U.S. patent application number 13/824709 was filed with the patent office on 2013-07-11 for refrigeration circuit.
This patent application is currently assigned to Daikin Industries, Ltd.. The applicant listed for this patent is Noriyuki Okuda, Takamune Okui, Takayuki Setoguchi, Keisuke Tanimoto. Invention is credited to Noriyuki Okuda, Takamune Okui, Takayuki Setoguchi, Keisuke Tanimoto.
Application Number | 20130174595 13/824709 |
Document ID | / |
Family ID | 45892828 |
Filed Date | 2013-07-11 |
United States Patent
Application |
20130174595 |
Kind Code |
A1 |
Okuda; Noriyuki ; et
al. |
July 11, 2013 |
REFRIGERATION CIRCUIT
Abstract
A refrigeration circuit includes a compressor, an outdoor heat
exchanger, an expansion valve, an indoor heat exchanger, and a
refrigerant storage tank provided between the outdoor heat
exchanger and the expansion value. Refrigerant sequentially flows
through the compressor, the outdoor heat exchanger, the expansion
valve and the indoor heat exchanger during an air-cooling
operation. Refrigerant sequentially flows through the compressor,
the indoor heat exchanger, the expansion valve, and the outdoor
heat exchanger during an air-warming operation. Preferably the
indoor heat exchanger is a cross-fin heat exchanger, and the
outdoor heat exchanger is a stacked heat exchanger. Preferably, a
capacity of the outdoor heat exchanger is no more than 100% of a
capacity of the indoor heat exchanger.
Inventors: |
Okuda; Noriyuki; (Sakai-shi,
JP) ; Setoguchi; Takayuki; (Sakai-shi, JP) ;
Tanimoto; Keisuke; (Sakai-shi, JP) ; Okui;
Takamune; (Sakai-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Okuda; Noriyuki
Setoguchi; Takayuki
Tanimoto; Keisuke
Okui; Takamune |
Sakai-shi
Sakai-shi
Sakai-shi
Sakai-shi |
|
JP
JP
JP
JP |
|
|
Assignee: |
Daikin Industries, Ltd.
Osaka
JP
|
Family ID: |
45892828 |
Appl. No.: |
13/824709 |
Filed: |
September 22, 2011 |
PCT Filed: |
September 22, 2011 |
PCT NO: |
PCT/JP2011/071612 |
371 Date: |
March 18, 2013 |
Current U.S.
Class: |
62/238.6 |
Current CPC
Class: |
F25B 13/00 20130101;
F25B 2500/01 20130101; F25B 2400/19 20130101; F25B 45/00 20130101;
F25B 30/02 20130101; F25B 2313/02741 20130101; F25B 2400/23
20130101; F28D 2021/0068 20130101 |
Class at
Publication: |
62/238.6 |
International
Class: |
F25B 30/02 20060101
F25B030/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 30, 2010 |
JP |
2010-222719 |
Claims
1. A refrigeration circuit comprising: a compressor; an outdoor
heat exchanger; an expansion valve; an indoor heat exchanger; and a
refrigerant storage tank provided between the outdoor heat
exchanger and the expansion valve, refrigerant sequentially flowing
through the compressor, the outdoor heat exchanger, the expansion
valve and the indoor heat exchanger during an air-cooling
operation, refrigerant sequentially flowing through the compressor,
the indoor heat exchanger, the expansion valve, and the outdoor
heat exchanger during an air-warming operation, the indoor heat
exchanger being a cross-fin heat exchanger, and the outdoor heat
exchanger being a stacked heat exchanger.
2. A refrigeration circuit comprising: a compressor; an outdoor
heat exchanger; an expansion valve; an indoor heat exchanger, and a
refrigerant storage tank provided between the outdoor heat
exchanger and the expansion valve, refrigerant sequentially flowing
through the compressor, the outdoor heat exchanger, the expansion
valve and the indoor heat exchanger during an air-cooling
operation, refrigerant sequentially flowing through the compressor,
the indoor heat exchanger, the expansion valve, and the outdoor
heat exchanger during an air-warming operation, and a capacity of
the outdoor heat exchanger being no more than 100% of a capacity of
the indoor heat exchanger.
3. The refrigeration circuit according to claim 2, wherein the
outdoor heat exchanger is a stacked heat exchanger having a
plurality of flattened tubes arranged so as to overlap with spaces
therebetween, and fins placed between adjacent flattened tubes.
4. The refrigeration circuit according to claim 2, wherein the
outdoor heat exchanger is a stacked heat exchanger having a
flattened tube molded into a serpentine shape, and fins placed
between mutually adjacent surfaces of the flattened tube.
5. The refrigeration circuit according to claim 2, wherein the
outdoor heat exchanger and the indoor heat exchanger are both
cross-fin heat exchangers, and a heat transfer tube diameter of the
outdoor heat exchanger is smaller than a heat transfer tube
diameter of the indoor heat exchanger.
6. The refrigeration circuit according to claim 2, further
comprising a bypass channel arranged to lead a gas component of
refrigerant retained in the refrigerant storage tank to one of the
compressor and a refrigerant tube on an intake side of the
compressor.
7. The refrigeration circuit according to claim 6, wherein the
bypass channel has a flow-rate-regulating mechanism.
