JPH09119725A - Binary refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate liquid of sufficiently high temperature with high efficiency by the binary operation of both low and high temperature side refirgerating circuits. SOLUTION: At the time of low outer atmoshere, the water of a liquid heat exchanger 6 is heated by the condensing operation of a high-temperature side refrigerant, and heated by the sensible heat of the discharge gas of a low- temperature side refrigerant by an auxiliary heat exchanger 7 by the binary operation, the compression ratio per one of compressors 1, 3 is reduced to enhance the efficiency, and hot water temperature is effectively enhanced by the low-temperature side discharge gas at about 100 deg.C. At the time of high atmosphere, in the case of a single stage operation at the high-temperature side, the evaporating capacity is supplemented by an auxiliary evaporator 9 to obtain the heating amount of water by the exchanger 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual refrigerating apparatus which is provided with two refrigerating circuits, a low temperature side refrigerating circuit and a high temperature side refrigerating circuit, and which is applied to a water heater or the like for the purpose of supplying hot water.

[0002]

2. Description of the Related Art Conventionally, as this type of refrigerating device, there is one disclosed in Japanese Patent Laid-Open No. 4-254156 and shown in FIG. 5, which is provided with the following components a to f.

A. Low temperature side refrigeration circuit L having a low temperature side compressor LC.

B. High temperature side refrigeration circuit H having a high temperature side compressor HC.

C. The high pressure refrigerant of the low temperature side refrigeration circuit L and the low pressure refrigerant of the high temperature side refrigeration circuit H are latently heat-exchanged to condense the high pressure gas refrigerant of the low temperature side refrigeration circuit L and the high temperature side refrigeration circuit H.
Refrigerant heat exchanger M for evaporating the low-pressure liquid refrigerant of.

D. A liquid heat exchanger N that condenses the discharge gas of the high temperature side compressor HC to generate hot water that is a high temperature liquid.

E. A preheat heat exchanger K that further condenses the gas-liquid mixed refrigerant that has passed through the refrigerant heat exchanger M in the low temperature side refrigeration circuit L and preheats the liquid to be produced before being supplied to the liquid heat exchanger N.

F. A heat source side heat exchanger J, which is interposed in the low temperature side refrigeration circuit L and obtains a heat source of the refrigerant condensed in the refrigerant heat exchanger M and the preheat heat exchanger K.

LV is a low temperature side expansion mechanism, HV is a high temperature side expansion mechanism, T is a hot water storage tank for storing generated hot water, O is a hot water circulation pump, and V is a temperature control flow control valve.

In this device, the dual refrigeration circuit on the low temperature side and the high temperature side is used to reduce the compression ratio of each of the compressors LC and HC on the low temperature side and the high temperature side. It is designed to operate with higher efficiency than the integrated system.

[0011]

However, firstly, the condensation temperature of the low temperature side refrigerant in the preheat heat exchanger K is relatively low at about 30 to 40 ° C. in the most general case of R22. , If the inlet temperature of the water to be produced is cold water that is lower than its condensation temperature, this cold water can be preheated, but if the temperature of the water rises and exceeds the condensation temperature,
Preheating can no longer be performed, and the adverse effect of lowering the temperature of the water occurs.

Secondly, although the dual operation is performed for the purpose of high efficiency, the decrease in efficiency due to the increase of the compression ratio becomes a problem mainly due to the heat source side heat exchanger J. This is the case when the temperature of the outside air provided is low. This is because the evaporation pressure in the heat source side heat exchanger J decreases, the differential pressure with the condensing pressure increases, and the compression ratio to be ensured in the compressor increases. Therefore, the compression ratio does not become too large under the condition that the outside air temperature is high, and the compressors LC and H on both the low temperature side and the high temperature side are daringly dared.
It is not necessary to carry out a dual operation in which C is also used, and a single stage operation of only the high temperature side compressor HC is sufficient, and rather a single stage operation is more efficient.

