JP2012132573A - Heat pump system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent frost formation of an evaporator in a refrigeration circuit 2 at a low temperature side, or to defrost thereof while preventing degradation in operation capacity for heating/hot water supply in a cascade-type heat pump system.SOLUTION: The cascade-type heat pump system includes a low temperature side refrigeration circuit 2, a high temperature side refrigeration circuit 3, and a cascade heat exchanger 4 for exchanging heat at a high temperature side of the low temperature side refrigeration circuit 2 and at low temperature side of the high temperature side refrigeration circuit 3. The cascade-type heat pump system includes: a circulation circuit 6 which returns again a circulation liquid from the high temperature side of the high temperature side refrigeration circuit 3 to the high temperature side of the high temperature side refrigeration circuit 3 through an evaporator 24 of the low temperature side refrigeration circuit 2; and a circulating liquid-refrigerant heat exchanger 7 for heat exchanging between the circulating liquid flowing through the circulation circuit 6 and a high temperature side refrigerant of the high temperature side refrigeration circuit 3.

Description

  The present invention relates to a cascade heat pump.

  One of the defrosting techniques in the conventional heat pump system is a hot gas defrost system. In this method, switching from heating operation to cooling operation is performed, and the air-refrigerant heat exchanger that has been functioning as an evaporator until now is operated as a condenser, and defrosting is performed using a gas refrigerant as a heat source. And this system is a cascade heat exchanger for exchanging heat between the low temperature side refrigeration circuit (heat source side cycle), the high temperature side refrigeration circuit (use side cycle), the high temperature side of the low temperature side refrigeration circuit and the low temperature side of the high temperature side refrigeration circuit. Also in a cascade heat pump system having

  However, in the above method, since the heating / hot water supply operation must be interrupted during the defrosting operation, the following measures are taken.

  First, in order to shorten the defrosting time, the control logic, the improvement of detection of the frost acceleration state, the use of hot gas in the high temperature side cycle, and the like are included.

  However, even if the defrosting operation is shortened by this measure, there is a problem that the heating / hot water supply operation must be stopped during the defrosting operation.

  Next, it is also conceivable that only the low temperature side refrigeration circuit is defrosted so that the high temperature side refrigeration circuit can be operated for heating and hot water supply (see Patent Document 1).

  However, although the problem of stopping the heating / hot water supply operation during the defrosting operation is solved, there is a problem that the heating / hot water supply capacity is reduced. In addition, a system that can replace the cascade heat exchanger with an air-refrigerant heat exchanger or an additional evaporator is required.

JP 2000-320914 A

  Therefore, the present invention has been made to solve the above-mentioned problems all at once, and in a cascade heat pump system, while preventing a decrease in heating and hot water supply capacity, it prevents frosting of the evaporator of the low temperature side refrigeration circuit. Or defrosting is the main desired task.

  That is, the heat pump system according to the present invention includes a cascade having a low temperature side refrigeration circuit, a high temperature side refrigeration circuit, and a cascade heat exchanger for exchanging heat between the high temperature side of the low temperature side refrigeration circuit and the low temperature side of the high temperature side refrigeration circuit. A circulation circuit for returning the circulating fluid from the high temperature side of the high temperature side refrigeration circuit to the high temperature side of the high temperature side refrigeration circuit via the evaporator of the low temperature side refrigeration circuit, and the circulation circuit It has a circulating fluid-refrigerant heat exchanger for exchanging heat between the flowing circulating fluid and the high temperature side refrigerant of the high temperature side refrigeration circuit.

  In such a case, the circulating fluid flowing through the circulating circuit and the high-temperature side refrigerant of the high-temperature side refrigeration circuit are heat-exchanged by the circulating fluid-refrigerant heat exchanger, By flowing through the evaporator, frost formation and defrosting of the evaporator can be performed. Thus, the present invention uses the heat of condensation of the high temperature side refrigeration circuit to stop the heating / hot water supply operation and prevent frosting of the evaporator of the low temperature side refrigeration circuit while preventing a decrease in the heating / hot water supply capacity. Prevention and defrosting can be performed.