8. The refrigeration circuit according to claim 2, wherein the
refrigerant storage tank is a gas-liquid separator.
9. The refrigeration circuit according to claim 1, wherein the
stacked outdoor heat exchanger has a plurality of flattened tubes
arranged so as to overlap with spaces therebetween, and fins placed
between adjacent flattened tubes.
10. The refrigeration circuit according to claim 1, wherein the
stacked outdoor heat exchanger has a flattened tube molded into a
serpentine shape, and fins placed between mutually adjacent
surfaces of the flattened tube.
11. The refrigeration circuit according to claim 1, further
comprising a bypass channel arranged to lead a gas component of
refrigerant retained in the refrigerant storage tank to one of the
compressor and a refrigerant tube on an intake side of the
compressor.
12. The refrigeration circuit according to claim 1 wherein the
bypass channel has a flow-rate-regulating mechanism.
13. The refrigeration circuit according to claim 1, wherein the
refrigerant storage tank is a gas-liquid separator.
Description
TECHNICAL FIELD
[0001] The present invention relates to a refrigeration circuit,
and particularly relates to a refrigeration circuit used in an air
conditioner.
BACKGROUND ART
[0002] In a refrigeration circuit of an air conditioning apparatus,
the optimal refrigerant quantity during an air-cooling operation is
different from the optimal refrigerant quantity during an
air-warming operation, and the capacity of an outdoor heat
exchanger functioning as a condenser during the air-cooling
operation is therefore different from the capacity of an indoor
heat exchanger functioning as a condenser during the air-warming
operation. Normally, the capacity of the outdoor heat exchanger is
greater than the capacity of the indoor heat exchanger, and
refrigerant that cannot be accumulated in the indoor heat exchanger
during the air-warming operation is temporarily stored in an
accumulator or the like.
SUMMARY OF THE INVENTION
Technical Problem
[0003] However, when a small high-performance capacitor such as is
disclosed in Patent Literature 1 (Japanese Laid-open Patent
Application No. 6-143991) is used in an outdoor heat exchanger of a
refrigeration circuit of an air conditioning apparatus, the
capacity of the outdoor heat exchanger is less than the capacity of
the indoor heat exchanger, there will for the moment be refrigerant
(surplus refrigerant) that could not be accommodated in the outdoor
heat exchanger during the air-cooling operation, and the quantity
of this refrigerant exceeds the quantity that can be stored in the
accumulator or the like.
[0004] An object of the present invention is to provide a
refrigeration circuit that can accommodate surplus refrigerant
occurring during the air-cooling operation when the capacity of the
outdoor heat exchanger is less than the capacity of the indoor heat
exchanger.
Solution to Problem
[0005] A refrigeration circuit according to a first aspect of the
present invention is a refrigeration circuit in which refrigerant
flows sequentially to a compressor, an outdoor heat exchanger, an
expansion valve, and an indoor heat exchanger during an air-cooling
operation, and refrigerant flows sequentially to the compressor,
the indoor heat exchanger, the expansion valve, and the outdoor
heat exchanger during an air-warming operation; wherein the indoor
heat exchanger is a cross-fin type heat exchanger and the outdoor
heat exchanger is a stacked heat exchanger. A refrigerant storage
tank is provided between the outdoor heat exchanger and the
expansion valve.
[0006] The capacity of the stacked heat exchanger is less than the
capacity of the cross-fin type heat exchanger having the same heat
exchange performance. In comparison with a refrigeration circuit in
which both the outdoor heat exchanger and the indoor heat exchanger
are cross-fin type heat exchangers, for example, when only the
outdoor heat exchanger is replaced with a stacked heat exchanger
having the same heat exchange performance, the capacity of the
stacked heat exchanger is not only less than what would be the
capacity of a cross-fin type outdoor heat exchanger, but is also
less than the capacity of the cross-fin type indoor heat exchanger
to which it is connected.
[0007] Due to the capacity of the outdoor heat exchanger being less
than the capacity of the indoor heat exchanger, surplus refrigerant
occurs during the air-cooling operation, but because the surplus
refrigerant is accommodated in the refrigerant storage tank in this
refrigeration circuit, the surplus refrigerant is prevented from
hindering refrigeration control.
[0008] A refrigeration circuit according to a second aspect of the
present invention is a refrigeration circuit in which refrigerant
flows sequentially to a compressor, an outdoor heat exchanger, an
expansion valve, and an indoor heat exchanger during an air-cooling
operation, and refrigerant flows sequentially to the compressor,
the indoor heat exchanger, the expansion valve, and the outdoor
heat exchanger during an air-warming operation; wherein the
capacity of the outdoor heat exchanger is 100% or less of the
capacity of the indoor heat exchanger. A refrigerant storage tank
is provided between the outdoor heat exchanger and the expansion
valve.
[0009] In this refrigeration circuit, due to the capacity of the
outdoor heat exchanger being equal to or less than the capacity of
the indoor heat exchanger, surplus refrigerant occurs during the
air-cooling operation, but because the surplus refrigerant is
accommodated in the refrigerant storage tank, the surplus
refrigerant is prevented from hindering refrigeration control.
