JP2008070053A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To mainly provide a sufficient degree of supercooling in an air conditioner. <P>SOLUTION: The air conditioner 1 has a first heat exchanger 26 and a second heat exchanger 27 as an indoor heat exchanger 25 of an indoor unit 2, and the heat exchangers 26, 27 are connected via a branch pipe 28. The branch pipe 28 is connected to a passage 35 in an inner side of a coolant type supercooler 32 after providing a flow control valve 31. The coolant type supercooler 32 has a double tube structure, and a coolant having passed through the second heat exchanger 27 is inputted into an outer side passage 41. The second heat exchanger 27 functions as an air-cooled supercooler during cooling operation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air-cooled supercooler and an air conditioner including the supercooler.

  The air conditioner is configured to perform cooling operation and heating operation by circulating the refrigerant discharged from the compressor between the outdoor unit heat exchanger and the indoor heat exchanger. It is known that during cooling operation, if the refrigerant is supercooled and then supplied to the indoor unit, the liquid refrigerant is prevented from being vaporized in the piping from the outdoor unit to the indoor unit, and the efficiency of the refrigeration cycle can be improved. Examples of means for supercooling the refrigerant include an air-cooled supercooler that uses heat exchange with air and a refrigerant-type supercooler that uses heat exchange with the refrigerant.

Here, in the conventional air conditioner, the refrigerant condensed in the outdoor heat exchanger during the cooling operation is supplied to the air-cooled supercooler through the liquid receiver and then supercooled. There is one that supercools again with a cooler (see, for example, Patent Document 1). A part of the liquid refrigerant flowing out from the air-cooled supercooler is branched and depressurized by a capillary, and then supplied to the refrigerant-type supercooler as a low-temperature heat source. The remaining liquid refrigerant is supplied to the supercooler as a high-temperature heat source. In the refrigerant-type supercooler, the decompressed refrigerant as a low-temperature heat source takes the amount of heat corresponding to the latent heat of vaporization from the liquid refrigerant going to the indoor unit and vaporizes, and the refrigerant going to the indoor unit is supercooled. Note that the refrigerant branched as a low-temperature heat source bypasses the indoor unit and is collected by the compressor.
JP 2006-90563 A

However, if a part of the liquid refrigerant after passing through the air-cooled supercooler is branched to generate a low-temperature heat source, the pressure of the liquid refrigerant (refrigerant supplied to the indoor unit) will drop, resulting in a result. In the state where the supercooling degree obtained by the air-cooled subcooler is lowered, the refrigerant flows into the refrigerant subcooler. For this reason, it was difficult to obtain a sufficient degree of supercooling.
In order to increase the degree of supercooling in the refrigerant subcooler, the amount of refrigerant that branches as a low-temperature heat source may be increased. However, if the amount of refrigerant that is branched increases, the amount of liquid refrigerant (refrigerant supplied to indoor units) Since the pressure further decreases, the degree of supercooling decreases. Thus, in the conventional air conditioning apparatus, there existed a subject that cooling capacity fell, so that a supercooling degree was raised.
The present invention has been made in view of such circumstances, and a main object thereof is to obtain a sufficient degree of supercooling.

  The invention according to claim 1 of the present invention for solving the above problems is an air conditioner that performs heating or cooling by flowing a refrigerant compressed by a compressor into a heat exchanger and exchanging heat with air. The heat exchanger is a first heat exchanger that becomes a condenser during cooling operation and serves as an evaporator during heating operation, and a second heat exchanger that serves as an air-cooled subcooler during cooling operation and serves as an evaporator during heating operation. A bypass circuit that bypasses the indoor unit by branching a part of the refrigerant flowing out of the first heat exchanger during cooling operation before flowing into the second heat exchanger. The air characterized in that the bypass circuit is provided with a flow rate adjusting valve and a refrigerant-type subcooler that further subcools the refrigerant that has been subcooled by the second heat exchanger using the refrigerant flowing through the bypass circuit. A harmony device was used.

  In this air conditioner, part of the refrigerant condensed in the first heat exchanger during the cooling operation flows into the refrigerant subcooler without passing through the air cooling subcooler. When this refrigerant is used as a low-temperature heat source and the refrigerant air-cooled by the second heat exchanger is used as a high-temperature heat source, the refrigerant going to the outdoor unit through the refrigerant-type subcooler is further subcooled.

