Fuel cell cooling unit

Abstract

The fuel cell cooling system can be used in more forms. A fuel cell cooling unit is provided with: a primary refrigerant circulation path through which a refrigerant circulates; a fuel cell cooled by the refrigerant flowing in the primary refrigerant circulation path; and a heat exchanger. The heat exchanger has a primary flow path and a secondary flow path, and the primary flow path constitutes a part of the primary refrigerant circulation path and exchanges heat between the primary flow path and the secondary flow path. The upstream end and the downstream end of the secondary flow path are respectively provided with a connection structure capable of assembling and disassembling piping.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a fuel cell cooling unit. Background Art

[0002] A fuel cell cooling system is known that cools a fuel cell through a radiator. This fuel cell cooling system has a refrigerant circulation path for circulating a refrigerant. The refrigerant cooled by the radiator is supplied to the fuel cell through the refrigerant circulation path, thereby cooling the fuel cell. In order to ensure insulation between the fuel cell and the radiator, a material with low electrical conductivity is used as the refrigerant.

[0003] Japanese Patent Application Publication No. 2022-98553 discloses a fuel cell cooling system in which the refrigerant circulation circuit on the fuel cell side (hereinafter referred to as the primary refrigerant circulation circuit) and the refrigerant circulation circuit on the radiator side (hereinafter referred to as the secondary refrigerant circulation circuit) are independent. A heat exchanger for performing heat exchange between the primary refrigerant circulation circuit and the secondary refrigerant circulation circuit is provided in the fuel cell cooling system. According to this structure, the insulation between the fuel cell and the radiator can be further improved.

[0004] Conventionally, manufacturers provide a fuel cell cooling system that includes a radiator and a fuel cell as a whole. However, in such a provision form, it is difficult to cope with the diversification of the use forms of the fuel cell. In this specification, a technology that can use a fuel cell cooling system in a more diverse form is proposed. Summary of the invention

[0005] The fuel cell cooling unit disclosed in this specification comprises: a primary refrigerant circulation circuit for refrigerant circulation; a fuel cell cooled by the refrigerant flowing in the primary refrigerant circulation circuit; and a heat exchanger. The heat exchanger comprises a primary flow path and a secondary flow path, the primary flow path constitutes a part of the primary refrigerant circulation circuit, and heat exchange is performed between the primary flow path and the secondary flow path. Connection structures capable of loading and unloading pipes are respectively provided at the upstream end and the downstream end of the secondary flow path.

[0006] In the fuel cell cooling unit, the user can use the fuel cell cooling unit by connecting the secondary refrigerant circulation circuit (i.e., the refrigerant circulation circuit on the radiator side) to the secondary flow path. That is, in this structure, the user can prepare the secondary refrigerant circulation circuit. The primary flow path constituting the primary refrigerant circulation circuit and the secondary flow path constituting the secondary refrigerant circulation circuit are independent, so insulation is ensured between the primary refrigerant circulation circuit and the secondary refrigerant circulation circuit. Therefore, the user can connect the secondary refrigerant circulation circuit to the fuel cell cooling unit without considering the insulation of the secondary refrigerant circulation circuit. In addition, since the primary flow path and the secondary flow path are independent, the pressure distribution in the secondary refrigerant circulation circuit will not affect the pressure distribution in the primary refrigerant circulation circuit. Therefore, the user can connect the secondary refrigerant circulation circuit to the fuel cell cooling unit without considering the pressure distribution in the primary refrigerant circulation circuit. In this way, the user can set the secondary refrigerant circulation circuit without being restricted by insulation and the pressure distribution in the primary refrigerant circulation circuit. Therefore, according to the fuel cell cooling unit, a fuel cell cooling system can be constructed in various forms.

[0007] In addition, in this specification, a fuel cell cooling system that is easy to manage the conductivity of the refrigerant is proposed. The second fuel cell cooling system has: a primary refrigerant circulation circuit for refrigerant circulation; a fuel cell that is cooled by the refrigerant flowing in the above-mentioned primary refrigerant circulation circuit; a secondary refrigerant circulation circuit for refrigerant circulation; a radiator that cools the refrigerant flowing in the above-mentioned secondary refrigerant circulation circuit; and a heat exchanger. The above-mentioned heat exchanger has a primary flow path and a secondary flow path, the above-mentioned primary flow path constitutes a part of the above-mentioned primary refrigerant circulation circuit, and the above-mentioned secondary flow path constitutes a part of the above-mentioned secondary refrigerant circulation circuit, and heat exchange is performed between the above-mentioned primary flow path and the above-mentioned secondary flow path. The conductivity of the above-mentioned refrigerant in the above-mentioned secondary refrigerant circulation circuit is higher than the conductivity of the above-mentioned refrigerant in the above-mentioned primary refrigerant circulation circuit.