[0010] A refrigeration circuit according to a third aspect of the
present invention is the refrigeration circuit according to the
first or second aspect, wherein the outdoor heat exchanger is a
stacked heat exchanger having a plurality of flattened tubes and
fins. The flattened tubes are arranged so as to overlap with spaces
therebetween. The fins are placed between adjacent flattened
tubes.
[0011] In this refrigeration circuit, similar to the refrigeration
circuit according to the first or second aspect, the refrigerant
quantity in the refrigeration circuit is reduced because the
capacity of the outdoor heat exchanger is less than the capacity of
the indoor heat exchanger. Surplus refrigerant occurs during the
air-cooling operation, but because the surplus refrigerant is
accommodated in the refrigerant storage tank, the surplus
refrigerant is prevented from hindering refrigeration control.
[0012] A refrigeration circuit according to a fourth aspect of the
present invention is the refrigeration circuit according to the
first or second aspect, wherein the outdoor heat exchanger is a
stacked heat exchanger having a flattened tube and fins. The
flattened tube is molded into a serpentine shape. The fins are
placed between mutually adjacent surfaces of the flattened
tube.
[0013] In this refrigeration circuit, similar to the refrigeration
circuit according to the first or second aspect, the refrigerant
quantity in the refrigeration circuit is reduced because the
capacity of the outdoor heat exchanger is less than the capacity of
the indoor heat exchanger. Surplus refrigerant occurs during the
air-cooling operation, but because the surplus refrigerant is
accommodated in the refrigerant storage tank, the surplus
refrigerant is prevented from hindering refrigeration control.
[0014] A refrigeration circuit according to a fifth aspect of the
present invention is the refrigeration circuit according to the
second aspect, wherein the outdoor heat exchanger and the indoor
heat exchanger are both cross-fin type heat exchangers. The heat
transfer tube diameter of the outdoor heat exchanger is less than
the heat transfer tube diameter of the indoor heat exchanger.
[0015] In this refrigeration circuit, similar to the refrigeration
circuit according to the second aspect, the refrigerant quantity in
the refrigeration circuit is reduced because the capacity of the
outdoor heat exchanger is less than the capacity of the indoor heat
exchanger. Surplus refrigerant occurs during the air-cooling
operation, but because the surplus refrigerant is accommodated in
the refrigerant storage tank, the surplus refrigerant is prevented
from hindering refrigeration control.
[0016] A refrigeration circuit according to a sixth aspect of the
present invention is the refrigeration circuit according to the
first or second aspect, wherein a bypass channel is also provided.
The bypass channel leads a gas component of the refrigerant
retained in the refrigerant storage tank to the compressor or to a
refrigerant tube on the intake side of the compressor.
[0017] In this refrigeration circuit, during the air-warming
operation, or in other words when the outdoor heat exchanger
functions as an evaporator, the refrigerant is separated into a
liquid and a gas in the refrigerant storage tank in front of the
entrance of the outdoor heat exchanger, and the gas component heads
to the bypass channel. As a result, the gas component, which does
not contribute to evaporation, does not enter the outdoor heat
exchanger, the refrigerant quantity flowing through the outdoor
heat exchanger is reduced proportionately, and the pressure loss of
the refrigerant in the outdoor heat exchanger is suppressed.
[0018] A refrigeration circuit according to a seventh aspect is the
refrigeration circuit according to the sixth aspect, wherein the
bypass channel has a flow-rate-regulating mechanism.
[0019] When the operating frequency of the compressor is high,
there is a possibility that gas-liquid mixed refrigerant will
return from the refrigerant storage tank to the intake side of the
compressor via the bypass channel, and will be drawn into the
compressor. However, because a flow-rate-regulating mechanism is
provided to the bypass channel in this refrigeration circuit, the
liquid component of the gas-liquid mixed refrigerant is
depressurized and evaporated. As a result, the liquid component is
prevented from returning to the refrigerant tube on the intake side
of the compressor.
[0020] In this refrigeration circuit, because refrigerant that has
passed through the flow-rate-regulating mechanism evaporates in the
outdoor heat exchanger and mixes with refrigerant heading to the
compressor, when the flow-rate-regulating mechanism is an electric
expansion valve, the state of the refrigerant immediately before
being drawn into the compressor can be more optimally regulated by
controlling the valve opening degree. Furthermore, in this
refrigeration circuit, when the flow-rate-regulating mechanism is
an electric expansion valve, the refrigerant quantity returning to
the compressor can be increased or reduced by controlling the valve
opening degree, and the refrigerant circulation quantity in the
refrigeration circuit can therefore also be controlled in
accordance with the load on the indoor heat exchanger side.
[0021] A refrigeration circuit according to an eighth aspect of the
present invention is the refrigeration circuit according to the
first or second aspect, wherein the refrigerant storage tank is a
gas-liquid separator. In this refrigeration circuit, the gas-liquid
separator has the function of separating liquid refrigerant and gas
refrigerant in addition to the refrigerant storage function for
retaining liquid refrigerant, and the refrigeration circuit is
therefore simplified without the need for both a refrigerant
storage container and a gas-liquid separator.
Advantageous Effects of Invention
[0022] In the refrigeration circuit according to any of the first
through fifth aspects of the present invention, because the surplus
refrigerant is accommodated in the refrigerant storage tank, the
surplus refrigerant is prevented from hindering refrigeration
control.
