Electrochemical stack

Abstract

SOLUTION: An electrochemical stack 12 comprises a water flow member 34 interposed between two electrochemical cells 30 located in a central region in the stacking direction of the electrochemical cells 30 among a plurality of electrochemical cells 30. The water flow member 34 is provided with a water introduction portion 20 and a flow path 50. The water introduction portion 20 introduces water supplied from the outside. The flow path 50 causes the water introduced from the water introduction portion 20 to flow along the electrochemical cells 30 and guides the water to a water introduction communication hole 36 that penetrates the plurality of electrochemical cells 30 in the stacking direction of the electrochemical cells 30.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to electrochemical stacks. [Background technology]

[0002] There are electrochemical stacks that have stacked electrochemical cells. Electrochemical stacks include water electrolysis stacks, hydrogen booster stacks (electrochemical hydrogen pump stacks), and fuel cell stacks. A water electrolysis stack has multiple stacked water electrolysis cells. A hydrogen booster stack has stacked hydrogen booster cells. A fuel cell stack has multiple stacked unit cells.

[0003] Patent Document 1 below discloses a water electrolysis system including a water electrolysis stack. In this water electrolysis system, water stored in a gas-liquid separator is supplied into the water electrolysis stack, and water that has not been electrolyzed and remains unreacted in the water electrolysis stack is discharged to the gas-liquid separator. The water supplied into the water electrolysis stack is then supplied to each of a plurality of water electrolysis cells. The unreacted water that has not been electrolyzed in each of the plurality of water electrolysis cells is then supplied from the water electrolysis stack to the gas-liquid separator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-123899 Summary of the Invention [Problem to be solved by the invention]

[0005] The electrochemical stack generates heat during operation, causing the temperature of the electrochemical stack to rise. The temperature distribution within the electrochemical stack is not uniform but varies. The rate of deterioration of the electrolyte membrane provided in the electrochemical cells that reach a relatively high temperature tends to progress faster than the rate of deterioration of the electrolyte membrane provided in the electrochemical cells that reach a relatively low temperature. Therefore, there is a need for a method to cool the electrochemical cells that reach a relatively high temperature.

[0006] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0007] An aspect of the present disclosure is an electrochemical stack comprising: a plurality of stacked electrochemical cells; a water inlet section for introducing water supplied from the outside; a water outlet section for discharging the water to the outside; a water inlet passage that penetrates the plurality of electrochemical cells in the stacking direction of the electrochemical cells and guides the water to a first port provided in each of the plurality of electrochemical cells; a water outlet passage that penetrates the plurality of electrochemical cells in the stacking direction and guides the water discharged from a second port provided in each of the plurality of electrochemical cells to the water outlet section; and a water distribution member interposed between two of the plurality of electrochemical cells that are located in a central region of the stacking direction, wherein the water distribution member is provided with the water inlet section and a flow path that flows the entire amount of water introduced from the water inlet section along the electrochemical cells and guides the entire amount of water to the water inlet passage. [Effects of the Invention]

[0008] According to the aspects of the present disclosure, it is possible to increase the degree of cooling of the electrochemical cells in the end regions and the electrochemical cells in the central region, which have a relatively high temperature. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a water supply system according to the first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the electrochemical stack according to the first embodiment. [Figure 3] FIG. 3 is a diagram showing a water supply system according to the second embodiment. [Figure 4] FIG. 4 is a schematic diagram showing an electrochemical stack according to the second embodiment. [Figure 5] FIG. 5 is a schematic diagram showing the configuration of the water flow member. [Figure 6] FIG. 6 is a diagram showing the flow of water in the water circulation channel during the first circulation operation. [Figure 7] FIG. 7 is a diagram showing the flow of water in the electrochemical stack during the first circulation operation. [Figure 8] FIG. 8 is a diagram showing the flow of water in the water circulation channel during the second circulation operation. [Figure 9] FIG. 9 is a diagram showing the flow of water in the electrochemical stack during the second circulation operation. [Figure 10] Figure 10A is a schematic diagram showing the temperature distribution of the electrochemical cell when only the first circulation operation is performed, Figure 10B is a schematic diagram showing the temperature distribution of the electrochemical cell when only the second circulation operation is performed, and Figure 10C is a schematic diagram showing the temperature distribution of the electrochemical cell when the first circulation operation and the second circulation operation are alternately repeated. DETAILED DESCRIPTION OF THE INVENTION