[0008] In the fuel cell cooling system, since the primary refrigerant circulation circuit and the secondary refrigerant circulation circuit are independent, and the conductivity of the refrigerant in the primary refrigerant circulation circuit is low, the insulation between the fuel cell and the secondary refrigerant circulation circuit is ensured. Therefore, even if the conductivity of the refrigerant in the secondary refrigerant circulation circuit is high, the insulation between the radiator and the fuel cell can be ensured. In addition, even if the conductivity of the refrigerant in the secondary refrigerant circulation circuit is high, there is no problem, so there is no need for a process to reduce the conductivity of the refrigerant in the secondary refrigerant circulation circuit (for example, a process to remove ions from the refrigerant). Therefore, in the fuel cell cooling system, it is easy to manage the conductivity of the refrigerant. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1is a structural diagram of the fuel cell cooling system 100 .

[0010] Figure 2 1 is a diagram showing the connection between the pump 50 and the heat exchanger 30 .

[0011] Figure 3 It is a structural diagram of a fuel cell cooling system according to a modified example. DETAILED DESCRIPTION

[0012] The fuel cell cooling unit or fuel cell cooling system may also include: a parallel flow path connected in parallel with the portion of the primary refrigerant circulation path that passes through the fuel cell, i.e., the fuel cell flow path; and an ion exchanger that removes ions from the refrigerant in the parallel flow path. It may also be configured such that when the refrigerant circulates in the primary refrigerant circulation path, the refrigerant always flows to the fuel cell flow path and the parallel flow path.

[0013] According to this configuration, it is possible to prevent an increase in the electrical conductivity of the refrigerant in the primary refrigerant circulation path.

[0014] The fuel cell cooling unit or fuel cell cooling system may further include a pump for circulating the refrigerant in the primary refrigerant circulation path. The discharge port of the pump may be connected to the upstream end of the primary flow path by a flange connection.

[0015] According to this structure, the connection strength at the discharge port of the pump is improved, so the discharge pressure of the pump can be increased.

[0016] The above-mentioned fuel cell cooling unit or fuel cell cooling system may also further include: a bypass flow path connecting the upstream and downstream parts of the above-mentioned secondary flow path relative to the above-mentioned heat exchanger; and an intercooler, which is arranged in the above-mentioned bypass flow path and cools the air supplied to the above-mentioned fuel cell.

[0017] According to this configuration, it is possible to prevent ions from eluting from the intercooler into the refrigerant in the primary refrigerant circulation path.

[0018] Figure 1 The fuel cell cooling unit 10 shown is assembled in a fuel cell cooling system 100. The fuel cell cooling unit 10 has a fuel cell 20. The fuel cell cooling system 100 is mounted on an electric vehicle. Hydrogen is supplied to the fuel cell 20 from a tank not shown, and compressed air is supplied to the fuel cell 20 from a compressor not shown. The fuel cell 20 generates electricity by reacting hydrogen with oxygen in the compressed air, and supplies the generated electricity to a driving motor of the electric vehicle.

[0019] The fuel cell cooling unit 10 is a product configured to be circulated. The parts other than the fuel cell cooling unit 10 in the fuel cell cooling system 100 (ie, the radiator 110 , the pipes 122 , 124 , etc.) are connected to the fuel cell cooling unit 10 from the rear.

[0020] The fuel cell cooling unit 10 has a heat exchanger 30 and a primary refrigerant circulation path 40. The heat exchanger 30 has a primary flow path 31 and a secondary flow path 32. The heat exchanger 30 performs heat exchange between the primary flow path 31 and the secondary flow path 32. The primary refrigerant circulation path 40 is an annular flow path for refrigerant to circulate inside. The primary refrigerant circulation path 40 is composed of the primary flow path 31 of the heat exchanger 30, the piping 42, the fuel cell flow path 22 provided inside the fuel cell 20, and the piping 44. The piping 42 connects the downstream end of the primary flow path 31 with the upstream end of the fuel cell flow path 22. The piping 44 connects the downstream end of the fuel cell flow path 22 with the upstream end of the primary flow path 31. A pump 50 is provided between the piping 44 and the primary flow path 31. The pump 50 sends the refrigerant from the piping 44 toward the primary flow path 31. When the pump 50 is operated, the refrigerant sequentially flows into the primary flow path 31 , the pipe 42 , the fuel cell flow path 22 , and the pipe 44 . That is, the refrigerant circulates in the primary refrigerant circulation path 40 .