[0023] In the refrigeration circuit according to the sixth aspect
of the present invention, the gas component, which does not
contribute to evaporation, does not enter the outdoor heat
exchanger, the refrigerant quantity flowing through the outdoor
heat exchanger is reduced proportionately, and the pressure loss of
the refrigerant in the outdoor heat exchanger is suppressed.
[0024] In the refrigeration circuit according to the seventh aspect
of the present invention, the liquid component is prevented from
returning to the refrigerant tube on the intake side of the
compressor. The state of the refrigerant immediately before being
drawn into the compressor can also be more optimally regulated.
Furthermore, the refrigerant circulation quantity in the
refrigeration circuit can therefore also be controlled in
accordance with the load on the indoor heat exchanger side.
[0025] In the refrigeration circuit according to the eighth aspect
of the present invention, the gas-liquid separator has the function
of separating liquid refrigerant and gas refrigerant in addition to
the refrigerant storage function for retaining liquid refrigerant,
and the refrigeration circuit is therefore simplified without the
need for both a refrigerant storage container and a gas-liquid
separator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a structural view of an air conditioning apparatus
provided with a refrigeration circuit according to an embodiment of
the present invention;
[0027] FIG. 2 is a front view of an indoor heat exchanger;
[0028] FIG. 3 is an external perspective view of an outdoor heat
exchanger;
[0029] FIG. 4 is a graph showing the ratio of outdoor heat
exchanger capacity to indoor heat exchanger capacity in the
refrigeration circuit, according to capability; and
[0030] FIG. 5 is a simple cross-sectional view of a gas-liquid
separator.
DESCRIPTION OF EMBODIMENTS
[0031] Embodiments of the present invention are described
hereinbelow while referring to the drawings. The embodiments
hereinbelow, which are specific examples of the present invention,
do not limit the technological scope of the present invention.
(1) Air Conditioning Apparatus
(1-1) Overall Configuration
[0032] FIG. 1 is a structural view of an air conditioning apparatus
provided with a refrigeration circuit according to an embodiment of
the present invention. In FIG. 1, an air conditioning apparatus 1,
which is an air conditioning apparatus capable of an air-cooling
operation and an air-warming operation, comprises an outdoor unit
3, an indoor unit 5, and a liquid refrigerant communication tube 7
and a gas refrigerant communication tube 9 for connecting the
outdoor unit 3 with the indoor unit 5.
(1-2) Indoor Unit
[0033] The indoor unit 5 has an indoor heat exchanger 51 and an
indoor fan 53. The indoor heat exchanger 51, which is a cross-fin
type heat exchanger, can evaporate or condense refrigerant flowing
through the interior by heat exchange with indoor air, and can also
cool or heat indoor air.
[0034] (1-2-1) Indoor Heat Exchanger
[0035] FIG. 2 is a front view of the indoor heat exchanger. In FIG.
2, the indoor heat exchanger 51 comprises heat transfer fins 511
and heat transfer tubes 513. The heat transfer fins 511 are thin
flat plates made of aluminum, and a plurality of through-holes are
formed in one heat transfer fin 511. The heat transfer tubes 513
are composed of straight tubes 513a inserted through the
through-holes of the heat transfer fins 511, and first U tubes 513b
and second U tubes 513c for connecting the ends of adjacent
straight tubes 513a to each other.
[0036] After being inserted into the through-hole of the heat
transfer fins 511, the straight tubes 513a are expanded by a tube
expander and adhered to the heat transfer fins 511. The straight
tubes 51.3a and the first U tubes 513b are formed integrally, and
the second U tubes 513c are joined to the ends of the straight
tubes 513a by welding the like after the straight tubes 513a have
been inserted into the through-hole of the heat transfer fins 511
and expanded.
[0037] (1-2-2) Indoor Fan
[0038] The indoor fan 53 takes in indoor air and blows air to the
indoor heat exchanger 51 by rotating, and facilitates heat exchange
between the indoor heat exchanger 51 and the indoor air.
(1-3) Outdoor Unit
[0039] In FIG. 1, the outdoor unit 3 has primarily a compressor 21,
a four-way switching valve 23, an outdoor heat exchanger 25, a
refrigerant storage tank 27, an expansion valve 29, a liquid-side
shutoff valve 37, a gas-side shutoff valve 39, an accumulator 31,
and a bypass channel 33. Furthermore, the outdoor unit 3 also has
an outdoor fan 41.
[0040] (1-3-1) Compressor, Four-Way Switching Valve, and
Accumulator
[0041] The compressor 21 draws in and compresses gas refrigerant.
The accumulator 31 is disposed in front of the intake port of the
compressor 21, and liquid refrigerant is not drawn directly into
the compressor 21.
[0042] The four-way switching valve 23 switches the direction of
refrigerant flow when a switch is made between the air-cooling
operation and the air-warming operation. During the air-cooling
operation, the four-way switching valve 23 connects the discharge
side of the compressor 21 and the gas side of the outdoor heat
exchanger 25, and also connects the intake side of the compressor
21 and the gas-side shutoff valve 39. In other words, the state is
as shown by the solid lines in the four-way switching valve 23 in
FIG. 1.