[0010] (First embodiment) 1 is a diagram showing a water supply system 10 according to a first embodiment. The water supply system 10 includes an electrochemical stack 12, a water circulation channel 14, a heat exchanger 16, and a circulation pump 18.

[0011] The electrochemical stack 12 is a stack capable of performing an electrochemical reaction. The electrochemical stack 12 may be a water electrolysis stack capable of performing water electrolysis. Alternatively, the electrochemical stack 12 may be a hydrogen booster stack (electrochemical hydrogen pump stack) capable of performing hydrogen (hydrogen gas) electrolysis. Alternatively, the electrochemical stack 12 may be a fuel cell stack capable of performing an electrochemical reaction between hydrogen (hydrogen gas) and oxygen (oxygen gas). The electrochemical stack 12 is formed, for example, in a substantially cylindrical shape.

[0012] The electrochemical stack 12 is provided with a water inlet 20 for introducing water from the outside and a water outlet 22 for discharging the water introduced from the water inlet 20. The water outlet 22 includes a first water outlet 24 and a second water outlet 26.

[0013] The water circulation flow path 14 is a passage for flowing water through the electrochemical stack 12. The water circulation flow path 14 is connected to the electrochemical stack 12. The water circulation flow path 14 includes a first flow path section 14a, a second flow path section 14b, and a third flow path section 14c. The first flow path section 14a connects the water inlet section 20 and the circulation pump 18. The second flow path section 14b connects the first water outlet section 24 and the circulation pump 18. The third flow path section 14c connects the second water outlet section 26 and the second flow path section 14b. The third flow path section 14c may also connect the second water outlet section 26 and the circulation pump 18. In this case, the second flow path section 14b connects the first water outlet section 24 and the third flow path section 14c.

[0014] The heat exchanger 16 is provided in a portion of the water circulation flow path 14 between the connection portion of the second flow path portion 14b and the third flow path portion 14c and the circulation pump 18. The heat exchanger 16 cools water heated by heat generated in the electrochemical stack 12. The heat exchanger 16 may be a radiator.

[0015] A circulation pump 18 circulates water between the heat exchanger 16 and the electrochemical stack 12 via the water circulation passage 14 .

[0016] 2 is a schematic diagram showing an electrochemical stack 12 according to the first embodiment. The electrochemical stack 12 includes a plurality of electrochemical cells 30, end plates 32a and 32b, a water distribution member 34, a water inlet communication hole 36, and a water outlet communication hole 38.

[0017] The electrochemical cells 30 are stacked between end plates 32a and 32b. The end plate 32a is a plate that constitutes one end of the electrochemical stack 12 in the stacking direction of the electrochemical cells 30. The end plate 32b is a plate that constitutes the other end of the electrochemical stack 12 in the stacking direction of the electrochemical cells 30.

[0018] The electrochemical cell 30 may be a water electrolysis cell capable of electrolyzing water. Alternatively, the electrochemical cell 30 may be a hydrogen booster cell (electrochemical hydrogen pump cell) capable of electrolyzing hydrogen. Alternatively, the electrochemical stack 12 may be a unit cell capable of performing an electrochemical reaction between hydrogen and oxygen.

[0019] Although detailed illustration is omitted, a membrane electrode assembly is provided in each of the multiple electrochemical cells 30. The membrane electrode assembly includes an electrolyte membrane and an anode power supply (anode electrode) and a cathode power supply (cathode electrode) disposed on both sides of the electrolyte membrane in the thickness direction.

