AU2006293191B2

AU2006293191B2 - Air conditioning apparatus

Info

Publication number: AU2006293191B2
Application number: AU2006293191A
Authority: AU
Inventors: Makoto Kojima; Takayuki Setoguchi
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2005-09-22
Filing date: 2006-09-15
Publication date: 2009-11-19
Anticipated expiration: 2026-09-15
Also published as: JP2007085647A; EP1944562A1; CN101268312A; KR20080042178A; EP1944562A4; CN101268312B; WO2007034745A1; KR100905995B1; AU2006293191A1; US20090282861A1; JP3982545B2; EP1944562B1

Description

SPECIFICATION AIR CONDITIONING APPARATUS 5 TECHNICAL FIELD The present invention relates to an air conditioning apparatus that uses a supercooling heat exchanger. 10 BACKGROUND ART FIG. 4 shows a configuration of an air conditioning apparatus that uses a conventional supercooling heat exchanger. In this air conditioning apparatus, a compressor 1, a four-way switching valve 2, 15 an outdoor-side heat exchanger 3 that functions as a condenser during the cooling operation and as an evaporator during the heating operation, a heating expansion valve 4, a receiver 5, a cooling expansion valve 6, an indoor-side heat exchanger 8 that functions as an evaporator during the cooling operation and as a condenser during the heating operation, and other components are connected sequentially via the four-way 20 switching valve 2, thereby constituting a refrigerating cycle for air conditioning as is shown in the drawing. The switching operation of the four-way switching valve 2 allows a refrigerant to be reversibly circulated in the direction shown by solid arrows in the drawing during the cooling operation, and in the direction shown by dashed arrows in the drawing 25 during the heating operation, thereby resulting in cooling and heating, respectively. The outdoor-side heat exchanger 3 and the indoor-side heat exchanger 8 are both configured to include numerous refrigerant paths. Therefore, even if the capacity of the flow divider portion to distribute the refrigerant is improved to a maximum, it is difficult to distribute the refrigerant evenly throughout the refrigerant paths. 30 2 In view of this, when the outdoor-side heat exchanger 3 or the indoor-side heat exchanger 8 functions as the evaporator, the amount of pressure reduction in the heating expansion valve 4 or cooling expansion valve 6 is appropriately set so that the refrigerant of the exit side of the outdoor-side heat exchanger 3 or the indoor-side heat 5 exchanger 8 is in appropriately humidified condition. Thus, maximum performance as the evaporator can be guaranteed even if, for example, the refrigerant drifts into the outdoor-side heat exchanger 3 or the indoor-side heat exchanger 8, and therefore the evaporator can be made as compact as possible. The performance of the evaporator can be further improved by removing the 10 refrigerant supercooling of the exit side of the condenser, increasing the difference in enthalpy of the evaporator side to reduce circulating volume, and reducing the pressure loss on the evaporator side. This is accomplished by providing a liquid-gas heat exchanger 13 having a double pipe structure, composed of a low-pressure refrigerant suction pipe 14 as an inner pipe and a high-pressure liquid refrigerant pipe 15 as an 15 outer pipe, as a supercooling heat exchanger. In this liquid-gas heat exchanger 13, e.g., the flow rate of the refrigerant, the length of the double pipes, the inside diameter of the outer pipe, and the outside diameter of the inner pipe are set in a predetermined manner appropriately. As the liquid-gas heat exchanger 13 is provided in this manner, the refrigerant of 20 the exit side of the evaporator is superheated, backflow into the compressor I can be prevented, the refrigerant of the exit side of the condenser is supercooled, and the difference in enthalpy of the evaporator side can be increased to reduce circulating volume. Therefore, the pressure loss can also be reduced, and the evaporator 8 (or the evaporator 3) can be made even more compact (see Patent Document I as an example). 25 [Patent Document I] Japanese Laid-open Patent Publication No. 5-332641 (Specification pg. 1-5, FIGS. 1-5) 30 3 Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the 5 field relevant to the present invention as it existed before the priority date of each claim of this application. SUMMARY Throughout this specification the word "comprise", or variations such as 10 "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. In a first aspect the invention provides an air conditioning apparatus in which: a compressor, a four-way switching valve, an outdoor-side heat exchanger that 15 functions as a condenser during the cooling operation and as an evaporator during the heating operation, and an indoor-side heat exchanger that functions as an evaporator during the cooling operation and as a condenser during the heating operation, are connected in the stated order via the four-way switching valve, the switching operation of the four-way switching valve allows refrigerant to be 20 reversely circulated to be circulated, and a supercooling heat exchanger for exchanging heat between a low-pressure refrigerant and a high-pressure refrigerant is disposed between the four-way switching valve and a suction side of the compressor, and is composed of a low-pressure refrigerant suctioning pipe and a high-pressure liquid refrigerant pipe, 25 wherein the high-pressure liquid refrigerant pipe of the supercooling heat exchanger is divided into two first and second heat exchanger parts so as to allow refrigerants to flow in mutually opposite directions through their first and second heat exchanger parts, and wherein one of the first heat exchanger part and the second heat exchanger part 30 is disposed so that the high-pressure refrigerant and low-pressure refrigerant flow counter current to each other, and the other of the first heat exchanger part and the second heat exchanger part is disposed so that the high-pressure refrigerant and low pressure refrigerant flow parallel to each other. In an embodiment of the invention, the first and second heat exchangers may 35 both be configured by winding a high-pressure liquid refrigerant pipe around the external periphery of a low-pressure refrigerant suction pipe.

