U.S. patent application number 14/765864 was filed with the patent office on 2015-12-24 for air-conditioning apparatus.
This patent application is currently assigned to Mitsubishi Electric Corporation. The applicant listed for this patent is Takayoshi HONDA, Osamu MORIMOTO, Yuji MOTOMURA, Koji NISHIOKA, Tatsuo ONO, Daisuke SHIMAMOTO. Invention is credited to Takayoshi HONDA, Osamu MORIMOTO, Yuji MOTOMURA, Koji NISHIOKA, Tatsuo ONO, Daisuke SHIMAMOTO.
Application Number | 20150369498 14/765864 |
Document ID | / |
Family ID | 51390793 |
Filed Date | 2015-12-24 |
United States Patent
Application |
20150369498 |
Kind Code |
A1 |
MOTOMURA; Yuji ; et
al. |
December 24, 2015 |
AIR-CONDITIONING APPARATUS
Abstract
In a case where frost is deposited a heat-source-side heat
exchanger during a heating operation mode, an air-conditioning
apparatus executes either a "heat recovery defrosting operation
mode" using a heat capacity held in a heat medium or a "bypass
defrosting operation mode" not using the heat capacity held in the
heat medium.
Inventors: |
MOTOMURA; Yuji; (Tokyo,
JP) ; SHIMAMOTO; Daisuke; (Tokyo, JP) ; HONDA;
Takayoshi; (Tokyo, JP) ; MORIMOTO; Osamu;
(Tokyo, JP) ; NISHIOKA; Koji; (Tokyo, JP) ;
ONO; Tatsuo; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MOTOMURA; Yuji
SHIMAMOTO; Daisuke
HONDA; Takayoshi
MORIMOTO; Osamu
NISHIOKA; Koji
ONO; Tatsuo |
Chiyoda-ku, Tokyo
Chiyoda-ku, Tokyo
Chiyoda-ku, Tokyo
Chiyoda-ku, Tokyo
Chiyoda-ku, Tokyo |
|
JP
JP
JP
JP
JP
US |
|
|
Assignee: |
Mitsubishi Electric
Corporation
Tokyo
JP
|
Family ID: |
51390793 |
Appl. No.: |
14/765864 |
Filed: |
February 25, 2013 |
PCT Filed: |
February 25, 2013 |
PCT NO: |
PCT/JP2013/054788 |
371 Date: |
August 5, 2015 |
Current U.S.
Class: |
62/160 |
Current CPC
Class: |
F25B 2313/02732
20130101; F25B 2700/21151 20130101; F25B 2313/0314 20130101; F25B
2600/2513 20130101; F25B 2700/21152 20130101; F25B 2313/02741
20130101; F25B 47/025 20130101; F24F 3/065 20130101; F25B 13/00
20130101; F25B 25/005 20130101; F25B 2700/21161 20130101; F25B
2700/21175 20130101; F25B 2313/0315 20130101; F25B 2313/0312
20130101; F25B 49/02 20130101; F25B 2700/21163 20130101; F25B
2500/19 20130101; F25B 2700/21162 20130101; F25B 2500/26 20130101;
F25B 2313/0231 20130101; F25B 2700/21173 20130101; F24F 5/001
20130101; F25B 2700/21174 20130101; F25B 2313/003 20130101 |
International
Class: |
F24F 5/00 20060101
F24F005/00; F25B 49/02 20060101 F25B049/02; F25B 13/00 20060101
F25B013/00 |
Claims
1. An air-conditioning apparatus comprising: a refrigerant
circulation circuit to circulate therein a heat-source-side
refrigerant, the refrigerant circulation circuit connecting, by
refrigerant pipes, a compressor, a heat-source-side heat exchanger,
a plurality of expansion devices, refrigerant-side flow passages of
a plurality of intermediate heat exchangers, and a plurality of
refrigerant flow switching devices to switch a refrigerant
circulation passage; a heat medium circulation circuit to circulate
therein a heat medium, the heat medium circuit connecting, by heat
medium conveyance pipes, a plurality of heat medium conveyance
devices provided in association with the plurality of intermediate
heat exchangers, a plurality of use-side heat exchangers, and
heat-medium-side flow passages for the plurality of intermediate
heat exchangers; and a bypass pipe installed so as to return the
heat-source-side refrigerant to the compressor by bypassing at
least the intermediate heat exchangers, the plurality of
intermediate heat exchangers exchanging heat between the
heat-source-side refrigerant and the heat medium, the
air-conditioning apparatus being configured to execute a heating
operation mode switching the refrigerant flow switching devices to
a side of heating operation, heating the heat medium by at least
one of the intermediate heat exchangers, operating at least one of
the heat medium conveyance devices, and supplying the heated heat
medium to at least one of the use-side heat exchangers, a heat
recovery defrosting operation mode melting frost formed around the
heat-source-side heat exchanger by switching, during the heating
operation mode, the refrigerant flow switching devices to a side of
cooling operation, operating at least one of the heat medium
conveyance devices, and causing the heat-source-side refrigerant to
receive heat of the heat medium by at least one of the intermediate
heat exchangers, and a bypass defrosting operation mode melting
frost formed around the heat-source-side heat exchanger by
switching, during the heating operation mode, the refrigerant flow
switching devices to the side of cooling operation and causing part
or whole of the heat-source-side refrigerant to flow to the bypass
pipe, wherein the heating operation mode includes a heating main
operation mode switching the refrigerant flow switching devices to
the side of heating operation, heating the heat medium by at least
one of the intermediate heat exchangers, and cooling the heat
medium by rest of intermediate heat exchangers, and the bypass
defrosting operation mode includes a second bypass defrosting
operation mode for melting frost formed around the heat-source-side
heat exchanger by switching the refrigerant flow switching devices
to the side of cooling operation, causing the cold heat medium to
flow to at least one of the intermediate heat exchangers, and
causing part of the heat medium to flow to the bypass pipe while
causing the intermediate heat exchanger having executed cooling
during the heating main operation mode to continue cooling.
2. The air-conditioning apparatus of claim 1, wherein in the heat
recovery defrosting operation mode, at least one of the
intermediate heat exchangers to cause the heat-source-side
refrigerant to receive the heat of the heat medium is same as the
at least one of the intermediate heat exchangers having heated the
heat medium before execution of the heat recovery defrosting
operation mode.
3. The air-conditioning apparatus of claim 1, further comprising: a
heat medium temperature sensor provided at any position of a flow
passage on an outlet side of the heat medium of the intermediate
heat exchangers, wherein the heat recovery defrosting operation
mode is executed when a temperature of the heat medium detected by
the heat medium temperature sensor is higher than a setting
temperature, and wherein the bypass defrosting operation mode is
executed when the temperature of the heat medium detected by the
heat medium temperature sensor is lower than the setting
temperature.
4. The air-conditioning apparatus of claim 3, further comprising: a
use-side air temperature sensor detecting a temperature of air
flowing through the use-side heat exchangers, wherein the setting
temperature is equal to or higher than the temperature detected by
the use-side air temperature sensor.
5-6. (canceled)
7. The air-conditioning apparatus of claim 1, wherein the heat
recovery defrosting operation mode includes a second heat recovery
defrosting operation mode melting frost formed around the
heat-source-side heat exchanger by switching the refrigerant flow
switching devices to the side of cooling operation, causing the
cold heat medium to flow to all of the intermediate heat
exchangers, and causing the heat-source-side refrigerant to receive
heat held in the heat medium by the at least one of the
intermediate heat exchangers having executed heating during the
heating main operation mode while causing the at least one of the
intermediate heat exchangers having executed cooling during the
heating main operation mode to continue cooling, and wherein when
the air-conditioning apparatus is switched from the heating main
operation mode to the second heat recovery defrosting operation
mode to perform defrosting, each of the expansion devices
corresponding to the at least one of the intermediate heat
exchangers having executed heating during the heating main
operation mode is fully opened in the second heat recovery
defrosting operation mode, and defrosting is performed by switching
to the second bypass defrosting mode from the second heat recovery
operation mode.
8. (canceled)
9. The air-conditioning apparatus of claim 1, wherein in the heat
recovery defrosting operation mode, a blower device blowing air to
at least one of the use-side heat exchangers having executed a
heating operation before starting a defrosting operation is
stopped, and a blower device blowing air to at least one of the
use-side heat exchangers having executed a cooling operation before
starting the defrosting operation is operated.
10. The air-conditioning apparatus of claim 1, further comprising:
a plurality of indoor units accommodating each of the plurality of
use-side heat exchangers; at least one outdoor unit accommodating
the compressor and the heat-source-side heat exchanger; and at
least one relay unit accommodating the plurality of intermediate
heat exchangers, the plurality of expansion devices, the plurality
of heat medium conveyance devices, and the plurality of refrigerant
flow switching devices, wherein the indoor units, the outdoor unit,
and the relay unit are configured to be formed independently of one
another and installed at positions separated from one another.
11. The air-conditioning apparatus of claim 1, wherein in the
bypass defrosting operation mode, the heating operation continues
to be performed by using a heat capacity of the heat medium having
been used for the heating operation.
12. The air-conditioning apparatus of claim 11, wherein in
continuing the heating operation, an amount of air blown to one of
the use-side heat exchangers that continues to perform the heating
operation is reduced to be less than a setting air volume.
13. The air-conditioning apparatus of claim 12, wherein even when
air is blown by using outdoor air taken in for a purpose of
ventilation, hot air is suppliable by performing a heating
operation using the heat medium.
Description
TECHNICAL FIELD
[0001] The present invention relates to an air-conditioning
apparatus applied to, for example, a multi-air-conditioning
apparatus for buildings.
BACKGROUND ART
[0002] A conventional air-conditioning apparatus such as a
multi-air-conditioning apparatus for buildings, for example, causes
refrigerant to circulate between an outdoor unit, which is a heat
source unit arranged outside a structure, and an indoor unit
arranged inside the structure. The refrigerant transfers or
receives heat, and the heated or cooled air causes air-conditioning
target space to be cooled or heated. As a refrigerant used for such
an air-conditioning apparatus, for example, an HFC
(hydro-fluorocarbon) refrigerant is often used. Furthermore, use of
a natural refrigerant such as carbon dioxide (CO.sub.2) has also
been proposed.
[0003] Furthermore, in an air-conditioning apparatus called a
chiller, a heat source unit arranged outside a structure generates
cooling energy or heating energy. Then, a heat exchanger arranged
inside the heat source unit heats or cools water, antifreeze, or
the like, and the heated or cooled water, antifreeze, or the like
is conveyed to a fan coil unit, a panel heater, or the like, which
is an indoor unit, thereby performing cooling or heating (see, for
example, Patent Literature 1).
[0004] An apparatus called an exhaust heat recovery-type chiller
has also been available in which four water pipes are connected
between a heat source unit and an indoor unit, cooled or heated
water or the like is simultaneously supplied, and cooling or
heating can be freely selected in the indoor unit (see, for
example, Patent Literature 2).
[0005] An apparatus has also been available which is configured
such that heat exchangers for a primary refrigerant and a secondary
refrigerant are arranged in the vicinity of each indoor unit and
the secondary refrigerant is conveyed to the indoor unit (see, for
example, Patent Literature 3).
[0006] Furthermore, an apparatus has also been available which is
configured such that an outdoor unit and a branch unit that
includes a heat exchanger are connected by two pipes and a
secondary refrigerant is conveyed to an indoor unit (see, for
example, Patent Literature 4).
[0007] Moreover, an air-conditioning apparatus such as a
multi-air-conditioning apparatus for buildings has also been
available which is configured such that by causing refrigerant to
circulate from an outdoor unit to a relay unit and causing a heat
medium such as water to circulate from the relay unit to an indoor
unit, the heat medium such as water may be caused to circulate to
the indoor unit (see, for example, Patent Literature 5).
CITATION LIST
Patent Literatures
[0008] Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2005-140444 (P. 4, FIG. 1 etc.)
[0009] Patent Literature 2: Japanese Unexamined Patent Application
Publication No. 5-280818 (P. 4 to 5, FIG. 1 etc.)
[0010] Patent Literature 3: Japanese Unexamined Patent Application
Publication No. 2001-289465 (P. 5 to 8, FIG. 1, FIG. 2, etc.)
[0011] Patent Literature 4: Japanese Unexamined Patent Application
Publication No. 2003-343936 (P. 5, FIG. 1)
[0012] Patent Literature 5: International Publication No. WO
2010/050002 (P. 11 to 15, FIG. 8 etc.)
SUMMARY OF INVENTION
Technical Problem
[0013] In conventional multi-air-conditioning apparatuses for
buildings, since refrigerant is caused to circulate to an indoor
unit, the refrigerant may be leaked to an indoor space or the like.
On the other hand, in the air-conditioning apparatuses described in
Patent Literature 1 and Patent Literature 2, refrigerant does not
pass through an indoor unit. However, in the air-conditioning
apparatuses described in Patent Literature 1 and Patent Literature
2, there is a need to heat or cool a heat medium at a heat source
unit outside a structure and to convey the heated or cooled heat
medium to an indoor unit side. Therefore, the length of the
circulation passage for a heat medium increases. In conveying heat
which functions to heat or cool an object to a certain extent using
a heat medium, the energy consumption by the conveyance force or
the like of the heat medium becomes greater than that of
refrigerant. Therefore, the increase in the length of the
circulation passage greatly increases the conveyance force. As is
clear for the above, in the air-conditioning apparatuses,
effectively controlling circulation of a heat medium achieves an
energy saving effect.
[0014] In the air-conditioning apparatus described in Patent
Literature 2, four pipes need to be used to connect an outdoor side
to an indoor side so that cooling or heating may be selected for
each indoor unit, thereby the workability being degraded. In the
air-conditioning apparatus described in Patent Literature 3, a
secondary medium circulation unit such as a pump needs to be
provided for individual indoor units. Therefore, not only does the
system become expensive, noise also increases. Thus, such an
air-conditioning apparatus has not been practical. In addition,
since a heat exchanger is provided in the vicinity of an indoor
unit, it has been possible to eliminate the possibility that
refrigerant may be leaked at a place near the indoor unit.
[0015] The air-conditioning apparatus described in Patent
Literature 4 has a configuration which is wasteful in terms of
energy since a primary refrigerant after being subjected to heat
exchange flows into the same flow passage as that for a primary
refrigerant before being subjected to heat exchange and each of a
plurality of indoor units thus cannot exhibit the maximum
performance when the plurality of indoor units are connected.
