Water electrolysis and fuel cell systems

Abstract

To provide a water electrolysis and fuel cell system that can reduce the pressure drop in a heat medium channel that circulates a heat medium between a water electrolysis module (WEM) and a fuel cell module (FCM) while suppressing the hypofunction of a WEM.SOLUTION: A heat medium channel 41 has a channel 411 that performs heat exchange between a heat medium and WEM 2, a channel 412 that performs heat exchange between the heat medium and an FCM 3 downstream of the heat medium flow from the channel 411, a channel 413 that bypasses a WEM 2, and a channel 414 that bypasses the FCM 3. A controller opens the channel 411 and closes the channel 413 with a control valve 421 and closes the channel 412 and opens the channel 414 with a second control valve 422 during operation of the WEM 2 and shutdown of the FCM 3. When the WEM 2 is stopped and the FCM 3 is in operation, the controller closes the channel 411 and opens the channel 413 with the control valve 421, and opens the channel 412 and closes the channel 414 with the control valve 422.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a water electrolysis / fuel cell system including a water electrolysis module and a fuel cell module. [Background technology]

[0002] A fuel cell system having a refrigerant cooling device and multiple fuel cell modules has been known for some time (see Patent Document 1 below). The fuel cell system described in Patent Document 1 is capable of suppressing variations in the flow rate of the refrigerant flowing through multiple fuel cell bodies, while adjusting the flow rate of the refrigerant according to the state of each fuel cell body.

[0003] Also known is a charge / discharge system that uses a reversible cell that integrates a solid polymer water electrolysis cell and a fuel cell (see Patent Document 2 below). In the charge / discharge system described in Patent Document 2, raw water is supplied to an oxygen generating electrode that generates oxygen during water electrolysis operation, and hydrogen is supplied during fuel cell operation, and an oxidant is supplied to a hydrogen generating electrode that generates hydrogen during water electrolysis operation, during fuel cell operation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2022-118947 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-194916 Summary of the Invention [Problem to be solved by the invention]

[0005] Assume that at least one of the fuel cell modules in the fuel cell system described in Patent Document 1 is replaced with a water electrolysis module. In this case, if the heat medium flow path through which the heat medium that exchanges heat with the fuel cell module flows and the heat medium flow path through which the heat medium that exchanges heat with the water electrolysis module flows are connected in series, pressure loss will increase. Furthermore, a heat medium with a temperature higher than the operating temperature of the water electrolysis module may flow into the heat medium flow path through which the heat medium that exchanges heat with the water electrolysis module flows, which could degrade the function of the water electrolysis module.

[0006] The present disclosure provides a water electrolysis / fuel cell system that can reduce pressure loss in a heat medium flow path that circulates a heat medium through a water electrolysis module and a fuel cell module, and can also suppress deterioration of the function of the water electrolysis module. [Means for solving the problem]

[0007] One aspect of the present disclosure is a water electrolysis / fuel cell system including a water electrolysis module, a fuel cell module, a heat medium circulation device that circulates a heat medium that exchanges heat with the water electrolysis module and the fuel cell module, and a control device that controls the heat medium circulation device, wherein the heat medium circulation device has a heat medium flow path through which the heat medium circulates, and a plurality of control valves that are controlled by the control device to open and close the heat medium flow path, and the heat medium flow path includes a first heat exchange flow path that exchanges heat between the heat medium and the water electrolysis module, a second heat exchange flow path that exchanges heat between the heat medium and the fuel cell module downstream of the first heat exchange flow path in the flow of the heat medium, a first bypass flow path that bypasses the water electrolysis module, and a second bypass flow path that bypasses the fuel cell module. the control valves include a first control valve capable of opening and closing the first heat exchange passage and the first bypass passage, and a second control valve capable of opening and closing the second heat exchange passage and the second bypass passage; and the control device, during operation of the water electrolysis module and while the fuel cell module is stopped, opens the first heat exchange passage and closes the first bypass passage with the first control valve and closes the second heat exchange passage and opens the second bypass passage with the second control valve; and, during stoppage of the water electrolysis module and operation of the fuel cell module, closes the first heat exchange passage and opens the first bypass passage with the first control valve and opens the second heat exchange passage and closes the second bypass passage with the second control valve. [Effects of the Invention]