Nevertheless, in the above-mentioned one, only the dual operation in which both the compressors LC and HC are used together can be performed, and only the high temperature side compressor HC is operated in a single stage to operate only the high pressure side refrigeration circuit H. I can't let you. The reason why the liquid heat exchanger N of the high temperature side refrigeration circuit H can heat the liquid is that the refrigerant heat exchanger M evaporates the high temperature side refrigerant to take the heat source. This is because in order to evaporate the refrigerant, it is necessary to operate the low temperature side refrigeration circuit L, condense the low temperature side refrigerant in the refrigerant heat exchanger M, and perform latent heat exchange between the low temperature side refrigerant and the high temperature side refrigerant. Therefore, it is always necessary to operate the two compressors LC and HC together to generate hot water, and there is a problem that high efficiency operation cannot be guaranteed when the outside air is high.

Thirdly, the heat source side heat exchanger J interposed in the low temperature side refrigeration circuit L acts as an evaporator, and particularly when the outside air is low,
Since the frost is formed on the fins, the refrigerant flow direction is switched,
The discharge gas discharged from the low temperature side compressor LC may be guided to the heat source side heat exchanger J to perform defrost operation. In this case, since the preheat heat exchanger K acts as an evaporator, there is a problem that the temperature of the hot water is greatly lowered, and in order to solve this problem, the high temperature side refrigeration circuit H is operated in combination and the liquid heat exchanger is operated. When ensuring the heating at N, the refrigerant heat exchanger M, which is the only evaporator for the high temperature side refrigerant circuit H, is also the evaporator of the low temperature side refrigeration circuit L, so that the evaporation of the high temperature side refrigerant is performed. Is hindered, and there is a problem that smooth driving cannot be maintained.

The main object of the present invention is to solve the first problem and to generate a liquid of sufficiently high temperature with high efficiency by a binary operation in which a low temperature side and a high temperature side refrigeration circuit are used in combination. The point is to provide a dual refrigeration system that can be used.

[0016]

According to the first aspect of the present invention,
In order to achieve the above main purpose, as shown in FIG.
It is assumed that each of the components has elements F to F.

A. A low temperature side refrigeration circuit 2 having a low temperature side compressor 1. R22 and the like are typical examples of the low temperature side refrigerant that flows into the low temperature side refrigeration circuit 2.

B. High temperature side refrigeration circuit 4 having a high temperature side compressor 3. A representative example of the high temperature side refrigerant flowing in the high temperature side refrigeration circuit 4 is HFC-134a or the like.

C. A refrigerant heat exchanger 5 that enables latent heat exchange between the high-pressure refrigerant of the low-temperature side refrigeration circuit 2 and the low-pressure refrigerant of the high-temperature side refrigeration circuit 4. This refrigerant heat exchanger 5 is for exchanging heat between refrigerants, and is a so-called double-tube heat exchanger, plate heat exchanger, shell-and-tube heat exchanger, and other various types of heat exchangers. It is a concept that includes vessels.

D. A liquid heat exchanger 6 that condenses a discharge gas discharged from the high temperature side compressor 3 to generate a high temperature liquid. As shown in FIG. 1, this liquid heat exchanger 6 is of a type in which a refrigerant pipe 60 is installed inside a container 600 connected to inlet / outlet pipes 61 and 62 to a separate hot water supply tank (not shown). Or
There is a system in which piping is directly installed in the hot water tank.

E. An auxiliary heat exchanger 7 for exchanging sensible heat between the discharge gas of the low temperature side compressor 1 and the liquid to be generated by the liquid heat exchanger 6. As shown in FIG. 1, the auxiliary heat exchanger 7 is a concept that includes not only the type of piping inside the liquid heat exchanger 6 but also the type of external attachment to the outside.

F. A heat source side heat exchanger 8 interposed in the low temperature side refrigeration circuit 2. As shown in FIG. 1, this heat source side heat exchanger 8 is typically a pneumatic type such as a cross fin coil in which a fan 81 is attached and a large number of fins 82 and a plurality of paths of the refrigerant pipe 80 are orthogonal to each other. It is a target.