Furthermore, the configuration in which the connection between a
branch unit and an extension pipe is achieved using four pipes in
total, that is, two pipes for cooling and two pipes for heating, is
consequently similar to the configuration of the system in which an
outdoor unit and a branch unit are connected by four pipes, thereby
degrading the workability.
[0016] Moreover, in a known air-conditioning apparatus such as a
multi-air-conditioning apparatus for buildings, frosting occurs on
the surface of an outdoor heat exchanger by heat exchange with
outdoor air at an outdoor unit during execution of a heating
operation. Therefore, it is necessary to periodically execute a
defrosting operation mode. However, during execution of a
defrosting operation, a high-temperature, high-pressure refrigerant
which is necessary for an indoor unit to perform a heating
operation cannot be conveyed to the indoor unit. Therefore, a
heating operation according to a required indoor-side heating load
cannot be performed.
[0017] Moreover, even with an air-conditioning apparatus which has
a function for taking in outdoor air and conveying the outdoor air
toward an indoor space for the purpose of ventilation, during a
defrosting operation, a blower device is stopped in order to
prevent cold air from flowing toward the indoor space in accordance
with the intake of the outdoor air. In the above way, a heating
operation cannot be performed in accordance with the required
indoor-side heating load.
[0018] In the air-conditioning apparatus described in Patent
Literature 5, a reduction in the room temperature may be suppressed
by causing a secondary heat medium to circulate to an indoor unit
during a defrosting operation. However, continuation of a heating
operation by an indoor unit including ventilation by intake of
outdoor air is not taken into consideration.
[0019] The present invention has been made to solve the above
problem, and an object of the present invention is to provide an
air-conditioning apparatus that has a plurality of defrosting
operation modes to achieve maintenance of comfort.
Solution to Problem
[0020] An air-conditioning apparatus according to the present
invention includes a refrigerant circulation circuit to circulate
therein a heat-source-side refrigerant, the refrigerant circulation
circuit connecting, by refrigerant pipes, a compressor, a
heat-source-side heat exchanger, a plurality of expansion devices,
refrigerant-side flow passages of a plurality of intermediate heat
exchangers, and a plurality of refrigerant flow switching devices
to switch a refrigerant circulation passage; a heat medium
circulation circuit to circulate therein a heat medium, the heat
medium circuit connecting, by heat medium conveyance pipes, a
plurality of heat medium conveyance devices provided in association
with the plurality of intermediate heat exchangers, a plurality of
use-side heat exchangers, and heat-medium-side flow passages for
the plurality of intermediate heat exchangers; and a bypass pipe
installed so as to return the heat-source-side refrigerant to the
compressor by bypassing at least the intermediate heat exchangers,
the plurality of intermediate heat exchangers exchanging heat
between the heat-source-side refrigerant and the heat medium, the
air-conditioning apparatus being configured to execute a heating
operation mode switching the refrigerant flow switching devices to
a side of heating operation, heating the heat medium by at least
one of the intermediate heat exchangers, operating at least one of
the heat medium conveyance devices, and supplying the heated heat
medium to at least one of the use-side heat exchangers, a heat
recovery defrosting operation mode melting frost formed around the
heat-source-side heat exchanger by switching, during the heating
operation mode, the refrigerant flow switching devices to a side of
cooling operation, operating at least one of the heat medium
conveyance devices, and causing the heat-source-side refrigerant to
receive heat of the heat medium by at least one of the intermediate
heat exchangers, and a bypass defrosting operation mode melting
frost formed around the heat-source-side heat exchanger by
switching, during the heating operation mode, the refrigerant flow
switching devices to the side of cooling operation and causing part
or whole of the heat-source-side refrigerant to flow to the bypass
pipe.
Advantageous Effects of Invention
[0021] An air-conditioning apparatus according to the present
invention has, as a defrosting operation mode, a "heat recovery
defrosting operation mode" and a "bypass defrosting operation
mode". Therefore, either one of the defrosting operation modes may
be executed, and maintenance of comfort may thus be achieved.
BRIEF DESCRIPTION OF DRAWINGS
[0022] FIG. 1 is a schematic diagram illustrating an exemplary
installation of an air-conditioning apparatus according to
Embodiment of the present invention.
[0023] FIG. 2 is a schematic circuit configuration diagram
illustrating an example of a circuit configuration of the
air-conditioning apparatus according to Embodiment of the present
invention.
[0024] FIG. 3 is a refrigerant circuit diagram illustrating the
flow of refrigerant in a cooling only operation mode of the
air-conditioning apparatus according to Embodiment of the present
invention.
[0025] FIG. 4 is a refrigerant circuit diagram illustrating the
flow of refrigerant in a heating only operation mode of the
air-conditioning apparatus according to Embodiment of the present
invention.
[0026] FIG. 5 is a refrigerant circuit diagram illustrating the
flow of refrigerant in a cooling and heating mixed operation mode
of the air-conditioning apparatus according to Embodiment of the
present invention.
[0027] FIG. 6 is a refrigerant circuit diagram illustrating the
flow of refrigerant and the flow of a heat medium in a "first heat
recovery defrosting operation mode (1)" of the air-conditioning
apparatus according to Embodiment of the present invention.
[0028] FIG. 7 is a refrigerant circuit diagram illustrating the
flow of refrigerant and the flow of a heat medium in a "first heat
recovery defrosting operation mode (2)" of the air-conditioning
apparatus according to Embodiment of the present invention.
[0029] FIG. 8 is a refrigerant circuit diagram illustrating the
flow of refrigerant and the flow of a heat medium in a "second heat
recovery defrosting operation mode" of the air-conditioning
apparatus according to Embodiment of the present invention.
[0030] FIG. 9 is a refrigerant circuit diagram illustrating the
flow of refrigerant and the flow of a heat medium in a "first
bypass defrosting operation mode" of the air-conditioning apparatus
according to Embodiment of the present invention.
[0031] FIG. 10 is a graph illustrating an example of the
relationship between the air volume of a fan for each temperature
to which the temperature of a heat medium may be reduced and the
time during which the heat medium temperature may be maintained in
the case where a heating operation continues to be performed with
the air volume.
[0032] FIG. 11 is a refrigerant circuit diagram illustrating the
flow of refrigerant and the flow of a heat medium in a "second
bypass defrosting operation mode" of the air-conditioning apparatus
according to Embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS
[0033] Hereinafter, Embodiment of the present invention will be
explained with reference to the drawings.
[0034] FIG. 1 is a schematic diagram illustrating an exemplary
installation of an air-conditioning apparatus according to
Embodiment of the present invention. An exemplary installation of
an air-conditioning apparatus will be explained with reference to
FIG. 1. In the air-conditioning apparatus, by using a refrigeration
cycle (a refrigerant circulation circuit A, a heat medium
circulation circuit B) through which refrigerant (a
heat-source-side refrigerant, a heat medium) circulates, each
indoor unit can freely select, as an operation mode, a cooling mode
or a heating mode. FIG. 1 schematically illustrates the overall
configuration of an air-conditioning apparatus including a
plurality of indoor units 3 connected. In the drawings provided
below including FIG. 1, the size relationship of individual
component members may differ from the actual size relationship.
[0035] In FIG. 1, the air-conditioning apparatus according to
Embodiment includes an outdoor unit (heat source unit) 1, a
plurality of indoor units 3, and a relay unit 2 which is arranged
between the outdoor unit 1 and the indoor units 3. The relay unit 2
exchanges heat between a heat-source-side refrigerant and a heat
medium. The outdoor unit 1 and the relay unit 2 are connected by
refrigerant pipes 4 through which the heat-source-side refrigerant
flows. The relay unit 2 and the indoor units 3 are connected by
pipes (heat medium conveyance pipes) 5 through which the heat
medium flows. Cooling energy or heating energy generated at the
outdoor unit 1 is delivered to the indoor units 3 via the relay
unit 2.
[0036] The outdoor unit 1 is normally placed in an outdoor space 6,
which is a space (for example, a rooftop etc.) outside a structure
9 such as a building, and supplies cooling energy or heating energy
to the indoor units 3 via the relay unit 2. The indoor units 3 are
placed at positions from which cooling air or heating air may be
supplied to an indoor space 7, which is a space (for example, a
living room etc.) inside the structure 9, and supplies the cooling
air or the heating air to the indoor space 7 serving as an
air-conditioning target space. The relay unit 2 is configured to be
installed at a position which is different from the outdoor space 6
and the indoor space 7 as a housing which is different from the
outdoor unit 1 and the indoor units 3. The relay unit 2 is
connected to the outdoor unit 1 and the indoor units 3 by the
refrigerant pipes 4 and the pipes 5, respectively, and transmits to
the indoor units 3 the cooling energy or heating energy supplied
from the outdoor unit 1.
[0037] An operation of the air-conditioning apparatus according to
Embodiment of the present invention will be briefly explained
below.
[0038] A heat-source-side refrigerant is conveyed from the outdoor
unit 1 to the relay unit 2 via the refrigerant pipes 4. The
conveyed heat-source-side refrigerant exchanges heat with a heat
medium at an intermediate heat exchanger (an intermediate heat
exchanger 25 described later) inside the relay unit 2 to heat or
cool the heat medium. That is, hot water or cold water is generated
at the intermediate heat exchanger. The hot water or the cold water
generated at the relay unit 2 is conveyed by a heat medium
conveyance device (a pump 31 described later) to the indoor units 3
via the pipes 5, and is used at the indoor units 3 for a heating
operation (may be an operation state requiring hot water) or a
cooling operation (may be an operation state requiring cold water)
for the indoor space 7.
[0039] As a heat-source-side refrigerant, for example, a
single-component refrigerant such as R-22, R-134a, or R-32, a
near-azeotropic refrigerant mixture such as R-410A or R-404A, a
non-azeotropic refrigerant mixture such as R-407C, a refrigerant
having a relatively small global warming potential, such as
CF.sub.3CF.dbd.CH.sub.2, which has a double bond in its chemical
formula or a mixture of such refrigerants, or a natural refrigerant
such as CO.sub.2 or propane, may be used.
[0040] In contrast, as a heat medium, for example, water,
antifreeze, a liquid mixture of antifreeze and water, a liquid
mixture of water and an additive having high anti-corrosion effect,
or the like may be used.
[0041] As illustrated in FIG. 1, in the air-conditioning apparatus
according to Embodiment, the outdoor unit 1 and the relay unit 2
are connected by the two refrigerant pipes 4, and the relay unit 2
and each of the indoor units 3 are connected by the two pipes 5. As
described above, in the air-conditioning apparatus according to
Embodiment, by connecting the individual units (the outdoor unit 1,
the indoor units 3, and the relay unit 2) by the two pipes (the
refrigerant pipes 4, the pipes 5), easy construction can be
achieved.
[0042] In FIG. 1, a state is illustrated as an example in which the
relay unit 2 is installed in a space (hereinafter, simply referred
to as a space 8) such as a space above a ceiling, which is a space
that is within the structure 9 but is different from the indoor
space 7. Therefore, the relay unit 2 may be installed in any place
other than the space above the ceiling as long as it is a space
ventilated to the outside to some extent and is not a living space.
For example, the relay unit 2 may be installed in a space which is
ventilated to the outside, such as a common space in which an
elevator or the like is located, or the like. Furthermore, the
relay unit 2 may be installed at a position near the outdoor unit
1. However, when the distance from the relay unit 2 to the indoor
units 3 is too long, the heat medium conveyance force is
significantly large. Therefore, it should be noted that an energy
saving effect is reduced.
[0043] In FIG. 1, the case where the outdoor unit 1 is installed in
the outdoor space 6 is illustrated as an example. However, the
outdoor unit 1 is not necessarily installed as described above. For
example, the outdoor unit 1 may be installed in an enclosed space,
such as a machine room with a ventilation opening. The outdoor unit
1 may be installed inside the structure 9 as long as waste heat can
be exhausted outside the structure 9 via an exhaust duct.
Alternatively, an outdoor unit 1 of a water-cooled type may be
installed inside the structure 9. When the outdoor unit 1 is
installed in such a place, there will be no particular problem.
[0044] In FIG. 1, the case where the indoor units 3 are of a
ceiling cassette type is illustrated as an example. However, the
indoor units 3 are not necessarily of the above type. The indoor
units 3 may be of any type such as a ceiling concealed type or
ceiling suspended type as long as they are able to blow heating air
or cooling air to the indoor space 7 directly or through a duct or
the like.
[0045] Furthermore, the number of connected outdoor units 1, indoor
units 3, and relay units 2 is not limited to that illustrated in
FIG. 1. The number of connected outdoor units 1, indoor units 3,
and relay units 2 may be determined in accordance with the
structure 9 in which the air-conditioning apparatus according to
Embodiment is installed.
[0046] In the case where the plurality of relay units 2 are
connected to the single outdoor unit 1, the plurality of relay
units 2 may be installed in different positions in a common space
in a structure such as a building or a space such as a space above
a ceiling. By installing the plurality of relay units 2 as
described above, an intermediate heat exchanger inside each of the
relay units 2 is able to cover an air-conditioning load.
Furthermore, the indoor units 3 may be installed at a distance or a
height within an allowable conveyance range of the heat medium
conveyance device in the individual relay units 2, and an
arrangement for the entire structure such as a building can be
attained.
[0047] FIG. 2 is a schematic circuit configuration diagram
illustrating an example of a circuit configuration of the
air-conditioning apparatus (hereinafter, referred to as an
air-conditioning apparatus 100) according to Embodiment of the
present invention. The configuration of the air-conditioning
apparatus 100, that is, the workings of individual actuators
forming a refrigerant circuit, will be explained in detail with
reference to FIG. 2. As illustrated in FIG. 2, the outdoor unit 1
and the relay unit 2 are connected by the refrigerant pipes 4 via
an intermediate heat exchanger (refrigerant-water heat exchanger)
25a and an intermediate heat exchanger (refrigerant-water heat
exchanger) 25b which are provided in the relay unit 2. Furthermore,
the relay unit 2 and the indoor units 3 are connected by the pipes
5 via the intermediate heat exchanger 25a and the intermediate heat
exchanger 25b.
[Outdoor Unit 1]
[0048] In the outdoor unit 1, a compressor 10, a first refrigerant
flow switching device 11 such as a four-way valve, a
heat-source-side heat exchanger 12, and an accumulator 19 are
provided by being connected in series by the refrigerant pipes 4.
