Fuel cell module

Abstract

Provided is a technique for reducing the size of a fuel cell module having a shunt flow path. This fuel cell module is provided with: a fuel cell stack comprising a plurality of stacked fuel cells, the fuel cell stack having a first end surface on one side in the stacking direction of the plurality of fuel cells, and a second end surface on the other side in the stacking direction; an oxidant gas inlet manifold having, on a first end surface, an oxidant gas supply port for receiving supply of oxidant gas, and having, on a second end surface, a first oxidant gas discharge port; an oxidant gas outlet manifold configured so as to allow the oxidant gas passing through each fuel cell to flow therethrough, the oxidant gas outlet manifold having a second oxidant gas discharge port on a second end surface; a discharge flow path connected to the oxidant gas second discharge port and discharging the oxidant gas from the oxidant gas outlet manifold; and a shunt flow path connecting the first oxidant gas discharge port and the discharge flow path.

Description

Technical Field

[0001] The technology disclosed in this specification relates to fuel cell modules. Background Technology

[0002] Patent Document 1 discloses a fuel cell module comprising a fuel cell stack consisting of multiple fuel cell units stacked together. The fuel cell stack generates electricity by reacting fuel gas with oxidant gas.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-155212

[0004] In fuel cell modules, a split flow path is sometimes provided, connecting an oxidant gas supply path upstream of the fuel cell stack to an oxidant gas discharge path downstream of the fuel cell stack. By adjusting the oxidant gas flow rate in the split flow path, the flow rate of oxidant gas flowing to the fuel cell stack can be adjusted. In many fuel cell modules, the oxidant gas supply path is connected to one end of the fuel cell stack, and the oxidant gas discharge path is connected to the other end. Therefore, the total length of the split flow path is longer than the total length of the fuel cell stack, making it difficult to miniaturize the fuel cell module. This specification proposes a technique for miniaturizing fuel cell modules with split flow paths. Summary of the Invention

[0005] (Method 1)

[0006] The fuel cell module disclosed in this specification includes: a fuel cell stack comprising a plurality of stacked fuel cell units, having a first end face on one side of the stacking direction of the plurality of fuel cell units and a second end face on the other side of the stacking direction; an oxidant gas inlet manifold extending inside the fuel cell stack along the stacking direction, having an oxidant gas supply port on the first end face for receiving oxidant gas and a first oxidant gas outlet on the second end face, configured to allow oxidant gas to flow from the oxidant gas inlet manifold to each fuel cell unit; an oxidant gas outlet manifold extending inside the fuel cell stack along the stacking direction, configured to allow oxidant gas to flow through each fuel cell unit, and having a second oxidant gas outlet on the second end face; a discharge path connected to the second oxidant gas outlet to discharge oxidant gas from the oxidant gas outlet manifold; and a diversion path connecting the first oxidant gas outlet to the discharge path.

[0007] In the aforementioned fuel cell module, the shunt flow path connects the first oxidant gas outlet located on the second end face to the outlet flow path extending from the second end face, thus shortening the shunt flow path. Therefore, the fuel cell module can be miniaturized. Attached Figure Description

[0008] Figure 1 This is a simplified diagram of a fuel cell module.

[0009] Figure 2 This is a flowchart of the operation process of the fuel cell module.

[0010] Figure 3 This is a flowchart of the operation process of the fuel cell module.

[0011] Figure 4 This is a flowchart of the operation process of the fuel cell module.

[0012] Figure 5 This is a flowchart of the operation process of the fuel cell module. Detailed Implementation

[0013] Following on method 1 above, the additional structure of the fuel cell system disclosed in this specification will be described below.

[0014] (Method 2)

[0015] According to the fuel cell module described in Method 1, it further comprises: an air compressor for supplying oxidant gas from the oxidant gas supply port to the oxidant gas inlet manifold; a first valve for opening and closing the discharge flow path upstream of the connection between the discharge flow path and the branch flow path; a second valve for opening and closing the branch flow path; and a control device for performing an exhaust and drainage operation after the power generation of the fuel cell stack stops, wherein, in the exhaust and drainage operation, the first valve is closed and the second valve is open, oxidant gas is supplied to the oxidant gas inlet manifold through the air compressor.

[0016] (Method 3)

[0017] The fuel cell module according to method 1 or 2 further comprises: an air compressor for supplying oxidant gas from the oxidant gas supply port to the oxidant gas inlet manifold; and a control device for performing a fuel gas concentration reduction operation before the power generation of the fuel cell stack begins, wherein, during the fuel gas concentration reduction operation, the pressure of the oxidant gas in the oxidant gas inlet manifold is repeatedly increased or decreased by the air compressor while the discharge flow path and the diversion flow path are closed.

