by the first liquid passage 17, the
ejector 12, the extractor 13, the first pump 14, the third pump 18,
the cooler 16, and the second pump 15 are connected to one another
in this order by the pipes 17a to 17f.
[0055] The third pump 18 is disposed on the first liquid passage 17
between the first pump 14 and the second pump 15. Specifically, the
third pump 18 is disposed on the first liquid passage 17 between
the outlet of the first pump 14 and the inlet of the second pump
15. More specifically, the third pump 18 is disposed on the first
liquid passage 17 between the outlet of the first pump 14 and the
inlet of the cooler 16. The third pump 18 is a dynamic pump. One or
more pumps may be additionally provided on the first liquid passage
17 between the first pump 14 and the second pump 15. That is, on
the first liquid passage 17 between the outlet of the first pump 14
and the inlet of the second pump 15, a plurality of pumps including
the third pump 18 to an N-th pump (where N is an integer of four or
more) may be disposed in this order in a flow direction of
refrigerant liquid. These pumps can be dynamic pumps.
[0056] In the heat exchange apparatus 300, the second pump 15 is
disposed between the outlet of the cooler 16 and the liquid inlet
of the ejector 12. The second pump 15 may be disposed between the
outlet of the N-th pump and the inlet of the cooler 16. That is,
the third pump 18 and the additional pumps can be disposed between
the outlet of the first pump 14 and the inlet of the second pump
15, independently of the location of the cooler 16.
[0057] In the second embodiment, the plurality of dynamic pumps are
disposed on the first liquid passage 17. Such multiple stages of
dynamic pumps individually provide speeds to fluid (refrigerant
liquid) passing through the pumps. Thus, the efficiency of the
entire multi-stage dynamic pumps can be significantly increased, as
compared to a case where a single dynamic pump is provided. The
total NPSHr of the dynamic pumps is smaller than the NPSHr of the
second pump 15. The ratio of (total NPSHr of dynamic pumps)/(NPSHr
of second pump 15) is less than or equal to 0.1, for example.
[0058] In the second embodiment, the width of the pressure increase
by the first pump 14 can be further reduced so that the NPSHr of
the first pump 14 can be further reduced, resulting in further size
reduction of the heat exchange apparatus 300.
(Variations)
[0059] The heat exchange apparatus 200 illustrated in FIG. 1 and
the heat exchange apparatus 300 illustrated in FIG. 3 may be
charged domestic with a refrigerant whose saturation vapor pressure
is negative (lower than atmospheric pressure in an absolute
pressure) at an ordinary temperature (Japanese Industrial
Standards: 20.degree. C.+-.15.degree. C./JIS Z8703). Examples of
such a refrigerant include a refrigerant including water alcohol,
or ether as a main component. In an operation of the heat exchange
apparatus 200 or 300, the internal pressure of the heat exchange
apparatus 200 or 300 is lower than the atmospheric pressure. The
pressure at the outlet of the refrigerant supply source 11 is in
the range from 5 to 15 kPaA, for example. To prevent freezing, for
example, the refrigerant may be a refrigerant containing water as a
main component and includes 10 to 40%, in terms of mass %, of
ethylene glycol, Nybrine (registered trademark), or mineral salts,
for example. The "main component" herein refers to a component
occupying the largest proportion in mass ratio. In a case where the
heat exchange apparatus 200 or 300 is charged with such a
refrigerant, the size of the system tends to increase, as compared
to a case where an apparatus is charged with a refrigerant whose
pressure saturation vapor pressure at an ordinary temperature is
positive. Thus, the technique disclosed herein is significantly
effective for a system using a refrigerant whose saturation vapor
pressure at an ordinary temperature is negative.
THIRD EMBODIMENT
[0060] FIG. 4 illustrates a configuration of a heat pump apparatus
according to a third embodiment. A heat pump apparatus 400
(refrigeration cycle apparatus) according to the third embodiment
includes a first heat exchange unit 40, a second heat exchange unit
42, a compressor 31, and a vapor passage 26. The first heat
exchange unit 40 and the second heat exchange unit 42 form a
heat-dissipation side circuit and a heat-absorption side circuit,
respectively. Refrigerant vapor generated by the second heat
exchange unit 42 is supplied to the first heat exchange unit 40 via
the compressor 31 and the vapor passage 26.
[0061] The compressor 31, a downstream portion 26b of the vapor
passage 26, and the first heat exchange unit 40 correspond to the
heat exchange apparatus 200 described with reference to FIG. 1.