[0021] Figure 2 FIG. 4 shows the connection between the pump 50 and the heat exchanger 30 (i.e., the upstream end of the primary flow path 31). Figure 2 As shown, the discharge port 50a of the pump 50 is connected to the upstream end of the primary flow path 31 through a flange connection. In addition, although not shown, a gasket is arranged on the sealing surface between the pump 50 and the heat exchanger 30 to prevent leakage of the refrigerant. Generally, the discharge port of the pump is connected to the heat exchanger via a rubber tube. In this case, since the pressure resistance of the rubber tube is low, the discharge pressure of the pump is limited. In contrast, if Figure 2 In this way, the discharge port 50a of the pump 50 is connected to the heat exchanger 30 (i.e., the primary flow path 31) by flange connection, and the strength of the connection portion is high, so the discharge pressure of the pump 50 can be increased. By increasing the discharge pressure of the pump 50, the suction side pressure of the pump 50 also becomes higher, which can suppress the generation of cavitation and the compression of the pipe 44 (e.g., rubber tube) due to negative pressure. In this way, by using flange connection, the pressure range in which the pump 50 can operate can be expanded.

[0022] The frame of the vehicle body of the electric vehicle is used as an electrical grounding point. The housing of the heat exchanger 30 and the housing of the pump 50 are connected to the frame of the electric vehicle via a grounding wire (i.e., grounded). On the other hand, the fuel cell 20 is a power source and is therefore insulated from the frame of the electric vehicle. Therefore, the fuel cell 20 needs to be insulated from the heat exchanger 30 and the pump 50. In the fuel cell cooling unit 10, the pipes 42 and 44 are composed of insulating components (e.g., rubber tubes). In addition, in the fuel cell cooling unit 10, the conductivity of the refrigerant flowing in the primary refrigerant circulation path 40 is low. Therefore, the fuel cell 20 is insulated from the heat exchanger 30 and the pump 50.

[0023] like Figure 1 As shown, the fuel cell cooling unit 10 has a parallel flow path 62 and an ion exchanger 60. The parallel flow path 62 is connected to the primary refrigerant circulation path 40 at each position on the upstream side and the downstream side of the heat exchanger 30. The parallel flow path 62 is connected in parallel with respect to the fuel cell flow path 22. The ion exchanger 60 is arranged in the parallel flow path 62. No valve is arranged in the parallel flow path 62. Therefore, when the pump 50 is working and the refrigerant circulates in the primary refrigerant circulation path 40, the refrigerant always flows to the fuel cell flow path 22 and the parallel flow path 62. The ion exchanger 60 removes ions from the refrigerant flowing in the parallel flow path 62. In the refrigerant in the primary refrigerant circulation path 40, ions are dissolved from each component (i.e., piping, etc.) constituting the primary refrigerant circulation path 40. The ion exchanger 60 suppresses the increase of the ion concentration in the refrigerant by removing ions from the refrigerant. This suppresses an increase in the electrical conductivity of the refrigerant in the primary refrigerant circulation path 40 , and maintains insulation of the fuel cell 20 with respect to the heat exchanger 30 and the pump 50 .

[0024] The fuel cell cooling unit 10 includes a storage tank 70. The storage tank 70 is connected to the primary refrigerant circulation path 40 at each position on the upstream side and the downstream side of the heat exchanger 30. The storage tank 70 stores the excess refrigerant in the primary refrigerant circulation path 40.