  According to the present invention, the refrigerant before being supercooled by air cooling is used as a low-temperature heat source, and the refrigerant after being supercooled by air cooling is further subcooled. It is possible to improve the capacity of the refrigerant subcooler. For this reason, the degree of supercooling of the refrigerant toward the outdoor unit can be sufficiently ensured, and the vaporization of the liquid refrigerant in the pipe is prevented. Moreover, when it has a some indoor unit, generation | occurrence | production of the capability difference between indoor units is prevented.

  The best mode for carrying out the invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same component in each following embodiment. Moreover, the description which overlaps with each embodiment is abbreviate | omitted.

(First embodiment)
As shown in FIG. 1, in an air conditioner 1, an outdoor unit 2 and an indoor unit 3 are connected via a liquid pipe 4 and a gas pipe 5. In the indoor unit 3, two indoor unit units 10 are connected in parallel. In each indoor unit 10, an indoor heat exchanger 11 and an expansion valve 12 are connected in series, and air can be sent to the outer periphery of the indoor heat exchanger 11 by a fan 13. In FIG. 1, the indoor unit 3 includes two indoor unit units 10, but the number of indoor unit units may be one or three or more.

  The outdoor unit 2 includes a compressor 21 that compresses a gas refrigerant, and a discharge pipe 22 connected to a discharge port of the compressor 21 is connected to a first port 23 a of a four-way valve 23. The four-way valve 23 has four ports, and when the first port 23a and the second port 23b are connected, the third port 23c and the fourth port 23d are connected. Further, when the first port 23a and the third port 23c are connected, the second port 23b and the fourth port 23d are connected. The second port 23 b of the four-way valve 23 is connected to the inlet / outlet of the outdoor heat exchanger 25 through the pipe 24.

The outdoor heat exchanger 25 has a first heat exchanger 26 to which the pipe 24 is connected, and a second heat exchanger 27 connected to the first heat exchanger 26 via a branch pipe 28. The air blower 29 can send air to the outer peripheries of the heat exchangers 26 and 27. Both the first and second heat exchangers 26 and 27 function as an evaporator during heating operation. During the cooling operation, the first heat exchanger 26 functions as a condenser, and the second heat exchanger 27 functions as an air-cooled supercooler. For this reason, the first heat exchanger 26 has a capacity sufficient to bring the gas refrigerant into a substantially saturated liquid state during the cooling operation.
The branch pipe 28 has a bypass pipe 30 (bypass circuit) that branches a part of the liquid refrigerant from the inlet / outlet of the first heat exchanger 26 to the inlet / outlet of the second heat exchanger 27 during the cooling operation, The bypass pipe 30 is connected to the refrigerant subcooler 32 after the flow rate adjustment valve 31 is provided. The flow rate adjusting valve 31 is a means for adjusting the amount of refrigerant to be bypassed and generating a low-temperature heat source for use in the refrigerant subcooler 32, and its opening degree is controlled by the control device 33.

  The refrigerant subcooler 32 has a double pipe structure, and the bypass pipe 30 of the branch pipe 28 is connected to the inlet 35 a of the inner flow path 35. The outlet 35b of the inner flow path 35 is connected to the accumulator 40 via a bypass pipe 36 (bypass circuit). The pipe 42 connected to one inflow / outflow port 41a of the outer flow path 41 is connected to the inflow / outflow port of the second heat exchanger 27 after the expansion valve 43 used for heating is provided. A liquid pipe 44 is connected to the other inlet / outlet 41 b of the outer channel 41. The liquid pipe 44 is provided with a thermometer 45 for measuring the temperature of the refrigerant in the vicinity of the inlet / outlet 41 b and is connected to the liquid pipe 4 via a valve 46.

  The gas pipe 5 is connected to the gas pipe 48 through a valve 47. The gas pipe 48 is connected to the third port 23 c of the four-way valve 23. A pipe 49 is connected to the fourth port 23 d of the four-way valve 23. The pipe 49 is connected to the accumulator 40 after joining the bypass pipe 36 extending from the refrigerant subcooler 32 on the way. A suction pipe 50 extends from the accumulator 40 and is connected to the suction port of the compressor 21.