[0008] According to the above aspect of the present disclosure, it is possible to provide a water electrolysis / fuel cell system that can reduce pressure loss in a heat medium flow path that circulates a heat medium through a water electrolysis module and a fuel cell module, and that can suppress deterioration of the performance of the water electrolysis module. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram showing a first embodiment of a water electrolysis and fuel cell system according to the present disclosure. [Figure 2]FIG. 2 is a schematic diagram showing a modified example of the water electrolysis and fuel cell system of FIG. 1. [Figure 3] 2 is a time chart illustrating the operation of the water electrolysis and fuel cell system of FIG. 1. [Figure 4] FIG. 1 is a schematic configuration diagram showing a second embodiment of a water electrolysis / fuel cell system according to the present disclosure. [Figure 5] FIG. 1 is a schematic configuration diagram showing a third embodiment of a water electrolysis and fuel cell system according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of a water electrolysis / fuel cell system according to the present disclosure will be described with reference to the drawings.

[0011] [Embodiment 1] Fig. 1 is a schematic diagram showing a first embodiment of a water electrolysis and fuel cell system according to the present disclosure. Fig. 2 is a schematic diagram showing a modified example of the water electrolysis and fuel cell system 1 of Fig. 1. In the following description, unless otherwise required, the water electrolysis module 2 will be abbreviated as "WEM2" and the fuel cell module 3 will be abbreviated as "FCM3."

[0012] 1 and 2, the water electrolysis / fuel cell system 1, 1A of this embodiment includes a WEM 2, an FCM 3, a heat medium circulator 4, and a control device (not shown). For example, the WEM 2 and the FCM 3 are not operated simultaneously but are operated alternately.

[0013] The WEM 2 is configured, for example, by a water electrolysis stack 21 in which a plurality of water electrolysis cells are stacked. The water electrolysis cells are, for example, solid polymer water electrolysis cells that electrolyze water to produce hydrogen. The WEM 2 includes, for example, a water supply system that supplies water to the water electrolysis stack 21, a power supply system that supplies power to the water electrolysis stack 21, and a hydrogen recovery system that recovers hydrogen produced in the water electrolysis stack 21.

[0014] The FCM 3 is configured, for example, like the WEM 2, by a fuel cell stack 31 in which multiple fuel cell cells are stacked. The fuel cell cells are, for example, polymer electrolyte fuel cells, and generate electricity when supplied with hydrogen and oxygen. The FCM 3 includes, for example, a hydrogen supply system that supplies hydrogen to the fuel cell stack 31, an air supply system that supplies air to the fuel cell stack 31, and an off-gas recovery system that recovers off-gas discharged from the fuel cell stack 31.

[0015] The heat medium circulator 4 circulates a heat medium that exchanges heat with the WEM 2 and the FCM 3. The heat medium circulator 4 has a heat medium flow path 41 through which the heat medium circulates, and a plurality of control valves 42 that are controlled by a control device to open and close the heat medium flow path 41. The heat medium circulator 4 also has, for example, a pump 43, an ion exchanger 44, and a cooling device 45.

[0016] In the water electrolysis / fuel cell system 1 shown in Fig. 1, the heat medium circulated through the heat medium circulator 4 is, for example, pure water. In the water electrolysis / fuel cell system 1A shown in Fig. 2, the heat medium circulated through the heat medium circulator 4 is, for example, fuel cell coolant (FCC). Fuel cell coolant has antifreeze properties and higher electrical insulation than long life coolant (LLC) used in power control units.

[0017] When the heat transfer medium is FCC, the water supply system of the WEM2 includes, for example, a pure water tank 22 for storing pure water, a pure water flow path 23 for supplying pure water from the pure water tank 22 to the WEM2, and a pure water pump 24 provided in the pure water flow path 23 for pumping the pure water, as shown in FIG.

[0018] The heat medium flow path 41 has a first heat exchange flow path 411 , a second heat exchange flow path 412 , a first bypass flow path 413 , and a second bypass flow path 414 .

[0019] The first heat exchange passage 411 includes, for example, inter-cell passages passing between the multiple water electrolysis cells constituting the water electrolysis stack 21 of the WEM 2, and pipes connected to the inlets and outlets of the manifolds of the inter-cell passages. The first heat exchange passage 411 circulates a heat medium to exchange heat between the heat medium and the WEM 2.