The outdoor unit 1 also includes a refrigerant connection pipe 4a,
a refrigerant connection pipe 4b, a check valve 13a, a check valve
13b, a check valve 13c, and a check valve 13d. By providing the
refrigerant connection pipe 4a, the refrigerant connection pipe 4b,
the check valve 13a, the check valve 13b, the check valve 13c, and
the check valve 13d, the flow of a heat-source-side refrigerant
which is to be caused to flow into the relay unit 2 may be fixed to
a certain direction, irrespective of the operation required by the
indoor units 3.
[0049] The compressor 10 sucks a heat-source-side refrigerant,
compresses the heat-source-side refrigerant into a high-temperature
and high-pressure state, and conveys the heat-source-side
refrigerant to the refrigerant circulation circuit A. The
compressor 10 may be, for example, an inverter compressor whose
capacity can be controlled. The first refrigerant flow switching
device 11 switches between providing the flow of a heat-source-side
refrigerant in a heating operation mode (in a heating only
operation mode and a heating main operation mode) and providing the
flow of a heat-source-side refrigerant in cooling operation mode
(in a cooling only operation mode and a cooling main operation
mode).
[0050] The heat-source-side heat exchanger 12 serves as an
evaporator during a heating operation and serves as a condenser (or
a radiator) during a cooling operation. The heat-source-side heat
exchanger 12 exchanges heat between fluid such as air supplied from
a blower device such as a fan, which is not illustrated in the
drawing, and a heat-source-side refrigerant to evaporate and gasify
or condense and liquefy the heat-source-side refrigerant. The
accumulator 19 is provided on the suction side of the compressor
10, and stores excess refrigerant caused by a difference between
the heating operation time and the cooling operation time or excess
refrigerant with respect to a transient change in the
operation.
[0051] The check valve 13c is provided at a position of the
refrigerant pipe 4 between the relay unit 2 and the first
refrigerant flow switching device 11, and allows a heat-source-side
refrigerant to flow only in a specific direction (direction from
the relay unit 2 to the outdoor unit 1). The check valve 13a is
provided at a position of the refrigerant pipe 4 between the
heat-source-side heat exchanger 12 and the relay unit 2, and allows
a heat-source-side refrigerant to flow only in a specific direction
(direction from the outdoor unit 1 to the relay unit 2). The check
valve 13d is provided at the refrigerant connection pipe 4a, and
causes the heat-source-side refrigerant discharged from the
compressor 10 to flow to the relay unit 2 during a heating
operation. The check valve 13b is provided at the refrigerant
connection pipe 4b, and causes the heat-source-side refrigerant
returned from the relay unit 2 to flow to the suction side of the
compressor 10 during a heating operation.
[0052] The refrigerant connection pipe 4a allows connection between
a portion of the refrigerant pipe 4 between the first refrigerant
flow switching device 11 and the check valve 13c and a portion of
the refrigerant pipe 4 between the check valve 13a and the relay
unit 2 in the outdoor unit 1. The refrigerant connection pipe 4b
allows connection between a portion of the refrigerant pipe 4
between the check valve 13c and the relay unit 2 and a portion of
the refrigerant pipe 4 between heat-source-side heat exchanger 12
and the check valve 13a in the outdoor unit 1. In FIG. 2, the case
where the refrigerant connection pipe 4a, the refrigerant
connection pipe 4b, the check valve 13a, the check valve 13b, the
check valve 13c, and the check valve 13d are provided is
illustrated as an example. However, the configuration is not
limited to the above. The above components are not necessarily
provided.
[Indoor Unit 3]
[0053] In each of the indoor units 3, a use-side heat exchanger 35
is provided. The use-side heat exchangers 35 are connected to heat
medium flow control devices 34 and second heat medium flow
switching devices 33 of the relay unit 2 by the pipes 5. The
use-side heat exchangers 35 exchange heat between air which is
supplied from a blower device such as a fan, which is not
illustrated in the drawing, and a heat medium, and generate heating
air or cooling air to be supplied to the indoor space 7.
[0054] Furthermore, in the indoor units 3, a duct 43 or the like is
attached to the use-side heat exchangers 35. By using the blower
device, which is not illustrated in the drawing, outdoor air is
taken into the indoor space 7 via the duct 43, and ventilation may
thus be attained.
[0055] In FIG. 2, the case where the four indoor units 3 are
connected to the relay unit 2 is illustrated as an example, and the
indoor units 3 are illustrated as an indoor unit 3a, an indoor unit
3b, an indoor unit 3c, and an indoor unit 3d in this order from the
top side of the drawing. Similarly, in association with the indoor
units 3a to 3d, the use-side heat exchangers 35 are illustrated as
a use-side heat exchanger 35a, a use-side heat exchanger 35b, a
use-side heat exchanger 35c, and a use-side heat exchanger 35d in
this order from the top side of the drawing. Similarly to the case
of FIG. 1, the number of connected indoor units 3 is not
necessarily four as illustrated in FIG. 2. Furthermore, although
the state in which the duct 43 is connected to the indoor unit 3a
is illustrated as an example in FIG. 2, the number of indoor units
3 with which the duct 43 may be connected is not necessarily the
indoor unit. The duct 43 may be connected to any of the indoor
units 3b to 3d.
[Relay Unit 2]
[0056] In the relay unit 2, the at least two or more intermediate
heat exchangers 25, two expansion devices 26, two opening and
closing devices (an opening and closing device 27 and an opening
and closing device 29), two second refrigerant flow switching
devices 28, two heat medium conveyance devices (hereinafter,
referred to as the pumps 31), four first heat medium flow switching
devices 32, the four second heat medium flow switching devices 33,
and the four heat medium flow control devices 34 are provided.
[0057] The two intermediate heat exchangers 25 (the intermediate
heat exchanger 25a and the intermediate heat exchanger 25b)
function as condensers (radiators) when supplying heating energy to
an indoor unit 3 that is performing a heating operation and
function as evaporators when supplying cooling energy to an indoor
unit 3 that is performing a cooling operation, exchange heat
between a heat-source-side refrigerant and a heat medium, and
transmit cooling energy or heating energy generated at the outdoor
unit 1 and stored in the heat-source-side refrigerant to the heat
medium. The intermediate heat exchanger 25a is provided between the
expansion device 26a and the second refrigerant flow switching
device 28a in the refrigerant circulation circuit A and is used for
cooling a heat medium in a cooling and heating mixed operation
mode. The intermediate heat exchanger 25b is provided between the
expansion device 26b and the second refrigerant flow switching
device 28b in the refrigerant circulation circuit A and is used for
heating a heat medium in a cooling and heating mixed operation
mode.
[0058] The two expansion devices 26 (the expansion device 26a and
the expansion device 26b) function as pressure reducing valves or
expansion valves to decompress and expanse a heat-source-side
refrigerant. The expansion device 26a is provided on the upstream
side of the intermediate heat exchanger 25a in the flow of a
heat-source-side refrigerant for a cooling operation. The expansion
device 26b is provided on the upstream side of the intermediate
heat exchanger 25b in the flow of a heat-source-side refrigerant
for a cooling operation. The two expansion devices 26 may be
devices whose opening degree may be controlled in a variable
manner, such as electronic expansion valves.
[0059] The two opening and closing devices (the opening and closing
device 27 and the opening and closing device 29) are solenoid
valves which may be opened and closed by electrical connection, and
open and close the refrigerant pipes 4. That is, the two opening
and closing devices are controlled to be opened and closed in
accordance with an operation mode, and switch the flow passage of a
heat-source-side refrigerant. The opening and closing device 27 is
provided at a portion of the refrigerant pipe 4 on a
heat-source-side refrigerant inlet side (a portion of the
refrigerant pipe 4 that connects the outdoor unit 1 with the relay
unit 2 and that is located at the most bottom side in the drawing).
The opening and closing device 29 is provided at a pipe (bypass
pipe 20) which connects the portion of the refrigerant pipe 4 on
the heat-source-side refrigerant inlet side with a portion of the
refrigerant pipe 4 on a heat-source-side refrigerant outlet side.
Devices whose opening degree may be controlled in a variable
manner, such as electrical expansion valves, may be used as the
opening and closing device 27 and the opening and closing device
29, as long as the devices may switch a refrigerant flow
passage.
[0060] The two second refrigerant flow switching devices 28 (the
second refrigerant flow switching device 28a and the second
refrigerant flow switching device 28b) are, for example, four-way
valves, and switch the flow of a heat-source-side refrigerant such
that the intermediate heat exchangers 25 operate as condensers or
evaporators in accordance with the operation mode. The second
refrigerant flow switching device 28a is provided on the downstream
side of the intermediate heat exchanger 25a in the flow of a
heat-source-side refrigerant for a cooling operation. The second
refrigerant flow switching device 28b is provided on the downstream
side of the intermediate heat exchanger 25b in the flow of a
heat-source-side refrigerant for a cooling only operation mode.
[0061] The two pumps 31 (the pump 31a and the pump 31b) cause a
heat medium that flows through the pipes 5 to circulate to the heat
medium circulation circuit B. The pump 31a is provided at a portion
of the pipe 5 between the intermediate heat exchanger 25a and the
second heat medium flow switching devices 33. The pump 31b is
provided at a portion of the pipe 5 between the intermediate heat
exchanger 25b and the second heat medium flow switching devices 33.
The two pumps 31 are, for example, pumps whose capacity can be
controlled, and may be configured such that the flow rate of the
pumps can be adjusted according to the size of the load in the
indoor units 3.
[0062] The four first heat medium flow switching devices 32 (the
first heat medium flow switching devices 32a to 32d) are three-way
valves or the like, and switch the flow passage of a heat medium
between the intermediate heat exchanger 25a and the intermediate
heat exchanger 25b. The number of first heat medium flow switching
devices 32 provided corresponds to the number of indoor units 3
installed (in this case, four). The first heat medium flow
switching devices 32 are provided on the outlet side of the heat
medium flow passages for the use-side heat exchangers 35 in such a
manner that one of the three ways is connected to the intermediate
heat exchanger 25a, another one of the three ways is connected to
the intermediate heat exchanger 25b, and the other one of the three
ways is connected to the heat medium flow control devices 34. In
association with the indoor units 3, they are illustrated as the
first heat medium flow switching device 32a, the first heat medium
flow switching device 32b, the first heat medium flow switching
device 32c, and the first heat medium flow switching device 32d in
this order from the top side of the drawing. Furthermore, switching
of a heat medium flow passage includes partial switching from one
side to the other side as well as full switching from one side to
the other side.
[0063] The four second heat medium flow switching devices 33 (the
second heat medium flow switching devices 33a to 33d) are three-way
valves or the like, and switch the flow passage of a heat medium
between the intermediate heat exchanger 25a and the intermediate
heat exchanger 25b. The number of second heat medium flow switching
devices 33 provided corresponds to the number of indoor units 3
installed (in this case, four). The second heat medium flow
switching devices 33 are provided on the inlet side of the heat
medium flow passages for the use-side heat exchangers 35 in such a
manner that one of the three ways is connected to the intermediate
heat exchanger 25a, another one of the three ways is connected to
the intermediate heat exchanger 25b, and the other one of the three
ways is connected to the heat medium flow control devices 35. In
association with the indoor units 3, they are illustrated as the
second heat medium flow switching device 33a, the second heat
medium flow switching device 33b, the second heat medium flow
switching device 33c, and the second heat medium flow switching
device 33d in this order from the top side of the drawing.
Furthermore, switching of a heat medium flow passage includes
partial switching from one side to the other side as well as full
switching from one side to the other side.
[0064] The four heat medium flow control devices 34 (the heat
medium flow control devices 34a to 34d) are two-way valves or the
like whose opening area can be controlled, and control the flow
rate of a heat medium flowing in the pipes 5. The number of heat
medium flow control devices 34 provided corresponds to the number
of indoor units 3 installed (in this case, four). The heat medium
flow control devices 34 are provided on the outlet side of the heat
medium flow passages for the use-side heat exchangers 35 in such a
manner that one of the two ways is connected to the use-side heat
exchangers 35 and the other one of the two ways is connected to the
first heat medium flow switching devices 32. That is, the heat
medium flow control devices 34 adjust the amount of heat medium
flowing into the indoor units 3 in accordance with the temperature
of the heat medium flowing into and flowing out of the indoor units
3 and may thus supply to the indoor units 3 an optimal amount of
heat medium for the indoor load.
[0065] In association with the indoor units 3, they are illustrated
as the heat medium flow control device 34a, the heat medium flow
control device 34b, the heat medium flow control device 34c, and
the heat medium flow control device 34d in this order from the top
side of the drawing. The heat medium flow control devices 34 may be
provided on the inlet side of the heat medium flow passages for the
use-side heat exchangers 35. Furthermore, the heat medium flow
control devices 34 may be provided at a portion that is on the
inlet side of the heat medium flow passages for the use-side heat
exchangers 35 and that is between the second heat medium flow
switching devices 33 and the use-side heat exchangers 35. Moreover,
when an indoor unit 3 requires no load, such as during stoppage or
thermo-OFF, the supply of a heat medium to the indoor unit 3 may be
stopped by fully closing the heat medium flow control devices
34.
[0066] If devices having functions of the heat medium flow control
devices 34 are used as the first heat medium flow switching devices
32 or the second heat medium flow switching devices 33, the heat
medium flow control devices 34 may be omitted.
[0067] Furthermore, in the relay unit 2, temperature sensors 40 (a
temperature sensor 40a and a temperature sensor 40b) for detecting
the temperature of a heat medium on the outlet side of the
intermediate heat exchanger 25 are provided. Information
(temperature information) detected by the temperature sensors 40 is
sent to a controller 50 that performs overall control of the
operation of the air-conditioning apparatus 100, and is used for
control of the driving frequency of the compressor 10, the rotation
speed of a blower device, which is not illustrated in the drawing,
switching of the first refrigerant flow switching device 11, the
driving frequency of the pumps 31, switching of the second
refrigerant flow switching devices 28, switching of the flow
passage of a heat medium, adjustment of the flow rate of a heat
medium in the indoor units 3, and the like. Although the case where
the controller 50 is provided separately from the individual units
is illustrated as an example, the configuration is not limited to
this. The controller 50 may be provided so as to be able to
communicate with at least one of the outdoor unit 1, the indoor
units 3, and the relay unit 2 or with the individual units.