[0043] During the air-warming operation, the four-way switching
valve 23 connects the discharge side of the compressor 21 and the
gas-side shutoff valve 39, and also connects the intake side of the
compressor 21 and the gas side of the outdoor heat exchanger 25. In
other words, the state is as shown by the dashed lines in the
four-way switching valve 23 in FIG. 1.
[0044] (1-3-2) Outdoor Heat Exchanger
[0045] The outdoor heat exchanger 25, which is a stacked heat
exchanger, can condense or evaporate refrigerant flowing through
the interior by heat exchange with outdoor air. The outdoor fan 41,
which is disposed so as to face the outdoor heat exchanger 25,
takes in outdoor air and blows air to the outdoor heat exchanger 25
by rotating, and facilitates heat exchange between the outdoor heat
exchanger 25 and the outdoor air.
[0046] FIG. 3 is an external perspective view of the outdoor heat
exchanger. In FIG. 3, the outdoor heat exchanger 25 has flattened
tubes 251, corrugated fins 253, and headers 255.
[0047] The flattened tubes 251, which are formed from aluminum or
an aluminum alloy, have fiat parts 251a as heat transfer surfaces
and a plurality of internal flow channels (not shown) through which
refrigerant flows. A plurality of the flattened tubes 251 are
arrayed with the flat parts 251a facing up and down.
[0048] The corrugated fins 253 are fins made of aluminum or an
aluminum alloy and are bent into corrugations. The corrugated fins
253 are disposed in ventilation spaces enclosed between adjacent
flattened tubes 251 above and below, and the dips and peaks thereof
are in contact with the flat parts 251a of the flattened tubes 251.
The dips, the peaks and the flat parts 251a are welded by
soldering.
[0049] The headers 255 are joined to both ends of the flattened
tubes 251 arrayed vertically in a plurality. The headers 255 have
the function of supporting the flattened tubes 251, the function of
leading refrigerant to the internal flow channels of the flattened
tubes 251, and the function of gathering refrigerant that has
exited the internal flow channels.
[0050] In the front view of FIG. 3, refrigerant flowing in from the
entrance 255a of the right-side header 255 (referred to hereinafter
as the first header) is distributed fairly equally to the internal
flow channels of the highest flattened tube 251, and the
refrigerant then flows to the left-side header 255 (referred to
hereinafter as the second header). The refrigerant that has reached
the second header is distributed equally to the internal flow
channels of the second flattened tube 251, and the refrigerant then
flows to the first header. Hereinafter the refrigerant in the
odd-numbered flattened tubes 251 flows to the second header, and
the refrigerant in the even-numbered flattened tubes 251 flows to
the first header. The refrigerant in the lowest and even-numbered
flattened tubes 251 flows to the first header where it is gathered
and let out through the exit 255b.
[0051] When the outdoor heat exchanger 25 functions as an
evaporator, the refrigerant flowing through the flattened tubes 251
absorbs heat from the air flowing through the ventilation spaces
via the corrugated fins 253. When the outdoor heat exchanger 25
functions as a condenser, the refrigerant flowing through the
flattened tubes 251 loses heat to the air flowing through the
ventilation spaces via the corrugated fins 253. In the present
embodiment, the capacity of the outdoor heat exchanger 25 is less
than the capacity of the indoor heat exchanger 51 due to the
outdoor heat exchanger 25 being a stacked heat exchanger as
described above.
[0052] FIG. 4 is a graph showing the ratio of outdoor heat
exchanger capacity to indoor heat exchanger capacity in the
refrigeration circuit, according to capability. In FIG. 4,
.diamond. indicates a normal type of package air conditioner (a
cross-fin type outdoor heat exchanger), .diamond-solid. indicates a
thin outdoor heat exchanger type of package air conditioner stacked
outdoor heat exchanger), .DELTA. indicates a normal type of room
air conditioner (a cross-fin type outdoor heat exchanger), and
.tangle-solidup. indicates a thin outdoor heat exchanger type of
room air conditioner (a stacked outdoor heat exchanger).
[0053] The ratio of outdoor heat exchanger capacity to indoor heat
exchanger capacity for a combination in which the outdoor heat
exchanger and the indoor heat exchanger are both cross-fin type
heat exchangers is less than 1.0 when only the outdoor heat
exchanger is replaced with a stacked heat exchanger having a
similar heat exchange performance, as shown in FIG. 4. This means
that the capacity of the stacked heat exchanger is not only less
than the capacity of the cross-fin type outdoor heat exchanger, but
is also less than the capacity of the cross-fin type indoor heat
exchanger connected thereto. Therefore, a surplus of refrigerant
arises during the air-cooling operation. In the refrigeration
circuit 11 of the present embodiment, the surplus refrigerant is
accommodated in the refrigerant storage tank 27.
[0054] When the ratio of outdoor heat exchanger capacity to indoor
heat exchanger capacity is 0.3 to 0.9, it is preferable to use the
refrigerant storage tank 27 for accommodating the surplus
refrigerant, but in cases in which the ratio of outdoor heat
exchanger capacity to indoor heat exchanger capacity is 1.0 as
well, stable refrigerant control is made possible by using the
refrigerant storage tank 27.