[0020] Each of the electrochemical cells 30 is provided with a first port 40, a second port 42, and a water supply channel 44. The first port 40 is connected to the water inlet passage 36. The first port 40 is located on the opposite side of the water inlet section 20 in a direction intersecting the stacking direction of the electrochemical cells 30 (the perpendicular direction). More specifically, the first port 40 is located 180° out of phase with the water inlet section 20 in the circumferential direction of the electrochemical stack 12. The second port 42 is connected to the water outlet passage 38. The second port 42 is located on the opposite side of the first port 40 in a direction intersecting the stacking direction of the electrochemical cells 30 (the perpendicular direction). The water supply channel 44 connects the first port 40 and the second port 42. The water supply channel 44 extends in a direction intersecting the stacking direction of the electrochemical cells 30 (the perpendicular direction). The number of water supply channels 44 may be one or more.

[0021] The water distribution member 34 is interposed between two electrochemical cells 30 located in a central region in the stacking direction among the plurality of electrochemical cells 30. No other electrochemical cells 30 are interposed between the two electrochemical cells 30 interposed by the water distribution member 34. The central region is, for example, the middle region obtained by dividing the plurality of electrochemical cells 30 into thirds in the stacking direction. The outer regions in the stacking direction are sometimes referred to as edge regions. However, the central region may also be, for example, the middle region obtained by dividing the plurality of electrochemical cells 30 into thirds in a ratio of 1:2:1 in the stacking direction.

[0022] In the present embodiment, the water distribution member 34 is interposed between an electrochemical cell 30 located at one end in the stacking direction among the plurality of electrochemical cells 30 and an electrochemical cell 30 located at the other end in the stacking direction among the plurality of electrochemical cells 30, but is not limited to this. Furthermore, the water distribution member 34 is formed in a plate shape (specifically, a disk shape), but is not limited to this.

[0023] Unlike the electrochemical cells 30, the water distribution member 34 does not include a membrane electrode assembly. Therefore, unlike the electrochemical cells 30, electricity is not supplied to the water distribution member 34. The water distribution member 34 is provided with a water inlet section 20 and a flow path 50. One end of the flow path 50 is connected to the water inlet section 20. The other end of the flow path 50 is connected to the water inlet manifold 36. The flow path 50 extends in the same direction as the water supply channel 44. The cross-sectional area of ​​the flow path 50 is larger than the cross-sectional area of ​​each of the water supply channels 44 of the multiple electrochemical cells 30, but is not limited to this. The flow path 50 causes water introduced from the water inlet section 20 to flow along the electrochemical cells 30 and guide it to the water inlet manifold 36. The flow path 50 may be a groove formed in the water distribution member 34. In this case, the groove is sandwiched between two electrochemical cells 30 to form the flow path 50.

[0024] The water inlet communication hole 36 extends along the stacking direction of the electrochemical cells 30, and penetrates through the multiple electrochemical cells 30 and the water distribution member 34 in the stacking direction. In other words, the water inlet communication hole 36 communicates with the flow path 50. The water inlet communication hole 36 is disposed near the first port 40 of each of the multiple electrochemical cells 30, and guides water supplied from the flow path 50 to the first port 40 of each of the multiple electrochemical cells 30. In other words, the water inlet communication hole 36 communicates with the flow path 50 and the first port 40 of each of the multiple electrochemical cells 30.

[0025] The water discharge communication hole 38 extends along the stacking direction of the electrochemical cells 30 and penetrates the plurality of electrochemical cells 30 in the stacking direction. The water discharge communication hole 38 communicates with the second port 42 of each of the plurality of electrochemical cells 30 but does not communicate with the flow path 50. The water discharge communication hole 38 may penetrate the water distribution member 34 as long as it does not communicate with the flow path 50. The water discharge communication hole 38 is disposed near the second port 42 of each of the plurality of electrochemical cells 30 and guides water discharged from the second port 42 provided in each of the plurality of electrochemical cells 30 to the water discharge portion 22 (first water discharge portion 24, second water discharge portion 26). The first water discharge portion 24 is provided in the electrochemical cell 30 located at one end of the plurality of electrochemical cells 30 in the stacking direction. The second water discharge portion 26 is provided in the electrochemical cell 30 located at the other end of the plurality of electrochemical cells 30 in the stacking direction.

