Cooling systems and fuel cell systems

Abstract

The present invention provides a cooling system and a fuel cell system that can suppress the increase in ions in the refrigerant while suppressing the deterioration of the antifreeze's performance. [Solution] The cooling system 60 cools the fuel cell 10 using a refrigerant containing antifreeze. The cooling system 60 comprises a refrigerant circulation circuit 61 through which the refrigerant circulates, and an ion exchanger 70 that adsorbs ions in the refrigerant flowing through the refrigerant circulation circuit 61. The ion exchanger 70 has a cation adsorption section 71 containing a cation exchange resin 710 that adsorbs cations, and an anion adsorption section 72 containing an anion exchange resin 720 that adsorbs anions. When the amount of ion reduction per unit time in the ion exchanger 70 relative to the total amount of ions in the refrigerant circulation circuit 61 is defined as the ion removal rate, the ion exchanger 70 is configured such that the ion removal rate for anions is smaller than the ion removal rate for cations.

Description

Technical Field

[0001] The present disclosure relates to a cooling system for cooling a fuel cell using a refrigerant containing an antifreeze, and a fuel cell system including the cooling system.

Background Art

[0002] Conventionally, there is known a refrigerant circulation circuit for a refrigerant that cools a fuel cell, in which an ion exchanger is provided (see, for example, Patent Document 1). This Patent Document 1 includes an ion exchange resin capable of removing impurities such as metal ions eluted from materials such as fuel cells.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, when an antifreeze is contained in the refrigerant, an organic acid that becomes an anion is generated by oxidation of the antifreeze. Therefore, the ion exchanger may be configured to include a cation exchange resin that adsorbs cations and an anion exchange resin that adsorbs anions. When an anion is adsorbed by the anion exchange resin, the concentration of the organic acid in the refrigerant decreases. However, according to the study by the present inventors, it has been found that the oxidation deterioration rate of the antifreeze tends to increase as the concentration of the organic acid in the antifreeze in the refrigerant decreases. An increase in the oxidation deterioration rate of the antifreeze is not desirable because it causes a deterioration in the performance of the antifreeze.

[0005] An object of the present disclosure is to provide a cooling system and a fuel cell system capable of suppressing an increase in ions in the refrigerant while suppressing a decrease in the performance of the antifreeze.

Means for Solving the Problems

[0006] The invention described in claim 1 is, A cooling system for cooling a fuel cell (10) using a refrigerant containing antifreeze, A refrigerant circulation circuit (61) through which the refrigerant circulates, The system includes an ion exchanger (70) that adsorbs ions in the refrigerant flowing through the refrigerant circulation circuit, The ion exchanger has a cation adsorption section (71) containing a cation exchange resin (710) that adsorbs cations and an anion adsorption section (72) containing an anion exchange resin (720) that adsorbs anions. When the ion removal rate is defined as the reduction in the amount of ions per unit time in the ion exchanger relative to the total amount of ions in the refrigerant circulation circuit, At least one of the refrigerant circulation circuit and the ion exchanger is configured such that the ion removal rate of anions is lower than the ion removal rate of cations.

[0007] Furthermore, the invention described in claim 6 is, A fuel cell system, A cooling system (60) according to any one of claims 1 to 5, It is equipped with a fuel cell.

[0008] According to these findings, the increase in ions in the refrigerant can be suppressed by adsorbing cations in the refrigerant with the cation exchange resin in the cation adsorption section and adsorbing anions containing organic acids in the antifreeze with the anion exchange resin in the anion adsorption section. In particular, the system of this disclosure is configured such that the ion removal rate is lower for anions than for cations. As a result, the decrease in the concentration of organic acids in the antifreeze due to the adsorption of anions in the anion adsorption section is suppressed, and the rate of oxidative degradation of the antifreeze is suppressed. Therefore, according to the system of this disclosure, the increase in ions in the refrigerant can be suppressed while suppressing the deterioration of the antifreeze's performance.

[0009] Note that the reference numerals in parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of Drawings

[0010] [Figure 1] It is a schematic configuration diagram of a fuel cell system including a cooling system according to the first embodiment. [Figure 2] It is an explanatory diagram for explaining an organic acid generated by oxidation of antifreeze. [Figure 3] It is an explanatory diagram for explaining the time change of the anion concentration in the refrigerant. [Figure 4] It is an explanatory diagram for explaining the anion concentration in the refrigerant and the oxidation degradation rate of the antifreeze. [Figure 5] It is a schematic configuration diagram of the cooling system according to the first embodiment. [Figure 6] It is an explanatory diagram for explaining the supply amount of the refrigerant to each ion adsorption part. [Figure 7] It is an explanatory diagram for explaining the ion removal rate in each ion adsorption part. [Figure 8] It is a schematic configuration diagram of the cooling system according to the second embodiment. [Figure 9] It is an explanatory diagram for explaining the pressure loss of each refrigerant pipe part. [Figure 10] It is a schematic configuration diagram of the cooling system according to the third embodiment. [Figure 11] It is an explanatory diagram for explaining the ion adsorption performance in each ion adsorption part. [Figure 12] It is a schematic configuration diagram of the cooling system according to the fourth embodiment. [Figure 13] It is an explanatory diagram for explaining the temperature of the refrigerant supplied to each ion adsorption part. [Figure 14] It is a schematic configuration diagram of the cooling system according to the fifth embodiment. [Figure 15] It is a schematic configuration diagram of the cooling system according to the seventh embodiment.

Modes for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to those described in the preceding embodiments may be denoted by the same reference numerals, and the description thereof may be omitted. Further, in the embodiments, when only a part of the components is described, the components described in the preceding embodiments can be applied to the other parts of the components. The following embodiments can be partially combined with each other as long as there is no problem in the combination, even if not specifically stated.