  In particular, when the heat pump system is used in a cold region, the circulating fluid flowing in the circulation circuit may be frozen. For this reason, it is desirable that the circulating liquid is an antifreeze liquid.

  A part of the low temperature side refrigeration circuit, a use side unit in which the high temperature side refrigeration circuit and a cascade heat exchanger are arranged, a heat source side unit in which a compressor and an evaporator of the low temperature side refrigeration circuit are arranged, and the use In the case of connecting the side unit and the heat source side unit and having the connecting pipe forming the flow path of the low temperature side refrigeration circuit, the following is desirable. That is, in this configuration, there is a problem that the refrigerant flowing through the refrigeration-side refrigeration circuit radiates heat to the outside through the connection pipe, resulting in performance degradation. Therefore, the connection pipe is a double pipe composed of an inner pipe and an outer pipe, the refrigerant of the low temperature side refrigeration circuit flows in the inner pipe, and the circulating fluid of the circulation circuit is interposed between the inner pipe and the outer pipe. By flowing the refrigerant, it is possible to prevent the heat radiation to the outside of the refrigerant without using a heat insulating material.

  Similarly, the connection pipe is a triple pipe including an inner pipe, an intermediate pipe, and an outer pipe. The refrigerant of the low-temperature side refrigeration circuit flows in the inner pipe, and an air layer is formed between the inner pipe and the intermediate pipe. It is desirable that the circulating fluid in the circulation circuit flows between the intermediate pipe and the outer pipe. If this is the case, heat radiation to the outside can be further prevented.

  At this time, the outer tube is preferably a resin tube. Thereby, heat radiation to the outside can be further prevented by using a resin pipe having low thermal conductivity.

  As a specific embodiment of the heat pump system, the high temperature side refrigeration circuit is configured by connecting a compressor, a water-refrigerant heat exchanger, the circulating liquid-refrigerant heat exchanger, a decompression device, and a cascade heat exchanger. It is desirable that the water flowing in the heating circuit or hot water storage tank to which the heating device is connected is heated by the water-refrigerant heat exchanger.

  In order to simplify the configuration of the heat pump system, it is desirable that the water-refrigerant heat exchanger and the liquid-refrigerant heat exchanger be a water-circulating liquid-refrigerant three-fluid heat exchanger configured integrally.

  As a variety of specific implementations for heating the evaporator, it is desirable that the circulation circuit passes through the inside of the evaporator of the low temperature side refrigeration circuit.

  Moreover, it is desirable that the circulation circuit has a radiator (radiator) provided on the windward side of the evaporator, which passes through the periphery of the evaporator of the low-temperature side refrigeration circuit.

  In order to effectively utilize household wastewater (sewage) and heat the evaporator of the low temperature side refrigeration circuit with energy saving, it is desirable that the circulation circuit has a second circulation circuit via a sewage tank. Since sewage heat uses domestic wastewater, it has a temperature characteristic that the temperature is low in summer and high in winter. Particularly in winter, even when the outside air temperature is lower than 5 ° C., the sewage heat may be kept at 10 ° C., and in an environment where the outside air temperature is about 0 ° C. where frost increases, the energy saving performance by the second circulation circuit is increased.

  It is desirable to have a circuit switching mechanism that switches a circuit through which the circulating fluid circulates between the circulation circuit and the second circulation circuit.

  It is desirable to have a control device that controls the circuit switching mechanism according to the refrigerant outlet temperature of the evaporator of the low temperature side refrigeration circuit and switches the circuit through which the circulating fluid circulates between the circulation circuit and the second circulation circuit. .