According to a second aspect of the present invention, in the first aspect of the present invention, the auxiliary heat exchanger 7 is replaced by the liquid heat exchanger 6 in order to effectively heat the liquid to be produced in the auxiliary heat exchanger 7. It is arranged such that it is arranged on the liquid take-out side.

The invention according to claim 3 also solves the above-mentioned second problem, and in the invention according to claim 1 or claim 2, only a dual operation in which a low temperature side and a high temperature side refrigeration circuit are used in combination. Of course, in order to enable single-stage operation only on the high temperature side, the high temperature side refrigeration circuit 4 has the auxiliary evaporator 9 interposed. Similar to the heat source side heat exchanger 8, the auxiliary evaporator 9 is also mainly of the air type, such as a cross fin coil in which the fins 82 having a large number of branches and the refrigerant pipes 90 having a plurality of paths are orthogonal to each other, but a liquid cooling type. It may be one.

In the invention according to claim 4, in which the dual operation and the single-stage operation are both possible, in the invention according to claim 3, since highly efficient operation is actually performed in accordance with the outside air condition, at the time of low outside air The low temperature side compressor 1 and the high temperature side compressor 3 are operated together, and the operation control means 101 corresponding to the outside air temperature is provided to operate the high temperature side compressor 3 in a single stage when the outside air is high.

According to a fifth aspect of the present invention, in the third or fourth aspect of the invention, the operation is switched between nighttime hot water storage operation and daytime additional heating operation, and the operation suitable for each is performed, The operation switching means 102 is provided for switching between the combined operation of the low temperature side compressor 1 and the high temperature side compressor 3 and the single-stage operation of the high temperature side compressor 3 in accordance with the input of the changeover command.

The invention according to claim 6 is also for solving the above-mentioned third problem, and in the invention according to any one of claims 3 to 5, the defrosting of the heat source side heat exchanger 8 is simplified. In addition, in order to perform well, the low temperature side refrigeration circuit 2
A switching mechanism 10 that reversibly flows the refrigerant between the refrigerant heat exchanger 5 and the heat source side heat exchanger 8 is provided so that the heat source side heat exchanger 8 can be defrosted. The switching mechanism 10 is
As shown in FIG. 1, in addition to the four-way switching valve, a plurality of solenoid valves may be used.

According to a seventh aspect of the invention, in the sixth aspect of the invention, when the heat source side heat exchanger 8 is defrosted, the temperature drop of the liquid to be produced is actually suppressed, so that the heat source side heat exchanger 8 is defrosted. At this time, the defrost operation control means 103 for operating the low temperature side compressor 1 and the high temperature side compressor 3 together is provided.

In the invention described in claim 8, in the invention described in any one of claims 3 to 7, in order to simplify the structure, an auxiliary evaporator 9 is attached to the heat source side heat exchanger 8 and the heat exchanger 8 passes through. It is configured to use air.

According to a ninth aspect of the present invention, in order to further improve the effect of the defrosting operation even when performing the defrosting operation in which the discharge gas is injected into the heat source side heat exchanger 8 in the eighth aspect of the invention. , As clearly shown in FIG.
The refrigerant pipe 80 of the heat source side heat exchanger 8 is arranged on the upwind side of the passing air shown by the white arrow, and the refrigerant pipe 90 of the auxiliary evaporator 9 is arranged on the downwind side of the passing air.

According to a tenth aspect of the present invention, in the invention according to any one of the first to ninth aspects, a large output is secured without the capacity of the high temperature side compressor 3 becoming excessively large.
A plurality of sets of refrigerant heat exchangers 5 and heat source side heat exchangers 8 are connected in parallel to the low temperature side compressor 1, and a plurality of sets of high temperature side refrigeration circuits 4 are provided corresponding to each refrigerant heat exchanger 5. It is configured to be provided independently.