[0012] (First Embodiment) This embodiment will be described with reference to FIGS. 1 to 7. In this embodiment, an example in which the fuel cell system 1 of the present disclosure is applied to large commercial mobility called HDV will be described. Examples of HDV include large trucks, railways, ships, construction machinery, agricultural machinery, industrial machinery, etc. Note that HDV is an abbreviation for Heavy Duty Vehicle.

[0013] The fuel cell system 1 includes a fuel cell 10 that generates electric power by utilizing an electrochemical reaction between hydrogen and oxygen as reaction gases. The fuel cell 10 outputs electric power to a power conversion device such as an inverter (not shown). The power conversion device supplies the electric power from the fuel cell 10 to load devices such as motors and batteries.

[0014] The fuel cell 10 is configured as a cell stack CS in which a plurality of cells as the minimum unit are stacked. The cell is composed of a solid polymer type cell (so-called PEFC) including an electrolyte membrane, a catalyst, a gas diffusion layer, and a separator. When hydrogen is supplied to the anode side and air is supplied to the cathode side of the cell, the cell outputs electric energy to an external circuit by an electrochemical reaction represented by the following reaction formulas F1 and F2. ·Anode: H2 → 2H + + 2e - ···(F1) ·Cathode: 2H+ +1 / 2O2+2e - →H2O ···(F2) The fuel cell 10 is connected to an air supply path 20, which is a path for supplying air to the fuel cell 10, and an air discharge path 30, which directs the off-gas (i.e., off-air) of air discharged from the fuel cell 10 to a muffler (not shown). An air pump 21 is provided in the air supply path 20. An air control valve 31 is provided in the air discharge path 30 to adjust the air pressure inside the fuel cell 10. In addition, a humidifier 22 is provided in both the air supply path 20 and the air discharge path 30 to humidify the air supplied to the fuel cell 10 with generated water contained in the off-air. The air pump 21 and the air control valve 31 are controlled based on control signals from a control device 100, which will be described later.

[0015] Furthermore, the fuel cell 10 is connected to a hydrogen supply path 40, which is a hydrogen supply path to the fuel cell 10, and a hydrogen discharge path 50, which directs the off-gas (i.e., off-fuel) of hydrogen discharged from the fuel cell 10 to a muffler (not shown). The hydrogen supply path 40 is equipped with a hydrogen tank 41 and a fuel control valve 42. The hydrogen discharge path 50 is equipped with an exhaust valve 51 for exhausting the off-fuel that has passed through the fuel cell 10. The hydrogen supply path 40 and the hydrogen discharge path 50 are connected via a recirculation path 43, so that a portion of the off-fuel flowing through the hydrogen discharge path 50 is returned to the hydrogen supply path 40 by a recycle pump 44. The fuel control valve 42, the recycle pump 44, and the exhaust valve 51 are controlled based on control signals from a control device 100, which will be described later. Although not shown, the hydrogen discharge path 50 downstream of the exhaust valve 51 is connected to an air discharge path 30. As a result, the off-fuel flowing through the hydrogen discharge path 50 is diluted by mixing with off-air before being exhausted from the muffler.

[0016] Incidentally, due to the high operating load and the limitations of cooling performance imposed by mounting space constraints, HDVs require the fuel cell 10 to operate in a medium temperature range (e.g., between 100°C and 150°C) that is even higher than the conventional operating range (e.g., below 100°C). Furthermore, operation in the medium temperature range is not limited to HDVs; it is sometimes required in small cars and passenger vehicles, known as LCVs, from the perspective of improving output and durability. LCV is an abbreviation for Light Commercial Vehicle.

[0017] Therefore, the fuel cell system 1 of this embodiment includes a cooling system 60 for adjusting the temperature of the fuel cell 10 to a medium temperature range. The cooling system 60 is a system that cools the fuel cell 10 using a refrigerant containing antifreeze.

[0018] The refrigerant used is a mixture of coolant and antifreeze. The low-temperature resistance of the refrigerant is adjusted by the concentration of the antifreeze. In this example, the antifreeze mainly contains ethylene glycol.

[0019] The cooling system 60 includes a refrigerant circulation circuit 61 through which the refrigerant circulates. The refrigerant circulation circuit 61 is connected to a refrigerant path 11 located inside the fuel cell 10. The refrigerant circulation circuit 61 is equipped with a circulation pump 62, a heat sink 63, a first bypass section 64, a flow path switching valve 65, a second bypass section 66, and an ion exchanger 70.

[0020] The circulation pump 62 is an electric pump that operates in response to a control signal from the control device 100. The heat exchanger 63 is an air-cooled heat exchanger that dissipates heat from the refrigerant flowing through the refrigerant circulation circuit 61 to the air blown in by the blower fan 63a.

[0021] The first bypass section 64 is a flow path that bypasses the radiator 63 for the refrigerant flowing through the refrigerant circulation circuit 61, and is composed of, for example, piping. The flow path switching valve 65 adjusts the ratio of the flow rate of refrigerant flowing into the radiator 63 to the flow rate of refrigerant flowing into the first bypass section 64, and is composed of, for example, an electrically operated three-way valve. The flow path switching valve 65 is provided at the connection point between the first bypass section 64 and the refrigerant inlet side of the radiator 63 in the refrigerant circulation circuit 61. Alternatively, the flow path switching valve 65 may be provided at the connection point between the first bypass section 64 and the refrigerant outlet side of the radiator 63 in the refrigerant circulation circuit 61.

[0022] The second bypass section 66 is a flow path that directs a portion of the refrigerant flowing through the refrigerant circulation circuit 61 to the ion exchanger 70, and is composed of, for example, piping. One end of the second bypass section 66 is connected to the flow path between the refrigerant outlet of the circulation pump 62 and the refrigerant inlet of the fuel cell 10, and the other end is connected to the flow path between the refrigerant outlet of the fuel cell 10 and the flow path switching valve 65. The pressure loss of the second bypass section 66 is higher than that of the radiator 63 and the first bypass section 54 so that a portion of the refrigerant flowing through the refrigerant circulation circuit 61 flows through it. In this embodiment, the second bypass section 66 is a flow path that bypasses the fuel cell 10 and directs the refrigerant to flow through it. The flow rate of the refrigerant flowing through the second bypass section 66 may be adjusted by a flow control valve.