  The heat pump system according to the present invention includes a cascade having a low temperature side refrigeration circuit, a high temperature side refrigeration circuit, and a cascade heat exchanger for exchanging heat between the high temperature side of the low temperature side refrigeration circuit and the low temperature side of the high temperature side refrigeration circuit. A circulation circuit for returning the circulating fluid from the high temperature side of the high temperature side refrigeration circuit to the high temperature side of the high temperature side refrigeration circuit via the evaporator of the low temperature side refrigeration circuit, and the circulation circuit A circulating fluid-refrigerant heat exchanger that exchanges heat between the circulating fluid flowing and the high-temperature side refrigerant of the high-temperature side refrigeration circuit, and a part of the low-temperature side refrigeration circuit, the high-temperature side refrigeration circuit, and the cascade heat exchanger It is characterized by comprising a use side unit arranged and a heat source side unit arranged with a compressor and an evaporator of the low temperature side refrigeration circuit.

  In order to have it in an apartment house, etc., a plurality of usage-side units are connected to the one heat source side unit, and the circulation circuit is provided to be branched for each usage-side unit. It is desirable that a unit switching mechanism for switching between the two is used, and the circuit is switched so that the circulating fluid circulates in the circulation circuit arranged in the user side unit corresponding to the user side unit being used.

  It is desirable that a circulation pump for circulating the circulating fluid is provided on the circulation circuit, and the circulation pump is a variable capacity type and can adjust the flow rate. At this time, it is desirable that the flow rate be variable depending on a refrigerant outlet temperature of the evaporator of the low-temperature side refrigeration circuit or a temperature difference between the inflow temperature of the connection pipe forming the flow path of the low-temperature side refrigeration circuit and the outside air temperature. .

  According to the present invention configured as described above, in the cascade heat pump system, it is possible to prevent frost formation or defrost of the evaporator of the low temperature side refrigeration circuit while preventing a decrease in heating / hot water supply capacity.

The schematic diagram which mainly shows the low temperature side freezing circuit of the heat pump system of this embodiment. The schematic diagram which mainly shows the high temperature side freezing circuit of the heat pump system of the embodiment. The schematic diagram which mainly shows the circulation circuit of the heat pump system of the embodiment. Sectional drawing which shows the structure of the connection piping of the embodiment. The schematic diagram which mainly shows the circulation circuit of the heat pump system of deformation | transformation embodiment. The schematic diagram which mainly shows the circulation circuit of the heat pump system of deformation | transformation embodiment. The schematic diagram which shows the structure of the heat pump system of deformation | transformation embodiment. The figure which shows the path | route through which the circulating fluid of deformation | transformation embodiment flows. The figure which shows the path | route through which the circulating fluid of deformation | transformation embodiment flows. The figure which shows the path | route through which the circulating fluid of deformation | transformation embodiment flows. The schematic diagram which shows the structure of the heat pump system at the time of applying to an apartment house. Sectional drawing which shows the structure of the connection piping of deformation | transformation embodiment.

  An embodiment of the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1 to 3, the heat pump system 100 according to the present embodiment includes a low temperature side refrigeration circuit 2, a high temperature side refrigeration circuit 3, a high temperature side of the low temperature side refrigeration circuit 2, and a low temperature of the high temperature side refrigeration circuit 3. It is a cascade heat pump system having a cascade heat exchanger 4 that exchanges heat on the side.

  As shown in FIG. 1, the low temperature side refrigeration circuit 2 includes a compressor 21, a four-way valve 22, a low temperature side heat transfer section of the cascade heat exchanger 4, a pressure reducing device (flow rate adjusting valve) 23, and an evaporator 24 in this order. A refrigeration cycle is formed by connecting. A gas-liquid separator (accumulator) 25 is provided between the evaporator 24 and the compressor 21 via a four-way valve 22. An on-off valve 26 is provided between the four-way valve 22 and the cascade heat exchanger 4. Further, a decompression device (flow control valve) 27 is provided between the cascade heat exchanger 4 and the decompression device 23.

  As shown in FIG. 2, the high temperature side refrigeration circuit 3 includes a compressor 31, a four-way valve 32, a water-refrigerant heat exchanger 33, a decompression device 34, and a high temperature side heat transfer section of the cascade heat exchanger 4 that are annularly connected in this order. This constitutes a refrigeration cycle. A gas-liquid separator (accumulator) 35 is provided between the cascade heat exchanger 4 and the compressor 31 via the four-way valve 21. Further, the water-refrigerant heat exchanger 33 heats the water flowing through the heating circuit 5 to which the heating / warming water unit 51 that is a heating device is connected.