[0026] In the water supply system 10 configured as above, the circulation pump 18 is driven during operation of the electrochemical stack 12. In response to the driving of the circulation pump 18, water is circulated as follows.

[0027] As shown in FIG. 1 , water output from the circulation pump 18 is supplied to the water inlet 20 (inside an electrochemical cell 30 located approximately in the center of the stacking direction of the electrochemical cells 30) via the first flow path 14a. As shown in FIG. 2 , the water supplied to the water inlet 20 flows through the flow path 50 of the water distribution member 34. The water flowing through the flow path 50 passes between two electrochemical cells 30 located in the center region of the stacking direction of the electrochemical cells 30 and flows into the water inlet communication hole 36. The water that flows into the water inlet communication hole 36 flows in the stacking direction of the electrochemical cells 30 and reaches the first port 40 of each of the multiple electrochemical cells 30. The water that reaches the first port 40 flows through the water supply channel 44 and the second port 42 into the water outlet communication hole 38. The water that flows into the water outlet communication hole 38 flows in the stacking direction of the electrochemical cells 30 and reaches the first water outlet section 24 or the second water outlet section 26. 1, the water that reaches the first water outlet 24 is supplied to the circulation pump 18 via the second flow path 14b. On the other hand, the water that reaches the second water outlet 26 flows into the second flow path 14b via the third flow path 14c and is supplied to the circulation pump 18.

[0028] The temperature of the electrochemical stack 12 rises in response to the operation of the electrochemical stack 12. It has been found that the temperature of the electrochemical stack 12 increases toward the electrochemical cells 30 located in the middle of the stacking direction. This is because the electrochemical cells 30 located in the middle are less able to dissipate heat than the electrochemical cells 30 located at the ends.

[0029] The electrochemical stack 12 of this embodiment is provided with a water distribution member 34. The water distribution member 34 is interposed between two electrochemical cells 30 located in a central region in the stacking direction of the electrochemical cells 30 among the plurality of electrochemical cells 30. The water distribution member 34 is provided with a flow path 50 that guides water supplied from the outside along the electrochemical cells 30 and to the water inlet passage 36. Therefore, the entire amount of water supplied from the outside passes through the electrochemical cells 30 in the central region, which has a relatively high temperature, before being distributed and supplied to each of the plurality of electrochemical cells 30. As a result, the amount of water flowing through the flow path 50 is greater than the amount of water flowing through each electrochemical cell 30, thereby increasing the degree of cooling of the electrochemical cells 30 in the central region, which has a relatively high temperature.

[0030] In this embodiment, when the first port 40 of each electrochemical cell 30 communicating with the water inlet passage 36 distributes water to each of the multiple electrochemical cells 30, the first port 40 is located on the opposite side to the water inlet section 20 that introduces water supplied from the outside (see FIG. 2). Therefore, it is easy to increase the distance that water must pass between the electrochemical cells 30, which become relatively hot.

[0031] In this embodiment, the cross-sectional flow area of ​​the flow path 50 is larger than the cross-sectional flow area of ​​the water supply path 44 provided in the electrochemical cell 30. Therefore, it is easier to increase the degree of cooling of the electrochemical cell 30 in the central region compared to when the cross-sectional area of ​​the flow path 50 is equal to or smaller than the cross-sectional area of ​​the water supply path 44. In particular, it is preferable that the cross-sectional flow area of ​​the flow path 50 is larger than the cross-sectional flow area of ​​the water supply path 44 when viewed from the stacking direction.

[0032] Furthermore, in this embodiment, the water distribution member 34 is interposed between an electrochemical cell 30 located at one end of the plurality of electrochemical cells 30 in the stacking direction and an electrochemical cell 30 located at the other end of the plurality of electrochemical cells 30 in the stacking direction, in other words, between the electrochemical cells 30 in the end regions. Therefore, compared to when the water distribution member 34 is interposed between the other two electrochemical cells 30, it is easier to increase the degree of cooling of the electrochemical cell 30 in the central region.