[0023] The ion exchanger 70 adsorbs ions in the refrigerant flowing through the refrigerant circulation circuit 61. The ion exchanger 70 is located in the second bypass section 66 in parallel with the fuel cell 10. The ion exchanger 70 includes a cation adsorption section 71 and an anion adsorption section 72. The cation adsorption section 71 has a cation exchange resin 710 that adsorbs metal ions eluted from materials such as the separator of the fuel cell 10. The anion adsorption section 72 has an anion exchange resin 720 that adsorbs anions containing organic acids generated by oxidation of the antifreeze, etc. The cation adsorption section 71 and the anion adsorption section 72 may be housed in the same case and constitute a single component, or they may be separated into different components.

[0024] Here, when ethylene glycol contained in the antifreeze is oxidized, it decomposes into anions such as glycolic acid with a hydroxyl group and formic acid with a carboxyl group, as shown in Figure 2. The oxidation of ethylene glycol progresses over time. Therefore, if anions are not adsorbed by the anion adsorption section 72, the concentration of anions in the refrigerant will increase over time, as shown in Figure 3. Note that the values ​​shown on the vertical axis in Figure 3 are just examples, and other values ​​may also be used.

[0025] Furthermore, antifreeze oxidizes more easily at higher refrigerant temperatures. Therefore, antifreeze oxidizes more easily when the fuel cell 10 is operated in a medium temperature range compared to when it is operated in a low temperature range below 100°C. Also, the rate of oxidation degradation of antifreeze tends to increase as the concentration of anions in the refrigerant decreases, as shown in Figure 4. A high rate of oxidation degradation of antifreeze is undesirable because it leads to a decrease in antifreeze performance. The rate of oxidation degradation can be calculated using the formula shown in the lower part of Figure 4. Note that the values ​​shown on the vertical axis in Figure 4 are examples, and other values ​​may also be used.

[0026] Based on these considerations, the cooling system 60 is configured such that the ion removal rate of anions is lower than the ion removal rate of cations. In this disclosure, "ion removal rate" is the ratio of the amount of ions reduced per unit time in the ion exchanger 70 to the total amount of ions in the refrigerant circulation circuit 61. Note that "ion removal rate" in this disclosure is different from the rate of ion reduction when the refrigerant passes through the ion exchanger 70.

[0027] Specifically, as shown in Figure 5, the ion exchanger 70 includes a first refrigerant pipe section 73 connected to the cation adsorption section 71 and a second refrigerant pipe section 74 connected to the anion adsorption section 72. The first refrigerant pipe section 73 and the second refrigerant pipe section 74 are connected at both ends such that the cation adsorption section 71 and the anion adsorption section 72 are in parallel.

[0028] Furthermore, the ion exchanger 70 is provided with a supply adjustment valve 75 for adjusting the ratio of the amount of refrigerant supplied to the cation adsorption section 71 and the amount of refrigerant supplied to the anion adsorption section 72. The supply adjustment valve 75 is provided at the connection point on the upstream side of the refrigerant flow between the first refrigerant pipe section 73 and the second refrigerant pipe section 74. Alternatively, the supply adjustment valve 75 may be provided at the connection point on the downstream side of the refrigerant flow between the first refrigerant pipe section 73 and the second refrigerant pipe section 74.

[0029] The supply amount control valve 75 is composed of an electrically operated three-way valve, and its operation is controlled according to a control signal from the control device 100, which will be described later. In this embodiment, the supply amount control valve 75 constitutes the “flow rate control valve” of this disclosure. Furthermore, in this embodiment, the supply amount control valve 75 and the control device 100 constitute an “adjustment unit” for adjusting the amount of refrigerant supplied to the cation adsorption unit 71 and the amount of refrigerant supplied to the anion adsorption unit 72.

[0030] In this embodiment, the cooling system 60 is controlled by the control device 100 such that the ion removal rate of anions is lower than the ion removal rate of cations. Specifically, the supply amount control valve 75 is controlled so that the amount of refrigerant supplied to the cation adsorption section 71 per unit time is greater than the amount of refrigerant supplied to the anion adsorption section 72 per unit time, so that the ion removal rate of anions is lower than the ion removal rate of cations. The control process of the supply amount control valve 75 by the control device 100 will be described later.

[0031] Next, the control device 100, which constitutes the electronic control unit of the fuel cell system 1, will be described. This control device 100 functions as the electronic control unit of the cooling system 60. The control device 100 consists of a computer including a processor and memory, and its peripheral devices. The memory of the control device 100 is a non-transitional tangible storage medium.

[0032] The control device 100 has a sensor group 110 consisting of various sensors, vehicle control equipment 120, etc., connected to its input side. The sensor group 110 includes, for example, a current sensor I that detects the output current from the fuel cell 10, a voltage sensor V that detects the output voltage from the fuel cell 10, and a temperature sensor T that detects the temperature of the refrigerant on the outlet side of the fuel cell 10. The temperature sensor TS is a sensor that indirectly detects the temperature of the fuel cell 10.

[0033] The control device 100 has various controllable devices connected to its output side, including an air pump 21, an air control valve 31, a fuel control valve 42, a recycle pump 44, an exhaust valve 51, a circulation pump 62, a flow path switching valve 65, and a supply amount control valve 75.

[0034] The control device 100 operates the controlled device connected to the output side and performs various control processes based on a control program stored in memory. In this embodiment, the control device 100 controls the controlled device connected to the output side so that power is output in accordance with the power requested by load equipment such as a traction motor. For example, the control device 100 sets a target current to be swept from the fuel cell 10 in accordance with the requested output to the fuel cell 10, and controls the operation of the controlled device so that the output current from the fuel cell 10 is maintained at the target current.