[0025] The portion of the secondary flow path 32 of the heat exchanger 30 that is on the upstream side of the heat exchanger 30 is formed by the pipe 32a. The portion of the secondary flow path 32 of the heat exchanger 30 that is on the downstream side of the heat exchanger 30 is formed by the pipe 32b. The pipes 32a and 32b are formed of a rigid body such as resin. The fuel cell cooling unit 10 has a bypass flow path 82 and an intercooler 80. The bypass flow path 82 connects the pipe 32a with the pipe 32b. The intercooler 80 cools the compressed air supplied to the fuel cell 20 by heat exchange with the refrigerant flowing in the bypass flow path 82. A connection structure capable of loading and unloading external pipes is provided in the pipe 32a. A connection structure capable of loading and unloading external pipes is provided in the pipe 32b. As these connection structures, a bolt-type connection structure and a connector-type connection structure can be adopted. In addition, the bolt-type connection structure is a structure in which pipes are connected to each other by tightening with bolts. The connector type connection structure is a connection structure that can switch between a state where the pipes are engaged with each other and a state where they are not engaged by moving a movable member. A pump 150 described later is detachably connected to the pipe 32a. A pipe 122 described later is detachably connected to the pipe 32b.

[0026] The fuel cell cooling system 100 includes a radiator 110, pipes 122, 124, and a pump 150 in addition to the fuel cell cooling unit 10. The upstream end of the pipe 122 is connected to the downstream end of the secondary flow path 32 of the heat exchanger 30 (i.e., the connection structure provided in the pipe 32b). The downstream end of the pipe 122 is connected to the upstream end of the refrigerant flow path (hereinafter referred to as the radiator flow path) provided inside the radiator 110. The downstream end of the radiator flow path is connected to the upstream end of the pipe 124. The downstream end of the pipe 124 is connected to the suction port of the pump 150. The discharge port of the pump 150 is connected to the upstream end of the secondary flow path 32 of the heat exchanger 30 (i.e., the connection structure provided in the pipe 32a). The secondary refrigerant circulation path 140 is formed by the radiator flow path, the pipes 122, 124, the pump 150, and the secondary flow path 32. The secondary refrigerant circulation path 140 is an annular flow path for the refrigerant to circulate inside. The conductivity of the refrigerant in the secondary refrigerant circulation path 140 is higher than the conductivity of the refrigerant in the primary refrigerant circulation path 40. The pump 150 sends the refrigerant from the piping 124 toward the secondary flow path 32. If the pump 150 is working, the refrigerant flows to the secondary flow path 32, the piping 122, the radiator flow path, and the piping 124 in sequence. That is, the refrigerant circulates in the secondary refrigerant circulation path 140. In addition, if the refrigerant circulates in the secondary refrigerant circulation path 140, the refrigerant also flows into the bypass flow path 82, and the intercooler 80 can operate.

[0027] The fuel cell cooling system 100 includes a storage tank 170. The storage tank 170 is connected to the secondary refrigerant circulation path 140 at each position on the upstream side and the downstream side of the heat exchanger 30. The storage tank 170 stores the excess refrigerant in the secondary refrigerant circulation path 140.

[0028] The air conditioning circuit 200 is connected to the pipe 122. The air conditioning circuit 200 includes an air conditioning refrigerant circulation path 210, a pump 220, a water heater 230, a heater core 240, a valve 250, and the like. When the valve 250 is opened, the refrigerant flows between the secondary refrigerant circulation path 140 and the air conditioning refrigerant circulation path 210. The air conditioning circuit 200 adjusts the temperature in the cabin of the electric vehicle by heat exchange with the refrigerant in the air conditioning refrigerant circulation path 210.

[0029] When the electric vehicle is in use, the fuel cell cooling system 100 is in operation. When the fuel cell cooling system 100 is in operation, the pump 150 circulates the refrigerant in the secondary refrigerant circulation path 140, and the pump 50 circulates the refrigerant in the primary refrigerant circulation path 40. The radiator 110 cools the refrigerant circulating in the secondary refrigerant circulation path 140. Therefore, the refrigerant cooled by the radiator 110 flows to the secondary flow path 32 of the heat exchanger 30. The heat exchanger 30 cools the refrigerant in the primary flow path 31 by heat exchange between the refrigerant in the secondary flow path 32 and the refrigerant in the primary flow path 31. Therefore, the refrigerant cooled by the heat exchanger 30 flows to the fuel cell flow path 22 of the fuel cell 20. Thus, the fuel cell 20 is cooled.