[0020] More specifically, when the temperature of the heat medium flowing through the first heat exchange flow path 411 is lower than the temperature of WEM2, WEM2 is cooled by the heat medium. On the other hand, when the temperature of the heat medium flowing through the first heat exchange flow path 411 is higher than the temperature of WEM2, WEM2 is heated by the heat medium.

[0021] The second heat exchange passage 412 includes, for example, inter-cell passages formed between the multiple fuel cell units that make up the fuel cell stack 31 of the FCM 3, and pipes connected to the inlets and outlets of the manifolds of the inter-cell passages. The second heat exchange passage 412 circulates a heat medium, thereby exchanging heat between the heat medium and the FCM 3 downstream of the first heat exchange passage 411 in the flow of the heat medium.

[0022] More specifically, when the temperature of the heat medium flowing through the second heat exchange passage 412 is lower than the temperature of the FCM 3, the FCM 3 is cooled by the heat medium. On the other hand, when the temperature of the heat medium flowing through the second heat exchange passage 412 is higher than the temperature of the FCM 3, the FCM 3 is heated by the heat medium.

[0023] The first bypass flow path 413 is provided so as to bypass the WEM 2. More specifically, the first bypass flow path 413 branches off from the upstream end of the first heat exchange flow path 411 in the flow direction of the heat medium in the heat medium flow path 41 and is connected to the downstream end of the first heat exchange flow path 411, for example, so as to bypass the first heat exchange flow path 411 and the WEM 2.

[0024] The second bypass flow path 414 is provided so as to bypass the FCM 3. More specifically, the second bypass flow path 414 branches off from an upstream end of the second heat exchange flow path 412 in the flow direction of the heat medium in the heat medium flow path 41 and is connected to a downstream end of the second heat exchange flow path 412, for example, so as to bypass the second heat exchange flow path 412 and the FCM 3.

[0025] The plurality of control valves 42 include a first control valve 421 and a second control valve 422. The first control valve 421 is provided so as to be able to open and close the first heat exchange passage 411 and the first bypass passage 413, respectively, and the second control valve 422 is provided so as to be able to open and close the second heat exchange passage 412 and the second bypass passage 414, respectively.

[0026] More specifically, the first control valve 421 has a first heat exchange valve 421a that opens and closes the first heat exchange passage 411, and a first bypass valve 421b that opens and closes the first bypass passage 413. The second control valve 422 has a second heat exchange valve 422a that opens and closes the second heat exchange passage 412, and a second bypass valve 422b that opens and closes the second bypass passage 414.

[0027] The first control valve 421 may be a three-way valve that can switch between, for example, a first heat exchange state in which the first heat exchange passage 411 is open and the first bypass passage 413 is closed, and a first bypass state in which the first heat exchange passage 411 is closed and the first bypass passage 413 is open. The second control valve 422 may be a three-way valve that can switch between a second heat exchange state in which the second heat exchange passage 412 is open and the second bypass passage 414 is closed, and a second bypass state in which the second heat exchange passage 412 is closed and the second bypass passage 414 is open.

[0028] The pump 43 is provided, for example, in the heat medium flow path 41 and pumps the heat medium. More specifically, the pump 43 is provided, for example, in the heat medium flow path 41 between the cooling device 45 and the ion exchanger 44 and pumps the heat medium from the outlet of the cooling device 45 to the inlet of the ion exchanger 44.

[0029] The ion exchanger 44 uses, for example, an ion exchange resin to remove impurity ions from the FCC or pure water, thereby maintaining the electrical insulation of the FCC and pure water. The ion exchanger 44 is provided, for example, upstream of the first heat exchange flow path 411 in the flow direction of the heat medium flowing through the heat medium flow path 41.

[0030] The cooling device 45 is, for example, a radiator that cools the heat medium by radiating the heat of the heat medium, the temperature of which has increased due to heat exchange with the WEM 2 or the FCM 3, to air passing through the cooling device 45.

[0031] A control device of the water electrolysis / fuel cell system 1, 1A (not shown) controls the heat medium circulating device 4 that circulates the heat medium through the WEM 2 and the FCM 3. The control device can be configured, for example, by one or more microcontrollers including a central processing unit (CPU), memories such as RAM and ROM, a timer, and an input / output unit. The control device controls the opening and closing of multiple control valves 42 of the heat medium circulating device 4, including a first control valve 421 and a second control valve 422, by, for example, executing a program stored in the memory using the CPU.