[0055] (1-3-3) Refrigerant Storage Tank
[0056] The refrigerant storage tank 27 is a container capable of
retaining surplus refrigerant. For example, in cases in which the
liquid refrigerant quantity that can be accommodated in the indoor
heat exchanger 51 during the air-warming operation when the indoor
heat exchanger 51 functions as a condenser is 1100 cc, and the
liquid refrigerant quantity that can be accommodated in the outdoor
heat exchanger 25 during the air-cooling operation when the outdoor
heat exchanger 25 functions as a condenser is 800 cc, the excess
300 cc of liquid refrigerant that could not be accommodated in the
outdoor heat exchanger 25 during the air-cooling operation is
temporarily accommodated in the refrigerant storage tank 27.
[0057] During the air-warming operation, for example, immediately
before entering the refrigerant storage tank 27, the refrigerant
contains a gas component produced when the refrigerant passed
through the expansion valve 29, but after entering the refrigerant
storage tank 27, the refrigerant is separated into liquid
refrigerant and gas refrigerant, the liquid refrigerant is stored
in the lower side, and the gas refrigerant is stored in the upper
side.
[0058] (1-3-4) Expansion Valve
[0059] To regulate refrigerant pressure and/or the refrigerant flow
rate, the expansion valve 29 is connected to the tube between the
refrigerant storage tank 27 and the liquid-side shutoff valve 37,
and the expansion valve has the function of expanding the
refrigerant during both the air-cooling operation and the
air-warming operation.
[0060] (1-3-5) Bypass Channel and Flow Rate Regulation Valve
[0061] The gas refrigerant separated in the refrigerant storage
tank 27 passes through the bypass channel 33 and flows to the
intake side of the compressor 21. The liquid refrigerant separated
in the refrigerant storage tank 27 flows to the outdoor heat
exchanger 25. A flow rate regulation valve 35 is connected at some
point in the bypass channel 33. In the present embodiment, the flow
rate regulation valve 35 is an electric expansion valve.
[0062] (1-3-6) Shutoff Valves and Refrigerant Communication
Tubes
[0063] The liquid-side shutoff valve 37 and the gas-side shutoff
valve 39 are connected respectively to the liquid refrigerant
communication tube 7 and the gas refrigerant communication tube 9.
The liquid refrigerant communication tube 7 connects the liquid
side of the indoor heat exchanger 51 of the indoor unit 5 and the
liquid-side shutoff valve 37 of the outdoor unit 3. The gas
refrigerant communication tube 9 connects the gas side of the
indoor heat exchanger 51 of the indoor unit 5 and the gas-side
shutoff valve 39 of the outdoor unit 3.
[0064] As a result, a refrigeration circuit 11 is formed in which
refrigerant flows sequentially to the compressor 21, the outdoor
heat exchanger 25, the expansion valve 29, and the indoor heat
exchanger 51 during the air-cooling operation, and refrigerant
flows sequentially to the compressor 21, the indoor heat exchanger
51, the expansion valve 29, and the outdoor heat exchanger 25
during the air-warming operation.
(2) Flow of Refrigerant During Air-Warming Operation
[0065] In FIG. 1, during the air-warming operation, the four-way
switching valve 23 connects the discharge side of the compressor 21
and the gas-side shutoff valve 39, and connects the intake side of
the compressor 21 and the gas side of the outdoor heat exchanger
25. The opening degree of the expansion valve 29 is narrowed. As a
result, the outdoor heat exchanger 25 functions as an evaporator of
refrigerant and the indoor heat exchanger 51 functions as a
condenser of refrigerant.
[0066] In the refrigeration circuit 11 in this state, low-pressure
refrigerant is drawn into the compressor 21, compressed to a high
pressure, and then discharged. The high-pressure refrigerant
discharged from the compressor 21 passes through the four-way
switching valve 23, the gas-side shutoff valve 39, and the gas
refrigerant communication tube 9, and enters the indoor heat
exchanger 51. The high-pressure refrigerant that has entered the
indoor heat exchanger 51 is condensed there by heat exchange with
the indoor air. The indoor air is thereby heated.
[0067] Because the capacity of the indoor heat exchanger 51 is
greater than the capacity of the outdoor heat exchanger 25, most of
the liquid refrigerant is accommodated in a condenser (the indoor
heat exchanger 51) during the air-warming operation. The
high-pressure refrigerant condensed in the indoor heat exchanger 51
passes through the liquid refrigerant communication tube 7 and the
liquid-side shutoff valve 37 and reaches the expansion valve
29.
[0068] The refrigerant is depressurized to a low pressure by the
expansion valve 29, after which the refrigerant enters the
refrigerant storage tank 27. Immediately before entering the
refrigerant storage tank 27, the refrigerant contains a gas
component produced when the refrigerant passed through the
expansion valve 29, but after entering the refrigerant storage tank
27, the refrigerant is separated into liquid refrigerant and gas
refrigerant, the liquid refrigerant is stored in the lower side,
and the gas refrigerant is stored in the upper side.
[0069] Because the flow rate regulation valve 35 is open, the gas
refrigerant passes through the bypass channel 33 and heads to the
intake side of the compressor 21. The liquid refrigerant is sent to
the outdoor heat exchanger 25 where it is evaporated by heat
exchange with the outdoor air supplied by the outdoor fan 41. Most
of the gas refrigerant does not enter through the entrance of the
outdoor heat exchanger 25, the refrigerant quantity flowing through
the outdoor heat exchanger 25 therefore decreases, and pressure
loss is suppressed proportionately.