[0018] According to method 2, after power generation stops, the water adhering to the second valve during power generation can be blown away using oxidant gas supplied from the air compressor.

[0019] According to method 3, when fuel gas accumulates in the oxidant gas inlet manifold during power generation shutdown, the fuel gas concentration in the oxidant gas inlet manifold can be reduced by a fuel gas concentration reduction action. Therefore, it is possible to prevent high concentrations of fuel gas from being discharged from the fuel cell stack to the outside at the start of power generation.

[0020] (Example 1)

[0021] Figure 1 The fuel cell module 100 of Embodiment 1 shown is mounted on a device powered by a fuel cell (e.g., a fuel cell vehicle). The fuel cell module 100 has a fuel cell stack 10. The fuel cell module 100 supplies power generated by the fuel cell stack 10 to motors, etc.

[0022] The fuel cell stack 10 has a plurality of stacked fuel cell units 12, end plates 14 and 16. One end of the stack of fuel cell units 12 is covered by end plate 14, and the other end of the stack of fuel cell units 12 is covered by end plate 16. That is, the stack of fuel cell units 12 is sandwiched between end plates 14 and end plates 16 in the stacking direction. Furthermore, hereafter, in the fuel cell stack 10, the end face on the end plate 14 side is referred to as the first end face 10a, and the end face on the end plate 16 side is referred to as the second end face 10b.

[0023] like Figure 1 As shown, an oxidant gas inlet manifold 20 is provided inside the fuel cell stack 10. The oxidant gas inlet manifold 20 passes through each fuel cell cell 12, end plate 14, and end plate 16, and extends along the stacking direction inside the fuel cell stack 10. The oxidant gas inlet manifold 20 has an oxidant gas supply port 20a and an oxidant gas outlet 20b. The oxidant gas supply port 20a is located on a first end face 10a. The oxidant gas outlet 20b is located on a second end face 10b. Oxidant gas (e.g., air) is supplied to the oxidant gas supply port 20a from the supply flow path 22 (described later). The oxidant gas supplied from the oxidant gas supply port 20a flows from the oxidant gas inlet manifold 20 to each fuel cell cell 12. Oxidant gas is supplied to each fuel cell cell 12 from the oxidant gas inlet manifold 20, and fuel gas (e.g., hydrogen) is supplied from a fuel gas manifold (not shown). Each fuel cell cell 12 generates electricity by reacting the oxidant gas with the fuel gas.

[0024] The fuel cell module 100 includes a supply path 22, an air compressor 24, an intercooler 26, and an inlet valve 28. The upstream end of the supply path 22 is connected to an oxidant gas supply source (not shown). The downstream end of the supply path 22 is connected to an oxidant gas supply port 20a. The supply path 22 supplies oxidant gas to the oxidant gas inlet manifold 20.

[0025] An air compressor 24 is located in the supply flow path 22. The air compressor 24 pressurizes the oxidant gas in the supply flow path 22 and sends it downstream.

[0026] Intercooler 26 is a supply flow path 22 located downstream of air compressor 24. High-pressure, high-temperature oxidant gas supplied from air compressor 24 flows to intercooler 26. Coolant is supplied to intercooler 26 via a cooling flow path (not shown). Intercooler 26 cools the oxidant gas using the coolant.

[0027] Inlet valve 28 is located downstream of intercooler 26 in supply flow path 22. Inlet valve 28 adjusts the flow rate of oxidant gas supplied from supply flow path 22 to oxidant gas inlet manifold 20 by adjusting the opening of supply flow path 22.

[0028] like Figure 1 As shown, an oxidant gas outlet manifold 30 is provided inside the fuel cell stack 10. The oxidant gas outlet manifold 30 passes through each fuel cell unit 12 and the end plate 16, and extends along the stacking direction inside the fuel cell stack 10. The oxidant gas outlet manifold 30 has an oxidant gas outlet 30a. The oxidant gas outlet 30a is located on the second end face 10b. Oxidant gas passing through each fuel cell unit 12 flows into the oxidant gas outlet manifold 30.