[0068] Furthermore, the controller 50 is composed of a
microcomputer or the like. The controller 50 controls the
individual actuators (driving parts including the pumps 31, the
first heat medium flow switching devices 32, the second heat medium
flow switching devices 33, the expansion devices 26, and the second
refrigerant flow switching devices 28), such as the driving
frequency of the compressor 10, the rotation speed of the blower
device (including ON/OFF), switching of the first refrigerant flow
switching device 11, driving of the pumps 31, the opening degree of
the expansion devices 26, opening and closing of the opening and
closing devices (the opening and closing device 27 and the opening
and closing device 29), switching of the second refrigerant flow
switching devices 28, switching of the first heat medium flow
switching devices 32, switching of the second heat medium flow
switching devices 33, and driving of the heat medium flow control
devices 34, in accordance with detection information from the
various detection units and instructions from a remote
controller.
[0069] The pipes 5 through which a heat medium flows include a pipe
which is connected to the intermediate heat exchanger 25a and a
pipe which is connected to the intermediate heat exchanger 25b.
Each of the pipes 5 branches out into branch pipes (in this
example, four branches) in accordance with the number of indoor
units 3 connected to the relay unit 2. The pipes 5 are connected to
the first heat medium flow switching devices 32 and the second heat
medium flow switching devices 33. The first heat medium flow
switching devices 32 and the second heat medium flow switching
devices 33 are controlled to determine whether a heat medium from
the intermediate heat exchanger 25a or a heat medium from the
intermediate heat exchanger 25b is to be caused to flow into the
use-side heat exchangers 35.
[0070] In the air-conditioning apparatus 100, the refrigerant
circulation circuit A is formed by connecting the compressor 10,
the first refrigerant flow switching device 11, the
heat-source-side heat exchanger 12, the opening and closing device
27, the opening and closing device 29, the second refrigerant flow
switching devices 28, the refrigerant flow passages for the
intermediate heat exchangers 25, the expansion devices 26, and the
accumulator 19 by the refrigerant pipes 4. Furthermore, the heat
medium circulation circuit B is formed by connecting the heat
medium flow passages for the intermediate heat exchangers 25, the
pumps 31, the first heat medium flow switching devices 32, the heat
medium flow control devices 34, the use-side heat exchangers 35,
and the second heat medium flow switching devices 33 by the pipes
5. That is, the plurality of use-side heat exchangers 35 are
connected in parallel to each of the intermediate heat exchangers
25 to form the heat medium circulation circuit B as multiple
systems.
[0071] Therefore, in the air-conditioning apparatus 100, the
outdoor unit 1 and the relay unit 2 are connected via the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b which are provided in the relay unit 2, and the relay unit 2
and the indoor units 3 are connected via the intermediate heat
exchanger 25a and the intermediate heat exchanger 25b. That is, in
the air-conditioning apparatus 100, heat is exchanged at the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b between a heat-source-side refrigerant which circulates through
the refrigerant circulation circuit A and a heat medium which
circulates through the heat medium circulation circuit B. With the
use of the above configuration, the air-conditioning apparatus 100
achieves an optimal cooling operation or an optimal heating
operation for the indoor load.
[Operation Mode]
[0072] Individual operation modes executed by the air-conditioning
apparatus 100 will be explained below. In accordance with an
instruction from each of the indoor units 3, the air-conditioning
apparatus 100 is able to cause the indoor unit 3 to perform a
cooling operation or a heating operation. That is, the
air-conditioning apparatus 100 is configured such that not only may
all of the indoor units 3 perform the same operation but also the
indoor units 3 may perform different operations.
[0073] Operation modes executed by the air-conditioning apparatus
100 include a heating only operation mode in which all of the
driving indoor units 3 perform a heating operation, a cooling only
operation mode in which all of the driving indoor units 3 perform a
cooling operation, a heating main operation mode, which is a
cooling and heating mixed operation mode in which the heating load
is larger than the cooling load, and a cooling main operation mode,
which is a cooling and heating mixed operation mode in which the
cooling load is larger than heating load. Furthermore, in the
heating only operation mode and the heating main operation mode, a
defrosting operation mode is available for removing frost attached
at the heat-source-side heat exchanger 12 as a result of heat
exchange with the outdoor air at the heat-source-side heat
exchanger 12. The individual operation modes will be described
below in accordance with the flow of a heat-source-side refrigerant
and a heat medium.
[Cooling Only Operation Mode]
[0074] FIG. 3 is a refrigerant circuit diagram illustrating the
flow of refrigerant in the cooling only operation mode of the
air-conditioning apparatus 100. With reference to FIG. 3, the
cooling only operation mode will be explained in accordance with an
example of the case where a cooling load is generated at all of the
use-side heat exchangers 35a to 35d. In FIG. 3, pipes indicated by
thick lines represent pipes through which a heat-source-side
refrigerant flows. Furthermore, in FIG. 3, solid arrows represent
the flow direction of a heat-source-side refrigerant, and broken
arrows represent the flow direction of a heat medium.
[0075] In the cooling only operation mode illustrated in FIG. 3, in
the outdoor unit 1, the first refrigerant flow switching device 11
is switched to cause a heat-source-side refrigerant discharged from
the compressor 10 to flow into the heat-source-side heat exchanger
12.
[0076] In the relay unit 2, the pump 31a and the pump 31b are
driven and the heat medium flow control devices 34a to 34d are
opened, so that a heat medium may circulate between each of the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b and the use-side heat exchangers 35a to 35d. Furthermore, the
second refrigerant flow switching device 28a and the second
refrigerant flow switching device 28b are switched to the side of
cooling operation, the opening and closing device 27 is opened, and
the opening and closing device 29 is closed.
[0077] First, the flow of a heat-source-side refrigerant in the
refrigerant circulation circuit A will be explained.
[0078] A low-temperature and low-pressure refrigerant is compressed
by the compressor 10 into a high-temperature and high-pressure gas
refrigerant, and is discharged. The high-temperature and
high-pressure gas refrigerant which has been discharged from the
compressor 10 passes via the first refrigerant flow switching
device 11 through the heat-source-side heat exchanger 12, is
subjected to heat exchange with air in the outdoor space 6
(hereinafter, referred to as outdoor air), turns into a
high-temperature and high-pressure liquid or two-phase refrigerant,
passes through the check valve 13a, flows through the refrigerant
connection pipe 4a, and flows out of the outdoor unit 1. The
high-temperature and high-pressure liquid or two-phase refrigerant
which has flowed out of the outdoor unit 1 passes through the
refrigerant pipe 4, and flows into the relay unit 2.
[0079] The high-temperature and high-pressure liquid or two-phase
refrigerant which has flowed into the relay unit 2 passes through
the opening and closing device 27, is split, and is expanded at the
expansion device 26a and the expansion device 26b into
low-temperature and low-pressure two-phase refrigerant flows. The
two-phase refrigerant flows flow into the intermediate heat
exchanger 25a and the intermediate heat exchanger 25b, evaporate
and liquefy while receiving heat from a heat medium circulating in
the heat medium circulation circuit B, and turn into
low-temperature gas refrigerant. The gas refrigerant flows which
have flowed out of the intermediate heat exchanger 25a and the
intermediate heat exchanger 25b pass through the second refrigerant
flow switching device 28a and the second refrigerant flow switching
device 28b, flow out of the relay unit 2, flow through the
refrigerant pipe 4, pass through the check valve 13c, and are
sucked again to the compressor 10 via the first refrigerant flow
switching device 11 and the accumulator 19.
[0080] At this time, the opening degree of the expansion devices 26
is controlled such that the superheat (degree of superheat)
obtained as a difference between the value obtained by converting
the pressure of a heat-source-side refrigerant flowing between the
intermediate heat exchangers 25 and the expansion devices 26 into
saturation temperature and the temperature on the outlet side of
the intermediate heat exchangers 25 is constant. If the temperature
at the intermediate position of the intermediate heat exchangers 25
can be measured, the saturation temperature obtained by conversion
of the temperature at the intermediate position may be used
instead. In this case, there is no need to install a pressure
sensor, and the system can be configured at low cost.
[0081] Next, the flow of a heat medium in the heat medium
circulation circuit B will be explained.
[0082] In the cooling only operation mode, the cooling energy of a
heat-source-side refrigerant is transferred to a heat medium at
both of the intermediate heat exchanger 25a and the intermediate
heat exchanger 25b, the cooled heat medium is pressurized at and
flows out of the pump 31a and the pump 31b, and flows into the
use-side heat exchangers 35a to 35d via the second heat medium flow
switching devices 33a to 33d. Then, the heat medium receives heat
from the indoor air at the use-side heat exchangers 35a to 35d, and
cooling of the indoor space 7 is thus performed.
[0083] After that, the heat medium flows out of the use-side heat
exchangers 35a to 35d, and flows into the heat medium flow control
devices 34a to 34d. At this time, due to the operation of the heat
medium flow control devices 34a to 34d, the flow rate of a heat
medium is controlled to a flow rate necessary for an
air-conditioning load required for the indoor space, and the heat
medium is thus caused to flow into the use-side heat exchangers 35a
to 35d. The heat medium which has flowed out of the heat medium
flow control devices 34a to 34d passes through the first heat
medium flow switching devices 32a to 32d, flows into the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b, delivers to a refrigerant side the amount of heat received
from the indoor space 7 through the indoor units 3, and is sucked
again into the pump 31a and the pump 31b.
[0084] In the pipes 5 for the use-side heat exchangers 35, a heat
medium flows in the direction from the second heat medium flow
switching devices 33 via the heat medium flow control devices 34 to
the first heat medium flow switching devices 32. Furthermore, the
air-conditioning load required for the indoor space 7 may be
carried by controlling the temperature detected by the temperature
sensors 40 or the difference between the temperature detected by
the temperature sensors 40 and the temperature of a heat medium
flowing out of the use-side heat exchangers 35 to be maintained at
a target value. As the outlet temperature of the intermediate heat
exchangers 25, any one of the temperature of the temperature sensor
40a and the temperature of the temperature sensor 40b or the
average of these temperatures may be used.
[0085] At this time, the first heat medium flow switching devices
32 and the second heat medium flow switching devices 33 may be
controlled to intermediate opening degrees or opening degrees
corresponding to the heat medium temperature at the outlet of the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b so that the flow passages for the flow to both of the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b are secured. Originally, the use-side heat exchangers 35 should
be controlled based on the temperature difference between the inlet
and outlet thereof. However, since the heat medium temperature on
the inlet side of the use-side heat exchangers 35 is substantially
the same as the temperature detected by the temperature sensors 40.
Therefore, with the use of the temperature sensors 40, the number
of temperature sensors may be reduced, and the system may thus be
configured at low cost.
[0086] In executing the cooling only operation mode, there is no
need to cause a heat medium to flow to the use-side heat exchangers
35 with no thermal load. Therefore, the flow passages are closed by
the heat medium flow control devices 34, so that no heat medium
flows to the use-side heat exchangers 35. In FIG. 3, since there is
a thermal load in all of the use-side heat exchangers 35a to 35d, a
heat medium is caused to flow to the use-side heat exchangers 35a
to 35d. However, if no thermal load exists in any of the use-side
heat exchangers 35a to 35d, the corresponding heat medium flow
control device 34 may be fully closed. If a thermal load is
generated again, the corresponding heat medium flow control device
34 is opened, so that a heat medium may be caused to circulate.
This also applies to the other operation modes which will be
described later.
[Heating Only Operation Mode]
[0087] FIG. 4 is a refrigerant circuit diagram illustrating the
flow of refrigerant in the heating only operation mode of the
air-conditioning apparatus 100. With reference to FIG. 4, the
heating only operation mode will be explained in accordance with an
example of the case where a heating load is generated at all of the
use-side heat exchangers 35a to 35d. In FIG. 4, pipes indicated by
thick lines represent pipes through which a heat-source-side
refrigerant flows. Furthermore, in FIG. 4, solid arrows represent
the flow direction of a heat-source-side refrigerant, and broken
arrows represent the flow direction of a heat medium.
[0088] In the heating only operation mode illustrated in FIG. 4, in
the outdoor unit 1, the first refrigerant flow switching device 11
is switched to cause a heat-source-side refrigerant discharged from
the compressor 10 to flow into the relay unit 2 without passing
through the heat-source-side heat exchanger 12. In the relay unit
2, the pump 31a and the pump 31b are driven and the heat medium
flow control devices 34a to 34d are opened, so that a heat medium
may circulate between each of the intermediate heat exchanger 25a
and the intermediate heat exchanger 25b and the use-side heat
exchangers 35a to 35d. Furthermore, the second refrigerant flow
switching device 28a and the second refrigerant flow switching
device 28b are switched to the side of heating operation, the
opening and closing device 27 is closed, and the opening and
closing device 29 is opened.
[0089] First, the flow of a heat-source-side refrigerant in the
refrigerant circulation circuit A will be explained.
[0090] A low-temperature and low-pressure refrigerant is compressed
by the compressor 10 into a high-temperature and high-pressure gas
refrigerant, and is discharged. The high-temperature and
high-pressure gas refrigerant which has been discharged from the
compressor 10 passes via the first refrigerant flow switching
device 11, flows through the refrigerant connection pipe 4a, passes
through the check valve 13d, and flows out of the outdoor unit 1.
The high-temperature and high-pressure gas refrigerant which has
flowed out of the outdoor unit 1 passes through the refrigerant
pipe 4, and flows into the relay unit 2. The high-temperature and
high-pressure gas refrigerant which has flowed into the relay unit
2 is split. The split gas refrigerant flows pass through the second
refrigerant flow switching device 28a and the second refrigerant
flow switching device 28b, and flow into the intermediate heat
exchanger 25a and the intermediate heat exchanger 25b.
[0091] The high-temperature and high pressure gas refrigerant flows
which have flowed into the intermediate heat exchanger 25a and the
intermediate heat exchanger 25b condense and liquefy while
transferring heat to a heat medium circulating in the heat medium
circulation circuit B, and turn into high-pressure liquid
refrigerant flows. The liquid refrigerant flows that have flowed
out of the intermediate heat exchanger 25a and the intermediate
heat exchanger 25b are expanded at the expansion device 26a and the
expansion device 26b into low-temperature and low-pressure,
two-phase refrigerant flows. These two-phase refrigerant flows are
merged together. The merged two-phase refrigerant passes through
the opening and closing device 29, flows out of the relay unit 2,
passes through the refrigerant pipe 4, and flows into the outdoor
unit 1 again. The refrigerant which has flowed into the outdoor
unit 1 flows through the refrigerant connection pipe 4b, passes
through the check valve 13b, and flows into the heat-source-side
heat exchanger 12 operating as an evaporator.