[0032] The operation of the water electrolysis / fuel cell system 1, 1A will be described below with reference to Fig. 3. Fig. 3 is a time chart illustrating the operation of the water electrolysis / fuel cell system 1, 1A shown in Figs. 1 and 2. More specifically, the four charts at the top of Fig. 3 show the WEM operating flag and WEM warming-up flag that turn ON while the WEM 2 is operating and warming up, respectively, and the FCM operating flag and FCM warming-up flag that turn ON while the FCM 3 is operating and warming up, respectively.

[0033] 3 show, by a dashed line (upstream heat medium temperature) and a broken line (downstream heat medium temperature), the heat medium temperatures upstream and downstream of the water electrolysis module (WEM) 2, the fuel cell module (FCM) 3, and the heat medium temperatures upstream and downstream of the cooling device 45. The four charts in the bottom part of Fig. 3 show the open / closed states of the first control valve 421 and the second control valve 422, i.e., the first bypass valve 421b and the first heat exchange valve 421a, and the second bypass valve 422b and the second heat exchange valve 422a.

[0034] 3, in the water electrolysis / fuel cell system 1, 1A, for example, at time t0, the WEM 2 is in operation (WEM operation flag: ON) and the FCM 3 is stopped (FCM operation flag: OFF). In this state, the control device of the water electrolysis / fuel cell system 1, 1A opens the first heat exchange passage 411 and closes the first bypass passage 413 using the first control valve 421, and closes the second heat exchange passage 412 and opens the second bypass passage 414 using the second control valve 422. More specifically, the control device opens the first heat exchange valve 421a and closes the first bypass valve 421b, closes the second heat exchange valve 422a, and opens the second bypass valve 422b, for example, as shown in the four charts in the lower part of FIG.

[0035] As a result, the heat medium flowing through the heat medium flow path 41 passes through the first heat exchange flow path 411 and exchanges heat with the operating WEM 2, thereby cooling the WEM 2 and increasing its temperature. After that, the heat medium that has passed through the first heat exchange flow path 411 passes through the second bypass flow path 414, which bypasses the stopped FCM 3, without exchanging heat with the stopped FCM 3, and flows into the cooling device 45, where it is cooled and its temperature decreases.

[0036] As a result, as shown in the middle graph of Fig. 3, the heat medium temperature downstream of WEM2 (dashed line) is higher than the heat medium temperature upstream of WEM2 (dash-dotted line). Furthermore, by passing the heat medium through second bypass flow path 414, the heat medium temperature upstream of FCM3 (dash-dotted line) and the heat medium temperature downstream of FCM3 (dashed line) become roughly equal. Furthermore, the heat medium temperature downstream of cooling device 45 (dashed line) is lower than the heat medium temperature upstream of cooling device 45 (dash-dotted line).

[0037] Thereafter, for example, from time t1 to time t2 before the WEM 2 is stopped and before the FCM 3 is started, the control device turns on the FCM warm-up flag shown in the upper part of Fig. 3 to warm up the FCM 3. During this time from time t1 to time t2, the control device closes the second bypass valve 422b and opens the second heat exchange valve 422a, for example, as shown in the lower part of Fig. 3.

[0038] As a result, between time t1 and time t2, the heat medium whose temperature has increased after passing through the first heat exchange flow path 411 flows into the second heat exchange flow path 412, and the heat medium temperature (dashed line) upstream of the FCM 3 shown in the middle of Fig. 3 increases to a predetermined temperature. Then, as the heat medium with increased temperature passes through the second heat exchange flow path 412, it exchanges heat with the pre-startup FCM 3, warming up the FCM 3. As a result, as the temperature of the pre-startup FCM 3 increases, the heat medium temperature (dashed line) downstream of the FCM 3 gradually increases and becomes approximately equal to the heat medium temperature (dashed line) upstream of the FCM 3.

[0039] For example, at time t2, when the difference in heat medium temperature between the upstream and downstream sides of FCM 3 shown in the middle graph of Figure 3 becomes equal to or less than a predetermined value, the control device turns off the FCM warm-up flag and turns on the FCM operating flag, as shown in the top graph of Figure 3. The control device also turns off the WEM operating flag. At the same time, the control device stops operation of WEM 2 and starts FCM 3, for example.