[0029] The fuel cell module 100 has a discharge path 32 and a pressure regulating valve 34. The upstream end of the discharge path 32 is connected to the oxidant gas outlet 30a. Oxidant gas flowing in the oxidant gas outlet manifold 30 is discharged to the outside of the fuel cell stack 10 via the discharge path 32. A pressure regulating valve 34 is provided in the discharge path 32. The pressure regulating valve 34 opens and closes the flow path of the discharge path 32. In addition, the pressure in the oxidant gas outlet manifold 30 is adjusted by adjusting the opening degree of the pressure regulating valve 34.

[0030] The fuel cell module 100 has a flow branch path 40 and a flow branch valve 42. The upstream end of the flow branch path 40 is connected to the oxidant gas outlet 20b. The downstream end of the flow branch path 40 is connected to the discharge path 32 downstream of the pressure regulating valve 34. The flow branch valve 42 is provided in the flow branch path 40. The flow branch valve 42 opens and closes the flow path of the flow branch path 40. When the flow branch valve 42 is open, a portion of the oxidant gas flowing in the oxidant gas inlet manifold 20 flows into the flow branch path 40. The oxidant gas in the flow branch path 40 flows into the discharge path 32. If the opening degree of the flow branch valve 42 is changed, the flow rate of the oxidant gas flowing into the flow branch path 40 changes, and therefore the flow rate of the oxidant gas flowing into each fuel cell unit 12 also changes. Therefore, the flow rate of the oxidant gas flowing into each fuel cell unit 12 can be adjusted by the flow branch valve 42.

[0031] The fuel cell module 100 has a control device 50. The control device 50 controls the air compressor 24, the inlet valve 28, the pressure regulating valve 34, and the flow divider valve 42.

[0032] When the fuel cell module 100 generates electricity, the control device 50 opens the inlet valve 28, the pressure regulating valve 34, and the diversion valve 42. The control device 50 also drives the air compressor 24. Therefore, oxidant gas is supplied from the supply flow path 22 to the oxidant gas inlet manifold 20. Thus, oxidant gas is supplied from the oxidant gas inlet manifold 20 to each fuel cell unit 12. Additionally, the control device 50 supplies fuel gas to each fuel cell unit 12 by controlling the fuel gas supply system. Each fuel cell unit 12 generates electricity by reacting the oxidant gas with the fuel gas. The oxidant gas passing through each fuel cell unit 12 flows to the oxidant gas outlet manifold 30. The oxidant gas flows from the oxidant gas outlet manifold 30 to the discharge flow path 32. Furthermore, a portion of the oxidant gas in the oxidant gas inlet manifold 20 flows to the discharge flow path 32 through the diversion flow path 40. The oxidant gas in the discharge flow path 32 is discharged to the outside of the fuel cell module 100.

[0033] Additionally, if the oxidant gas reacts with the fuel gas in each fuel cell unit 12, water is generated. This generated water is discharged from each fuel cell unit 12 to the oxidant gas inlet manifold 20 and the oxidant gas outlet manifold 30. The generated water discharged to the oxidant gas inlet manifold 20 flows together with the oxidant gas through the branch flow path 40 to the outlet flow path 32. The generated water discharged to the oxidant gas outlet manifold 30 flows together with the oxidant gas to the outlet flow path 32. The generated water is discharged from the outlet flow path 32 to the outside of the fuel cell module 100.

[0034] As explained above, the oxidant gas flowing in the split flow path 40 bypasses each fuel cell unit 12 and flows to the discharge flow path 32. Both the oxidant gas outlet 20b of the oxidant gas inlet manifold 20 and the discharge flow path 32 are located on the second end face 10b side, thus shortening the split flow path 40 that connects them. That is, compared to the case where the split flow path is configured to connect the supply flow path 22 and the discharge flow path 32, the split flow path 40 can be shortened. Therefore, the fuel cell module 100 can be miniaturized.

[0035] During power generation, generated water sometimes adheres to the diversion path 40 and the diversion valve 42. In cold regions, the generated water adhering to the diversion valve 42 may freeze, causing the diversion valve 42 to deteriorate. Therefore, after power generation by the fuel cell stack 10 stops, the control device 50 can perform an venting and drainage operation to remove the generated water adhering to the diversion valve 42. The control device 50 follows... Figure 2 The flowchart selectively executes the exhaust and drainage actions.

[0036] In step S2, the control device 50 measures the external air temperature using a temperature sensor (not shown). The control device 50 determines whether the external air temperature is below a predetermined temperature T1 (e.g., 0°C). If the external air temperature is below the predetermined temperature T1, the control device 50 performs an exhaust and drainage operation in step S4. If the external air temperature is below the predetermined temperature T1, the control device 50 does not perform step S4 (i.e., the exhaust and drainage operation).