[0032]

In the invention described in claim 1, during the dual operation in which the low temperature side compressor 1 and the high temperature side compressor 3 are operated in combination,
In the low temperature side refrigeration circuit 2, as shown by the solid line arrow, the low temperature side compressor 1, the auxiliary heat exchanger 7, the refrigerant heat exchanger 5, the heat source side heat exchanger 8, and the low temperature side compressor 1 flow the low temperature side refrigerant in this order, On the other hand, in the high temperature side refrigeration circuit 4, the high temperature side refrigerant flows in the order of the high temperature side compressor 3, the liquid heat exchanger 6, the auxiliary evaporator 9, the refrigerant heat exchanger 5, and the high temperature side compressor 3.

As shown in FIG. 2, the low-temperature side discharge gas x discharged from the low-temperature side compressor 1 gives sensible heat to the liquid to be produced by the auxiliary heat exchanger 7, and the state of y in the Mollier diagram. And condensed in the refrigerant heat exchanger 5 and liquefied to the state of z,
The heat source side heat exchanger 8 evaporates and vaporizes from z ′ to w,
Return to the low temperature side compressor 1. On the other hand, as shown by the dotted line in FIG. 3, the high temperature side discharge gas discharged from the high temperature side compressor 3 is condensed and liquefied in the liquid heat exchanger 6 from the state of p to the state of q and then to the state of r, and the auxiliary evaporator 9 And, the refrigerant heat exchanger 5 evaporates from r ′ to the state of s and returns to the high temperature side compressor 3. in this case,
In the refrigerant heat exchanger 5, the high temperature side refrigerant takes away the latent heat of condensation of the low temperature side refrigerant and evaporates. In this way, the low temperature side refrigeration circuit 2 and the high temperature side refrigeration circuit 4 are binaryly linked, the liquid to be generated in the liquid heat exchanger 6 is heated by the condensation action of the high temperature side refrigerant, and the low temperature side refrigerant is discharged. It is heated by the sensible heat of the gas. At this time, when the outside air is low, the heat source side heat exchanger 8
Even if the evaporating pressure is low, a large condensing pressure in the liquid heat exchanger 6 can be secured, and the compression ratio for each of the low temperature side and high temperature side compressors 1 and 3 can be reduced, so that highly efficient operation can be performed. . Further, as shown in FIG. 2, the temperature of the discharge gas x on the low temperature side is as high as about 100 ° C. in the case of R22, which is higher than the normal take-out temperature of the liquid to be produced 60 to 70 ° C. Can be heated to Furthermore, the condensation temperature of the high temperature side refrigerant and the discharge gas temperature can be lowered by the amount of utilizing the sensible heat of the low temperature side discharge gas. HFC-13
In the case of 4a, as shown in FIG. 3, the discharge gas temperature can be lowered to 78 ° C. during the dual operation (dotted line), compared with 90 ° C. during the single-stage operation (solid line). For this reason, the compression ratio of the high temperature side compressor 3 can be further reduced, more highly efficient operation can be performed, and reliability can be improved.

According to the second aspect of the invention, during the binary operation, the auxiliary heat exchanger 7 can heat the liquid to be produced on the liquid take-out side of the liquid heat exchanger 6, and the liquid to be produced can be effectively heated. It is possible to further increase the temperature of the liquid to be taken out.

In the invention according to claim 3, the high temperature side compressor 3
It is also possible to efficiently perform only the single-stage operation. During this single-stage operation, only the high temperature side refrigeration circuit 4 has the high temperature side compressor 3, the liquid heat exchanger 6, the auxiliary evaporator 9, the refrigerant heat exchanger 5, The high temperature side refrigerant is made to flow in order of the high temperature side compressor 3.

As shown by the solid line in FIG. 3, the high temperature side compressor 3
The discharged gas discharged from is condensed and liquefied in the state of R through the state of P to Q in the liquid heat exchanger 6, and is evaporated and vaporized in the state of R ′ to S in the auxiliary evaporator 9 and the refrigerant heat exchanger 5. , And returns to the high temperature side compressor 3. In this case, the high temperature side refrigerant cannot use the latent heat of condensation of the low temperature side refrigerant in the refrigerant heat exchanger 5, but the auxiliary evaporator 9 can supplement the evaporation action.
Thus, the single-stage operation of only the high temperature side refrigeration circuit 4 can be performed, and the liquid to be produced in the liquid heat exchanger 6 is heated by the condensing action of the high temperature side refrigerant. At this time, when the outside air is high, the evaporation pressure is higher than when the outside air is low, and the differential pressure from the condensation pressure is not too large. Therefore, high-efficiency operation can be achieved by only the single-stage operation of the high temperature side compressor 3.