[0040] Furthermore, for example, during the period from time t2 to time t3 when WEM2 is stopped and FCM3 is operating, the control device closes the first heat exchange passage 411 and opens the first bypass passage 413 using the first control valve 421, and opens the second heat exchange passage 412 and closes the second bypass passage 414 using the second control valve 422. More specifically, for example, as shown in the four charts at the bottom of Fig. 3, the control device closes the first heat exchange valve 421a and opens the first bypass valve 421b, and opens the second heat exchange valve 422a and closes the second bypass valve 422b.

[0041] As a result, the heat medium flowing through the heat medium flow path 41 passes through the first bypass flow path 413, which bypasses the WEM 2 without exchanging heat with the WEM 2. The heat medium that has passed through the first bypass flow path 413 also flows through the second heat exchange flow path 412 and exchanges heat with the FCM 3, thereby cooling the FCM 3 and increasing its temperature. The heat medium that has passed through the second heat exchange flow path 412 then flows into the cooling device 45, where it is cooled and its temperature decreases.

[0042] As a result, as shown in the middle graph of Figure 3, after time t2, the heat medium temperature (dashed line) upstream of the stopped WEM2 and the heat medium temperature (dotted line) downstream of WEM2 become roughly equal. Furthermore, as the heat medium passes through the second heat exchange passage 412, the heat medium temperature (dashed line) downstream of the operating FCM3 becomes higher than the heat medium temperature (dashed line) upstream of the operating FCM3. Furthermore, the heat medium temperature (dashed line) downstream of the cooling device 45 is lower than the heat medium temperature (dashed line) upstream of the cooling device 45.

[0043] Thereafter, the control device warms up the WEM by turning on the WEM warm-up flag shown in the upper part of Fig. 3, for example, from time t3 to time t4 before starting up WEM 2 and before stopping FCM 3. During this time from time t3 to time t4, the control device closes the first bypass valve 421b and opens the first heat exchange valve 421a, for example, as shown in the lower part of Fig. 3.

[0044] As a result, from time t3 to time t4, the heat medium whose temperature has increased as it passed through the second heat exchange passage 412 is cooled by the cooling device 45, passes through the ion exchanger 44, and flows into the first heat exchange passage 411. As a result, the heat medium temperature (dashed line) upstream of WEM2 shown in the middle of Fig. 3 increases to a predetermined temperature. Then, as the heat medium with increased temperature passes through the first heat exchange passage 411, it exchanges heat with WEM2 before it is started, warming up WEM2.

[0045] As a result, the temperature of WEM2 before startup rises, causing the heat medium temperature downstream of WEM2 (dashed line) to gradually rise and approach the heat medium temperature upstream of WEM2 (chain line). Note that while WEM2 is warming up, the temperature of the heat medium flowing upstream of WEM2 in the first heat exchange flow path 411, i.e., the temperature of the heat medium at the outlet of the cooling device 45, must be below the heat resistance temperature of WEM2.

[0046] For example, at time t4, when the difference in heat medium temperature between the upstream and downstream sides of WEM2 shown in the middle graph of FIG. 3 becomes equal to or less than a predetermined value, the control device turns OFF the WEM warming-up flag and turns ON the WEM operating flag shown in the upper graph of FIG. 3. The control device also turns OFF the FCM operating flag. At the same time, the control device, for example, starts WEM2 and stops FCM3. When WEM2 is operating and FCM3 is stopped, the control device opens the first heat exchange passage 411 and closes the first bypass passage 413 with the first control valve 421, and closes the second heat exchange passage 412 and opens the second bypass passage 414 with the second control valve 422.

[0047] More specifically, as shown in the four charts at the bottom of Fig. 3, the control device opens the first heat exchange valve 421a and closes the first bypass valve 421b, and closes the second heat exchange valve 422a and opens the second bypass valve 422b. As a result, the heat medium passes through the first heat exchange passage 411 and exchanges heat with the WEM2, thereby cooling the WEM2 and increasing its temperature. The heat medium that has passed through the first heat exchange passage 411 also passes through the second bypass passage 414, which bypasses the FCM3 without exchanging heat with the FCM3, and flows into the cooling device 45, where it is cooled and its temperature is reduced.