[0037] During the exhaust and drainage operation, the control device 50 closes the pressure regulating valve 34 and opens the inlet valve 28 and the diversion valve 42. Additionally, the control device 50 drives the air compressor 24. When the air compressor 24 is driven, oxidant gas is supplied to the oxidant gas inlet manifold 20. Since the pressure regulating valve 34 is closed, oxidant gas does not flow from the oxidant gas inlet manifold 20 to the individual fuel cell units 12. Therefore, all oxidant gas supplied to the oxidant gas inlet manifold 20 is discharged to the outlet manifold 32 via the diversion path 40. Therefore, during the exhaust and drainage operation, the flow rate of oxidant gas flowing to the diversion valve 42 increases compared to the power generation operation. Therefore, the generated water adhering to the diversion valve 42 is blown away by the oxidant gas during the exhaust and drainage operation. Therefore, the generated water is removed from the diversion valve 42. Therefore, during power generation shutdown, it is possible to prevent the generated water from freezing on the surface of the diversion valve 42.

[0038] In addition, Figure 2 In this process, the control device 50 performs the exhaust and drainage operation when the external temperature is below the judgment temperature T1, but it is also possible that the control device 50 performs the exhaust and drainage operation after the power generation stops, regardless of the external temperature.

[0039] After power generation in the fuel cell stack 10 stops, fuel gas from the fuel gas manifold (not shown) sometimes flows into the oxidant gas inlet manifold 20 through each fuel cell unit 12, causing a high concentration of fuel gas in the oxidant gas inlet manifold 20. If power generation starts while the fuel gas concentration in the oxidant gas inlet manifold 20 is high, the high concentration of fuel gas in the oxidant gas inlet manifold 20 is discharged to the outside of the fuel cell module 100. Therefore, the control device 50 can perform a fuel gas concentration reduction action to reduce the concentration of fuel gas in the oxidant gas inlet manifold 20 before power generation in the fuel cell stack 10 begins. The control device 50 follows... Figure 3 The flowchart is used to selectively perform fuel gas concentration reduction actions.

[0040] The control device 50 can measure the elapsed time (hereinafter referred to as elapsed time t1) since the power generation of the fuel cell stack 10 has stopped using a timer (not shown). If the main switch of the fuel cell stack 10 is turned on, the control device 50 determines in step S10 whether the elapsed time t1 is longer than a predetermined time ta (e.g., half a day). If the elapsed time t1 is longer than the predetermined time ta, the control device 50 performs a fuel gas concentration reduction operation in step S12; if the time t1 is less than the predetermined time ta, the control device 50 does not perform step S12 (i.e., the fuel gas concentration reduction operation). The longer the elapsed time t1, the higher the fuel gas concentration in the oxidant gas inlet manifold 20. Therefore, according to the determination in step S10, a fuel gas concentration reduction operation can be performed when the fuel gas concentration in the oxidant gas inlet manifold 20 is high.

[0041] During the fuel gas concentration reduction operation, control device 50 opens inlet valve 28 and closes pressure regulating valve 34 and flow divider valve 42. Furthermore, control device 50 repeatedly increases and decreases the pressure of oxidant gas in oxidant gas inlet manifold 20 by repeatedly driving and stopping air compressor 24 at short cycles. Therefore, fuel gas is distributed throughout the supply path 22 downstream of air compressor 24 and the entire oxidant gas inlet manifold 20, reducing the fuel gas concentration within oxidant gas inlet manifold 20.

[0042] After performing the fuel gas concentration reduction action, the control device 50 opens the pressure regulating valve 34 and the diversion valve 42 to start power generation. When power generation begins, the fuel gas and oxidant gas in the oxidant gas inlet manifold 20 are discharged to the outside of the fuel cell module 100 via the pressure regulating valve 34 and the diversion valve 42. By reducing the fuel gas concentration, the concentration of fuel gas in the oxidant gas inlet manifold 20 is reduced, thus preventing high-concentration fuel gas from being discharged to the outside of the fuel cell module 100.

[0043] Furthermore, during the aforementioned fuel gas concentration reduction operation, the pressure of the oxidant gas in the oxidant gas inlet manifold 20 is repeatedly increased and decreased by repeatedly driving and stopping the air compressor 24 in short cycles. However, during the fuel gas concentration reduction operation, the air compressor 24 can also be driven in the surge region. If the air compressor 24 is driven in the surge region, the flow rate of the oxidant gas discharged from the air compressor 24 oscillates between positive and negative values. Therefore, the pressure of the oxidant gas in the oxidant gas inlet manifold 20 can be repeatedly increased and decreased.