That is, the heat pump apparatus 400 includes the heat exchange
apparatus 200. The compressor 31 corresponds to the refrigerant
supply source 11, compresses received refrigerant vapor, and
outputs the compressed refrigerant vapor to the ejector 12. Thus,
the heat pump apparatus 400 can obtain advantages similar to those
of the first embodiment.
[0062] Description similar to that of the heat exchange apparatus
200 in the first embodiment is applicable to the first heat
exchange unit 40.
[0063] The second heat exchange unit 42 includes an evaporator 19,
a pump 20 (evaporator-side pump), and a heat exchanger 21. The
evaporator 19 stores refrigerant liquid and vaporizes the
refrigerant liquid, thereby generating a refrigerant vapor to be
compressed in the compressor 31. The evaporator 19, the pump 20,
and the heat exchanger 21 are connected to one another by pipes 22a
to 22c to constitute a loop. The evaporator 19 is constituted by,
for example, a pressure-resistant container having heat insulating
properties. The pipes 22a to 22c constitute a second liquid passage
22 in which refrigerant liquid stored in the evaporator 19
circulates via the heat exchanger 21. The pump 20 is provided on
the second liquid passage 22 between a liquid outlet of the
evaporator 19 and an inlet of the heat exchanger 21. The pump 20
increases the pressure of the refrigerant liquid stored in the
evaporator 19 and pumps the refrigerant liquid to the heat
exchanger 21. The discharge pressure of the pump 20 is lower than
the atmospheric pressure. The pump 20 is disposed at a location at
which a height He from an inlet of the pump 20 to the liquid level
of refrigerant liquid in the evaporator 19 is larger than a
required head (NPSHr).
[0064] The heat exchanger 21 is constituted by a known heat
exchanger such as a fin-and-tube heat exchanger or a shell-and-tube
heat exchanger.
[0065] In the third embodiment, the evaporator 19 is a heat
exchanger that directly vaporizes, therein, refrigerant liquid
heated by circulating in the second liquid passage 22. The
refrigerant liquid stored in the evaporator 19 is in direct contact
with refrigerant liquid circulating in the second liquid passage
22. That is, part of the refrigerant liquid in the evaporator 19 is
heated by the heat exchanger 21 and is used as a heat source for
heating refrigerant liquid in a saturation state. An upstream end
of the pipe 22a is preferably connected to a lower portion of the
evaporator 19. A downstream end of the pipe 22c is preferably
connected to an intermediate portion of the evaporator 19. The
second heat exchange unit 42 may be configured in such a manner
that refrigerant liquid stored in the evaporator 19 is not mixed
with other refrigerant liquid circulating in the second liquid
passage 22. For example, in a case where the evaporator 19 has a
heat exchange configuration similar to that of a shell-and-tube
heat exchanger, refrigerant liquid stored in the evaporator 19 can
be heated and evaporated by a heating medium circulating in the
second liquid passage 22. In the heat exchanger 21, a heating
medium for heating the refrigerant liquid stored in the evaporator
19 flows.
[0066] The vapor passage 26 includes an upstream portion 26a and
the downstream portion 26b. On the vapor passage 26, the compressor
31 is disposed. An upper portion of the evaporator 19 is connected
to an inlet of the compressor 31 through the upstream portion 26a
of the vapor passage 26. An outlet of the compressor 31 is
connected to a second nozzle 25 of the ejector 12 through the
downstream portion 26b of the vapor passage 26. The compressor 31
is a centrifugal compressor or a positive-displacement compressor.
On the vapor passage 26, a plurality of compressors may be
provided. The compressor 31 sucks a refrigerant vapor from the
evaporator 19 of the second heat exchange unit 42 through the
upstream portion 26a and compresses the refrigerant vapor. The
compressed refrigerant vapor is supplied to the ejector 12 through
the downstream portion 26b.
[0067] In the third embodiment, the temperature and pressure of
refrigerant are increased in the ejector 12. Since work on the
compressor 31 can be reduced, the compression ratio of the
compressor 31 can be significantly reduced and the efficiency of
the heat pump apparatus 400 can be increased to a level equal or
higher than that in a conventional technique. In addition, the size
of the heat pump apparatus 400 can be reduced.
[0068] The heat pump apparatus 400 further includes a liquid back
passage 32 (required-return pipe) for returning refrigerant from
the first heat exchange unit 40 to the second heat exchange unit
42. In the third embodiment, the extractor 13 and the evaporator 19
are connected to each other by the liquid back passage 32 so that
refrigerant stored in the extractor 13 can be transferred to the
evaporator 19. Typically, a lower portion of the extractor 13 and a
lower portion of the evaporator 19 are connected to each other by
the liquid back passage 32. The refrigerant liquid returns from the
extractor 13 to the evaporator 19 through the liquid back passage
32. The liquid back passage 32 may be provided with an expansion
mechanism such as a capillary or an expansion valve.