[0092] The heat-source-side refrigerant which has flowed into the
heat-source-side heat exchanger 12 receives heat from the outdoor
air at the heat-source-side heat exchanger 12, and turns into a
low-temperature and low-pressure gas refrigerant. The
low-temperature and low-pressure gas refrigerant which has flowed
out of the heat-source-side heat exchanger 12 is sucked into the
compressor 10 again via the first refrigerant flow switching device
11 and the accumulator 19.
[0093] At this time, the opening degree of the expansion devices 26
is controlled such that the subcooling (degree of subcooling)
obtained as a difference between the value obtained by converting
the pressure of a heat-source-side refrigerant flowing between the
intermediate heat exchangers 25 and the expansion devices 26 into
saturation temperature and the temperature on the outlet side of
the intermediate heat exchangers 25 is constant. If the temperature
at the intermediate position of the intermediate heat exchangers 25
can be measured, the temperature at the intermediate position may
be used instead of the converted saturation temperature. In this
case, there is no need to install a pressure sensor, and the system
can be configured at low cost.
[0094] Next, the flow of a heat medium in the heat medium
circulation circuit B will be explained.
[0095] In the heating only operation mode, the heating energy of a
heat-source-side refrigerant is transferred to a heat medium at
both of the intermediate heat exchanger 25a and the intermediate
heat exchanger 25b, and the heated heat medium is caused by the
pump 31a and the pump 31b to flow in the pipes 5. The heat medium
which has been pressurized at and flowed out of the pump 31a and
the pump 31b flows into the use-side heat exchangers 35a to 35d via
the second heat medium flow switching devices 33a to 33d. Then, the
heat medium transfers heat to the indoor air at the use-side heat
exchangers 35a to 35d, and heating of the indoor space 7 is thus
performed.
[0096] After that, the heat medium flows out of the use-side heat
exchangers 35a to 35d, and flows into the heat medium flow control
devices 34a to 34d. At this time, due to the operation of the heat
medium flow control devices 34a to 34d, the flow rate of a heat
medium is controlled to a flow rate necessary for an
air-conditioning load required for an indoor space, and the heat
medium is thus caused to flow into the use-side heat exchangers 35a
to 35d. The heat medium which has flowed out of the heat medium
flow control devices 34a to 34d passes through the first heat
medium flow switching devices 32a to 32d, flows into the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b, receives the amount of heat supplied to the indoor space 7
through the indoor units 3, and is sucked again into the pump 31a
and the pump 31b.
[0097] In the pipes 5 for the use-side heat exchangers 35, a heat
medium flows in the direction from the second heat medium flow
switching devices 33 via the heat medium flow control devices 34 to
the first heat medium flow switching devices 32. Furthermore, the
air-conditioning load required for the indoor space 7 may be
carried by performing control so that the temperatures detected by
the temperature sensors 40 or the difference between the
temperatures detected by the temperature sensors 40 and the
temperature of a heat medium flowing out of the use-side heat
exchangers 35 to be maintained at a target value. As the outlet
temperature of the intermediate heat exchangers 25, any one of the
temperature of the temperature sensor 40a and the temperature of
the temperature sensor 40b or the average of these temperatures may
be used.
[0098] At this time, the first heat medium flow switching devices
32 and the second heat medium flow switching devices 33 may be
controlled to intermediate opening degrees or opening degrees
corresponding to the heat medium temperature at the outlet of the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b so that the flow passages for the flow to both of the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b are secured. Originally, the use-side heat exchangers 35 should
be controlled based on the temperature difference between the inlet
and outlet thereof. However, since the heat medium temperature on
the inlet side of the use-side heat exchangers 35 is substantially
the same as the temperature detected by the temperature sensors 40.
Therefore, with the use of the temperature sensors 40, the number
of temperature sensors may be reduced, and the system may thus be
configured at low cost.
[Cooling and Heating Mixed Operation Mode]
[0099] FIG. 5 is a refrigerant circuit diagram illustrating the
flow of refrigerant in the cooling and heating mixed operation mode
of the air-conditioning apparatus 100. With reference to FIG. 5,
the heating main operation mode of a cooling and heating mixed
operation in which a heating load is generated in some of the
use-side heat exchangers 35 and a cooling load is generated in the
rest of use-side heat exchangers 35 will be explained. In FIG. 5,
pipes indicated by thick lines represent pipes through which a
heat-source-side refrigerant circulates. Furthermore, in FIG. 5,
solid arrows represent the flow direction of a heat-source-side
refrigerant, and broken arrows represent the flow direction of a
heat medium.
[0100] In the heating main operation mode illustrated in FIG. 5, in
the outdoor unit 1, the first refrigerant flow switching device 11
is switched to cause a heat-source-side refrigerant discharged from
the compressor 10 to flow into the relay unit 2 without passing
through the heat-source-side heat exchanger 12. In the relay unit
2, the pump 31a and the pump 31b are driven and the heat medium
flow control devices 34a to 34d are opened, so that a heat medium
may circulate between the intermediate heat exchanger 25a and the
use-side heat exchanger 35 at which the cooling load is generated
and between the intermediate heat exchanger 25b and the use-side
heat exchanger 35 at which the heating load is generated.
Furthermore, the second refrigerant flow switching device 28a is
switched to the side of cooling operation, the second refrigerant
flow switching device 28b is switched to the side of heating
operation, the expansion device 26a is fully opened, the opening
and closing device 27 is closed, and the opening and closing device
29 is closed.
[0101] First, the flow of a heat-source-side refrigerant in the
refrigerant circulation circuit A will be explained.
[0102] A low-temperature and low-pressure refrigerant is compressed
by the compressor 10 into a high-temperature and high-pressure gas
refrigerant, and is discharged. The high-temperature and
high-pressure gas refrigerant which has been discharged from the
compressor 10 passes via the first refrigerant flow switching
device 11, flows through the refrigerant connection pipe 4a, passes
through the check valve 13d, and flows out of the outdoor unit 1.
The high-temperature and high-pressure gas refrigerant which has
flowed out of the outdoor unit 1 passes through the refrigerant
pipe 4, and flows into the relay unit 2. The high-temperature and
high-pressure gas refrigerant which has flowed into the relay unit
2 passes through the second refrigerant flow switching device 28b,
and flows into the intermediate heat exchanger 25b that operates as
a condenser.
[0103] The gas refrigerant which has flowed into the intermediate
heat exchanger 25b condenses and liquefies while transferring heat
to a heat medium circulating in the heat medium circulation circuit
B, and turns into a liquid refrigerant. The liquid refrigerant that
has flowed out of the intermediate heat exchanger 25b is expanded
at the expansion device 26b into a low-pressure, two-phase
refrigerant. The low-pressure, two-phase refrigerant passes through
the expansion device 26a and flows into the intermediate heat
exchanger 25a that operates as an evaporator. The low-pressure,
two-phase refrigerant that has flowed into the intermediate heat
exchanger 25a evaporates by receiving heat from a heat medium
circulating in the heat medium circulation circuit B, and thus
cools the heat medium. The low-pressure, two-phase refrigerant
flows out of the intermediate heat exchanger 25a, passes through
the second refrigerant flow switching device 28a, flows out of the
relay unit 2, passes through the refrigerant pipe 4, and flows into
the outdoor unit 1 again.
[0104] The low-temperature and low-pressure, two-phase refrigerant
which has flowed into the outdoor unit 1 passes through the check
valve 13b, and flows into the heat-source-side heat exchanger 12
that operates as an evaporator. Then, the refrigerant which has
flowed into the heat-source-side heat exchanger 12 receives heat
from the outdoor air at the heat-source-side heat exchanger 12, and
turns into a low-temperature and low-pressure gas refrigerant. The
low-temperature and low-pressure gas refrigerant which has flowed
out of the heat-source-side heat exchanger 12 is sucked into the
compressor 10 again via the first refrigerant flow switching device
11 and the accumulator 19.
[0105] The opening degree of the expansion device 26b is controlled
such that the subcooling (the degree of subcooling) of the
refrigerant at the outlet of the intermediate heat exchanger 25b is
a target value. By fully opening the expansion device 26b,
subcooling may be controlled using the expansion device 26a.
[0106] Next, the flow of a heat medium in the heat medium
circulation circuit B will be explained.
[0107] In the heating main operation mode, the heating energy of a
heat-source-side refrigerant is transferred to a heat medium at the
intermediate heat exchanger 25b, and the heated heat medium is
caused by the pump 31b to flow in the pipe 5. Furthermore, in the
heating main operation mode, the cooling energy of a
heat-source-side refrigerant is transferred to a heat medium at the
intermediate heat exchanger 25a, and the cooled heat medium is
caused by the pump 31a to flow in the pipe 5. The cooled heat
medium which has been pressurized by and flowed out of the pump 31a
flows via the second heat medium flow switching device 33 into the
use-side heat exchanger 35 at which the cooling load is generated,
and the heat medium which has been pressurized by and flowed out of
the pump 31b flows via the second heat medium flow switching device
33 into the use-side heat exchanger 35 at which the heating load is
generated.
[0108] At this time, the second heat medium flow switching device
33 is switched to a direction in which the intermediate heat
exchanger 25b and the pump 31b are connected when the connected
indoor unit 3 is in the heating operation mode, and is switched to
a direction in which the intermediate heat exchanger 25a and the
pump 31a are connected when the connected indoor unit 3 is in the
cooling operation mode. That is, the second heat medium flow
switching devices 33 allow a heat medium to be supplied to the
indoor units 3 to be used for heating or cooling.
[0109] The use-side heat exchangers 35 perform a cooling operation
for the indoor space 7 by causing a heat medium to receive heat
from the indoor air or a heating operation for the indoor space 7
by causing a heat medium to transfer heat to the indoor space. At
this time, due to the operation of the heat medium flow control
devices 34, the flow rate of a heat medium is controlled to a flow
rate necessary for an air-conditioning load required for an indoor
space, and the heat medium is thus caused to flow into the use-side
heat exchangers 35.
[0110] The heat medium whose temperature is slightly increased by
being used for a cooling operation and passing through the use-side
heat exchanger 35, passes through the heat medium flow control
device 34 and the first heat medium flow switching device 32, flows
into the intermediate heat exchanger 25a, and is sucked into the
pump 31a again. The heat medium whose temperature is slightly
decreased by being used for a heating operation and passing through
the use-side heat exchanger 35, passes through the heat medium flow
control device 34 and the first heat medium flow switching device
32, flows into the intermediate heat exchanger 25b, and is sucked
into the pump 31a again. At this time, the first heat medium flow
switching device 32 is switched to a direction in which the
intermediate heat exchanger 25b and the pump 31b are connected when
the connected indoor unit 3 is in the heating operation mode, and
is switched to a direction in which the intermediate heat exchanger
25a and the pump 31a are connected when the connected indoor unit 3
is in the cooling operation mode.
[0111] During this time, the hot heat medium and the cold heat
medium are not mixed together by the operation of the first heat
medium flow switching devices 32 and the second heat medium flow
switching devices 33, and are introduced to the use-side heat
exchangers 35 at which the heating load and the cooling load exist.
Accordingly, the heat medium that has been used for the heating
operation mode is caused to flow into the intermediate heat
exchanger 25b at which a refrigerant transfers heat for heating,
and the heat medium that has been used for the cooling operation
mode is caused to flow into the intermediate heat exchanger 25a at
which a refrigerant receives heat for cooling. Then, each of the
heat media is subjected to heat exchange with a refrigerant, and is
transferred to the pump 31a and the pump 31b.
[0112] In the pipes 5 for the use-side heat exchangers 35, for both
the side of heating operation and the side of cooling operation, a
heat medium flows in the direction from the second heat medium flow
switching devices 33 via the heat medium flow control devices 34 to
the first heat medium flow switching devices 32. Furthermore, the
air-conditioning load required for the indoor space 7 may be
carried by controlling, for the side of heating operation, the
difference between the temperature detected by the temperature
sensor 40b and the temperature of a heat medium which has flowed
out of the use-side heat exchanger 35, and for the side of cooling
operation, the difference between the temperature of a heat medium
which has flowed out of the use-side heat exchanger 35 and the
temperature detected by the temperature sensor 40a to be maintained
at a target value.
[0113] Moreover, in the cooling and heating mixed operation mode of
the air-conditioning apparatus 100 in FIG. 5, also in the cooling
main operation mode of a mixed operation in which a cooling load is
generated in some of the use-side heat exchangers 35 and a heating
load is generated in the rest of use-side heat exchangers 35, the
flow of a heat-source-side refrigerant in the refrigerant
circulation circuit A and the flow of a heat medium in the heat
medium circulation circuit B are similar to those in the heating
main operation mode.
[Defrosting Operation Mode]
[0114] As described above, in the air-conditioning apparatus 100,
when the heating only operation mode or the heating main operation
mode is executed, the heat-source-side heat exchanger 12 in the
outdoor unit 1 operates as an evaporator to exchange heat with the
outdoor air. Therefore, if the outdoor air temperature is low, the
evaporating temperature of the heat-source-side heat exchanger 12
decreases, and frosting occurs to the surface of the
heat-source-side heat exchanger 12 due to the moisture of the
outdoor air. Consequently, the performance of heat exchange may be
degraded. In the air-conditioning apparatus 100, for example, the
outdoor unit 1 detects evaporating temperature. When the detected
evaporating temperature becomes too low, the defrosting operation
mode for removing frost on the surface of the heat-source-side heat
exchanger 12 is executed. The heating only operation mode and the
heating main operation mode correspond to the "heating operation
mode" in the present invention.
[0115] In the air-conditioning apparatus 100, in execution of the
defrosting operation mode, the heat capacity that has been held by
a heat medium in the heating operation may be used. That is, during
the heating operation mode, the air-conditioning apparatus 100 can
melt frost formed around the heat-source-side heat exchanger 12 by
switching the first refrigerant flow switching device 11 to the
side of cooling operation, causing at least one of the pumps 31 to
operate, and causing a refrigerant to receive heat held by a heat
medium in at least one of the intermediate heat exchangers 25 (heat
recovery defrosting operation mode). With the above operation, the
air-conditioning apparatus 100 is able to remove frost on the
surface of the heat-source-side heat exchanger 12 more quickly than
conventional techniques. Meanwhile, the air-conditioning apparatus
100 is able to continue execution of the heating operation mode in
the use-side heat exchangers 35.
[0116] Furthermore, the air-conditioning apparatus 100 has a bypass
defrosting operation mode for melting frost formed around the
heat-source-side heat exchanger 12 by switching the first
refrigerant flow switching device 11 to the side of cooling
operation to cause part or whole of the refrigerant to flow to the
bypass pipe 20 during the heating operation mode.