Next, the operation of the air conditioner 1 will be described.
During the cooling operation, the first port 23a and the second port 23b of the four-way valve 23 are connected, and the third port 23c and the fourth port 23d are connected. Further, the flow rate adjustment valve 31 is slightly opened. The high-temperature and high-pressure gas refrigerant discharged from the compressor 21 is supplied to the first heat exchanger 26 of the outdoor heat exchanger 25 through the four-way valve 23. The first heat exchanger 26 functions as a condenser, and the gas refrigerant exchanges heat with the air sent by the blower fan 29 to form a substantially saturated liquid refrigerant. The liquid refrigerant flows out to the branch pipe 28 and a part thereof is supplied to the refrigerant subcooler 32. At this time, by passing through the flow control valve 31 that is slightly opened, it adiabatically expands and becomes a low-temperature liquid refrigerant. This low-temperature liquid refrigerant flows into the flow path 35 inside the refrigerant subcooler 32 as a low-temperature heat source. On the other hand, the liquid refrigerant that has flowed into the second heat exchanger 27 from the branch pipe 28 is supercooled by blowing air from the blowing fan 29. This liquid refrigerant flows into the one inlet / outlet 41 a of the flow path 41 outside the refrigerant subcooler 32 through the pipe 42. This liquid refrigerant becomes a high-temperature heat source having a relatively large amount of heat relative to the low-temperature heat source.

In the refrigerant subcooler 32, heat exchange is performed between the liquid refrigerant flowing outside and the low-temperature refrigerant flowing inside. Specifically, the refrigerant in the inner flow path 35 serving as the low-temperature heat source takes the heat from the liquid refrigerant in the outer flow path 41 serving as the high-temperature heat source and vaporizes. As a result, the liquid refrigerant in the outer channel 41 is supercooled by the amount of latent heat of evaporation required for the refrigerant in the inner channel 35 to evaporate. The supercooled liquid refrigerant is supplied to the indoor unit 3 through the liquid pipe 44.
In the indoor unit 3, heat is exchanged by the indoor heat exchanger 11, and the amount of heat corresponding to the latent heat of vaporization is taken from the air and vaporized. This cools the room using the cooled air. The gas refrigerant flowing out from the indoor heat exchanger 11 is collected by the outdoor unit 2 through the gas pipe 5. In the outdoor unit 2, the gas flows from the gas pipe 48 through the third port 23 c and the fourth port 23 d of the four-way valve 23 to the pipe 49, joins the gas refrigerant flowing in from the refrigerant subcooler 32, and then accumulator 40. Flow into. Further, the gas refrigerant is sucked into the compressor 21 from the accumulator 40.

  Here, the control device 33 adjusts the opening degree of the flow rate adjustment valve 31 while monitoring the temperature of the thermometer 45. As shown in FIG. 2, the degree of supercooling in the refrigerant subcooler 32 increases as the amount of refrigerant passing inside the refrigerant subcooler 32 by increasing the bypass amount, that is, the opening of the flow rate adjustment valve 31. As the capacity of the refrigerant subcooler 32 increases, the temperature rises. Since the supercooling degree of the air-cooled subcooler is substantially constant regardless of the change in the bypass amount, the total supercooling degree of the air-cooled subcooler and the refrigerant subcooler 32 increases. By increasing the amount of bypass, the amount of refrigerant supplied to the indoor unit 3 decreases, but the total degree of supercooling increases, so the difference in enthalpy between the inlet and outlet of the indoor heat exchanger 11 can be increased, A decrease in cooling capacity can be suppressed. For example, when the supercooling degree of the liquid refrigerant flowing out from the refrigerant supercooler 32 is set to 20K, the liquid refrigerant is vaporized in the middle even when the liquid pipe 4 is long or there are many indoor unit units 10. And sufficient cooling capacity can be obtained.

  During heating operation, the flow rate adjustment valve 31 is closed and the refrigerant subcooler 32 is not used. Further, both the first and second heat exchangers 26 and 27 are used as an evaporator. Heating capacity can be improved by using the second heat exchanger 27 as an evaporator.

  In this embodiment, the air-cooled subcooler and the refrigerant subcooler 32 are provided in substantially parallel, and the refrigerant before being supercooled by the air-cooled subcooler is guided to the refrigerant subcooler 32 as a low-temperature heat source. As a result, the degree of supercooling can be stabilized even when the air temperature fluctuates. When two types of supercoolers are provided in series as in the prior art, a part of the air-cooled liquid refrigerant is used as a low-temperature heat source, so that the pressure of the liquid refrigerant is reduced and the refrigerant-type supercooler 32 inlet is overheated. Although the degree of cooling decreased and the degree of supercooling could not be increased even when passing through the refrigerant type subcooler 32, in this embodiment, the refrigerant before air cooling is used as a low-temperature heat source. The capacity of the cooler 32 can be increased. Although the amount of the refrigerant circulating to the indoor unit 3 is reduced by the bypass, the capacity of the refrigerant subcooler 32 is increased, so that the cooling capacity can be prevented from greatly decreasing. As a result, when the liquid pipe 4 and the gas pipe 5 are long pipes or when a plurality of indoor unit units 10 are connected, it is possible to prevent a decrease in the capacity of the indoor unit 10 and a variation in capacity.