[0035] Furthermore, the control device 100 controls the operation of the cooling system 60 so that the temperature of the fuel cell 10 is maintained at a temperature suitable for power generation when the fuel cell 10 is in operation. When the operation of the fuel cell 10 is started, the control device 100 activates the circulation pump 62 to circulate the refrigerant in the refrigerant circulation circuit 61. The control device 100 then controls the flow path switching valve 65 so that the refrigerant flows to the first bypass section 64 when the temperature of the fuel cell 10 is below the lower limit of the appropriate temperature, and to the refrigerant flows to the radiator 63 when the temperature of the fuel cell 10 exceeds the lower limit of the appropriate temperature.

[0036] Furthermore, as mentioned above, if the concentration of anions in the refrigerant is low, the rate of oxidative degradation will increase. Taking this into consideration, the control device 100 of this embodiment controls the supply amount control valve 75 so that the ion removal rate of anions is lower than the ion removal rate of cations. For example, the control device 100 controls the supply amount control valve 75 so that the ion removal rate of anions is about 10% to 90% of the ion removal rate of cations. However, if the ion removal rate of anions becomes too low, there is a risk that the conductivity of the refrigerant will increase. For this reason, it is desirable that the relationship between the ion removal rate of anions and the ion removal rate of cations be set taking into account both the rate of oxidative degradation of the antifreeze and the conductivity of the refrigerant.

[0037] The ion removal rate at each ion adsorption section 71 and 72 increases as the amount of refrigerant supplied increases. Based on this, the control device 100 of this embodiment controls the supply amount adjustment valve 75 so that the amount of refrigerant supplied to the cation adsorption section 71 per unit time is greater than the amount of refrigerant supplied to the anion adsorption section 72 per unit time, as shown in Figure 6. Specifically, the control device 100 controls the supply amount adjustment valve 75 so that the opening area on the first refrigerant pipe section 73 side of the supply amount adjustment valve 75 is larger than the opening area on the second refrigerant pipe section 74 side of the supply amount adjustment valve 75. As a result, for example, as shown in Figure 7, the ion removal rate of anions becomes smaller than the ion removal rate of cations. The control device 100 may also intermittently open and close the opening on the second refrigerant pipe section 74 side of the supply amount adjustment valve 75 to reduce the amount of refrigerant supplied to the anion adsorption section 72 compared to the amount of refrigerant supplied to the cation adsorption section 71.

[0038] The cooling system 60 described above comprises a refrigerant circulation circuit 61 through which a refrigerant containing antifreeze circulates, and an ion exchanger 70 that adsorbs ions in the refrigerant flowing through the refrigerant circulation circuit 61. The ion exchanger 70 has a cation adsorption section 71 containing a cation exchange resin 710 that adsorbs cations, and an anion adsorption section 72 containing an anion exchange resin 720 that adsorbs anions. The ion exchanger 70 is configured such that the ion removal rate of anions is smaller than the ion removal rate of cations.

[0039] According to this method, the increase in ions in the refrigerant can be suppressed by adsorbing cations in the refrigerant with the cation exchange resin 710 of the cation adsorption section 71, and by adsorbing anions containing organic acids in the antifreeze with the anion exchange resin 720 of the anion adsorption section 72.

[0040] In particular, the ion exchanger 70 is configured such that the ion removal rate for anions is lower than that for cations. This suppresses the decrease in the concentration of organic acids in the antifreeze due to the adsorption of anions in the anion adsorption section 72, thereby preventing an increase in the rate of oxidative degradation of the antifreeze.

[0041] Therefore, according to the cooling system 60 of this embodiment and the fuel cell system 1 including the cooling system 60, it is possible to suppress the increase in ions in the refrigerant while suppressing the deterioration of the antifreeze performance.

[0042] Furthermore, the cooling system 60 of this embodiment has the following features. (1) The ion exchanger 70 is equipped with an adjustment unit for adjusting the amount of refrigerant supplied to the anion adsorption unit 72 and the amount of refrigerant supplied to the cation adsorption unit 71. This adjustment unit adjusts the amount of refrigerant supplied to the anion adsorption unit 72 and the cation adsorption unit 71 so that the amount of refrigerant supplied to the cation adsorption unit 71 per unit time is greater than the amount of refrigerant supplied to the anion adsorption unit 72 per unit time. The ion removal rate in each ion adsorption unit 71 and 72 increases as the amount of refrigerant supplied increases. Therefore, by adjusting the amount of refrigerant supplied to each ion adsorption unit 71 and 72 so that the amount of refrigerant supplied to the cation adsorption unit 71 is greater than the amount of refrigerant supplied to the anion adsorption unit 72, the ion removal rate of anions can be made smaller than the ion removal rate of cations.

[0043] (2) The adjustment unit described above includes a supply adjustment valve 75 that adjusts the amount of refrigerant supplied to the anion adsorption unit 72 and the amount of refrigerant supplied to the cation adsorption unit 71. As a result, the ion exchanger 70 is configured to supply more refrigerant to the cation adsorption unit 71 than to the amount of refrigerant supplied to the anion adsorption unit 72.

[0044] (3) Incidentally, the amount of metal ions leached from materials such as the fuel cell 10 is highest in the early stages of the product's life and tends to decrease over time. In the later stages of the life, the amount of cations leached into the refrigerant decreases, which increases the proportion of anions that affect the overall conductivity of the refrigerant. Therefore, it is desirable to configure the system so that the ion removal rate of anions is small.