[0048] As a result, as shown in the middle graph of Figure 3, the heat medium temperature downstream of WEM2 (dashed line) becomes higher than the heat medium temperature upstream of WEM2 (dash-dotted line). Furthermore, as the heat medium passes through second bypass flow path 414, which bypasses the stopped FCM3, the heat medium temperature upstream of FCM3 (dash-dotted line) and the heat medium temperature downstream of FCM3 (dashed line) decrease and become approximately equal. Furthermore, the heat medium temperature downstream of cooling device 45 (dashed line) is lower than the heat medium temperature upstream of cooling device 45 (dash-dotted line). The operation of water electrolysis and fuel cell system 1, 1A from time t5 onwards is the same as that from time t1 onwards.

[0049] As described above, the water electrolysis / fuel cell system 1, 1A according to this embodiment and its modified examples includes the water electrolysis module 2, the fuel cell module 3, the heat medium circulator 4 that circulates a heat medium that exchanges heat with the water electrolysis module 2 and the fuel cell module 3, and a controller that controls the heat medium circulator 4. The heat medium circulator 4 includes a heat medium flow path 41 through which the heat medium circulates and a plurality of control valves 42 that are controlled by the controller to open and close the heat medium flow path 41. The heat medium flow path 41 includes a first heat exchange flow path 411 that exchanges heat between the heat medium and the water electrolysis module 2, a second heat exchange flow path 412 that exchanges heat between the heat medium and the fuel cell module 3 downstream of the first heat exchange flow path 411 in the heat medium flow direction, a first bypass flow path 413 that bypasses the water electrolysis module 2, and a second bypass flow path 414 that bypasses the fuel cell module 3. The control valves 42 include a first control valve 421 that can open and close the first heat exchange channel 411 and the first bypass channel 413, and a second control valve 422 that can open and close the second heat exchange channel 412 and the second bypass channel 414. When the water electrolysis module 2 is in operation and the fuel cell module 3 is stopped, the control device opens the first heat exchange channel 411 and closes the first bypass channel 413 with the first control valve 421, and closes the second heat exchange channel 412 and opens the second bypass channel 414 with the second control valve 422. When the water electrolysis module 2 is stopped and the fuel cell module 3 is in operation, the control device closes the first heat exchange channel 411 and opens the first bypass channel 413 with the first control valve 421, and opens the second heat exchange channel 412 and closes the second bypass channel 414 with the second control valve 422.

[0050] With this configuration, when WEM2 is operating and FCM3 is stopped, the heat medium flows through the first heat exchange passage 411, thereby cooling WEM2 through heat exchange between the heat medium and WEM2. Furthermore, the heat medium that has passed through the first heat exchange passage 411 bypasses FCM3 through the second bypass passage 414, thereby reducing pressure loss compared to when the heat medium passes through the second heat exchange passage 412. Similarly, when WEM2 is stopped and FCM3 is operating, the heat medium flows through the first bypass passage 413 that bypasses WEM2, thereby reducing pressure loss compared to when the heat medium passes through the first heat exchange passage 411. Furthermore, the heat medium that has passed through the first bypass passage 413 flows through the second heat exchange passage 412, thereby cooling FCM3 through heat exchange between the heat medium and FCM3. Furthermore, by arranging the first heat exchange passage 411 upstream of the second heat exchange passage 412 in the flow direction of the heat medium in the heat medium passage 41, the heat medium that has cooled the FCM 3 and whose temperature has risen above the operating temperature of the WEM 2 is prevented from flowing into the first heat exchange passage 411. This makes it possible to prevent a deterioration in the function of the WEM 2.

[0051] Furthermore, in the water electrolysis / fuel cell systems 1 and 1A of this embodiment and its modifications, the first control valve 421 includes a first heat exchange valve 421a that opens and closes the first heat exchange passage 411 and a first bypass valve 421b that opens and closes the first bypass passage 413. The second control valve 422 includes a second heat exchange valve 422a that opens and closes the second heat exchange passage 412 and a second bypass valve 422b that opens and closes the second bypass passage 414. The control device closes the second bypass valve 422b and opens the second heat exchange valve 422a before shutting down the water electrolysis module 2 and before starting up the fuel cell module 3, and closes the first bypass valve 421b and opens the first heat exchange valve 421a before starting up the water electrolysis module 2 and before shutting down the fuel cell module 3.