(Second Embodiment)
As shown in FIG. 3, in the air conditioner 61, the outdoor heat exchanger 25 has a first heat exchanger 26 and a second heat exchanger 27, and these heat exchangers 26, 27 are liquid receivers. It is connected via a device 63. Further, liquid refrigerant is supplied to the refrigerant subcooler 32 from the liquid receiver 63. More specifically, the pipe 64 connected to the inlet / outlet (outlet during cooling operation) of the first heat exchanger 26 is inserted into the liquid receiver 63. A pipe 65 connected to the inlet / outlet of the second heat exchanger 27 (inlet during cooling operation) is also inserted into the liquid receiver 63. A bypass pipe 66 that forms a bypass circuit extends from a substantially bottom portion of the liquid receiver 63 and is connected to an inlet 35a of a flow path 35 inside the refrigerant subcooler 32 after the flow rate adjustment valve 31 is provided. . Other configurations are the same as those of the first embodiment.

Next, the operation of the air conditioner 61 will be described.
During the cooling operation, the gas refrigerant discharged from the compressor 21 flows into the first heat exchanger 26. The first heat exchanger 26 functions as a condenser, and a high-pressure liquid refrigerant is formed by heat exchange. This liquid refrigerant flows into the liquid receiver 63 from the pipe 64. The liquid refrigerant is accumulated in the liquid receiver 63 and the pressure is reduced. The bypass pipe 66 is connected to the substantially bottom portion of the liquid receiver 63, and the flow rate adjustment valve 31 is slightly open. Therefore, only the refrigerant extremely close to the saturated liquid is taken out and decompressed by the flow rate adjustment valve 31. The low-temperature heat source is supplied to the flow path 35 inside the refrigerant subcooler 32.
Further, the liquid refrigerant is also supplied from the liquid receiver 63 to the second heat exchanger 27. The liquid refrigerant supplied to the second heat exchanger 27 (air-cooled supercooler) is further supercooled by the refrigerant-type supercooler 32 after being supercooled by air cooling and supplied to the indoor unit 3.
The liquid refrigerant taken out for the low-temperature heat source bypasses the indoor unit 3 and is sucked into the compressor 21. The degree of opening of the flow rate adjustment valve 31 is adjusted so that the degree of supercooling is 20K, for example, by measuring the degree of supercooling as described above.

  During the heating operation, the flow rate adjustment valve 31 is closed. In addition to the first heat exchanger 26, the second heat exchanger 27 functions as an evaporator, so that a high heating capacity is exhibited.

According to this embodiment, a part of the liquid refrigerant is branched from the liquid receiver 63 before passing through the air-cooled subcooler and used as a low-temperature heat source for the refrigerant subcooler 32. The same effects as those of the embodiment can be obtained. In particular, since the receiver 63 is used when the refrigerant for the low-temperature heat source is branched, the dryness of the bypassed refrigerant can be extremely reduced. As a result, the difference in enthalpy between the inlet 35a and the outlet 35b on the low-temperature heat source side of the refrigerant subcooler 32 can be increased. Therefore, even when the same refrigerant amount is bypassed, the degree of supercooling can be increased, and the degree of supercooling can be increased while suppressing a decrease in cooling capacity.
Furthermore, since the functions of the condenser (first heat exchanger 26) and the air-cooled supercooler (second heat exchanger 27) are separated by the liquid receiver 63, the air-cooled type even if the operating conditions fluctuate. The capacity of the subcooler can be obtained stably.