[0117] In order to perform the operation mentioned above, the
air-conditioning apparatus 100 increases the temperature of a heat
medium through the intermediate heat exchangers 25 during the
heating operation mode immediately before execution of the
defrosting operation mode. Then, after detecting that the
temperature of the heat medium whose temperature has been increased
and which is detected by the temperature sensors 40 is higher than
a setting temperature (for example, 43 degrees Centigrade), the
air-conditioning apparatus 100 executes the defrosting operation
mode. With the above operation, the air-conditioning apparatus 100
may ensure the heat capacity to be used for the defrosting
operation mode and the amount of heat for continuing the heating
operation mode.
[0118] Specifically, when the temperature of a heat medium detected
by the temperature sensors 40 is higher than the setting
temperature (for example, 43 degrees Centigrade), the
air-conditioning apparatus 100 executes the "heat recovery
defrosting operation mode" which utilizes the heat capacity held by
the heat medium. In contrast, when the temperature of the heat
medium detected by the temperature sensors 40 is lower than the
setting temperature (for example, 43 degrees Centigrade), the
air-conditioning apparatus 100 executes the "bypass defrosting
operation mode" which does not utilize the heat capacity held by
the heat medium. The setting temperature may be changed to any
temperature. However, it is desirable to provide a use-side air
temperature sensor for detecting the temperature of air blown to
the use-side heat exchangers 35 and set the setting temperature to
a value equal to or higher than the temperature detected by the
use-side air temperature sensor. By setting to the above
temperature, either the "heat recovery defrosting operation mode"
or the "bypass defrosting operation mode" can be executed while
maintaining comfort.
[0119] As described above, the defrosting operation mode executed
by the air-conditioning apparatus 100 includes two types of
defrosting operation modes (the "heat recovery defrosting operation
mode" and the "bypass defrosting operation mode") according to the
flow of a heat-source-side refrigerant.
[0120] The "heat recovery defrosting operation mode" that is
executed during the heating only operation mode will be referred to
as a "first heat recovery defrosting operation mode".
[0121] The "heat recovery defrosting operation mode" that is
executed during the heating main operation mode will be referred to
as a "second heat recovery defrosting operation mode".
[0122] The "bypass defrosting operation mode" that is executed
during the heating only operation mode will be referred to as a
"first bypass defrosting operation mode".
[0123] The "bypass defrosting operation mode" that is executed
during the heating main operation mode will be referred to as a
"second bypass defrosting operation mode".
[First Heat Recovery Defrosting Operation Mode]
[0124] The "first heat recovery defrosting operation mode" executed
during the heating only operation mode of the air-conditioning
apparatus 100 further includes two types of defrosting operation
modes (a "first heat recovery defrosting operation mode (1)" and a
"first heat recovery defrosting operation mode (2)") according to
the flow of a heat-source-side refrigerant.
(First Heat Recovery Defrosting Operation Mode (1))
[0125] FIG. 6 is a refrigerant circuit diagram illustrating the
flow of refrigerant and the flow of a heat medium in the "first
heat recovery defrosting operation mode (1)" of the
air-conditioning apparatus 100. In FIG. 6, the "first heat recovery
defrosting operation mode (1)" will be explained. In FIG. 6, pipes
indicated by thick lines represent pipes through which a
heat-source-side refrigerant circulates. Furthermore, in FIG. 6,
solid arrows represent the flow direction of a heat-source-side
refrigerant, and broken arrows represent the flow direction of a
heat medium.
[0126] The "first heat recovery defrosting operation mode (1)" is a
defrosting operation mode to be executed during the heating only
operation mode of the air-conditioning apparatus 100 when frosting
occurs to the heat-source-side heat exchanger 12 in the outdoor
unit 1 due to moisture of the outdoor air and the evaporating
temperature decreases.
[0127] In the case of the "first heat recovery defrosting operation
mode (1)" illustrated in FIG. 6, in the outdoor unit 1, the first
refrigerant flow switching device 11 is switched to cause a
heat-source-side refrigerant discharged from the compressor 10 to
flow into the heat-source-side heat exchanger 12.
[0128] In the relay unit 2, the pump 31a and the pump 31b are
driven and the heat medium flow control devices 34a to 34d are
opened, so that a heat medium may circulate between each of the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b and the use-side heat exchangers 35a to 35d. Furthermore, the
second refrigerant flow switching device 28a and the second
refrigerant flow switching device 28b are switched to the side of
cooling operation, the opening and closing device 27 is opened, and
the opening and closing device 29 is closed. Furthermore, the
expansion device 26a and the expansion device 26b are fully opened.
However, the expansion device 26a and the expansion device 26b are
not necessarily strictly fully opened.
[0129] First, the flow of a heat-source-side refrigerant in the
refrigerant circulation circuit A will be explained.
[0130] A low-temperature and low-pressure refrigerant is compressed
by the compressor 10 into a high-temperature and high-pressure gas
refrigerant, and is discharged. The high-temperature and
high-pressure gas refrigerant which has been discharged from the
compressor 10 passes via the first refrigerant flow switching
device 11, and flows into the heat-source-side heat exchanger 12.
The refrigerant that has flowed into the heat-source-side heat
exchanger 12 exchanges heat with a frosting part on the
heat-source-side heat exchanger 12. The frosting part on the
heat-source-side heat exchanger 12 is melted by the
high-temperature, high-pressure refrigerant. The low-temperature
and high-pressure refrigerant that has exchanged heat with the
frosting part on the heat-source-side heat exchanger 12 passes
through the check valve 13a, and then flows out of the outdoor unit
1. The low-temperature and high-pressure refrigerant which has
flowed out of the outdoor unit 1 passes through the refrigerant
pipe 4, and flows into the relay unit 2.
[0131] The refrigerant which has flowed into the relay unit 2
passes through the opening and closing device 27, and is split. The
split refrigerant flows pass through the expansion device 26a and
the expansion device 26b and flow into the intermediate heat
exchanger 25a and the intermediate heat exchanger 25b. The
low-temperature and high-pressure refrigerant flows which have
flowed into the intermediate heat exchanger 25a and the
intermediate heat exchanger 25b are subjected to heat exchange with
a heat medium which has been used for heating and turn into
high-temperature, high-pressure refrigerant flows. The refrigerant
flows which have flowed out of the intermediate heat exchanger 25a
and the intermediate heat exchanger 25b pass through the second
refrigerant flow switching device 28a and the second refrigerant
flow switching device 28b, flow out of the relay unit 2, flow
through the refrigerant pipe 4, pass through the check valve 13c,
and are sucked again to the compressor 10 via the first refrigerant
flow switching device 11 and the accumulator 19.
(First Heat Recovery Defrosting Operation Mode (2))
[0132] FIG. 7 is a refrigerant circuit diagram illustrating the
flow of refrigerant and the flow of a heat medium in the "first
heat recovery defrosting operation mode (2)" of the
air-conditioning apparatus 100. In FIG. 7, the "first heat recovery
defrosting operation mode (2)" will be explained. In FIG. 7, pipes
indicated by thick lines represent pipes through which a
heat-source-side refrigerant circulates. Furthermore, in FIG. 7,
solid arrows represent the flow direction of a heat-source-side
refrigerant, and broken arrows represent the flow direction of a
heat medium.
[0133] Similar to the "first heat recovery defrosting operation
mode (1)", the "first heat recovery defrosting operation mode (2)"
is a defrosting operation mode to be executed during the heating
only operation mode of the air-conditioning apparatus 100 when
frosting occurs to the heat-source-side heat exchanger 12 in the
outdoor unit 1 due to moisture of the outdoor air and the
evaporating temperature decreases. However, the flow of a
heat-source-side refrigerant in the "first heat recovery defrosting
operation mode (2)" differs from that in the "first heat recovery
defrosting operation mode (1)". The air-conditioning apparatus 100
may select any one of the "first heat recovery defrosting operation
mode (1)" and the "first heat recovery defrosting operation mode
(2)".
[0134] In the case of the "first heat recovery defrosting operation
mode (2)" illustrated in FIG. 7, in the outdoor unit 1, the first
refrigerant flow switching device 11 is switched to cause a
heat-source-side refrigerant discharged from the compressor 10 to
flow into the heat-source-side heat exchanger 12.
[0135] In the relay unit 2, the pump 31a and the pump 31b are
driven and the heat medium flow control devices 34a to 34d are
opened, so that a heat medium may circulate between each of the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b and the use-side heat exchangers 35a to 35d. Furthermore, both
of the second refrigerant flow switching device 28a and the second
refrigerant flow switching device 28b maintain the opening
direction on the side of heating operation, the opening and closing
device 27 is closed, and the opening and closing device 29 is
opened. Furthermore, the expansion device 26a and the expansion
device 26b are fully opened. However, the expansion device 26a and
the expansion device 26b are not necessarily strictly fully
opened.
[0136] First, the flow of a heat-source-side refrigerant in the
refrigerant circulation circuit A will be explained.
[0137] A low-temperature and low-pressure refrigerant is compressed
by the compressor 10 into a high-temperature and high-pressure gas
refrigerant, and is discharged. The high-temperature and
high-pressure gas refrigerant which has been discharged from the
compressor 10 passes via the first refrigerant flow switching
device 11, and flows into the heat-source-side heat exchanger 12.
The refrigerant that has flowed into the heat-source-side heat
exchanger 12 exchanges heat with a frosting part on the
heat-source-side heat exchanger 12. The frosting part on the
heat-source-side heat exchanger 12 is melted by the
high-temperature, high-pressure refrigerant. The low-temperature
and high-pressure refrigerant that has exchanged heat with the
frosting part on the heat-source-side heat exchanger 12 passes
through the check valve 13a, and then flows out of the outdoor unit
1. The low-temperature and high-pressure gas refrigerant which has
flowed out of the outdoor unit 1 passes through the refrigerant
pipe 4, and flows into the relay unit 2.
[0138] The low-temperature and high-pressure gas refrigerant which
has flowed into the relay unit 2 is split. The split gas
refrigerant flows pass through the second refrigerant flow
switching device 28a and the second refrigerant flow switching
device 28b, and flow into the intermediate heat exchanger 25a and
the intermediate heat exchanger 25b. The low-temperature and
high-pressure refrigerant flows which have flowed into the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b are subjected to heat exchange with a heat medium which has
been used for heating and turn into high-temperature, high-pressure
refrigerant flows. The refrigerant flows which have flowed out of
the intermediate heat exchanger 25a and the intermediate heat
exchanger 25b pass through the expansion device 26a and the
expansion device 26b, flow out of the relay unit 2 via the opening
and closing device 29, flow through the refrigerant pipe 4, pass
through the check valve 13c, and are sucked again to the compressor
10 via the first refrigerant flow switching device 11 and the
accumulator 19.
[0139] Next, the flow of a heat medium in the heat medium
circulation circuit B in the "first heat recovery defrosting
operation mode" will be explained. The flow of a heat medium in the
heat medium circulation circuit B is common between the "first heat
recovery defrosting operation mode (1)" illustrated in FIG. 6 and
the "first heat recovery defrosting operation mode (2)" illustrated
in FIG. 7. Therefore, the flow of a heat medium will be explained
below in accordance with an example of the "first heat recovery
defrosting operation mode (2)".
[0140] In the "first heat recovery defrosting operation mode (2)",
a heat medium is subjected to heat exchange with a low-temperature
and high-pressure gas refrigerant at both of the intermediate heat
exchanger 25a and the intermediate heat exchanger 25b and turns
into a low-temperature heat medium. The heat medium whose
temperature has been decreased at the intermediate heat exchanger
25a and the intermediate heat exchanger 25b is pressurized by the
pump 31a and the pump 31b, and flows into the use-side heat
exchangers 35a to 35d via the second heat medium flow switching
devices 33a to 33d. At this time, the opening degree of the second
heat medium flow switching devices 33 is controlled to an
intermediate opening degree or an opening degree corresponding to
the heat medium temperature at the outlet of the intermediate heat
exchanger 25a and the intermediate heat exchanger 25b so that the
heat medium conveyed from both of the intermediate heat exchanger
25a and the intermediate heat exchanger 25b may be supplied to the
indoor units 3.
[0141] After that, the heat medium flows out of the use-side heat
exchangers 35a to 35d, and flows into the heat medium flow control
devices 34a to 34d. The heat medium which has flowed out of the
heat medium flow control devices 34a to 34d passes through the
first heat medium flow switching devices 32a to 32d. At this time,
the same opening degree adjustment as the second heat medium flow
switching devices 33 is performed on the first heat medium flow
switching devices 32, and the heat medium flow control devices 34
are fully opened.
[0142] The heat medium which has passed through the first heat
medium flow switching devices 32a to 32d flows into the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b, and is subjected to heat exchange again with flows of
refrigerant flowing in the intermediate heat exchanger 25a and the
intermediate heat exchanger 25b. After the amount of heat of the
heat medium is supplied to the refrigerant side, the heat medium is
sucked into the pump 31a and the pump 31b again.
[0143] The indoor unit 3 that has been performing a heating
operation in the "first heat recovery defrosting operation mode"
receives information indicating that the outdoor unit 1 is in the
defrosting operation mode, and stops a blower device (hereinafter,
simply referred to as a fan") for blowing air to the use-side heat
exchanger 35. However, if the indoor air temperature and the
indoor-unit blown-out air temperature may be detected, no problem
occurs if the fan continues operating as far as the indoor unit
blown-out air temperature is not lower than the indoor air
temperature. Furthermore, the fan may continue to operate as long
as the heat medium temperature at the outlet of the intermediate
heat exchanger 25 detected by the temperature sensor 40 is not
lower than the indoor air temperature.
[0144] Thus, by performing heat exchange with a heat medium at the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b in the relay unit 2 during the execution of the "first heat
recovery defrosting operation mode" of the outdoor unit 1, the
amount of heat supplied from the heat medium to the refrigerant
side may be supplied to the heat-source-side heat exchanger 12 of
the outdoor unit 1. Therefore, the time for melting frost may be
shortened.
[Second Heat Recovery Defrosting Operation Mode]
[0145] FIG. 8 is a refrigerant circuit diagram illustrating the
flow of refrigerant and the flow of a heat medium in the "second
heat recovery defrosting operation mode" of the air-conditioning
apparatus 100. In FIG. 8, the "second heat recovery defrosting
operation mode" will be explained. In FIG. 8, pipes indicated by
thick lines represent pipes through which a heat-source-side
refrigerant circulates. Furthermore, in FIG. 8, solid arrows
represent the flow direction of a heat-source-side refrigerant, and
broken arrows represent the flow direction of a heat medium.