[0033] (Second embodiment) In the second embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals. In the second embodiment, descriptions that overlap with those in the first embodiment will be omitted. Figure 3 is a diagram showing a water supply system 10 according to the second embodiment.

[0034] In the present embodiment, the water supply system 10 further includes a plurality of on-off valves 60A, 60B, 60C, 60D, 60E, and 60F and a control unit 62. The plurality of on-off valves 60A, 60B, 60C, 60D, 60E, and 60F are provided in the water circulation flow path 14. The control unit 62 drives the circulation pump 18 during operation of the electrochemical stack 12. The control unit 62 controls the plurality of on-off valves 60A, 60B, 60C, 60D, 60E, and 60F during operation of the electrochemical stack 12.

[0035] In this embodiment, the electrochemical stack 12 has two water inlet portions 20, two first water outlet portions 24, and two second water outlet portions 26. One of the two water inlet portions 20 is referred to as water inlet portion 20x, and the other of the two water inlet portions 20 is referred to as water inlet portion 20y. The water inlet portion 20y is provided at a position 180° out of phase with the water inlet portion 20x in the circumferential direction of the electrochemical stack 12. One of the two first water outlet portions 24 is referred to as first water outlet portion 24x, and the other of the two first water outlet portions 24 is referred to as first water outlet portion 24y. The first water outlet portion 24y is provided at a position 180° out of phase with the first water outlet portion 24x in the circumferential direction of the electrochemical stack 12. One of the two second water outlet portions 26 is referred to as second water outlet portion 26x, and the other of the two second water outlet portions 26 is referred to as second water outlet portion 26y. Second water outlet portion 26y is provided at a position that is 180° out of phase with second water outlet portion 26x in the circumferential direction of the electrochemical stack 12.

[0036] In this embodiment, the water circulation flow path 14 further includes a fourth flow path section 14d, a fifth flow path section 14e, and a sixth flow path section 14f. The fourth flow path section 14d connects the first flow path section 14a and the water inlet section 20y. The fifth flow path section 14e connects the second flow path section 14b and the first water outlet section 24y. The sixth flow path section 14f connects the fifth flow path section 14e and the second water outlet section 26y. The sixth flow path section 14f may also connect the second flow path section 14b and the second water outlet section 26y. In this case, the fifth flow path section 14e connects the sixth flow path section 14f and the second water outlet section 26y.

[0037] An on-off valve 60A is provided in the first flow path section 14a near the water inlet section 20x. An on-off valve 60B is provided in the fourth flow path section 14d near the water inlet section 20y. An on-off valve 60C is provided in the second flow path section 14b near the first water outlet section 24x. An on-off valve 60D is provided in the fifth flow path section 14e near the first water outlet section 24y. An on-off valve 60E is provided in the third flow path section 14c near the second water outlet section 26x. An on-off valve 60F is provided in the sixth flow path section 14f near the second water outlet section 26y.

[0038] FIG. 4 is a schematic diagram showing an electrochemical stack 12 according to a second embodiment. In this embodiment, the electrochemical stack 12 has two water lead-out inlet / outlet communication holes 64 instead of the water lead-in communication hole 36 and the water lead-out communication hole 38. One of the two water lead-out inlet / outlet communication holes 64 is referred to as the water lead-out inlet / outlet communication hole 64x, and the other of the two water lead-out inlet / outlet communication holes 64 is referred to as the water lead-out inlet / outlet communication hole 64y. The water lead-out inlet / outlet communication hole 64x and the water lead-out inlet / outlet communication hole 64y function as the water lead-in communication hole 36 or the water lead-out communication hole 38. When the water lead-out inlet / outlet communication hole 64x functions as the water lead-in communication hole 36, the water lead-out inlet / outlet communication hole 64y functions as the water lead-out communication hole 38. Conversely, when the water lead-out inlet / outlet communication hole 64y functions as the water lead-in communication hole 36, the water lead-out inlet / outlet communication hole 64x functions as the water lead-out communication hole 38.