[0045] (Modified version of the first embodiment) In the first embodiment, a supply amount control valve 75 is provided with respect to the ion exchanger 70, but the invention is not limited to this, and the supply amount control valve 75 may also be provided with respect to the refrigerant circulation circuit 61. Furthermore, instead of a single three-way valve, the supply amount control valve 75 may be composed of variable throttle valves provided on at least one of each refrigerant pipe section 73, 74. In addition, one end of the second bypass section 66 may be connected to a path between the refrigerant outlet of the fuel cell 10 and the refrigerant inlet of the flow path switching valve 65, and the other end may be connected to a path between the refrigerant outlet of the radiator 63 and the refrigerant inlet of the circulation pump 62.

[0046] (Second Embodiment) Next, a second embodiment will be described with reference to Figures 8 and 9. In this embodiment, the differences from the first embodiment will be mainly described.

[0047] As shown in Figure 8, the cooling system 60 of this embodiment omits the supply amount control valve 75 described in the first embodiment. Instead, as shown in Figure 9, the cooling system 60 has a smaller refrigerant pressure loss in the first refrigerant pipe section 73 than in the second refrigerant pipe section 74. Specifically, the first refrigerant pipe section 73 is composed of refrigerant piping with a larger flow path cross-sectional area than the refrigerant piping that makes up the second refrigerant pipe section 74. In addition, the first refrigerant pipe section 73 has fewer bends and a shorter flow path length than the second refrigerant pipe section 74.

[0048] In the cooling system 60 configured in this way, the difference in pressure loss between the refrigerant pipes 73 and 74 causes the refrigerant to flow more easily to the first refrigerant pipe section 73 than to the other refrigerant pipes 73 and 74. In other words, in this embodiment, the cooling system 60 is adjusted so that the amount of refrigerant supplied to the cation adsorption section 71 per unit time is greater than the amount of refrigerant supplied to the anion adsorption section 72, due to the difference in pressure loss between the refrigerant pipes 73 and 74. In this embodiment, the first refrigerant pipe section 73 and the second refrigerant pipe section 74 constitute an "adjustment section" for adjusting the amount of refrigerant supplied to the cation adsorption section 71 and the amount of refrigerant supplied to the anion adsorption section 72.

[0049] Other aspects are the same as in the first embodiment. The cooling system 60 of this embodiment can obtain the same effects as in the first embodiment, which are achieved from a configuration common to or equivalent to that of the first embodiment.

[0050] Furthermore, the cooling system 60 of this embodiment has the following features. (1) The cooling system 60 has a first refrigerant pipe section 73 connected to the cation adsorption section 71 and a second refrigerant pipe section 74 connected to the anion adsorption section 72, which serve as adjustment sections for the amount of refrigerant supplied to each ion adsorption section 71 and 72. The pressure loss of the refrigerant is smaller in the first refrigerant pipe section 73 than in the second refrigerant pipe section 74. This makes it possible to supply more refrigerant to the cation adsorption section 71 than to the anion adsorption section 72 without consuming electricity.

[0051] (Modified version of the second embodiment) The first refrigerant pipe section 73 may be composed of refrigerant piping such that at least one of the flow path cross-sectional area, number of bends, and flow path length is equivalent to that of the refrigerant piping constituting the second refrigerant pipe section 74, provided that the refrigerant pressure loss is smaller in the first refrigerant pipe section 73 than in the second refrigerant pipe section 74. In addition, the ion exchanger 70 may be provided with a resistor that acts as resistance to the flow of refrigerant relative to the second refrigerant pipe section 74, such that the refrigerant pressure loss is smaller in the first refrigerant pipe section 73 than in the second refrigerant pipe section 74.

[0052] (Third embodiment) Next, a third embodiment will be described with reference to Figures 10 and 11. In this embodiment, the differences from the first embodiment will be mainly described.

[0053] As shown in Figure 10, the cooling system 60 of this embodiment omits the supply adjustment valve 75 described in the first embodiment. Instead, as shown in Figure 11, the cooling system 60 has higher ion adsorption performance in the cation adsorption section 71 than in the anion adsorption section 72, such that the ion removal rate of anions is lower than that of cations. Specifically, the amount of cation exchange resin 710 packed in the cation adsorption section 71 is greater than the amount of anion exchange resin 720 packed in the anion adsorption section 72.

[0054] In the cooling system 60 configured in this way, the ion adsorption performance at the cation adsorption section 71 is higher than that at the anion adsorption section 72 due to the difference in the amount of ion exchange resin packed in each ion adsorption section 71 and 72. As a result, the cooling system 60 has a lower ion removal rate for anions than for cations.

[0055] Other aspects are the same as in the first embodiment. The cooling system 60 of this embodiment can obtain the same effects as in the first embodiment, which are achieved from a configuration common to or equivalent to that of the first embodiment.

[0056] Furthermore, the cooling system 60 of this embodiment has the following features. (1) The ion exchanger 70 is designed so that the ion removal rate of anions is lower than that of cations, with higher ion adsorption performance in the cation adsorption section 71 than in the anion adsorption section 72. This also makes it possible to make the ion removal rate of anions lower than that of cations.

[0057] (Modified version of the third embodiment) In the third embodiment, the ion adsorption performance in the cation adsorption section 71 is increased by making the amount of cation exchange resin 710 in the cation adsorption section 71 greater than the amount of anion exchange resin 720 in the anion adsorption section 72, but the ion adsorption performance in the cation adsorption section 71 is not limited to this. For example, the ion exchanger 70 may be configured to increase the ion adsorption performance in the cation adsorption section 71 by making the number of cation adsorption sections 71 greater than the number of anion adsorption sections 72.

[0058] (Fourth Embodiment) Next, the fourth embodiment will be described with reference to Figures 12 and 13. In this embodiment, the differences from the third embodiment will be mainly described.

[0059] The cooling system 60 of this embodiment has a third bypass section 68 added. The third bypass section 68 is a flow path that directs a portion of the refrigerant flowing on the refrigerant outlet side of the fuel cell 10 in the refrigerant circulation circuit 61 to the refrigerant inlet of the circulation pump 62, and is configured, for example, by piping.