[0070] The low-pressure refrigerant evaporated in the outdoor heat
exchanger 25 passes through the four-way switching valve 23 to be
drawn back into the compressor 21.
(3) Flow of Refrigerant During Air-Cooling Operation
[0071] In FIG. 1, during the air-cooling operation, the four-way
switching valve 23 connects the discharge side of the compressor 21
and the gas side of the outdoor heat exchanger 25, and also
connects the intake side of the compressor 21 and the gas-side
shutoff valve 39. The opening degree of the expansion valve 29 is
narrowed. As a result, the outdoor heat exchanger 25 functions as a
condenser of refrigerant and the indoor heat exchanger 51 functions
as an evaporator of refrigerant.
[0072] In the refrigerant circuit in such a state, the low-pressure
refrigerant is taken into the compressor 21, compressed to a high
pressure, and then discharged. The high-pressure refrigerant
discharged from the compressor 21 is passed through the four-way
switching valve 23 and sent to the outdoor heat exchanger 25.
[0073] The high-pressure refrigerant sent to the outdoor heat
exchanger 25 there exchanges heat with the outdoor air and
condenses. The high-pressure refrigerant condensed in the outdoor
heat exchanger 25 is sent to the refrigerant storage tank 27.
Because the capacity of the outdoor heat exchanger 25 is less than
the capacity of the indoor heat exchanger 51, the condenser (the
outdoor heat exchanger 25) is incapable of accommodating all of the
liquid refrigerant during the air-cooling operation. Therefore, the
liquid refrigerant that could not be accommodated in the outdoor
heat exchanger 25 is retained in the refrigerant storage tank 27,
and the refrigerant storage tank 27 is filled with the liquid
refrigerant. Because the flow rate regulation valve 35 is closed,
the liquid refrigerant does not flow to the bypass channel 33.
[0074] Liquid refrigerant that has left the refrigerant storage
tank 27 is sent to the expansion valve 29 and depressurized to a
low pressure. The low-pressure refrigerant depressurized in the
expansion valve 29 passes through the liquid-side shutoff valve 37
and the liquid refrigerant communication tube 7 and enters the
indoor heat exchanger 51.
[0075] The low-pressure refrigerant that has entered the indoor
heat exchanger 51 there exchanges heat with the indoor air and
evaporates. The indoor air is thereby cooled. The low-pressure
refrigerant that has evaporated in the indoor heat exchanger 51 is
passed through the gas refrigerant communication tube 9, the
gas-side shutoff valve 39, and the four-way switching valve 23, and
is again drawn into the compressor 21.
(4) Characteristics
(4-1)
[0076] In the refrigeration circuit 11, the indoor heat exchanger
51 is a cross-fin type heat exchanger and the outdoor heat
exchanger 25 is a stacked heat exchanger. The refrigerant storage
tank 27 is provided between the outdoor heat exchanger 25 and the
expansion valve 29. Because the capacity of the outdoor heat
exchanger 25 is less than the capacity of the indoor heat exchanger
51, surplus refrigerant occurs during the air-cooling operation,
but because the surplus refrigerant is accommodated in the
refrigerant storage tank 27 in this refrigeration circuit, the
surplus refrigerant is prevented from hindering refrigeration
control.
(4-2)
[0077] In the refrigeration circuit 11, the capacity of the outdoor
heat exchanger 25 is 100% or less of the capacity of the indoor
heat exchanger 51. The refrigerant storage tank 27 is provided
between the outdoor heat exchanger 25 and the expansion valve 29.
Due to the capacity of the outdoor heat exchanger 25 being equal to
or less than the capacity of the indoor heat exchanger 51, surplus
refrigerant is present during the air-cooling operation, but
because the surplus refrigerant is accommodated in the refrigerant
storage tank, the surplus refrigerant is prevented from hindering
refrigeration control.
(4-3)
[0078] In the refrigeration circuit 11, the bypass channel 33 is
provided. The bypass channel 33 leads the gas component of the
refrigerant retained in the refrigerant storage tank 27 to the
compressor 21 or to the refrigerant tube on the intake side of the
compressor 21. During the air-warming operation, i.e. when the
outdoor heat exchanger 25 functions as an evaporator, the
refrigerant is separated into a liquid and a gas in the refrigerant
storage tank 27 before the entrance of the outdoor heat exchanger
25, and the gas component heads toward the bypass channel. As a
result, the gas component which does not contribute to evaporation
does not enter the outdoor heat exchanger 25, the refrigerant
quantity flowing through the outdoor heat exchanger 25 decreases,
and pressure loss of the refrigerant in the outdoor heat exchanger
25 is suppressed proportionately.
(4-4)
[0079] When the operating frequency of the compressor 21 is high,
there is a possibility that gas-liquid mixed refrigerant from the
refrigerant storage tank 27 will return to the intake side of the
compressor 21 via the bypass channel 33 and be drawn into the
compressor 21, but because the flow rate regulation valve 35 is
provided to the bypass channel 33, the liquid component of the
gas-liquid mixed refrigerant is depressurized and evaporated. As a
result, the liquid component is prevented from returning to the
refrigerant tube on the intake side of the compressor 21.