[0030] The conductivity of the refrigerant in the primary refrigerant circulation circuit 40 is lower than the conductivity of the refrigerant in the secondary refrigerant circulation circuit 140. In addition, an ion exchanger 60 is provided in the primary refrigerant circulation circuit 40 via a parallel flow path 62. As described above, when the refrigerant circulates in the primary refrigerant circulation circuit 40, the refrigerant also always flows to the parallel flow path 62, and the ions in the refrigerant are removed by the ion exchanger 60. Therefore, the increase in the conductivity of the refrigerant in the primary refrigerant circulation circuit 40 is suppressed. Therefore, a higher insulation is ensured between the fuel cell 20 and the heat exchanger 30 (i.e., the grounding point). On the other hand, since an ion exchanger is not provided in the secondary refrigerant circulation circuit 140, the conductivity of the refrigerant in the secondary refrigerant circulation circuit 140 is higher. Therefore, the insulation resistance between the radiator 110 and the heat exchanger 30 is lower. However, since the heat exchanger 30 is insulated from the fuel cell 20, the insulation between the radiator 110 and the fuel cell 20 is ensured.

[0031] By dividing the refrigerant circulation path into the primary refrigerant circulation path 40 and the secondary refrigerant circulation path 140 and making the conductivity of the refrigerant in the secondary refrigerant circulation path 140 higher than the conductivity of the refrigerant in the primary refrigerant circulation path 40 , the following advantages can be obtained.

[0032] The first advantage is that the ion concentration in the refrigerant in the primary refrigerant circulation path 40 is not easy to increase. When the radiator and the fuel cell are connected by one refrigerant circulation path, the refrigerant circulation path becomes longer. In contrast, when the primary refrigerant circulation path 40 and the secondary refrigerant circulation path 140 are independently provided, the primary refrigerant circulation path 40 and the secondary refrigerant circulation path 140 are respectively shortened. By shortening the primary refrigerant circulation path 40, the amount of ions dissolved from the components of the primary refrigerant circulation path 40 (i.e., piping, etc.) into the refrigerant is reduced. Generally speaking, the component that easily causes ions to dissolve into the refrigerant is the radiator. In the fuel cell cooling system 100, the radiator 110 is separated from the primary refrigerant circulation path 40, so that ions do not dissolve from the radiator 110 into the refrigerant in the primary refrigerant circulation path 40. Furthermore, in the fuel cell cooling system 100, the intercooler 80 and the air conditioning circuit 200 are also separated from the primary refrigerant circulation path 40, so that ions are not eluted from the intercooler 80 and the air conditioning circuit 200 into the refrigerant in the primary refrigerant circulation path 40. Therefore, the ion concentration is not easy to increase in the refrigerant in the primary refrigerant circulation path 40. Therefore, the amount of ions removed in the ion exchanger 60 is also reduced, and the ion exchanger 60 can be miniaturized.

[0033] The second advantage is the reduction in component costs. In the fuel cell cooling system 100, insulation is ensured between the fuel cell 20 and the heat exchanger 30, so there is no need to ensure insulation between the radiator 110 and the heat exchanger 30. Therefore, a refrigerant with a higher conductivity can be used as the refrigerant in the secondary refrigerant circulation path 140. In addition, there is no need to manage the conductivity of the refrigerant in the secondary refrigerant circulation path 140, so the material of the components (i.e., piping, etc.) of the secondary refrigerant circulation path 140 can be selected without considering the dissolution of ions. In this way, the range of choices for the refrigerant and components of the secondary refrigerant circulation path 140 is expanded, so inexpensive components can be used.

[0034] The third advantage is the reduction in cleaning costs. When using a refrigerant with low conductivity, it is necessary to clean the inside of the pipes before the vehicle leaves the factory. This is to suppress the dissolution of ions into the refrigerant. In the fuel cell cooling system 100, the circuit using the refrigerant with low conductivity is only the primary refrigerant circulation path 40, so there is no need to clean the inside of the secondary refrigerant circulation path 140. Since the primary refrigerant circulation path 40 is shorter and the radiator 110, intercooler 80, air conditioning circuit 200, etc. are not connected to the primary refrigerant circulation path 40, the primary refrigerant circulation path 40 can be easily cleaned. Therefore, the cost required for cleaning before leaving the factory can be reduced.