[0060] The ion exchanger 70 has a cation adsorption section 71 provided in the third bypass section 68 and an anion adsorption section 72 provided in the second bypass section 66. The second bypass section 66 is connected to the refrigerant inlet side of the fuel cell 10. The third bypass section 68 is connected to the refrigerant outlet side of the fuel cell 10, and the refrigerant that has been heated by the heat of the fuel cell 10 flows through it. Therefore, the temperature of the refrigerant flowing through the third bypass section 68 is higher than the temperature of the refrigerant flowing through the second bypass section 66.

[0061] The amount of refrigerant supplied to each ion adsorption section 71 and 72 is adjusted by resistors, flow control valves, etc. (not shown) so that the amount of refrigerant supplied to the cation adsorption section 71 per unit time is greater than the amount of refrigerant supplied to the anion adsorption section 72 per unit time. In this embodiment, the third bypass section 68 constitutes the first refrigerant pipe section 73, and the second bypass section 66 constitutes the second refrigerant pipe section 74.

[0062] Here, the cation exchange resin 710 and the anion exchange resin 720 have temperature characteristics such that their ion adsorption performance increases as the temperature rises. Based on this, in the cooling system 60 of this embodiment, the ion adsorption units 71 and 72 are connected to the refrigerant circulation circuit 61 such that the cation adsorption unit 71 is supplied with a refrigerant at a higher temperature than the refrigerant supplied to the anion adsorption unit 72.

[0063] Specifically, the cooling system 60 is configured such that the refrigerant inlet side of the third bypass section 68 is connected to the refrigerant outlet side of the fuel cell 10 in the refrigerant circulation circuit 61, so that a high-temperature refrigerant, heated by heat from the fuel cell 10, is supplied to the cation adsorption section 71. In addition, the refrigerant outlet side of the third bypass section 68 is connected to the refrigerant inlet side of the circulation pump 62 in the refrigerant circulation circuit 61.

[0064] Furthermore, the cooling system 60 is configured such that the refrigerant inlet side of the second bypass section 66 is connected to the refrigerant outlet side of the circulation pump 62 in the refrigerant circulation circuit 61, so that the anion adsorption section 72 is supplied with low-temperature refrigerant before it is supplied to the fuel cell 10. The refrigerant outlet side of the second bypass section 66 is connected to the refrigerant inlet side of the fuel cell 10 in the refrigerant circulation circuit 61.

[0065] In the cooling system 60 configured in this way, the amount of refrigerant supplied to each ion adsorption section 71 and 72 is adjusted so that the amount of refrigerant supplied to the cation adsorption section 71 per unit time is greater than the amount of refrigerant supplied to the anion adsorption section 72 per unit time. As a result, the cooling system 60 has a lower ion removal rate for anions than for cations.

[0066] In addition, the refrigerant supplied to the cation adsorption section 71 is configured to be at a higher temperature than the refrigerant supplied to the anion adsorption section 72. Due to the temperature difference of the refrigerants supplied to each ion adsorption section 71 and 72, the ion adsorption performance at the cation adsorption section 71 is higher than that at the anion adsorption section 72. As a result, the cooling system 60 has a lower ion removal rate for anions than for cations.

[0067] Other aspects are the same as in the third embodiment. The cooling system 60 of this embodiment can obtain the same effects as in the third embodiment, which are achieved from a configuration common to or equivalent to that of the third embodiment.

[0068] (Modification of the fourth embodiment) In the fourth embodiment, the cooling system 60 is configured such that the amount of refrigerant supplied to the cation adsorption section 71 is greater than the amount of refrigerant supplied to the anion adsorption section 72, but it is not limited to this configuration. The cooling system 60 may also be configured such that the amount of refrigerant supplied to the anion adsorption section 72 is equal to the amount of refrigerant supplied to the cation adsorption section 71, so as to the amount of refrigerant supplied to the anion adsorption section 72. This is also true in subsequent embodiments.

[0069] The ion exchanger 70 may differ from that described in the fourth embodiment above, as long as it is configured to supply a high-temperature refrigerant to the cation adsorption unit 71. For example, the ion exchanger 70 may have a refrigerant inlet side portion of the third bypass unit 68 connected between the radiator 63 and the flow path switching valve 65 in the refrigerant circulation circuit 61.

[0070] Furthermore, the ion exchanger 70 may differ from that described in the fourth embodiment above, as long as it is configured to supply a low-temperature refrigerant to the anion adsorption unit 72. For example, the ion exchanger 70 may have a refrigerant inlet side in the second bypass unit 66 connected to the refrigerant outlet side of the heat sink 63 in the refrigerant circulation circuit 61.

[0071] (Fifth embodiment) Next, the fifth embodiment will be described with reference to Figure 14. In this embodiment, the differences from the fourth embodiment will be mainly described.

[0072] As shown in Figure 14, the cooling system 60 has a refrigerant inlet side of the second bypass section 66 connected to the refrigerant outlet side of the fuel cell 10 in the refrigerant circulation circuit 61, so that the refrigerant that has passed through the fuel cell 10 is supplied to the cation adsorption section 71. The refrigerant outlet side of the second bypass section 66 is connected to the refrigerant inlet side of the flow path switching valve 65 in the refrigerant circulation circuit 61 so that the refrigerant that has passed through the cation adsorption section 71 flows to the radiator 63 or the first bypass section 64. Furthermore, the cooling system 60 is configured such that the refrigerant that has passed through the heat sink 63 or the first bypass section 64 is supplied to the anion adsorption section 72, with the refrigerant inlet side of the third bypass section 68 connected to the downstream side of the refrigerant flow of the heat sink 63 and the first bypass section 64.