(Third embodiment)
In FIG. 4, the external view of the outdoor unit 2 of the air conditioning apparatus 1 is shown. In the outdoor unit 2, each component is accommodated in a substantially rectangular parallelepiped case 71. A blowout port 73 is provided on the ceiling surface 72 of the case 71, and a blowout fan 74 (blower fan) is disposed here. Suction ports 81 and 82 (the suction ports of the side surface 77 and the back surface 78 are not shown) are formed as openings for taking in air on the side of the case 71, that is, the front surface 75 and the two side surfaces 76 and 77 and the back surface 78, respectively. Has been. Inside the front surface 75, the 2nd heat exchanger 27 which functions as an air-cooling type subcooler is arrange | positioned facing the suction inlet. The first heat exchanger 26 is disposed so as to face the respective suction ports 82 of the two side surfaces 76 and 77 and the back surface 78, and is substantially U-shaped in a plan view as indicated by a broken line, for example. . In addition, as for each surface 75-78, all may be a suction inlet. Further, a suction port may be formed in a part of the panel forming each surface.

  When the air conditioner 1 is operated, the upper blowing fan 74 rotates. Air is sucked from the four suction ports 81 and 82 on the four sides 75 to 78 on the side, and is discharged from the upper blowing port 73 through the first and second heat exchangers 26 and 27. At this time, heat exchange is performed with the refrigerant flowing in the first and second heat exchangers 26 and 27.

In the outdoor unit 2, since the first and second heat exchangers 26 and 27 are disposed so as to surround the blower fan 74 in a plan view along the rotation axis of the blower fan 74, fan efficiency is improved. . For this reason, the total air volume can be increased by the amount of air flowing through the second heat exchanger 27 without decreasing the air volume flowing through the first heat exchanger 26. Since the air flowing through each of the first heat exchanger 26 and the second heat exchanger 27 is ensured separately, each air does not affect the characteristics of the heat exchangers and stable performance. Is obtained. From these things, at the time of air_conditionaing | cooling operation, a big supercooling degree can be obtained, ensuring a condensing capability, and the fall of air_conditioning | cooling capability can be suppressed also with long piping. Moreover, the heating capacity can be improved with the increase in the air volume even during the heating operation.
Here, you may make the outdoor unit 62 of the air conditioning apparatus 61 in 2nd Embodiment into the same shape. The same operations and effects as described above can be obtained.

The present invention can be widely applied without being limited to the above-described embodiments.
For example, a thermometer 45 is provided on the outlet 35b side of the flow path 35 inside the refrigerant subcooler 32, and the flow rate is adjusted by estimating the degree of supercooling of the liquid refrigerant supplied to the indoor unit 3 from the temperature of the refrigerant flowing out. The opening degree of the valve 31 may be controlled.
In FIG. 4, the second heat exchanger 27 may be arranged over two or more surfaces. The first heat exchanger 26 may be disposed on only one surface, or may be disposed on two or four surfaces.

It is a figure which shows schematic structure of the air conditioning apparatus which concerns on embodiment of this invention. It is a graph which shows the relationship between a bypass amount, cooling capacity, and a supercooling degree. It is a figure which shows schematic structure of the air conditioning apparatus provided with the liquid receiver. It is an external view of an outdoor unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,61 Air conditioning apparatus 2,62 Outdoor unit 3 Outdoor unit 25 Outdoor heat exchanger 26 First heat exchanger 27 Second heat exchanger 30, 36, 64 Bypass piping (bypass circuit)
31 Flow Control Valve 32 Refrigerant Subcooler 63 Receiving Unit 71 Case 74 Blowing Fan 81, 82 Suction Port (Opening)

Claims (3)

In an air conditioner that performs heating or cooling by allowing refrigerant compressed by a compressor to flow into a heat exchanger and exchanging heat with air,
The heat exchanger of the outdoor unit becomes a condenser during cooling operation and becomes an evaporator during heating operation, and an air-cooled subcooler during cooling operation and becomes an evaporator during heating operation. A bypass circuit having a second heat exchanger and branching a part of the refrigerant flowing out of the first heat exchanger during cooling operation before flowing into the second heat exchanger to bypass the indoor unit Characterized in that a flow rate adjusting valve is provided in the bypass circuit, and a refrigerant-type subcooler that further subcools the refrigerant subcooled in the second heat exchanger using the refrigerant flowing through the bypass circuit. Air conditioner to do.   The liquid receiver is provided between the first heat exchanger and the second heat exchanger, and the bypass circuit is connected to a substantially bottom portion of the liquid receiver. Air conditioner.   The outdoor unit has a substantially rectangular parallelepiped case to which a fan for blowing air is attached, the first heat exchanger in the case so as to surround the fan when viewed from the rotation axis direction of the fan, A second heat exchanger is disposed, and an opening for passing air is formed in a side portion of the case facing the first heat exchanger and the second heat exchanger. The air conditioning apparatus according to claim 1 or 2.

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