According to the fourth aspect of the present invention, the low temperature side compressor 1 is operated by the operation control means 101 corresponding to the outside air temperature when the outside air is low.
And dual operation using the high temperature side compressor 3 together,
Since the single-stage operation of the high temperature side compressor 3 is performed, it is possible to actually perform high efficiency operation according to the outside air condition.

In the invention according to claim 5, the operation switching means 1
02, according to the input of the switching command, the low temperature side compressor 1
Also, since the dual operation in which the high temperature side compressor 3 is used in combination and the single stage operation of the high temperature side compressor 3 are switched, the operation is switched between the nighttime hot water storage operation and the daytime additional heating operation, etc. Can be done.

In the sixth aspect of the invention, the flow of the refrigerant in the low temperature side refrigeration circuit 2 can be easily reversed by switching the switching mechanism 10, and the discharge gas is supplied to the heat source side heat exchanger 8. Therefore, the defrosting of the heat source side heat exchanger 8 can be performed easily and satisfactorily. During the defrost operation, in the low temperature side refrigeration circuit 2 as shown in FIG.
Low temperature side compressor 1, heat source side heat exchanger 8, refrigerant heat exchanger 5,
The low temperature side refrigerant flows in the order of the auxiliary heat exchanger 7 and the low temperature side compressor 1, and the discharge gas discharged from the low temperature side compressor 1 is
The heat source side heat exchanger 8 condenses and liquefies from w to z ′ state, and the refrigerant heat exchanger 5 and the auxiliary heat exchanger 7 evaporate and vaporize from z to x state and return to the low temperature side compressor 1. At this time, the sensible heat of the liquid to be generated in the liquid heat exchanger 6 can be recovered by the auxiliary heat exchanger 7, so that the heat quantity of the discharge gas supplied to the heat source side heat exchanger 8 can be increased, and the heat source Side heat exchanger 8
It is possible to effectively remove the frost formation in the. Further, since the temperature of the liquid to be produced is lowered due to the recovery of sensible heat in the auxiliary heat exchanger 7, the high temperature side refrigeration circuit 4 is also operated to secure the heating in the liquid heat exchanger 6. In this case, the refrigerant heat exchanger 5 is not the only evaporator for the high temperature side refrigerant circuit 4, and the auxiliary evaporator 9 compensates for the evaporation action, so that the smooth operation in the high temperature side refrigeration circuit 4 can be maintained. . In this way, the heat source side heat exchanger 8 can be suitably adapted to the defrosting, and the defrosting can be performed easily and satisfactorily.

According to the seventh aspect of the invention, the defrost operation control means 103 simultaneously operates the low temperature side compressor 1 and the high temperature side compressor 3 when the heat source side heat exchanger 8 is defrosted. The temperature drop of the liquid can be actually suppressed.

In the invention according to claim 8, since the auxiliary evaporator 9 is attached to the heat source side heat exchanger 8 and the passing air is used, the heat exchangers 8 and 9 are provided independently of each other. The configuration can be simplified as compared with the case where a fan is installed.

According to the ninth aspect of the invention, when the passing air between the heat source side heat exchanger 8 and the auxiliary evaporator 9 is put into service, the frost is often generated on the heat source side heat exchanger where the low temperature side refrigerant evaporates. 8 side, the refrigerant pipe 80 of the heat source side heat exchanger 8 is arranged on the windward side of the passing air, and the refrigerant pipe 90 of the auxiliary evaporator 9 is arranged on the leeward side of the passing air. Frost can be effectively removed, and even when the auxiliary evaporator 9 is operated by operating the high temperature side refrigeration circuit 4 together, it is possible to reduce the adverse effect due to the cooling in the auxiliary evaporator 9. Thus, even when the defrost operation in which the discharge gas is thrown into the heat source side heat exchanger 8 is performed, the effect of the defrost can be further improved.