[0073] In the cooling system 60 configured in this way, the amount of refrigerant supplied to each ion adsorption section 71 and 72 is adjusted so that the amount of refrigerant supplied to the cation adsorption section 71 is greater than the amount supplied to the anion adsorption section 72. In addition, the temperature of the refrigerant supplied to the cation adsorption section 71 is higher than the temperature of the refrigerant supplied to the anion adsorption section 72. As a result of the temperature difference of the refrigerants supplied to each ion adsorption section 71 and 72, the ion adsorption performance at the cation adsorption section 71 is higher than that at the anion adsorption section 72. For this reason, in the cooling system 60 of this embodiment, the ion removal rate for anions is lower than that for cations.

[0074] Other aspects are the same as in the fourth embodiment. The cooling system 60 of this embodiment can obtain the same effects as in the fourth embodiment, which are achieved from a configuration common to or equivalent to that of the fourth embodiment.

[0075] (Sixth Embodiment) Next, the sixth embodiment will be described. In this embodiment, the differences from the first to third embodiments will be mainly described.

[0076] Although not shown in the figures, in this embodiment, the cooling system 60 has one end of the second bypass section 66 connected to the flow path between the refrigerant outlet of the circulation pump 62 and the refrigerant inlet of the fuel cell 10, and the other end connected to the flow path between the refrigerant outlet of the radiator 63 and the refrigerant inlet of the circulation pump 62. The pressure loss of the second bypass section 66 is higher than that of the fuel cell 10 so that a portion of the refrigerant flowing through the refrigerant circulation circuit 61 flows through it. The flow rate of the refrigerant flowing through the second bypass section 66 may be adjusted by a flow control valve.

[0077] Furthermore, an ion exchanger 70, as described in any of the first to third embodiments, is arranged in the second bypass section 66. This also allows the refrigerant at a low temperature before it flows into the fuel cell 10 to be supplied to the ion exchanger 70.

[0078] Other aspects are the same as in the first to third embodiments. The cooling system 60 of this embodiment can obtain the same effects as in the first to third embodiments, which are achieved from a configuration common to or equivalent to that of the first to third embodiments.

[0079] (Seventh Embodiment) Next, the seventh embodiment will be described with reference to Figure 15. In this embodiment, the differences from the first to third embodiments will be mainly described. As shown in Figure 15, the cooling system 60 has a second bypass section 66 connected to the first bypass section 64 so that a portion of the refrigerant flowing through the first bypass section 64 flows into the ion exchanger 70. In this embodiment, the second bypass section 66 is designed not to bypass system components such as the fuel cell 10 and the heat exchanger 63 so as not to change the flow rate of the refrigerant to these components. Specifically, both ends of the second bypass section 66 are connected to the first bypass section 64.

[0080] In this configuration, even with the addition of an ion exchanger 70, the flow rate of refrigerant to the system components such as the fuel cell 10 and the heat exchanger 63 does not change, thus ensuring sufficient cooling performance for the fuel cell 10.

[0081] (Modified version of the sixth embodiment) In the above-described embodiment, an example was given in which both ends of the second bypass section 66 are connected to the first bypass section 64, but the position of the second bypass section 66 is not limited to this. Both ends of the second bypass section 66 may be connected to any of the following: a refrigerant flow path from the circulation pump 62 to the fuel cell 10, a refrigerant flow path from the circulation pump 62 to the fuel cell 10, or a refrigerant flow path from the fuel cell 10 to the flow path switching valve 65. Alternatively, both ends of the second bypass section 66 may be connected to any of the following: a refrigerant flow path from the flow path switching valve 65 to the radiator 63, a refrigerant flow path from the radiator 63 to the junction with the first bypass section 64, or a refrigerant flow path from the junction with the first bypass section 64 to the circulation pump 62.

[0082] (Other embodiments) While representative embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above and can be modified in various ways, for example, as follows. In the above-described embodiment, a refrigerant circulation circuit 61 is provided as an example, which includes a circulation pump 62, a heat sink 63, a first bypass section 64, a flow path switching valve 65, a second bypass section 66, and an ion exchanger 70. However, the circuit configuration of the refrigerant circulation circuit 61 is not limited to this. The refrigerant circulation circuit 61 may have a different configuration in part from that described above. For example, the first bypass section 64 and the flow path switching valve 65 may be omitted in the refrigerant circulation circuit 61. Also, the heat sink 63 may be a liquid-cooled heat exchanger instead of an air-cooled heat exchanger. Furthermore, the antifreeze may contain propylene glycol as its main component instead of ethylene glycol.

[0083] In the above-described embodiment, an example was given in which the ion exchanger 70 is located in the second bypass section 66, but the arrangement of the ion exchanger 70 is not limited to this. The ion exchanger 70 may be located in the first bypass section 64, the refrigerant flow path from the circulation pump 62 to the fuel cell 10, the refrigerant flow path from the circulation pump 62 to the fuel cell 10, or the refrigerant flow path from the fuel cell 10 to the flow path switching valve 65. Alternatively, the ion exchanger 70 may be located in the refrigerant flow path from the flow path switching valve 65 to the radiator 63, the refrigerant flow path from the radiator 63 to the junction with the first bypass section 64, or the refrigerant flow path from the junction with the first bypass section 64 to the circulation pump 62.

[0084] In the embodiments described above, an ion exchanger 70 having one cation adsorption section 71 and one anion adsorption section 72 was illustrated, but the ion exchanger 70 is not limited to this. The ion exchanger 70 may be configured to have multiple units of at least one of each ion adsorption section 71 and 72.

[0085] In the embodiments described above, an example of applying the fuel cell system 1 of this disclosure to an HDV was explained, but the application of the fuel cell system 1 is not limited to HDVs. The fuel cell system 1 of this disclosure can also be applied to LCVs and private automobiles, for example. Furthermore, the cooling system 60 may be configured to adjust the temperature of the fuel cell 10 to a low temperature range lower than the medium temperature range.