(4-5)
[0080] Refrigerant that has passed through the flow rate regulation
valve 35 merges with the refrigerant that evaporates in the outdoor
heat exchanger 25 and heads toward the compressor 21; therefore,
when the flow rate regulation valve 35 is an electric expansion
valve, the state of the refrigerant immediately before it is drawn
into the compressor 21 can be more optimally regulated by
controlling the valve opening degree.
(4-6)
[0081] Furthermore, when the flow rate regulation valve 35 is an
electric expansion valve, the refrigerant quantity returning to the
compressor 21 can be increased or reduced by controlling the valve
opening degree, and it is therefore also possible to control the
refrigerant circulation quantity of the refrigeration circuit 11 in
accordance with the load in the side having the indoor heat
exchanger 51.
(5) Modifications
[0082] There follows a description of a modification in which the
refrigerant storage tank 27 is a gas-liquid separator. FIG. 5 is a
simple cross-sectional view of a gas-liquid separator. In FIG. 5,
the gas-liquid separator is a cyclone type of separator, having a
cylindrical container 271, a first connecting tube 273, a second
connecting tube 275, and a third connecting tube 277.
[0083] The first connecting tube 273 is joined in tangent to the
peripheral side wall of the cylindrical container 271,
communicating the interior of the cylindrical container 271 and the
expansion valve 29. The second connecting tube 275 is joined to the
bottom wall of the cylindrical container 271, communicating the
interior of the cylindrical container 271 and the outdoor heat
exchanger 25. The third connecting tube 277 is joined to the
ceiling wall of the cylindrical container 271, communicating the
interior of the cylindrical container 271 and the bypass channel
33.
[0084] During the air-warming operation, refrigerant that has been
depressurized in the expansion valve 29 into a gas-liquid mixed
state flows into the cylindrical container 271 from the first
connecting tube 273, eddying along the internal peripheral surface
271b of the peripheral side wall thereof, at which time the liquid
refrigerant adheres to the internal peripheral surface 271b and the
liquid refrigerant and gas refrigerant are efficiently
separated.
[0085] The liquid refrigerant descends under gravity to be retained
in the bottom, passes through the second connecting tube 275, and
heads toward the outdoor heat exchanger 25. Meanwhile, the gas
refrigerant rises while swirling, passes through the third
connecting tube 277, and flows to the bypass channel 33.
[0086] During the air-cooling operation, high-pressure refrigerant
that has condensed in the outdoor heat exchanger 25 to a saturated
liquid flows into the cylindrical container 271 from the second
connecting tube 275, and the cylindrical container 271 is filled
with liquid refrigerant. The liquid refrigerant passes through the
first connecting tube 273 and heads to the expansion valve 29.
Meanwhile, some of the liquid refrigerant in the cylindrical
container 271 passes through the third connecting tube 277 and
heads to the bypass channel 33.
[0087] As described above, in the refrigeration circuit 11
according to the modification, because the refrigerant storage tank
27 is a cyclone type of gas-liquid separator, liquid refrigerant
adheres to the internal peripheral surface 271b of the gas-liquid
separator while the refrigerant is swirling along the internal
peripheral surface, and gas-liquid separation is performed
efficiently.
[0088] In addition to the refrigerant storage function of retaining
liquid refrigerant, the gas-liquid separator has the function of
separating liquid refrigerant and gas refrigerant, and the
refrigeration circuit is therefore simplified without the need to
provide both a refrigerant storage container and a gas-liquid
separator.
(6) Other Embodiments
(6-1)
[0089] In the above embodiment, the outdoor heat exchanger 25 is a
stacked heat exchanger having a plurality of flattened tubes 251
and corrugated fins 253, the flattened tubes 251 being arranged so
as to overlap with spaces therebetween, and the corrugated fins 253
being placed between adjacent flattened tubes 251.
[0090] However, the outdoor heat exchanger 25 is not limited to a
configuration such as the one described above, and the same effects
as the above embodiment are achieved even with a configuration in
which, for example, the flattened tubes are molded into a
serpentine shape and the fins are placed between adjacent surfaces
of flattened tubes.
(6-2)
[0091] In the case of a refrigeration apparatus in which the
outdoor heat exchanger 25 is cooled by water during the air-cooling
operation, the same effects as the above embodiment are achieved
even with a configuration in which the outdoor heat exchanger 25
and the indoor heat exchanger 51 are both cross-fin type heat
exchangers, and the heat transfer tubes of the outdoor heat
exchanger 25 have smaller diameter than the heat transfer tubes of
the indoor heat exchanger 51.
INDUSTRIAL APPLICABILITY
[0092] As described above, according to the present invention,
because a simple refrigeration circuit of high performance is
provided, the present invention is not limited to air conditioning
apparatuses and is also useful in heat-pump type hot water supply
equipment.
REFERENCE SIGNS LIST
[0093] 11 Refrigeration circuit [0094] 21 Compressor [0095] 25
Outdoor heat exchanger [0096] 27 Refrigerant storage tank [0097] 29
Expansion valve [0098] 33 Bypass channel [0099] 35 Flow rate
regulation valve (flow-rate-regulating mechanism) [0100] 51 Indoor
heat exchanger
CITATION LIST
Patent Literature
[0100] [0101] [Patent Literature 1] Japanese Laid-open Patent
Application No. 6-143991
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