  As shown in FIG. 2, the heating circuit 5 includes a heating hot water unit 51, a water pump 52, a water-refrigerant heat exchanger 33, and a three-way valve 53 that are annularly connected in this order. A hot water storage tank 54 is connected in parallel with the heating / hot water unit 51.

  However, in the heat pump system 100 of the present embodiment, as shown in FIG. 3, the circulating fluid that is the antifreeze liquid is again supplied from the high temperature side of the high temperature side refrigeration circuit 3 via the evaporator 24 of the low temperature side refrigeration circuit 2. 3 and a circulating circuit-refrigerant heat exchanger 7 for exchanging heat between the circulating fluid flowing through the circulating circuit 6 and the high-temperature side refrigerant of the high-temperature side refrigeration circuit 3.

  The circulation circuit 6 passes through the inside of the evaporator 24 of the low-temperature side refrigeration circuit 2, and specifically, the piping forming the circulation circuit 6 is configured to be integrated with the fins of the evaporator 24. ing. In addition, a liquid circulation pump 61 for circulating the circulating liquid is provided on the circulation circuit 6. In addition, the circulating liquid-refrigerant heat exchanger 7 of the present embodiment has a water-circulating liquid-refrigerant 3 fluid integrated with the water-refrigerant heat exchanger 33 of the high-temperature side refrigeration circuit 3 in order to simplify the system configuration. The heat exchanger 8 is used.

  In this embodiment, a part of the low temperature side refrigeration circuit 2, the high temperature side refrigeration circuit 3, the cascade heat exchanger 4 and the heating circuit 5 are arranged, and the compressor 21 of the low temperature side refrigeration circuit 2 is disposed. And the heat source side unit 102 in which the evaporator 24 is disposed, the first and second connection pipes 91 and 92 that connect the use side unit 101 and the heat source side unit 102 and form the flow path of the low temperature side refrigeration circuit 2. Have The use side unit 101 is installed indoors, and the heat source unit 102 is installed outdoors.

  As shown in FIG. 4, the first and second connection pipes 91 and 92 are double pipes composed of an inner pipe 9a and an outer pipe 9b, and the refrigerant of the low temperature side refrigeration circuit 2 flows into the inner pipe 9a. The circulating fluid of the circulation circuit 6 flows between the inner tube 9a and the outer tube 9b. This prevents the refrigerant in the low temperature side refrigeration circuit 2 from radiating heat to the outside in the first and second connection pipes 91 and 92 without using a heat insulating material. The outer tube 9b is made of a resin tube having a low thermal conductivity, and further prevents heat dissipation.

  Next, the operation of the circulation circuit 6 of the heat pump system 100 configured as described above will be briefly described. First, after the heat pump system 100 is activated (the heat source side unit 102 and the utilization side unit 101 are activated), the circulating fluid that is the antifreeze liquid that has passed through the water-circulating liquid-refrigerant 3 fluid heat exchanger 8 is supplied to the circulation circuit 6 by the liquid circulating pump 61. Is circulating. The circulating fluid passes outside the first connection pipe 91 that is routed outdoors, and prevents heat dissipation of the refrigerant in the first connection pipe 91. At the same time, the heat of the circulating fluid moves to the refrigerant in the low temperature side refrigeration circuit 2 (when the circulating fluid temperature> the refrigerant temperature). After passing through the first connection pipe 91, it passes through the pipe in the heat source side unit 102 and reaches the evaporator 24 to prevent frosting of the evaporator 24. After passing through the evaporator 24, the refrigerant passes through the outside of the second connection pipe 92, and heat dissipation of the refrigerant in the second connection pipe 92 is prevented. After passing through the second connection pipe 92, it passes through the pipe in the use side unit 101, and again flows into the water-circulating liquid-refrigerant 3 fluid heat exchanger 8 and circulates.