In the tenth aspect of the invention, a plurality of sets of refrigerant heat exchangers 5 and heat source side heat exchangers 8 are connected in parallel to the low temperature side compressor 1, and each of the refrigerant heat exchangers 5 corresponds to a high temperature. Since the plurality of side refrigeration circuits 4 are independently provided, the capacity of each high temperature side compressor 3 does not become excessive,
The liquid heat exchanger 6 can be heated by a plurality of high temperature side compressors 3. Therefore, the extraction output of the liquid heat exchanger 6 can be effectively improved.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION The binary refrigeration system shown in FIG. 1 has a low temperature side compressor 1, a low temperature side refrigeration circuit 2 using R22 as a low temperature side refrigerant, and a high temperature side compressor 3, and an HFC-type compressor. 134
and a high temperature side refrigeration circuit 4 using a as a high temperature side refrigerant, and a high pressure side refrigerant of the low temperature side refrigeration circuit 2 and a low pressure side refrigerant of the high temperature side refrigeration circuit 4 through which they undergo latent heat exchange. It is a cooperation.

Reference numeral 6 denotes a discharge gas discharged from the high temperature side compressor 3, which is made to flow through a refrigerant pipe 60 connected to an external hot water supply tank via a circulation pump to a refrigerant pipe 60 to be condensed, whereby hot water which is a high temperature liquid. Liquid heat exchanger for generating 7
Is an auxiliary heat exchanger for exchanging sensible heat between the discharge gas of the low temperature side compressor 1 and the hot water on the outlet side of the liquid heat exchanger 6, and 8 is equipped with a fan 81, and has a large number of fins 82 and a plurality of paths. The heat source side heat exchanger 9 composed of a cross fin coil orthogonal to the refrigerant pipe 80 serves the heat source side heat exchanger 8, the fan 81 and the fins 82, and the heat source side heat exchanger 8 has a refrigerant pipe 80. Auxiliary evaporators 10 each having a plurality of refrigerant pipes 90 arranged on the leeward side include a refrigerant heat exchanger 5 and a heat source side heat exchanger 8.
Is a switching mechanism composed of a four-way switching valve that causes the refrigerant to flow reversibly between and. Further, 21 is a low temperature side expansion mechanism, 41 is a high temperature side expansion mechanism, 61 is an inlet pipe for guiding hot water from an external hot water supply tank to the container 600, and 62 is the same outlet pipe.

Two sets of the refrigerant heat exchanger 5 and the heat source side heat exchanger 8 are connected in parallel to one low-temperature side compressor 1, and the high-temperature side compressor 5 is made to correspond to each refrigerant heat exchanger 5. Refrigeration circuit 4
Are independently provided in two sets.

The compressors 1 and 3 and the switching mechanism 10 are controlled to start and stop and switch according to a command from the controller 100. The controller 100 includes an outside air temperature sensor 201.
When the outside air temperature input from is low, the low temperature side compressor 1 and the high temperature side compressor 3 are operated together, and when the outside air temperature is high, the operation control means 101 corresponding to the outside air temperature is provided to operate the high temperature side compressor 3 in a single stage. . Further, the low temperature side compressor 1 and the high temperature side compressor 3 are operated together during the daytime additional heating operation in response to a switching command from the mode selector 202 that switches the operation mode between the nighttime hot water storage operation and the daytime additional heating operation. The operation switching means 102 for operating the high temperature side compressor 3 in a single stage during the hot water storage operation at night is provided. Further, the mechanism 10 is switched to change the heat source side heat exchanger 8
When defrosting, to prevent the temperature drop of hot water,
A defrost operation control means 103 for operating the low temperature side compressor 1 and the high temperature side compressor 3 together is provided.