[0052] With this configuration, for example, as between times t1 and t2 in Fig. 3 , before WEM 2 is stopped and FCM 3 is started, the heat medium that has passed through the first heat exchange passage 411 and whose temperature has increased through heat exchange with WEM 2 can be circulated through the second heat exchange passage 412 to warm up FCM 3. Similarly, as between times t3 and t4 in Fig. 3 , before WEM 2 is started and FCM 3 is stopped, the heat medium that has passed through the second heat exchange passage 412 and whose temperature has increased through heat exchange with FCM 3 can be circulated through the first heat exchange passage 411 to warm up WEM 2. Furthermore, in the flow direction of the heat medium in the heat medium passage 41, the first heat exchange passage 411 that exchanges heat between the heat medium and WEM 2 is disposed upstream of the second heat exchange passage 412 that exchanges heat between the heat medium and FCM 3. This not only prevents cationic eluates from FCM3 from flowing into WEM2 during warm-up of WEM2, but also prevents the operating temperature of WEM2 from increasing, preventing performance degradation of the water electrolysis cells that make up WEM2.

[0053] 2, the heat medium circulating through the heat medium circulator 4 is a fuel cell coolant. In this case, the water electrolysis module 2 includes a water electrolysis stack 21 and a pure water flow path 23 for supplying pure water to the water electrolysis stack 21. With this configuration, pure water can be supplied to the water electrolysis stack 21 of the WEM 2 while using FCC, which has excellent functionality, as a heat medium.

[0054] As described above, the present embodiment and its modified examples can provide the water electrolysis / fuel cell system 1, 1A that can reduce pressure loss in the heat medium flow path 41, which circulates the heat medium through the water electrolysis module 2 and the fuel cell module 3, and that can suppress performance degradation of the water electrolysis module 2.

[0055] [Embodiment 2] A second embodiment of a water electrolysis and fuel cell system according to the present disclosure will now be described with reference to Fig. 4. Fig. 4 is a schematic diagram showing the configuration of a second embodiment of a water electrolysis and fuel cell system according to the present disclosure. In a water electrolysis and fuel cell system 1B of this embodiment, components similar to those in the water electrolysis and fuel cell systems 1 and 1A described above are designated by the same reference numerals, and descriptions thereof will be omitted.

[0056] The water electrolysis / fuel cell system 1B of this embodiment uses FCC as the heat medium, similar to the water electrolysis / fuel cell system 1A shown in Fig. 2. Therefore, the water electrolysis module 2 includes a pure water tank 22 that stores pure water. The heat medium flow path 41 also includes a third heat exchange flow path 415 that is located downstream of the second heat exchange flow path 412 in the heat medium flow direction and exchanges heat between the heat medium and the pure water stored in the pure water tank 22.

[0057] With this configuration, even under operating conditions where the temperature of the external environment of the water electrolysis / fuel cell system 1B is below freezing, the pure water stored in the pure water tank 22 can be heated by heat exchange between the pure water stored in the pure water tank 22 and the heat medium flowing through the third heat exchange passage 415. Therefore, the pure water stored in the pure water tank 22 can be prevented from freezing.

[0058] [Embodiment 3] A third embodiment of a water electrolysis and fuel cell system according to the present disclosure will now be described with reference to Fig. 5. Fig. 5 is a schematic diagram showing the configuration of a third embodiment of a water electrolysis and fuel cell system according to the present disclosure. In a water electrolysis and fuel cell system 1C of this embodiment, components similar to those in the water electrolysis and fuel cell systems 1 and 1A described above are designated by the same reference numerals, and descriptions thereof will be omitted.

[0059] The heat medium flow path 41 constituting the heat medium circulator 4 of the water electrolysis / fuel cell system 1C of this embodiment has a heat exchanger 6 provided in the first heat exchange flow path 411 upstream of the water electrolysis module 2 in the heat medium flow direction. The heat exchanger 6 has a refrigerant flow path 61 through which a refrigerant that exchanges heat with the heat medium flowing through the first heat exchange flow path 411 flows.