<Effect of this embodiment>
According to the heat pump system 100 according to the present embodiment configured as described above, the water-circulating liquid-refrigerant 3 fluid heat exchanger 8 heats the circulating liquid flowing through the circulation circuit 6 and the high-temperature side refrigerant of the high-temperature side refrigeration circuit 3. By exchanging and flowing the circulating fluid having a high temperature to the evaporator 24 of the low temperature side refrigeration circuit 2, frosting of the evaporator 24 can be prevented and defrosting can be performed.

<Other modified embodiments>
The present invention is not limited to the above embodiment.

  For example, in the above-described embodiment, the circulating liquid-refrigerant heat exchanger 7 and the water-refrigerant heat exchanger 33 are integrally configured, but may be separated as shown in FIG. At this time, the circulating liquid-refrigerant heat exchanger 7 is provided between the water-refrigerant heat exchanger 33 and the pressure reducing device (flow rate adjusting valve) 34.

  In addition, as shown in FIG. 6, the circulation circuit 6 passes through the periphery of the evaporator 24 of the low temperature side refrigeration circuit 2, and a radiator (radiator) 62 provided on the windward side of the evaporator 24 is provided. You may have. Thereby, since the heat from the radiator 62 can be applied to the evaporator 24, frost formation of the evaporator 24 and defrosting can be performed.

  Furthermore, as shown in FIG. 7, the circulation circuit 6 may be one that effectively utilizes household wastewater (sewage). In this case, the circulation circuit 6 includes a second circulation circuit 63 that passes through a sewage tank 200 in which sewage is stored. The second circulation circuit 63 is formed by branching on the upstream side and the downstream side of the evaporator 24 in the circulation circuit 6. The second circulation circuit 63 is provided on the upstream and downstream sides of the liquid circulation pump 64 and the evaporator 24, respectively. And valves 65 and 66. The two on-off valves 65 and 66 constitute a circuit switching mechanism that switches a circuit through which the circulating fluid circulates between the circulation circuit 6 and the second circulation circuit 63.

  The circulation circuit 6 is connected to the first folded pipe 10 that bypasses the flow path on the use side unit 101 side with respect to the first and second connection pipes 91 and 92, and to the first and second connection pipes 91 and 92. And a second folded pipe 11 that bypasses the flow path on the heat source side unit 102 side. The first return pipe 11 is connected to the circulation circuit 6 via the first and second three-way valves 12 and 13, and the second return pipe 12 is connected to the circulation circuit 6 with the third and fourth three-way valves 14. , 15 are connected. The two on-off valves 65 and 66 and the three-way valves 12 to 15 are controlled by a control device (not shown).

  Specifically, the control device acquires the refrigerant outlet temperature of the evaporator 24 of the low-temperature side refrigeration circuit 2 by a temperature sensor (not shown), and controls the circuit switching mechanism according to the temperature, thereby supplying the circulating fluid to the second circulation circuit. The operation is switched to the operation using sewage heat to be circulated to 63 or the operation using heat pump heat to circulate the circulating fluid to the circulation circuit 6.

  The operation will be briefly described. When the heat source side unit 102 is activated, the control device first activates the liquid circulation pump 64 of the second circulation circuit 63. At this time, the control device opens the two on-off valves 65 and 66 and controls the three-way valves 12 to 15 so that the circulating fluid flows through the first return pipe 10 and does not pass through the second return pipe 11. . Accordingly, the circulating fluid circulates through the second circulation circuit 63 and flows through the evaporator 24, the first connection pipe 91, the first folded pipe 10, the second connection pipe 92, and the sewage tank 200 as shown in FIG. The temperature of the circulating fluid rises using sewage heat.

  After this circulation, the control device activates the heat source side unit 102. When the compressor 21 of the heat source side unit 102 starts to move, the refrigerant flows to the use side unit 101. At this time, the flow of the circulating fluid does not change. Further, after the heat source side unit 102 is activated, the control device activates the compressor 31 of the usage side unit 101. At this time, the flow of the circulating fluid does not change, but the flow rate is variable. Then, after the hot water temperature of the use side unit 101 reaches the set temperature, the control device determines whether the circulation circuit 6 is a sewage heat utilization operation or a heat pump heat utilization operation.