[0146] In the case of the "second heat recovery defrosting
operation mode" illustrated in FIG. 8, in the outdoor unit 1, the
first refrigerant flow switching device 11 is switched to cause a
heat-source-side refrigerant discharged from the compressor 10 to
flow into the heat-source-side heat exchanger 12.
[0147] In the relay unit 2, the pump 31a and the pump 31b are
driven, the heat medium flow control device 34 for the indoor unit
3 that is performing a cooling operation is opened so that a heat
medium may circulate between the intermediate heat exchanger 25a
and the use-side heat exchanger 35 of the indoor unit 3 that is
performing the cooling operation, and the heat medium flow control
device 34 for the indoor unit 3 that is performing a heating
operation so that a heat medium may circulate between the
intermediate heat exchanger 25b and the use-side heat exchanger 35
of the indoor unit 3 that is performing the heating operation.
Furthermore, both of the second refrigerant flow switching device
28a and the second refrigerant flow switching device 28b maintain
the opening direction on the side of cooling operation, the opening
and closing device 27 is opened, and the opening and closing device
29 is closed. Furthermore, the expansion device 26a is controlled
such that the refrigerant at the outlet of the intermediate heat
exchanger 25a becomes a gas state, and the expansion device 26b is
fully opened. However, the expansion device 26b is not necessarily
strictly fully opened.
[0148] First, the flow of a heat-source-side refrigerant in the
refrigerant circulation circuit A will be explained.
[0149] A low-temperature and low-pressure refrigerant is compressed
by the compressor 10 into a high-temperature and high-pressure gas
refrigerant, and is discharged. The high-temperature and
high-pressure gas refrigerant which has been discharged from the
compressor 10 passes via the first refrigerant flow switching
device 11, and flows into the heat-source-side heat exchanger 12.
The refrigerant that has flowed into the heat-source-side heat
exchanger 12 exchanges heat with a frosting part on the
heat-source-side heat exchanger 12. The frosting part on the
heat-source-side heat exchanger 12 is melted by the
high-temperature, high-pressure refrigerant. The low-temperature
and high-pressure refrigerant that has exchanged heat with the
frosting part on the heat-source-side heat exchanger 12 passes
through the check valve 13a, and then flows out of the outdoor unit
1. The low-temperature and high-pressure refrigerant which has
flowed out of the outdoor unit 1 passes through the refrigerant
pipe 4, and flows into the relay unit 2.
[0150] The refrigerant which has flowed into the relay unit 2
passes through the opening and closing device 27, and is split. The
split refrigerant flows pass through the expansion device 26a and
the expansion device 26b and flow into the intermediate heat
exchanger 25a and the intermediate heat exchanger 25b. In the
intermediate heat exchanger 25a, due to the operation of the
expansion device 26a, heat exchange with a heat medium continues to
be performed to generate a low-temperature heat medium for cooling,
and the generated low-temperature heat medium for cooling is
supplied to the indoor unit 3. Meanwhile, a heat-source-side
refrigerant whose heat capacity has been lost by defrosting of the
heat-source-side heat exchanger 12 is conveyed to the intermediate
heat exchanger 25b. By performing heat exchange with a
high-temperature heat medium which has been used for the heating
operation, the heat capacity can be secured.
[0151] The refrigerant flows which have flowed out of the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b pass through the second refrigerant flow switching device 28a
and the second refrigerant flow switching device 28b, flow out of
the relay unit 2, flow through the refrigerant pipe 4, pass through
the check valve 13c, and are sucked again to the compressor 10 via
the first refrigerant flow switching device 11 and the accumulator
19.
[0152] Next, the flow of a heat medium in the heat medium
circulation circuit B in the "second heat recovery defrosting
operation mode" will be explained.
[0153] In the "second heat recovery defrosting operation mode", the
heat medium whose temperature has been decreased at the
intermediate heat exchanger 25a and the heat medium whose
temperature has been decreased at the intermediate heat exchanger
25b are pressurized by the pump 31a and the pump 31b, and flow into
the use-side heat exchangers 35a to 35d via the second heat medium
flow switching devices 33a to 33d. At this time, the second heat
medium flow switching device 33 is switched to a direction in which
the intermediate heat exchanger 25b and the pump 31b are connected
when the connected indoor unit 3 is in the heating operation mode,
and is switched to a direction in which the intermediate heat
exchanger 25a and the pump 31a are connected when the connected
indoor unit 3 is in the cooling operation mode.
[0154] For the indoor unit 3 that has been performing the cooling
operation, the cooling operation continues to be performed by
causing the heat medium which has been caused by the pump 31a to
flow into the indoor unit 3 to be subjected to heat exchange with
the indoor air of the indoor space 7 at the use-side heat exchanger
35. Then, the heat medium which has been subjected to heat exchange
at the use-side heat exchanger 35 is conveyed into the relay unit 2
via the heat medium pipe 5 and the heat medium flow control device
34. The flow rate of the heat medium which has been conveyed to
each of the indoor units 3 is adjusted by the corresponding heat
medium flow control device 34. The heat medium which has flowed out
of the heat medium flow control device 34 passes through the first
heat medium flow switching devices 32.
[0155] At this time, the flow rate is adjusted at the heat medium
flow control device 34 based on a detected difference between the
temperature immediately before the pump 31a and the outlet
temperature of the connected indoor unit 3. Furthermore, the first
heat medium flow switching device 32 is switched to the direction
in which the intermediate heat exchanger 25a and the pump 31a are
connected.
[0156] Meanwhile, the pump 31b is driven, the fan of the indoor
unit 3 that has been executing the heating operation mode is
stopped, and the heating operation mode is thus stopped.
Furthermore, the second heat medium flow switching device 33 that
is connected to the indoor unit 3 that has been executing the
heating operation mode is directed toward the opening direction in
which the connected pump 31b is connected. Moreover, the heat
medium flow control device 34 after passing through the use-side
heat exchanger 35 is fully opened, and the opening degree of the
first heat medium flow switching device 32 is set to the same
opening degree of the second heat medium flow switching device
33.
[0157] The heat medium that has been conveyed to the indoor unit 3
that has been executing the heating operation mode is conveyed to
the intermediate heat exchanger 25b via the first heat medium flow
switching device 32, without being subjected to heat exchange at
the use-side heat exchanger 35. The heat medium that has flowed
into the intermediate heat exchanger 25b is subjected to heat
exchange again with a heat-source-side refrigerant that has flowed
into the intermediate heat exchanger 25b, and supplies the heat to
the refrigerant side. After that, the heat medium is sucked again
into the pump 31b.
[0158] The indoor unit 3 that has been performing a heating
operation in the "second heat recovery defrosting operation mode"
receives information indicating that the outdoor unit 1 is in the
defrosting operation mode, and stops the fan. However, if the
indoor air temperature and the indoor unit blown-out air
temperature may be detected, no problem occurs if the fan continues
operating as far as the indoor unit blown-out air temperature is
not lower than the indoor air temperature. Furthermore, the fan may
continue operating as long as the heat medium temperature at the
outlet of the intermediate heat exchanger 25 detected by the
temperature sensor 40 is not lower than the indoor air
temperature.
[First Bypass Defrosting Operation Mode]
[0159] FIG. 9 is a refrigerant circuit diagram illustrating the
flow of refrigerant and the flow of a heat medium in the "first
bypass defrosting operation mode" of the air-conditioning apparatus
100. In FIG. 9, the "first bypass defrosting operation mode" will
be explained. In FIG. 9, pipes indicated by thick lines represent
pipes through which a heat-source-side refrigerant circulates.
Furthermore, in FIG. 9, solid arrows represent the flow direction
of a heat-source-side refrigerant, and broken arrows represent the
flow direction of a heat medium.
[0160] Similar to the "first heat recovery defrosting operation
mode", the "first bypass defrosting operation mode" is a defrosting
operation mode to be executed during the heating only operation
mode of the air-conditioning apparatus 100 when frosting occurs to
the heat-source-side heat exchanger 12 in the outdoor unit 1 due to
moisture of the outdoor air and the evaporating temperature
decreases. However, unlike the "first heat recovery defrosting
operation mode", the refrigerant does not receive the heat capacity
from the heat medium. The "first bypass defrosting operation mode"
is executed during the execution of the "first heat recovery
defrosting operation mode" by being switched according to a change
in the setting temperature.
[0161] In the case of the "first bypass defrosting operation mode"
illustrated in FIG. 9, in the outdoor unit 1, the first refrigerant
flow switching device 11 is switched to cause a heat-source-side
refrigerant discharged from the compressor 10 to flow into the
heat-source-side heat exchanger 12.
[0162] In the relay unit 2, the pump 31a and the pump 31b are
driven and the heat medium flow control devices 34a to 34d are
opened, so that a heat medium may circulate between each of the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b and the use-side heat exchangers 35a to 35d. Furthermore, the
second refrigerant flow switching device 28a and the second
refrigerant flow switching device 28b maintain a state being
switched to the side of cooling operation, the opening and closing
device 27 is opened, and the opening and closing device 29 is
closed. Furthermore, the expansion device 26a and the expansion
device 26b are fully closed.
[0163] First, the flow of a heat-source-side refrigerant in the
refrigerant circulation circuit A will be explained.
[0164] A low-temperature and low-pressure refrigerant is compressed
by the compressor 10 into a high-temperature and high-pressure gas
refrigerant, and is discharged. The high-temperature and
high-pressure gas refrigerant which has been discharged from the
compressor 10 passes via the first refrigerant flow switching
device 11, and flows into the heat-source-side heat exchanger
12.
[0165] The refrigerant that has flowed into the heat-source-side
heat exchanger 12 exchanges heat with a frosting part on the
heat-source-side heat exchanger 12. The frosting part on the
heat-source-side heat exchanger 12 is melted by the
high-temperature, high-pressure refrigerant. The low-temperature
and high-pressure refrigerant that has exchanged heat with the
frosting part on the heat-source-side heat exchanger 12 passes
through the check valve 13a, and then flows out of the outdoor unit
1. The low-temperature and high-pressure refrigerant which has
flowed out of the outdoor unit 1 passes through the refrigerant
pipe 4, and flows into the relay unit 2.
[0166] The refrigerant which has flowed into the relay unit 2
passes through the opening and closing device 27, and then passes
through the opening and closing device 29. The expansion device 26a
and the expansion device 26b are fully closed. Therefore, no
refrigerant is conveyed to the intermediate heat exchanger 25a and
the intermediate heat exchanger 25b. The refrigerant which has
passed through the opening and closing device 29 directly flows out
of the relay unit 2, passes through the refrigerant pipe 4, and
flows into the outdoor unit 1. The refrigerant which has flowed
into the outdoor unit 1 passes through the check valve 13c, and is
sucked into the compressor 10 again via the first refrigerant flow
switching device 11 and the accumulator 19.
[0167] Next, the flow of a heat medium in the heat medium
circulation circuit B in the "first bypass defrosting operation
mode" will be explained.
[0168] The heat medium has been used for the heating operation, and
as described above, the heat capacity is secured by temporarily
increasing the temperature of the heat medium at the intermediate
heat exchanger 25 before execution of the defrosting operation
mode. Therefore, the heat medium maintains high temperature. Thus,
even in the defrosting operation mode, a high-temperature heat
medium may be conveyed to the use-side heat exchanger 35, that is,
the heating operation may continue to be performed in the indoor
unit 3.
[0169] Specifically, due to the operation of the pump 31a and the
pump 31b that are connected to the intermediate heat exchanger 25a
and the intermediate heat exchanger 25b, the heat medium is
conveyed. Furthermore, each of the second heat medium flow
switching devices 33 that are connected to the corresponding indoor
units 3 is set to have an intermediate opening degree. Moreover,
the heat medium flow control devices 34 are controlled such that
the outlet temperature of the intermediate heat exchangers 25 and
the outlet temperature of the use-side heat exchangers 35 are
constant. The first heat medium flow switching devices 32 are set
to have the same opening degree of the second heat medium flow
switching devices 33, and the heating operation by the conveyance
of the heat medium may continue to be performed.
[0170] In addition, as illustrated in FIG. 9, even in the case
where the indoor units 3 may be configured to perform ventilation,
a high-temperature heat medium may flow into the use-side heat
exchangers 35 during a defrosting operation, heat exchange with the
outdoor air by the operation of the fans may be performed, and a
heating operation by hot-air blowing may continue to be
performed.
[0171] In the case where a heating operation continues to be
performed by the operation of a fan, by making the air volume of
the fan lower than the air volume (setting air volume) of the fan
during a conventional heating operation, the heat capacity emitted
to the indoor space by the use-side heat exchanger 35 may be
limited, and the time during which the heat capacity of the heat
medium is maintained may be extended. The setting air volume, which
is the air volume of the fan during the conventional heating
operation may be varied.
[0172] FIG. 10 is a graph illustrating an example of the
relationship between the air volume of a fan for each temperature
to which a heat medium may be reduced and the time during which the
heat medium temperature may be maintained in the case where a
heating operation continues to be performed with the air volume. As
illustrated in FIG. 10, the emission amount and time of heat to the
indoor space by blowing air from the fan may be estimated with
respect to the heat capacity which may be held by the heat medium.
By the above estimation, an appropriate air volume ratio and air
volume maintenance time may be determined, and the heating
operation mode may continue to be performed during the appropriate
time at the appropriate temperature in the defrosting operation
mode.
[Second Bypass Defrosting Operation Mode]
[0173] FIG. 11 is a refrigerant circuit diagram illustrating the
flow of refrigerant and the flow of a heat medium in the "second
bypass defrosting operation mode" of the air-conditioning apparatus
100. In FIG. 11, the "second bypass defrosting operation mode" will
be explained. In FIG. 11, pipes indicated by thick lines represent
pipes through which a heat-source-side refrigerant circulates.
Furthermore, in FIG. 11, solid arrows represent the flow direction
of a heat-source-side cooling, and broken arrows represent the flow
direction of a heat medium. The "second bypass defrosting operation
mode" is executed during the execution of the "second heat recovery
defrosting operation mode" by being switched according to a change
in the setting temperature.
[0174] In the case of the "second bypass defrosting operation mode"
illustrated in FIG. 11, in the outdoor unit 1, the first
refrigerant flow switching device 11 is switched to cause a
heat-source-side refrigerant discharged from the compressor 10 to
flow into the heat-source-side heat exchanger 12.