3a Thus in this embodiment, when the first and second heat exchangers are both configured by winding the high-pressure liquid refrigerant pipe around the low pressure refrigerant suction pipe, the capacity of the heat exchanger itself may not need to be increased, and the supercooling heat exchangers may be made as small as possible. 5 In another embodiment, the first and second heat exchangers may be both configured by fitting a high-pressure liquid refrigerant pipe around the external periphery of a low-pressure refrigerant suction pipe in a coaxial structure, wherein the high-pressure liquid refrigerant pipe is larger in diameter than the low-pressure refrigerant suction pipe. 10 4 Thus in this embodiment, when the first and second supercooling heat exchangers both have a double-pipe structure in which the high-pressure liquid refrigerant pipe 15 is fitted coaxially over the low-pressure refrigerant suction pipe, the structures of the supercooling heat exchangers themselves may be simplified. 5 Embodiments of the invention may provide a supercooling heat exchanger that can maintain high heat exchange performance even when the flows of the refrigerants change direction during cooling and heating. As a result, the evaporator can be made more compact. In this case, when the each heat exchanger is configured by winding a high 10 pressure liquid refrigerant pipe around a low-pressure refrigerant suction pipe, the supercooling heat exchanger itself can be made as small as possible. Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of 15 any other element, integer or step, or group of elements, integers or steps. BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a refrigeration circuit diagram showing the configuration of an air conditioning apparatus according to Preferred Embodiment of the present invention; 20 FIG. 2 is an enlarged view showing the portion of the first and second liquid-gas heat exchangers as relevant parts of the same apparatus; FIG. 3 is an enlarged view showing a portion of the first and second liquid-gas heat exchangers according to another embodiment of the present invention; and FIG. 4 is a refrigerant circuit diagram showing the configuration of a 25 conventional example of air conditioning apparatus. DESCRIPTION OF THE REFERENCE SYMBOLS 1 Compressor 2 Four-way switching valve 30 3 Outdoor-side heat exchanger 4, 6 Expansion valves 5 Receiver 8 Indoor-side heat exchanger 13A First heat exchanger 5 13B Second heat exchanger 14 Low-pressure refrigerant suction pipe 15 High-pressure liquid refrigerant pipe 16 Muffler BEST MODE FOR CARRYING OUT THE INVENTION L 0 FIGS. 1 and 2 of the attached drawings show the configuration of the entirety and relevant parts of the refrigerant circuits in an air conditioning apparatus according to a preferred embodiment of the present invention. First, as shown in FIG. 1, in the air conditioning apparatus of this embodiment, a compressor 1, a four-way switching valve 2, an outdoor-side heat exchanger 3 that functions L 5 as a condenser during the cooling operation and as an evaporator during the heating operation, a heating expansion valve 4, a receiver 5, a cooling expansion valve 6, an indoor side heat exchanger 8 that functions as an evaporator during the cooling operation and as a condenser during the heating operation, and other components are connected sequentially via the four-way switching valve 2, thereby constituting a refrigerating cycle for air conditioning * 0 as shown in the drawing. The switching operation of the four-way switching valve 2 allows refrigerant to be reversibly circulated in the direction shown by solid arrows in the diagram during the cooling operation, and in the direction shown by dashed arrows in the diagram during the heating operation, thereby resulting in cooling and heating, respectively. .5 A liquid-gas heat exchanger 13 is provided in this embodiment as well as the case in FIG. 4 described previously. This liquid-gas heat exchanger 13 comprises a low-pressure refrigerant suction pipe 14 and a high-pressure liquid refrigerant pipe 15, and is used as a supercooling heat exchanger for exchanging heat between low-pressure refrigerant and high pressure refrigerant. 30 As the liquid-gas heat exchanger 13 is provided in this manner, refrigerant of the exit side of the evaporator is superheated, backflow into the compressor 1 can be prevented, the refrigerant of the exit side of the condenser is supercooled, and the difference in enthalpy of the evaporator side can be increased to reduce refrigerant circulating volume, as was described previously. Therefore, pressure loss can also be reduced, and the evaporator (the 5 indoor-side heat exchanger 8 during cooling or the outdoor-side heat exchanger 3 during heating) can be made as compact as possible. However, in this embodiment, unlike in the case in FIG 4 described previously, the liquid-gas heat exchanger 13 is divided into two liquid-gas heat exchangers, i.e., a first liquid 5 gas heat exchanger 13A and a second liquid-gas heat exchanger 13B in which refrigerants flow in mutually opposite directions. The first heat exchanger 13A may, for example, be disposed so that the high-pressure refrigerant and low-pressure refrigerant flow countercurrent to each other, and the second heat exchanger 13B may be disposed so that the high-pressure refrigerant and low-pressure refrigerant flow parallel to each other. L 0 Therefore, with this configuration, the liquid-gas heat exchanger 13 can maintain its performance without variation as shown in the diagrams, even when the refrigerant flow changes direction during cooling and heating. As a result, the refrigerant of the exit side of the condenser is supercooled without variation during heating, and the difference in enthalpy of the evaporator side can be increased to reduce the circulating volume. L 5 Moreover, the first and second liquid-gas heat exchangers 13A, 13B are both configured so that the high-pressure liquid refrigerant pipe 15 from the exit side of the condenser that is smaller in diameter than the low-pressure refrigerant suction pipe 14 is wound in a helical structure in mutually opposite directions, for example, as shown in detail in FIG 2, around the external periphery of the low-pressure refrigerant suction pipe 14. The 0 existing low-pressure refrigerant suction pipe 14 leads from the indoor-side heat exchanger (evaporator) 8 during cooling or from the outdoor-side heat exchanger (evaporator) 3 during heating back to the refrigerant suction inlet in the compressor 1 via the four-way switching valve 2. Therefore, the supercooling heat exchanger 13 itself can have a small capacity and can be made as small in size as possible. .5 The improvement in supercooling heat exchange efficiency is effective in contributing to making the evaporators themselves smaller and more compact. Furthermore, winding the high-pressure liquid refrigerant pipe 15 around the existing low-pressure refrigerant suction pipe 14 as shown in FIG 2 makes it possible to inhibit increases in suctioned gas pressure loss, and to prevent the COP from decreasing. 30 The reference numeral 16 in FIG. 2 denotes a muffler for gas refrigerant in the low pressure refrigerant suction pipe 14. (Other Embodiments) In the above embodiment, the divided first and second heat exchangers 13A, 13B have a structure in which a high-pressure liquid refrigerant pipe 15 having a small diameter is 6 helically wound around an existing low-pressure refrigerant suction pipe 14 that goes from the four-way switching valve 2 to the refrigerant suction inlet of the compressor 1, as shown in FIG 2. In another possible configuration, as shown in FIG 3, for example, the first and second heat exchangers 13A, 13B have a double-pipe structure in which a high-pressure 5 liquid refrigerant pipe 15 larger in diameter than the low-pressure refrigerant suction pipe 14 is fitted as a coaxial structure around the external periphery of the low-pressure refrigerant suction pipe 14, and these pipes are disposed so that the refrigerant flows in mutually opposite directions. Thus, as the first and second heat exchangers 13A, 13B for supercooling have a L o double-pipe structure in which the high-pressure liquid refrigerant pipe 15 is fitted as a coaxial structure around the low-pressure refrigerant suction pipe 14, the structure of the supercooling heat exchanger itself is simplified. INDUSTRIAL APPLICABILITY The present invention can be widely utilized within the field of air conditioning 15 apparatuses that use supercooling heat exchangers. 7