[0039] In this embodiment, the configuration of the water distribution member 34 is different from that of the first embodiment. Fig. 5 is a schematic diagram showing the configuration of the water distribution member 34. Fig. 5 shows the water distribution member 34 as viewed from the front in the stacking direction of the electrochemical cells 30. The water distribution member 34 shown in Fig. 5 is formed in a disk shape, but is not limited to this.

[0040] The water distribution member 34 is provided with a water inlet section 20x, a water inlet section 20y, and two flow paths 50. One of the two flow paths 50 is referred to as flow path 50x, and the other of the two flow paths 50 is referred to as flow path 50y. One end of flow path 50x is connected to the water inlet section 20x. The other end of flow path 50x is connected to the water lead-in / outlet communication hole 64x. One end of flow path 50y is connected to the water inlet section 20y. The other end of flow path 50y is connected to the water lead-in / outlet communication hole 64y. Flow paths 50x and flow path 50y are provided separately in the water distribution member 34 and do not communicate with each other.

[0041] In the water supply system 10 configured as above, the control unit 62 alternately repeats the first circulation operation and the second circulation operation while the electrochemical stack 12 is in operation.

[0042] Fig. 6 is a diagram showing the flow of water in the water circulation channel 14 during the first circulation operation. Fig. 7 is a diagram showing the flow of water in the electrochemical stack 12 during the first circulation operation. As shown in Fig. 6, during the first circulation operation, the control unit 62 opens the on-off valves 60A, 60C, and 60E and closes the on-off valves 60B, 60D, and 60F.

[0043] Water output from the circulation pump 18 is supplied to the water inlet 20x via the first flow path 14a. As shown in FIG. 5, the entire amount of water supplied to the water inlet 20x flows through the flow path 50x of the water distribution member 34. As shown in FIG. 7, the water flowing through the flow path 50x passes between two electrochemical cells 30 located in the central region in the stacking direction of the electrochemical cells 30 and flows into the water lead-out inlet / outlet communication hole 64x. The water lead-out inlet / outlet communication hole 64x functions as the water inlet communication hole 36. That is, the water that flows into the water lead-out inlet / outlet communication hole 64x flows in the stacking direction of the electrochemical cells 30 and reaches the first port 40 of each of the multiple electrochemical cells 30. The water that reaches the first port 40 flows through the water supply path 44 and flows out from the second port 42 to the water lead-out inlet / outlet communication hole 64y. The water lead-out inlet / outlet communication hole 64y functions as the water lead-out communication hole 38. That is, the water that flows out into the water lead-out inlet / outlet communication hole 64y flows in the stacking direction of the electrochemical cell 30 and reaches the first water lead-out portion 24x or the second water lead-out portion 26x. As shown in Fig. 6, the water that reaches the first water lead-out portion 24x is supplied to the circulation pump 18 via the second flow path portion 14b. On the other hand, the water that reaches the second water lead-out portion 26x flows into the second flow path portion 14b via the third flow path portion 14c and is supplied to the circulation pump 18.

[0044] Fig. 8 is a diagram showing the flow of water in the water circulation channel 14 during the second circulation operation. Fig. 9 is a diagram showing the flow of water in the electrochemical stack 12 during the second circulation operation. As shown in Fig. 8, during the second circulation operation, the control unit 62 opens the on-off valves 60B, 60D, and 60F and closes the on-off valves 60A, 60C, and 60E.