[0060] With this configuration, if the temperature of the heat medium flowing into the first heat exchange flow path 411 becomes higher than the heat resistance temperature of WEM2 during warm-up before WEM2 is started, the heat medium can be cooled by the heat exchanger 6 upstream of WEM2 in the first heat exchange flow path 411. This allows the temperature of the heat medium exchanging heat with WEM2 to be lowered below the heat resistance temperature of WEM2. Therefore, WEM2 can be warmed up at a temperature equal to or lower than the heat resistance temperature of WEM2 while utilizing the exhaust heat of FCM3.

[0061] The above has described in detail an embodiment of the water electrolysis / fuel cell system according to the present disclosure using the drawings, but the specific configuration is not limited to this embodiment, and even if there are design changes and the like within the scope of the present disclosure, they are also included in the present disclosure. [Explanation of symbols]

[0062] 1. Water electrolysis and fuel cell system 1A-1C Water electrolysis and fuel cell systems 2 Water Electrolysis Module (WEM) 21 Water electrolysis stack 22 Pure water tank 23 Pure water flow path 3 Fuel Cell Module (FCM) 4 Heat medium circulation device 41 Heat transfer medium flow path 411 First heat exchange channel 412 Second heat exchange channel 413 1st detour flow path 414 2nd detour flow path 415 Third heat exchange channel 42 Multiple control valves 421 First control valve 421a First heat exchange valve 421b First diversion valve 422 Second control valve 422a Second heat exchange valve 422b Second diversion valve 6 Heat exchanger 61 Refrigerant flow path

Claims

1. A water electrolysis and fuel cell system comprising: a water electrolysis module; a fuel cell module; a heat medium circulator that circulates a heat medium that exchanges heat with the water electrolysis module and the fuel cell module; and a controller that controls the heat medium circulator, the heat medium circulating device includes a heat medium flow path through which the heat medium circulates, and a plurality of control valves that are controlled by the control device to open and close the heat medium flow path; the heat medium flow path includes a first heat exchange flow path that exchanges heat between the heat medium and the water electrolysis module, a second heat exchange flow path that exchanges heat between the heat medium and the fuel cell module downstream of the first heat exchange flow path in the flow of the heat medium, a first bypass flow path that bypasses the water electrolysis module, and a second bypass flow path that bypasses the fuel cell module; the plurality of control valves include a first control valve capable of opening and closing the first heat exchange passage and the first bypass passage, and a second control valve capable of opening and closing the second heat exchange passage and the second bypass passage, the control device, during operation of the water electrolysis module and while the fuel cell module is stopped, opens the first heat exchange passage and closes the first bypass passage with the first control valve, and closes the second heat exchange passage and opens the second bypass passage with the second control valve; and, during operation of the water electrolysis module and while the fuel cell module is stopped, closes the first heat exchange passage and opens the first bypass passage with the first control valve, and opens the second heat exchange passage and closes the second bypass passage with the second control valve.

2. the first control valve includes a first heat exchange valve that opens and closes the first heat exchange passage and a first bypass valve that opens and closes the first bypass passage, the second control valve includes a second heat exchange valve that opens and closes the second heat exchange passage and a second bypass valve that opens and closes the second bypass passage, 2. The water electrolysis / fuel cell system according to claim 1, wherein the control device closes the second bypass valve and opens the second heat exchange valve before the water electrolysis module is stopped and the fuel cell module is started, and closes the first bypass valve and opens the first heat exchange valve before the water electrolysis module is started and the fuel cell module is stopped.

3. the heat medium is a fuel cell coolant, 2. The water electrolysis / fuel cell system according to claim 1, wherein the water electrolysis module comprises a water electrolysis stack and a pure water flow path for supplying pure water to the water electrolysis stack.

4. the water electrolysis module includes a pure water tank that stores the pure water; 4. The water electrolysis / fuel cell system according to claim 3, wherein the heat medium flow path includes a third heat exchange flow path that is provided downstream of the second heat exchange flow path in a flow direction of the heat medium and exchanges heat between the heat medium and the pure water stored in the pure water tank.

5. the heat medium flow path includes a heat exchanger provided in the first heat exchange flow path upstream of the water electrolysis module in the flow direction of the heat medium, 2. The water electrolysis / fuel cell system according to claim 1, wherein the heat exchanger has a refrigerant flow path through which a refrigerant flows that exchanges heat with the heat medium flowing through the first heat exchange flow path.

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