Claims

1. An air conditioning apparatus in which: a compressor, a four-way switching valve, an outdoor-side heat exchanger that functions as a condenser during the cooling operation and as an evaporator during the 5 heating operation, and an indoor-side heat exchanger that functions as an evaporator during the cooling operation and as a condenser during the heating operation, are connected in the stated order via the four-way switching valve, the switching operation of the four-way switching valve allows refrigerant to be reversely circulated to be circulated, and 10 a supercooling heat exchanger for exchanging heat between a low-pressure refrigerant and a high-pressure refrigerant is disposed between the four-way switching valve and a suction side of the compressor, and is composed of a low-pressure refrigerant suctioning pipe and a high-pressure liquid refrigerant pipe, wherein the high-pressure liquid refrigerant pipe of the supercooling heat 15 exchanger is divided into two first and second heat exchanger parts so as to allow refrigerants to flow in mutually opposite directions through their first and second heat exchanger parts, and wherein one of the first heat exchanger part and the second heat exchanger part is disposed so that the high-pressure refrigerant and low-pressure refrigerant flow 20 counter current to each other, and the other of the first heat exchanger part and the second heat exchanger part is disposed so that the high-pressure refrigerant and low pressure refrigerant flow parallel to each other.

2. The air conditioning apparatus according to claim 1, wherein the first and second heat exchanger parts are both configured with a high-pressure liquid refrigerant pipe 25 wound around the external periphery of a low-pressure refrigerant suction pipe in mutually opposite directions.

3. The air conditioning apparatus according to claim 1, wherein the first and second heat exchanger parts are both configured with a high-pressure liquid refrigerant pipe fitted around the external periphery of a low-pressure refrigerant suction pipe in a 30 coaxial structure, wherein the high-pressure liquid refrigerant pipe is larger in diameter than the low-pressure refrigerant suction pipe and a refrigerant inlet and a refrigerant exit of the low-pressure refrigerant suction pipe and a refrigerant inlet and a refrigerant exit of the high-pressure liquid refrigerant pipe are disposed in mutually opposite directions. 35

4. An air conditioning apparatus substantially as hereinbefore described with reference to Fig. I and Fig. 2 or Fig. 3 of the accompanying drawings.