[0045] Water output from the circulation pump 18 flows into the fourth flow path portion 14d via the first flow path portion 14a and is then supplied to the water inlet portion 20y. As shown in FIG. 5, the entire amount of water supplied to the water inlet portion 20y flows through the flow path 50y of the water distribution member 34. As shown in FIG. 9, the water flowing through the flow path 50y passes between two electrochemical cells 30 located in the central region in the stacking direction of the electrochemical cells 30 and flows into the water lead-in / outlet communication hole 64y. The water lead-in / outlet communication hole 64y functions as the water inlet communication hole 36. That is, the water that flows into the water lead-in / outlet communication hole 64y flows in the stacking direction of the electrochemical cells 30 and reaches the second port 42 of each of the multiple electrochemical cells 30. The water that reaches the second port 42 flows through the water supply channel 44 from the first port 40 to the water lead-in / outlet communication hole 64x. The water lead-in / outlet communication hole 64x functions as the water lead-out communication hole 38. That is, the water that flows out into the water lead-out inlet / outlet communication hole 64x flows in the stacking direction of the electrochemical cell 30 and reaches the first water lead-out portion 24y or the second water lead-out portion 26y. As shown in Fig. 8, the water that reaches the first water lead-out portion 24y flows into the second flow path portion 14b via the fifth flow path portion 14e and is supplied to the circulation pump 18. On the other hand, the water that reaches the second water lead-out portion 26y flows into the fifth flow path portion 14e via the sixth flow path portion 14f, and then flows into the second flow path portion 14b and is supplied to the circulation pump 18.

[0046] As described above, in the electrochemical stack 12 of this embodiment, similarly to the first embodiment, water supplied from the outside can be passed between the electrochemical cells 30 that reach a relatively high temperature, and then supplied to each of the plurality of electrochemical cells 30. As a result, the degree of cooling of the electrochemical cells 30 in the central region that reach a relatively high temperature can be increased.

[0047] Furthermore, in the electrochemical stack 12 of this embodiment, a first circulation operation and a second circulation operation are alternately repeated during operation of the electrochemical stack 12. In the first circulation operation, the control unit 62 adjusts the opening and closing of the multiple on-off valves 60A-60F so that water flows from the first port 40 to the second port 42 in each electrochemical cell 30. On the other hand, in the second circulation operation, the control unit 62 adjusts the opening and closing of the multiple on-off valves 60A-60F so that water flows from the second port 42 to the first port 40 in each electrochemical cell 30. Therefore, compared to when only the first circulation operation or the second circulation operation is performed, the difference between the temperature upstream and downstream of the water supply channel 44 can be reduced. That is, when only the first circulation operation is performed, the temperature near the second port 42 remains higher than the temperature near the first port 40, as shown in FIG. 10A . On the other hand, when only the second circulation operation is performed, the temperature near the first port 40 remains higher than the temperature near the second port 42, as shown in FIG. 10B. This means that variations in electrolysis efficiency and the degree of degradation occur within the surface of the membrane electrode assembly. By alternately repeating the first circulation operation and the second circulation operation during operation of the electrochemical stack 12, the difference between the upstream and downstream temperatures can be reduced, as shown in FIG. 10C. As a result, variations in electrolysis efficiency and the degree of degradation within the surface of the membrane electrode assembly can be reduced. Note that FIGS. 10A, 10B, and 10C show the temperature distribution of the electrochemical cell 30 when viewed from the stacking direction. Also, FIGS. 10A, 10B, and 10C illustrate the case where the electrochemical cell 30 is provided with a plurality of water supply channels 44.

[0048] The following additional notes are further disclosed regarding the above embodiment.

[0049] (Appendix 1) The electrochemical stack (12) of the present disclosure comprises a plurality of stacked electrochemical cells (30), a water inlet section (20) for introducing water supplied from the outside, a water outlet section (22) for discharging the water to the outside, a water inlet communication hole (36) that penetrates the plurality of electrochemical cells in the stacking direction of the electrochemical cells and guides the water to a first port (40) provided in each of the plurality of electrochemical cells, a water outlet communication hole (38) that penetrates the plurality of electrochemical cells in the stacking direction and guides the water discharged from a second port (42) provided in each of the plurality of electrochemical cells to the water outlet section, and a water distribution member (34) interposed between two of the plurality of electrochemical cells that are located in a central region in the stacking direction, wherein the water distribution member is provided with the water inlet section and a flow path (50) that flows the entire amount of water introduced from the water inlet section along the electrochemical cells and guides it to the water inlet communication hole.