[0069] The liquid back passage 32 is disposed in such a manner that
the liquid back passage 32 connects the extractor 13 and the
evaporator 19 to each other, refrigerant liquid having an amount
equal to an amount (mass flow rate) of a refrigerant vapor
transferred from the evaporator 19 to the extractor 13 by the
compressor 31 returns from the extractor 13 to the evaporator 19.
When the amount of refrigerant liquid in the evaporator 19 and the
amount of refrigerant liquid in the extractor 13 are balanced by
the liquid back passage 32, the heat pump apparatus 400 can be
stably operated. In a case where the amount of the refrigerant
liquid stored in the evaporator 19 and the extractor 13 is
sufficiently larger than the amount of refrigerant vapor
transferred by an operation of the heat pump apparatus 400, the
liquid back passage 32 may be omitted.
[0070] The liquid back passage 32 may be branched off at any
location on the first heat exchange unit 40. For example, the
liquid back passage 32 may be branched off at the pipe 17a
connecting the ejector 12 and the extractor 13 to each other, or
may be branched off at an upper portion of the extractor 13. The
first heat exchange unit 40 may be configured to discharge
redundant refrigerant when necessary. The second heat exchange unit
42 may be configured to add refrigerant when necessary.
[0071] In a manner similar to that of the heat exchange apparatus
200, the heat pump apparatus 400 can use a refrigerant whose
saturation vapor pressure at an ordinary temperature is
negative.
FOURTH EMBODIMENT
[0072] FIG. 5 illustrates a configuration of a heat pump apparatus
according to a fourth embodiment. A heat pump apparatus 500
(refrigeration cycle apparatus) according to the fifth embodiment
includes a first heat exchange unit 41, a second heat exchange unit
42, a compressor 31, and a vapor passage 26. The first heat
exchange unit 41 and the second heat exchange unit 42 constitute a
heat-dissipation side circuit and a heat-absorption side circuit,
respectively. A refrigerant vapor generated in the second heat
exchange unit 42 is supplied to the first heat exchange unit 41 via
the compressor 31 and the vapor passage 26.
[0073] The compressor 31, a downstream portion 26b of the vapor
passage 26, and the first heat exchange unit 41 correspond to the
heat exchange apparatus 300 described with reference to FIG. 3.
That is, the heat pump apparatus 500 includes a heat exchange
apparatus 300. The compressor 31 corresponds to a refrigerant
supply source 11, compresses received refrigerant vapor, and
outputs the compressed refrigerant vapor to the ejector 12. Thus,
in the heat pump apparatus 500, advantages similar to those
described in the second embodiment can be obtained.
[0074] Description similar to that of the heat exchange apparatus
300 in the second embodiment is applicable to the first heat
exchange unit 41. Detailed description of the second heat exchange
unit 42 is similar to that in the third embodiment.
[0075] In a manner similar to the heat exchange apparatus 300, the
heat pump apparatus 500 can use a refrigerant whose saturation
vapor pressure at an ordinary temperature is negative.
[0076] As described above, a heat exchange apparatus and a heat
pump apparatus described herein includes a first pump 14 (dynamic
pump) and a second pump 15 (positive displacement pump). The width
of pressure increase by the first pump 14 is set equal to the width
of pressure increase corresponding to the NPSHr of the second pump
15. Since the NPSHr of the second pump 15 is sufficiently smaller
than a required pressure of the ejector 12, a required width of
pressure increase by the first pump 14 is also small, and the NPSHr
of the first pump 14 is small. Thus, the height from the first pump
14 to the extractor 13 can be reduced. That is, the height of the
heat exchange apparatus or the heat pump apparatus can be reduced
so that the size of the entire system can be reduced.
[0077] The technique described herein can provide a small-size
efficient heat pump apparatus. Specifically, air-conditioning can
be performed by using a heat pump apparatus 400 or 500 even in a
building with a small installation space. In addition to
air-conditioning, hot water at higher temperatures can be supplied
in application of the heat pump apparatus 400 or 500 to hot water
supply.
[0078] A heat exchange apparatus and a heat pump apparatus
disclosed herein are applicable to a hot water heating apparatus
using vapor, air conditioners such as a domestic air-conditioner
and a business-use air-conditioner, and a water heater, for
example.
* * * * *