  Specifically, the control device performs a sewage heat utilization operation when the refrigerant outlet temperature of the evaporator 24 of the low temperature side refrigeration circuit 2 is equal to or higher than a predetermined temperature, and a heat pump heat utilization operation when the temperature is lower than the predetermined temperature. The predetermined temperature varies depending on the outside air temperature.

  More specifically, in the control device, the refrigerant outlet temperature is equal to or higher than a predetermined temperature, and the temperature difference between the outside air temperature and the inlet temperature of the first connection pipe 91 of the circulating fluid flowing from the heat source side unit 102 to the usage side unit 101 is less than the predetermined temperature. In this case, the flow of the antifreeze liquid is not changed as shown in FIG. Here, the flow rate of the circulating fluid is varied so that the refrigerant outlet temperature becomes a predetermined temperature. In other words, prevention of heat dissipation of the refrigerant is sewage heat utilization.

  On the other hand, when the refrigerant outlet temperature is equal to or higher than the predetermined temperature and the temperature difference between the outside air temperature and the inlet temperature of the first connection pipe 91 of the circulating fluid flowing from the heat source side unit 102 to the usage side unit 101 is equal to or higher than the predetermined temperature, FIG. As shown, the circulating fluid is circulated through the second circulation circuit 63 to use the sewage heat, and the circulating fluid is circulated through the circulation circuit 6 to use the heat pump heat. Here, the flow rate of the circulating fluid is varied so that the temperature difference between the outside air temperature and the inlet temperature of the first connection pipe 91 of the circulating fluid flowing from the heat source side unit 102 to the utilization side unit 101 becomes a predetermined temperature. That is, the control device prevents the circulating fluid flowing through the second circulation circuit 63 from flowing through the first and second folded pipes 10 and 11, and the circulating fluid flowing through the circulating circuit 6 passes through the first folded pipe 10. The first to fourth three-way valves 12 to 15 are switched so as to flow through the second folded pipe 11 without flowing. Thereby, the circulation circuit 6 exhibits the function as a circuit which prevents refrigerant | coolant heat dissipation, and the 2nd circulation circuit 63 functions as a circuit which prevents the frost formation of the evaporator 24, and defrosts.

  When the refrigerant outlet temperature is lower than the predetermined temperature, the control device closes the two on-off valves 65 and 66 on the second circulation circuit 63 and the circulating fluid flowing through the circulation circuit 6 is turned back to the first and second turns. Do not circulate the pipes 10 and 11. Thereby, the circulation circuit 6 functions as a circuit for preventing the refrigerant from radiating heat and a circuit for preventing and defrosting the evaporator 24. However, the flow rate of the circulating fluid is variable so that the refrigerant outlet temperature becomes a predetermined temperature.

  Next, a case where the heat pump system of the present invention is applied to an apartment house, that is, a case where a plurality of use side units 101 are connected to one heat source side unit 102 will be described. In this case, as shown in FIG. 11, the circulation circuit 6 is provided with a unit switching mechanism 300 for branching corresponding to each usage-side unit 101 and switching the branch circuits. Then, corresponding to the used side unit 101 being used, the circulating fluid is switched so as to circulate through the circulation circuit 6 arranged in the used side unit 101. Each branch circuit is provided with the first to fourth three-way valves 12 to 15 described with reference to FIG. 8, and the unit switching mechanism 300 is operated by the third and fourth three-way valves 14 and 15 of each branch circuit. Composed. FIG. 11 shows a case where the use side unit at home A and the use side unit at home C are activated. In this case, the low temperature side refrigeration circuit 2 is also branched corresponding to each use side unit 101. In this case, the operation when activating a plurality of usage-side units 101 is the same as in the case of the one usage-side unit 101 described above.