[0086] Furthermore, the fuel cell system 1 of this disclosure can be widely applied not only to mobile devices but also to power generation systems in houses, factories, etc. In addition, although the above-described embodiment exemplified a fuel cell 10 having a solid polymer type cell, the fuel cell 10 is not limited to this and may have other types of cells other than solid polymer type, such as solid oxide type cells.

[0087] In the embodiments described above, it goes without saying that the elements constituting the embodiments are not necessarily essential unless explicitly stated to be particularly essential or unless they are clearly considered essential in principle. In the embodiments described above, when numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiments are mentioned, the embodiments are not limited to those specific numbers unless explicitly stated to be particularly essential or unless they are clearly limited to a specific number in principle. In the embodiments described above, when the shapes, positional relationships, etc., of the components are mentioned, the embodiments are not limited to those shapes, positional relationships, etc., unless explicitly stated or unless they are clearly limited to a specific shape, positional relationship, etc.

[0088] The control unit and its method of this disclosure may be implemented in a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. The control unit and its method of this disclosure may be implemented in a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. The control unit and its method of this disclosure may be implemented in one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. The computer program may also be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0089] [Perspective of this disclosure] [First point of view] A cooling system for cooling a fuel cell (10) using a refrigerant containing antifreeze, A refrigerant circulation circuit (61) through which the refrigerant circulates, The refrigerant circulation circuit includes an ion exchanger (70) that adsorbs ions in the refrigerant flowing through the refrigerant, The ion exchanger has a cation adsorption section (71) containing a cation exchange resin (710) that adsorbs cations and an anion adsorption section (72) containing an anion exchange resin (720) that adsorbs anions. When the amount of ions reduced per unit time in the ion exchanger relative to the total amount of ions in the refrigerant circulation circuit is defined as the ion removal rate, A cooling system in which at least one of the refrigerant circulation circuit and the ion exchanger is configured such that the ion removal rate of anions is lower than the ion removal rate of cations. [Second perspective] The refrigerant circulation circuit and the ion exchanger are provided with adjustment units (67, 69, 73, 74, 75, 100) for adjusting the amount of refrigerant supplied to the anion adsorption unit and the amount of refrigerant supplied to the cation adsorption unit. The cooling system according to the first aspect, wherein the adjustment unit adjusts the amount of refrigerant supplied to the anion adsorption unit and the amount of refrigerant supplied to the cation adsorption unit so that the amount of refrigerant supplied to the cation adsorption unit per unit time is greater than the amount of refrigerant supplied to the anion adsorption unit per unit time. [Third perspective] The cooling system according to the second aspect, wherein the adjustment unit includes flow control valves (67, 69, 75) for adjusting the amount of refrigerant supplied to the anion adsorption unit and the amount of refrigerant supplied to the cation adsorption unit. [Fourth perspective] The cooling system according to the second or third aspect, wherein the adjustment section includes a first refrigerant pipe section (73) connected to the cation adsorption section and a second refrigerant pipe section (74) connected to the anion adsorption section, and the refrigerant pressure loss is smaller in the first refrigerant pipe section than in the second refrigerant pipe section. [Fifth perspective] The cooling system according to any one of the first to fourth aspects, wherein the ion exchanger has higher ion adsorption performance in the cation adsorption section than in the anion adsorption section, such that the ion removal rate of anions is lower than the ion removal rate of cations. [Sixth perspective] A fuel cell system, A cooling system (60) described in any one of the first to fifth aspects, The aforementioned fuel cell, A fuel cell system equipped with the following features. [Explanation of Symbols]

[0090] 10 fuel cell 60 Cooling System 61 Refrigerant circulation circuit 70 Ion exchanger 71 Cation adsorption section 710 Cation exchange resin 72 Anion adsorption section 720 Anion exchange resin

Claims

1. A cooling system for cooling a fuel cell (10) using a refrigerant containing antifreeze, A refrigerant circulation circuit (61) through which the refrigerant circulates, The system includes an ion exchanger (70) that adsorbs ions in the refrigerant flowing through the refrigerant circulation circuit, The ion exchanger has a cation adsorption section (71) containing a cation exchange resin (710) that adsorbs cations and an anion adsorption section (72) containing an anion exchange resin (720) that adsorbs anions. When the amount of ions reduced per unit time in the ion exchanger relative to the total amount of ions in the refrigerant circulation circuit is defined as the ion removal rate, A cooling system in which at least one of the refrigerant circulation circuit and the ion exchanger is configured such that the ion removal rate of anions is lower than the ion removal rate of cations.

2. The refrigerant circulation circuit and the ion exchanger are provided with adjustment units (67, 69, 73, 74, 75, 100) for adjusting the amount of refrigerant supplied to the anion adsorption unit and the amount of refrigerant supplied to the cation adsorption unit. The cooling system according to claim 1, wherein the adjustment unit adjusts the amount of refrigerant supplied to the anion adsorption unit and the amount of refrigerant supplied to the cation adsorption unit so that the amount of refrigerant supplied to the cation adsorption unit per unit time is greater than the amount of refrigerant supplied to the anion adsorption unit per unit time.

3. The cooling system according to claim 2, wherein the adjustment unit includes flow control valves (67, 69, 75) for adjusting the amount of refrigerant supplied to the anion adsorption unit and the amount of refrigerant supplied to the cation adsorption unit.

4. The cooling system according to claim 2, wherein the adjustment section includes a first refrigerant pipe section (73) connected to the cation adsorption section and a second refrigerant pipe section (74) connected to the anion adsorption section, and the pressure loss of the refrigerant is smaller in the first refrigerant pipe section than in the second refrigerant pipe section.

5. The cooling system according to claim 1, wherein the ion exchanger has higher ion adsorption performance in the cation adsorption section than in the anion adsorption section, such that the ion removal rate of anions is lower than the ion removal rate of cations.

6. A fuel cell system, A cooling system (60) according to any one of claims 1 to 5, The aforementioned fuel cell, A fuel cell system equipped with the following features.

Images