Thus, with the above configuration, the dual hot water supply operation mainly assuming low outside air, the high temperature side single stage operation mainly assuming high outside air, the defrost operation by the reverse cycle of the low temperature side refrigeration circuit 2, and It enables defrost operation by using both low temperature side and high temperature side.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a binary refrigeration system according to the present invention.

FIG. 2 is a Mollier diagram of the low temperature side refrigeration circuit.

FIG. 3 is a Mollier diagram of the high temperature side refrigeration circuit.

FIG. 4 is a side view of essential parts of a heat source side heat exchanger and an auxiliary evaporator portion.

FIG. 5 is a refrigerant circuit diagram of a conventional example.

[Explanation of symbols]

1; low temperature side compressor, 2; low temperature side refrigeration circuit, 3; high temperature side compressor, 4; high temperature side refrigeration circuit, 5; refrigerant heat exchanger, 6; liquid heat exchanger, 7; auxiliary heat exchanger, 8 ; Heat source side heat exchanger,
9; auxiliary evaporator, 10; switching mechanism

Claims (10)

[Claims] 1. A dual refrigeration system comprising the following components A to F: A. A low temperature side refrigeration circuit (2) having a low temperature side compressor (1). B. High temperature side refrigeration circuit (4) with high temperature side compressor (3). C. A refrigerant heat exchanger (5) capable of performing latent heat exchange between the high-pressure refrigerant of the low-temperature side refrigeration circuit (2) and the low-pressure refrigerant of the high-temperature side refrigeration circuit (4). D. A liquid heat exchanger (6) that condenses the discharge gas discharged from the high temperature side compressor (3) to generate a high temperature liquid. E. FIG. An auxiliary heat exchanger (7) for exchanging sensible heat between the discharge gas of the low temperature side compressor (1) and the liquid to be produced by the liquid heat exchanger (6). F. A heat source side heat exchanger (8) interposed in the low temperature side refrigeration circuit (2). 2. The dual refrigeration system according to claim 1, wherein the auxiliary heat exchanger (7) is arranged on the liquid take-out side of the liquid heat exchanger (6). 3. The dual refrigeration system according to claim 1, wherein an auxiliary evaporator (9) is provided in the high temperature side refrigeration circuit (4). 4. An operation corresponding to the outside air temperature, in which the low temperature side compressor (1) and the high temperature side compressor (3) are operated together when the outside air is low, and the high temperature side compressor (3) is operated in a single stage when the outside air is high. Control means (1
01) The dual refrigeration system according to claim 3 provided with. 5. An operation switching means for switching between a combined operation of the low temperature side compressor (1) and the high temperature side compressor (3) and a single stage operation of the high temperature side compressor (3) according to the input of a switching command. (10
The binary refrigeration system according to claim 3 or 4, further comprising 2). 6. The low temperature side refrigeration circuit (2) comprises a switching mechanism (10) for reversibly flowing the refrigerant between the refrigerant heat exchanger (5) and the heat source side heat exchanger (8), and the heat source side The dual refrigeration system according to any one of claims 3 to 5, which enables defrosting of the heat exchanger (8). 7. The defrosting of the heat source side heat exchanger (8),
7. The dual refrigeration system according to claim 6, further comprising defrost operation control means (103) for operating the low temperature side compressor (1) and the high temperature side compressor (3) together. 8. The heat source side heat exchanger (8) is further provided with an auxiliary evaporator (9) so that passing air can be used.
The binary refrigeration apparatus according to claim 7. 9. The refrigerant pipe (8) of the heat source side heat exchanger (8)
9. The dual refrigeration system according to claim 8, wherein 0) is arranged on the windward side of the passing air, and the refrigerant pipe (90) of the auxiliary evaporator (9) is arranged on the leeward side of the passing air. 10. A plurality of sets of refrigerant heat exchangers (5) and heat source side heat exchangers (8) are connected in parallel to the low temperature side compressor (1), and each refrigerant heat exchanger (5) is connected. Correspondingly, the high-temperature side refrigeration circuit (4) is independently provided in a plurality of sets, The binary refrigeration system according to any one of claims 1 to 9.