  Moreover, in the said embodiment, although 1st, 2nd connection piping was a double tube, as shown in FIG. 12, it is a triple tube which consists of the inner tube 9a, the intermediate tube 9c, and the outer tube 9b, The refrigerant of the low temperature side refrigeration circuit 2 flows in 9a, and the circulating fluid of the circulation circuit 6 flows between the intermediate pipe 9c and the outer pipe 9b with the space between the inner pipe 9a and the intermediate pipe 9c as an air layer. You may do it.

  In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 ... Heat pump system 101 ... Usage side unit 102 ... Heat source side unit 2 ... Low temperature side refrigeration circuit 21 ... Compressor 24 ... Evaporator 3 ... High temperature side refrigeration circuit 31 .... Compressor 33 ... Water-refrigerant heat exchanger 34 ... Pressure reducing device (flow rate adjusting valve)
DESCRIPTION OF SYMBOLS 4 ... Cascade heat exchanger 5 ... Heating circuit 51 ... Heating equipment 6 ... Circulation circuit 62 ... Radiator 63 ... Second circulation circuit 7 ... Circulating liquid-refrigerant heat Exchanger 8 ... water-circulating fluid-refrigerant 3 fluid heat exchanger 91 ... first connection pipe 92 ... second connection pipe 9a ... inner pipe 9b ... outer pipe 200 ... sewage tank

Claims (22)