[0035] Next, the advantages of the fuel cell cooling unit 10 will be described. As described above, the fuel cell cooling system 100 is manufactured by adding the radiator 110, the piping 122, 124, etc. to the fuel cell cooling unit 10 configured to be able to circulate. That is, the fuel cell cooling unit 10 is designed by the manufacturer of the fuel cell cooling unit 10, and the secondary refrigerant circulation path 140 is designed by the user of the fuel cell cooling unit 10 (that is, the manufacturer of the electric vehicle). In the fuel cell cooling unit 10, insulation is ensured between the fuel cell 20 and the heat exchanger 30, so the manufacturer of the electric vehicle can design the secondary refrigerant circulation path 140 without considering insulation. In addition, the secondary flow path 32 of the heat exchanger 30 is separated from the primary refrigerant circulation path 40, so the manufacturer of the electric vehicle can design the secondary refrigerant circulation path 140 without considering the influence of the pressure of the primary refrigerant circulation path 40 from the secondary refrigerant circulation path 140. In this way, by using the fuel cell cooling unit 10, various designs can be made as the secondary refrigerant circulation path 140. That is, by using the fuel cell cooling unit 10 , the fuel cell can be used in various forms.

[0036] In addition, in the above-mentioned embodiment, the intercooler 80 is provided on the secondary refrigerant circulation path 140 side, so in order to control the cooling of the fuel cell 20 and the intercooler 80, the pump 50 and the pump 150 need to be coordinated and controlled. Figure 3 The intercooler 80 is shown to be provided on the side of the primary refrigerant circulation path 40. According to this structure, the cooling of the fuel cell 20 and the intercooler 80 can be controlled only by controlling the pump 50.

[0037] Furthermore, in the above-mentioned embodiment, a fuel cell cooling system mounted on an electric vehicle is described, but the technology disclosed in this specification can also be applied to a fuel cell cooling system used in applications other than electric vehicles.

[0038] The above detailed description of the implementation methods is provided, but these are merely examples and do not limit the claims. The technology described in the claims includes various modifications and changes to the specific examples exemplified above. The technical elements described in this specification or the drawings exert technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of application. In addition, the technology exemplified in this specification or the drawings achieves multiple purposes at the same time, and achieving one of the purposes itself has technical usefulness.

Claims

1. A fuel cell cooling unit, wherein: The fuel cell cooling unit comprises: A primary refrigerant circulation circuit for refrigerant circulation; a fuel cell cooled by the refrigerant flowing in the primary refrigerant circulation path; and A heat exchanger having a primary flow path and a secondary flow path, and heat exchange is performed between the primary flow path and the secondary flow path, wherein the primary flow path constitutes a part of the primary refrigerant circulation path, A connection structure that enables detachable pipes is provided at the upstream end and the downstream end of the secondary flow path.

2. The fuel cell cooling unit according to claim 1, wherein: The fuel cell cooling unit also has: a parallel flow path connected in parallel with a fuel cell flow path, which is a portion of the primary refrigerant circulation path passing through the fuel cell; and an ion exchanger to remove ions from the refrigerant in the parallel flow path, When the refrigerant circulates in the primary refrigerant circulation path, the refrigerant always flows into the fuel cell flow path and the parallel flow path.

3. The fuel cell cooling unit according to claim 1 or 2, wherein: further comprising a pump for circulating the refrigerant in the primary refrigerant circulation path, The discharge port of the pump is connected to the upstream end of the primary flow path through a flange connection.

4. The fuel cell cooling unit according to claim 1 or 2, wherein: The fuel cell cooling unit also has: a bypass flow path connecting an upstream portion and a downstream portion of the secondary flow path relative to the heat exchanger; and The intercooler is provided in the bypass flow path and cools the air supplied to the fuel cell.

5. A fuel cell cooling system, wherein: The fuel cell cooling system comprises: A primary refrigerant circulation circuit for refrigerant circulation; a fuel cell cooled by the refrigerant flowing in the primary refrigerant circulation path; A secondary refrigerant circulation circuit for refrigerant circulation; a radiator for cooling the refrigerant flowing in the secondary refrigerant circulation path; as well as A heat exchanger having a primary flow path and a secondary flow path, and heat exchange is performed between the primary flow path and the secondary flow path, wherein the primary flow path constitutes a part of the primary refrigerant circulation path, and the secondary flow path constitutes a part of the secondary refrigerant circulation path, The electrical conductivity of the refrigerant in the secondary refrigerant circulation path is higher than the electrical conductivity of the refrigerant in the primary refrigerant circulation path.

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