[0050] (Appendix 2) In the electrochemical stack according to Supplementary Note 1, the first port may be located on an opposite side to the water inlet in a direction intersecting the stacking direction.

[0051] (Appendix 3) In the electrochemical stack according to Supplementary Note 1, a cross-sectional flow area of ​​the flow path may be larger than a cross-sectional flow area of ​​a water supply channel (44) connecting the first port and the second port.

[0052] (Appendix 4) In the electrochemical stack described in Appendix 1, the water distribution member may be interposed between an electrochemical cell located at one end of the plurality of electrochemical cells in the stacking direction and an electrochemical cell located at the other end of the plurality of electrochemical cells in the stacking direction.

[0053] (Appendix 5) In the electrochemical stack described in Appendix 1, the water lead-out section may have a first water lead-out section (24) provided in the electrochemical cell located at one end of the plurality of electrochemical cells in the stacking direction, and a second water lead-out section (26) provided in the electrochemical cell located at the other end of the plurality of electrochemical cells in the stacking direction.

[0054] (Appendix 6) In the electrochemical stack according to Supplementary Note 1, each of the plurality of electrochemical cells may be a water electrolysis cell that electrolyzes the water.

[0055] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments. [Explanation of symbols]

[0056] 10...Water supply system 12...Electrochemical stack 14...Water circulation channel 16...Heat exchanger 18...Circulation pump 20, 20x, 20y...Water inlet 22...Water outlet part 24, 24x, 24y...1st water outlet part 26, 26x, 26y... Second water outlet portion 30... Electrochemical cell 34...Water distribution member 36...Water introduction communication hole 38...Water outlet communication hole 40...First port 42...Second port 44...Water supply channel 50, 50x, 50y...flow path 60A, 60B, 60C, 60D, 60E, 60F...Shut-off valve 62...Control section 64, 64x, 64y...Water inlet / outlet communication holes

Claims

1. a plurality of electrochemical cells stacked together; a water inlet for introducing water supplied from the outside; a water outlet portion that discharges the water to the outside; a water inlet passage that penetrates the plurality of electrochemical cells in a stacking direction of the electrochemical cells and introduces the water to a first port provided in each of the plurality of electrochemical cells; a water outlet communication hole that penetrates the plurality of electrochemical cells in the stacking direction and that guides the water discharged from a second port provided in each of the plurality of electrochemical cells to the water outlet portion; a water distribution member interposed between two of the plurality of electrochemical cells that are located in a central region in the stacking direction; Equipped with the water distribution member is provided with the water inlet portion and a flow path that guides the entire amount of water introduced from the water inlet portion along the electrochemical cell and to the water inlet passage.

2. 10. The electrochemical stack of claim 1, The electrochemical stack, wherein the first port is located on the opposite side to the water inlet in a direction intersecting the stacking direction.

3. 10. The electrochemical stack of claim 1, an electrochemical stack, wherein a cross-sectional area of ​​the flow path is larger than a cross-sectional area of ​​a water supply channel connecting the first port and the second port;

4. 10. The electrochemical stack of claim 1, an electrochemical stack, wherein the water distribution member is interposed between an electrochemical cell located at one end of the plurality of electrochemical cells in the stacking direction and an electrochemical cell located at the other end of the plurality of electrochemical cells in the stacking direction.

5. 10. The electrochemical stack of claim 1, an electrochemical stack, wherein the water discharge section includes a first water discharge section provided in the electrochemical cell located at one end of the plurality of electrochemical cells in the stacking direction, and a second water discharge section provided in the electrochemical cell located at the other end of the plurality of electrochemical cells in the stacking direction.

6. 10. The electrochemical stack of claim 1, An electrochemical stack, wherein each of the plurality of electrochemical cells is a water electrolysis cell that electrolyzes the water.

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