A cascade heat pump system comprising a low temperature side refrigeration circuit, a high temperature side refrigeration circuit, and a cascade heat exchanger for exchanging heat between the high temperature side of the low temperature side refrigeration circuit and the low temperature side of the high temperature side refrigeration circuit,
A circulating circuit for returning the circulating fluid from the high temperature side of the high temperature side refrigeration circuit to the high temperature side of the high temperature side refrigeration circuit again via the evaporator of the low temperature side refrigeration circuit;
A heat pump system comprising: a circulating liquid-refrigerant heat exchanger for exchanging heat between the circulating liquid flowing in the circulation circuit and the high-temperature side refrigerant of the high-temperature side refrigeration circuit.   The heat pump system according to claim 1, wherein the circulating liquid is an antifreeze liquid. The high temperature side refrigeration circuit is configured by connecting a compressor, a water-refrigerant heat exchanger, the circulating liquid-refrigerant heat exchanger, a decompression device, and a cascade heat exchanger,
The heat pump system according to claim 1 or 2, wherein water flowing through a heating circuit to which a heating device is connected is heated by the water-refrigerant heat exchanger.   The heat pump system according to claim 3, wherein the water-refrigerant heat exchanger and the liquid-refrigerant heat exchanger are a water-circulating liquid-refrigerant three-fluid heat exchanger configured integrally.   The heat pump system according to any one of claims 1 to 4, wherein the circulation circuit passes through an inside of an evaporator of the low temperature side refrigeration circuit.   The heat pump system according to any one of claims 1 to 4, wherein the circulation circuit passes through the periphery of the evaporator of the low-temperature side refrigeration circuit and includes a radiator provided on the wind of the evaporator.   The heat pump system according to any one of claims 1 to 6, wherein the circulation circuit includes a second circulation circuit that passes through a sewage tank.   The heat pump system according to claim 7, further comprising a circuit switching mechanism that switches a circuit through which the circulating fluid circulates between the circulation circuit and the second circulation circuit.   The control apparatus which controls the said circuit switching mechanism according to the refrigerant | coolant exit temperature of the evaporator of the said low temperature side freezing circuit, and switches the circuit through which the said circulating fluid circulates between the said circulation circuit and the said 2nd circulation circuit. The described heat pump system.   The control device circulates the circulating fluid in the second circulation circuit when the refrigerant outlet temperature is equal to or higher than a predetermined temperature, and when the refrigerant outlet temperature is lower than the predetermined temperature, The heat pump system according to claim 9, wherein the circulating fluid is circulated. A part of the low temperature side refrigeration circuit, a use side unit in which the high temperature side refrigeration circuit and a cascade heat exchanger are arranged, a heat source side unit in which a compressor and an evaporator of the low temperature side refrigeration circuit are arranged, and the use Connecting the side unit and the heat source side unit, and having a connection pipe forming a flow path of the low temperature side refrigeration circuit,
The connection pipe is a double pipe composed of an inner pipe and an outer pipe. The refrigerant of the low temperature side refrigeration circuit flows in the inner pipe, and the circulating fluid of the circulation circuit flows between the inner pipe and the outer pipe. The heat pump system according to any one of claims 1 to 10, which is configured as described above. A part of the low temperature side refrigeration circuit, a use side unit in which the high temperature side refrigeration circuit and a cascade heat exchanger are arranged, a heat source side unit in which a compressor and an evaporator of the low temperature side refrigeration circuit are arranged, and the use Connecting the side unit and the heat source side unit, and having a connection pipe forming a flow path of the low temperature side refrigeration circuit,
The connecting pipe is a triple pipe including an inner pipe, an intermediate pipe, and an outer pipe, and the refrigerant of the low-temperature side refrigeration circuit flows in the inner pipe, and an air layer is formed between the inner pipe and the intermediate pipe. The heat pump system according to any one of claims 1 to 10, wherein the circulating fluid of the circulation circuit flows between a pipe and the outer pipe.   The heat pump system according to claim 11 or 12, wherein the outer pipe is a resin pipe.   The circulation circuit includes a first folded pipe that bypasses the flow path on the use side unit side with respect to the connection pipe, and a second folded pipe that bypasses the flow path on the heat source side unit side with respect to the connection pipe, 14. The device according to claim 11, wherein the first return pipe is connected to the circulation circuit via a three-way valve, and the second return pipe is connected to the circulation circuit via a three-way valve. The heat pump system according to crab. A cascade heat pump system comprising a low temperature side refrigeration circuit, a high temperature side refrigeration circuit, and a cascade heat exchanger for exchanging heat between the high temperature side of the low temperature side refrigeration circuit and the low temperature side of the high temperature side refrigeration circuit,
A circulating circuit for returning the circulating fluid from the high temperature side of the high temperature side refrigeration circuit to the high temperature side of the high temperature side refrigeration circuit via the evaporator of the low temperature side refrigeration circuit; the circulating fluid flowing through the circulation circuit and the high temperature side A circulating fluid-refrigerant heat exchanger that exchanges heat with the high-temperature side refrigerant of the refrigeration circuit
A heat pump comprising a part of the low temperature side refrigeration circuit, a use side unit in which the high temperature side refrigeration circuit and a cascade heat exchanger are arranged, and a heat source side unit in which a compressor and an evaporator of the low temperature side refrigeration circuit are arranged. unit.   The heat pump unit according to claim 15, wherein a plurality of use side units are connected to the one heat source side unit. The circulation circuit is provided for each use side unit and is provided with a unit switching mechanism for switching each branch circuit,
The heat pump unit according to claim 16, wherein the heat pump unit is switched so that the circulating fluid circulates in a circulation circuit arranged in the utilization side unit corresponding to the utilization side unit being used.   The heat pump system according to any one of claims 15 to 17, wherein the circulation circuit has a second circulation circuit passing through a sewage tank.   The heat pump system according to claim 18, further comprising a circuit switching mechanism that switches a circuit through which the circulating fluid circulates between the circulation circuit and the second circulation circuit.   The control apparatus which controls the said circuit switching mechanism with the refrigerant | coolant exit | outlet temperature of the evaporator of the said low temperature side freezing circuit, and switches the circuit through which the said circulating fluid circulates between the said circulation circuit and the said 2nd circulation circuit. The described heat pump system.   The heat pump system according to any one of claims 1 to 20, wherein a circulation pump that circulates a circulating fluid is provided on the circulation circuit, and the circulation pump is a variable capacity type and the flow rate can be adjusted.   The heat pump according to claim 21, wherein the flow rate is variable depending on a refrigerant outlet temperature of an evaporator of the low temperature side refrigeration circuit or a temperature difference between an inflow temperature of a connection pipe forming a flow path of the low temperature side refrigeration circuit and an outside air temperature. system.