[0175] In the relay unit 2, the pump 31a and the pump 31b are
driven and the heat medium flow control devices 34a to 34d are
opened, so that a heat medium may circulate between each of the
intermediate heat exchanger 25a and the intermediate heat exchanger
25b and the use-side heat exchangers 35a to 35d. Furthermore, the
second refrigerant flow switching device 28a and the second
refrigerant flow switching device 28b maintain a state being
switched to the side of cooling operation, the opening and closing
device 27 is opened, and the opening and closing device 29 is
opened. Furthermore, the expansion device 26a is controlled such
that the refrigerant at the outlet of the intermediate heat
exchanger 25a becomes a gas state, and the expansion device 26b is
fully closed.
[0176] First, the flow of a heat-source-side refrigerant in the
refrigerant circulation circuit A will be explained.
[0177] A low-temperature and low-pressure refrigerant is compressed
by the compressor 10 into a high-temperature and high-pressure gas
refrigerant, and is discharged. The high-temperature and
high-pressure gas refrigerant which has been discharged from the
compressor 10 passes via the first refrigerant flow switching
device 11, and flows into the heat-source-side heat exchanger 12.
The refrigerant that has flowed into the heat-source-side heat
exchanger 12 exchanges heat with a frosting part on the
heat-source-side heat exchanger 12. The frosting part on the
heat-source-side heat exchanger 12 is melted by the
high-temperature, high-pressure refrigerant. The low-temperature
and high-pressure refrigerant that has exchanged heat with the
frosting part on the heat-source-side heat exchanger 12 passes
through the check valve 13a, and then flows out of the outdoor unit
1. The low-temperature and high-pressure gas refrigerant which has
flowed out of the outdoor unit 1 passes through the refrigerant
pipe 4, and flows into the relay unit 2.
[0178] The refrigerant which has flowed into the relay unit 2
passes through the opening and closing device 27, and is split. The
split refrigerant flows pass through the opening and closing device
29 and the expansion device 26a. The refrigerant flows that have
passed through the expansion device 26a flow into the intermediate
heat exchanger 25a. In the intermediate heat exchanger 25a, due to
the operation of the expansion device 26a, heat exchange with a
heat medium continues to be performed to generate a low-temperature
heat medium for cooling, and the generated low-temperature heat
medium for cooling is supplied to the indoor unit 3. Meanwhile, no
refrigerant is conveyed to the intermediate heat exchanger 25b, and
heat exchange with a high-temperature heat medium which has been
used for the heating operation is not performed.
[0179] The refrigerant flows that have passed through the
intermediate heat exchanger 25a and the opening and closing device
29 are merged together. The merged refrigerant flows out of the
relay unit 2. The refrigerant which has flowed out of the relay
unit 2 passes through the refrigerant pipe 4, and flows into the
outdoor unit. The refrigerant which has flowed into the outdoor
unit 1 passes through the check valve 13c, and is sucked into the
compressor 10 again via the first refrigerant flow switching device
11 and the accumulator 19.
[0180] Next, the flow of a heat medium in the heat medium
circulation circuit B in the "second bypass defrosting operation
mode" will be explained.
[0181] In the "second bypass defrosting operation mode", the heat
medium whose temperature has been decreased at the intermediate
heat exchanger 25a is pressurized by the pump 31a, passes through a
corresponding one of the second heat medium flow switching devices
33a to 33d that corresponds to the indoor unit 3 in the cooling
operation mode, and flows into the corresponding one of the
use-side heat exchangers 35a to 35d. For the indoor unit 3 that has
been performing the cooling operation, the cooling operation
continues to be performed by causing the heat medium which has been
caused by the pump 31a to flow into the indoor unit 3 to be
subjected to heat exchange with the indoor air of the indoor space
7 at the use-side heat exchanger 35.
[0182] Then, the heat medium which has been subjected to heat
exchange at the use-side heat exchanger 35 is conveyed into the
relay unit 2 via the heat medium pipe 5 and the heat medium flow
control device 34. The flow rate of the heat medium which has been
conveyed to each of the indoor units 3 is adjusted by the
corresponding heat medium flow control device 34. The heat medium
which has flowed out of the heat medium flow control device 34
passes through the first heat medium flow switching device 32. The
heat medium that has passed through the first heat medium flow
switching device 32 is subjected to heat exchange again with a
heat-source-side refrigerant that has flowed into the intermediate
heat exchanger 25a, and supplies the heat to the refrigerant side.
After that, the heat medium is sucked again into the pump 31a.
[0183] In contrast, the heat medium flowing into the intermediate
heat exchanger 25b has been used for the heating operation, and as
described above, the heat capacity is secured by temporarily
increasing the temperature of the heat medium at the intermediate
heat exchanger before execution of the defrosting operation mode.
Therefore, the heat medium still has a high temperature. Thus, even
in the defrosting operation mode, a high-temperature heat medium
may be conveyed to the use-side heat exchanger 35 by conveyance of
the heat medium, that is, the heating operation may continue to be
performed in the indoor unit 3.
[0184] Specifically, due to the operation of the pump 31b that is
connected to the intermediate heat exchanger 25b, the heat medium
is conveyed. Furthermore, each of the second heat medium flow
switching devices 33 that are connected to the corresponding indoor
units 3 is directed toward the intermediate heat exchanger 25b.
Moreover, the heat medium flow control devices 34 after passing
through the use-side heat exchangers 35 are controlled such that
the outlet temperature of the intermediate heat exchanger 25b and
the outlet temperature of the use-side heat exchanger are constant.
Furthermore, the first heat medium flow switching devices 32 are
set to have the same opening degree of the second heat medium flow
switching devices 33, and the heating operation by the conveyance
of the heat medium may continue to be performed.
[0185] In addition, as illustrated in FIG. 11, even in the case
where the indoor units 3 may perform ventilation, a
high-temperature heat medium may flow into the use-side heat
exchangers 35 during a defrosting operation, heat exchange with the
outdoor air by the operation of the fans may be performed, and a
heating operation by hot-air blowing may continue to be
performed.
[0186] As described with reference to FIG. 10, in the case where a
heating operation continues to be performed by the operation of a
fan, by making the air volume of the fan smaller than a
conventional heating operation, the heat capacity emitted to the
indoor space by the use-side heat exchanger 35 may be limited, and
the time during which the heat capacity of the heat medium is
maintained may be extended.
[0187] As described above, the air-conditioning apparatus 100
exchanges heat between refrigerant and a heat medium via the relay
unit 2 without causing the refrigerant to directly circulate in the
indoor space in which the indoor units 3 are installed, and conveys
the heat medium to the indoor units 3. Accordingly, a cooling
operation and a heating operation can be achieved. Therefore, the
air-conditioning apparatus 100 is able to avoid leakage of
refrigerant into the indoor space. Furthermore, in the
air-conditioning apparatus 100, refrigerant is conveyed from the
outdoor unit 1 to the relay unit 2, and the relay unit 2 may thus
be installed at an appropriate position. Therefore, the conveyance
distance of a heat medium may be shortened, and the motive power of
the pump 31a and the pump 31b may be reduced. Consequently, energy
saving can be attained.
[0188] Furthermore, when the air-conditioning apparatus 100
performs a heating operation at a low outdoor air temperature,
frosting occurs in the outdoor unit 1. The air-conditioning
apparatus 100 has a defrosting operation mode for removing frost on
the heat-source-side heat exchanger 12 of the outdoor unit 1 based
on detection of the evaporating temperature or the like. In this
defrosting operation mode, refrigerant which has been subjected to
heat exchange by defrosting and whose temperature has been reduced
is conveyed to the indoor units 3 during a heating operation. In
addition, the refrigerant is subjected to heat exchange with a heat
medium whose temperature has been increased to a high temperature
immediately before a defrosting operation, and is conveyed to the
outdoor unit 1. By performing the above processing, with the
air-conditioning apparatus 100, the heat capacity held by a heat
medium may be utilized for defrosting, and a defrosting operation
time may be shortened.
[0189] Furthermore, in the defrosting operation mode, by reducing
the air volume of a fan and setting a fan operation maintenance
time corresponding to the air volume for the indoor unit 3 that has
been performing a heating operation, the air-conditioning apparatus
100 is able to continue an appropriate heating operation.
Furthermore, even when the indoor units 3 may take in the outdoor
air, the air-conditioning apparatus 100 may exchange heat with a
heat medium in the defrosting operation mode, and may continue to
perform a heating operation, as described above.
[0190] The first heat medium flow switching devices 32 and the
second heat medium flow switching devices 33 explained above in
Embodiment may be devices which may switch a flow passage, such as
a combination of three-way valves or the like which may switch
three-way flow passages and opening and closing valves or the like
which may open and close two-way flow passages. Furthermore, a
combination of stepping-motor mixing valves or the like which may
change the flow rate of three-way flow passages and electronic
expansion valves or the like which may change the flow rate of
two-way flow passages, or the like may be used as the first heat
medium flow switching devices 32 and the second heat medium flow
switching devices 33. In this case, water hammer caused by sudden
opening and closing of a flow passage may be prevented.
Furthermore, although the case where the heat medium flow control
devices 34 are two-way valves is explained as an example in
Embodiment, the heat medium flow switching devices 34 may be
configured as control valves having three-way flow passages and may
be installed together with a bypass pipe for bypassing the use-side
heat exchangers 35.
[0191] Furthermore, stepping-motor-driven devices which may control
the flow rate of flowing in a flow passage may be used as the heat
medium flow control devices 34. The devices may be two-way valves
or three-way valves whose one end is closed. Furthermore, opening
and closing valves or the like which open and close two-way flow
passages may be used as the heat medium flow control devices 34,
and the average flow rate may be controlled by repeatedly turning
on and off.
[0192] Furthermore, although it is illustrated as if the second
refrigerant flow switching devices 28 were four-way valves, the
second refrigerant flow switching devices 28 are not limited to
this. The second refrigerant flow switching devices 28 may be
configured such that refrigerant flows in the same manner by using
a plurality of two-phase flow passage switching valves or three-way
flow passage switching valves.
[0193] Furthermore, needless to say, similar effects are achieved
even when only one of the use-side heat exchangers 35 and the heat
medium flow control devices 34 is connected, and there is no
problem if a plurality of devices that perform the same operation
are installed as the intermediate heat exchangers 25 and the
expansion devices 26. Moreover, although the case where the heat
medium flow control devices 34 are built in the relay unit 2 is
explained as an example, the heat medium flow control devices 34
are not necessarily built in the relay unit 2. The heat medium flow
control devices 34 may be built in the indoor units 3 or may be
configured separately from the relay unit 2 and the indoor units
3.
[0194] As a heat medium, for example, brine (antifreeze), water, a
liquid mixture of brine and water, a liquid mixture of water and an
additive having high anti-corrosion effect, or the like may be
used. Therefore, in the air-conditioning apparatus 100, even if a
heat medium is leaked into the indoor space 7 via the indoor units
3, the use of a heat medium with a high safety contributes to an
improvement in the safety.
[0195] In Embodiment, although the case where the air-conditioning
apparatus 100 includes the accumulator 19 has been explained as an
example, the accumulator 19 is not necessarily provided.
Furthermore, generally, blower devices are attached to the
heat-source-side heat exchanger 12 and the use-side heat exchangers
35, and blowing air often prompts condensation and evaporation.
However, the configuration is not limited to this. For example,
panel heaters or the like which utilize radiation may be used as
the use-side heat exchangers 35. Devices of a water-cooled type for
moving heat by using water or antifreeze may be used as the
heat-source-side heat exchanger 12. That is, devices of any type
may be used as the heat-source-side heat exchanger 12 and the
use-side heat exchangers 35 as long as they have a structure which
may transfer heat or receive heat.
[0196] Although the case where the four use-side heat exchangers 35
are provided is explained as an example in Embodiment, the number
of use-side heat exchangers 35 is not particularly limited.
Furthermore, although the case where the two intermediate heat
exchanger 25a and the intermediate heat exchanger 25b are provided
is explained as an example, obviously, the number of intermediate
heat exchangers is not limited to this. Any number of intermediate
heat exchangers may be installed as long as the intermediate heat
exchangers are able to cool or/and heat a heat medium. Furthermore,
each of the number of pumps 31a and the number of pumps 31b is not
necessarily one. A plurality of compact pumps may be connected in
parallel to one another.
REFERENCE SIGNS LIST
[0197] 1: outdoor unit, 2: relay unit, 3: indoor unit, 3a: indoor
unit, 3b: indoor unit, 3c: indoor unit, 3d: indoor unit, 4:
refrigerant pipe, 4a: refrigerant connection pipe, 4b: refrigerant
connection pipe, 5: heat medium pipe, 6: outdoor space, 7: indoor
space, 8: space, 9: structure, 10: compressor, 11: first
refrigerant flow switching device, 12: heat-source-side heat
exchanger, 13a: check valve, 13b: check valve, 13c: check valve,
13d: check valve, 19: accumulator, 20: bypass pipe, 25:
intermediate heat exchanger, 25a: intermediate heat exchanger, 25b:
intermediate heat exchanger, 26: expansion device, 26a: expansion
device, 26b: expansion device, 27: opening and closing device, 28:
second refrigerant flow switching device (refrigerant flow
switching device), 28a: second refrigerant flow switching device
(refrigerant flow switching device), 28b: second refrigerant flow
switching device (refrigerant flow switching device), 29: opening
and closing device, 31: pump, 31a: pump, 31b: pump, 32: first heat
medium flow switching device, 32a: first heat medium flow switching
device, 32b: first heat medium flow switching device, 32c: first
heat medium flow switching device, 32d: first heat medium flow
switching device, 33: second heat medium flow switching device,
33a: second heat medium flow switching device, 33b: second heat
medium flow switching device, 33c: second heat medium flow
switching device, 33d: second heat medium flow switching device,
34: heat medium flow control device, 34a: heat medium flow control
device, 34b: heat medium flow control device, 34c: heat medium flow
control device, 34d: heat medium flow control device, 35: use-side
heat exchanger, 35a: use-side heat exchanger, 35b: use-side heat
exchanger, 35c: use-side heat exchanger, 35d: use-side heat
exchanger, 40: temperature sensor (heat medium temperature sensor),
40a: temperature sensor (heat medium temperature sensor), 40b:
temperature sensor (heat medium temperature sensor), 43: duct, 50:
controller, 100: air-conditioning apparatus, A: refrigerant
circulation circuit, B: heat medium circulation circuit.
* * * * *