[0044] In the above-described embodiment 1, when the elapsed time t1 is greater than or equal to a predetermined time ta, the control device 50 performs a fuel gas concentration reduction operation. In contrast, as... Figure 4 As shown in the flowchart, when the pressure value P1 of the fuel gas in the fuel gas flow path (not shown) is below the reference pressure value Pa, the control device 50 can also perform a fuel gas concentration reduction operation. Additionally, as... Figure 5 As shown in the flowchart, a fuel gas concentration reduction action can also be performed when the fuel gas concentration C1 in the split flow path 40 upstream of the split valve 42 is higher than the reference fuel gas concentration Ca. Figure 4 , Figure 5 In this structure, the fuel gas concentration can also be reduced when the fuel gas concentration in the oxidant gas inlet manifold 20 is high. Alternatively, the control device 50 can reduce the fuel gas concentration before power generation begins, regardless of the fuel gas concentration in the oxidant gas inlet manifold 20.

[0045] Oxidizing gas outlet 20b is an example of a "first oxidizing gas outlet". Oxidizing gas outlet 30a is an example of a "second oxidizing gas outlet".

[0046] Pressure regulating valve 34 is an example of a "first valve". Additionally, flow divider valve 42 is an example of a "second valve".

[0047] The embodiments have been described in detail above, but these are merely illustrative and do not limit the scope of protection claimed in this application. The technology described within the scope of protection of this application includes technologies obtained by modifications and alterations to the specific embodiments described above. The technical elements described in this specification or drawings exert their technical usefulness individually or in various combinations, and are not limited to the combinations described in the technical solution at the time of application. Furthermore, the technologies illustrated in this specification or drawings simultaneously achieve multiple objectives, and achieving one of these objectives is itself technically useful.

[0048] Explanation of reference numerals in the attached figures:

[0049] 10…Fuel cell stack; 10a…First end face; 10b…Second end face; 12…Fuel cell unit; 20…Oxidant gas inlet manifold; 20a…Oxidant gas supply port; 20b…Oxidant gas outlet; 22…Supply path; 24…Air compressor; 30…Oxidant gas outlet manifold; 30a…Oxidant gas outlet; 32…Discharge path; 34…Pressure regulating valve; 40…Branch path; 42…Branch valve; 50…Control device; 100…Fuel cell module.

Claims

1. A fuel cell module, wherein, Possess: a fuel cell stack composed of a plurality of fuel cell units stacked, having a first end surface on one side in a stacking direction of the plurality of fuel cell units, and having a second end surface on the other side in the stacking direction; an oxidant gas inlet manifold extending inside the fuel cell stack along the stacking direction, having an oxidant gas supply port that receives supply of oxidant gas at the first end surface, and having an oxidant gas first discharge port at the second end surface, configured to allow oxidant gas to flow from the oxidant gas inlet manifold to the respective fuel cell units; an oxidant gas outlet manifold extending inside the fuel cell stack along the stacking direction, configured to allow oxidant gas that has passed through the respective fuel cell units to flow, and having an oxidant gas second discharge port at the second end surface; an exhaust flow path connected to the oxidant gas second discharge port, and discharging oxidant gas from the oxidant gas outlet manifold; and a bypass flow path connecting the oxidant gas first discharge port and the exhaust flow path. Further provided are:

2. The fuel cell module of claim 1, wherein, an air compressor that supplies oxidant gas from the oxidant gas supply port to the oxidant gas inlet manifold; a first valve that opens and closes the exhaust flow path on an upstream side from a connection portion of the exhaust flow path and the bypass flow path; a second valve that opens and closes the bypass flow path; and a control device that, after power generation by the fuel cell stack is stopped, performs a gas exhaust and water discharge operation in which oxidant gas is supplied to the oxidant gas inlet manifold by the air compressor in a state in which the first valve is closed and the second valve is opened. Further provided are:

3. The fuel cell module of claim 1, wherein, an air compressor that supplies oxidant gas from the oxidant gas supply port to the oxidant gas inlet manifold; and a control device that, before power generation by the fuel cell stack is started, performs a fuel gas concentration reduction operation in which the pressure of oxidant gas inside the oxidant gas inlet manifold is repeatedly increased and decreased by the air compressor in a state in which the exhaust flow path and the bypass flow path are closed. ​

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