Fuel cell module

Abstract

We propose a technology for miniaturizing fuel cell modules with diversion channels. [Solution] A fuel cell module comprising a fuel cell stack composed of a plurality of stacked fuel cell cells, having a first end face on one side in the stacking direction of the plurality of fuel cell cells and a second end face on the other side in the stacking direction; an oxidant gas inlet manifold having an oxidant gas supply port for receiving oxidant gas on the first end face and a first oxidant gas outlet on the second end face; an oxidant gas outlet manifold configured to allow oxidant gas that has passed through each fuel cell to flow, and having a second oxidant gas outlet on the second end face; a discharge channel connected to the second oxidant gas outlet for discharging oxidant gas from the oxidant gas outlet manifold; and a diversion channel connecting the first oxidant gas outlet and the discharge channel.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a fuel cell module.

Background Art

[0002] The fuel cell module disclosed in Patent Document 1 has a fuel cell stack formed by stacking a plurality of fuel cells. The fuel cell stack generates electricity by reacting a fuel gas and an oxidant gas.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0006] In the fuel cell module described above, the diversion channel connects the first oxidizer gas outlet located on the second end face to the exhaust channel extending from the second end face, thus shortening the diversion channel. Consequently, the fuel cell module can be miniaturized. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram of a fuel cell module. [Figure 2] This is a flowchart of the operation process of a fuel cell module. [Figure 3] This is a flowchart of the operation process of a fuel cell module. [Figure 4] This is a flowchart of the operation process of a fuel cell module. [Figure 5] This is a flowchart of the operation process of a fuel cell module. [Modes for carrying out the invention]

[0008] Following the above description of Embodiment 1, additional configurations of the fuel cell system disclosed herein will be described below. (Aspect 2) The fuel cell module according to embodiment 1, further comprising: 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 discharge passage upstream of the connection between the discharge passage and the diversion passage; a second valve that opens and closes the diversion passage; and a control device that, after the power generation of the fuel cell stack stops, closes the first valve and opens the second valve, and then uses the air compressor to supply oxidant gas to the oxidant gas inlet manifold in an exhaust drainage operation. (Aspect 3) A fuel cell module according to embodiment 1 or 2, further comprising: 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 the start of power generation of the fuel cell stack, performs a fuel gas concentration reduction operation by repeatedly increasing or decreasing the pressure of the oxidant gas in the oxidant gas inlet manifold using the air compressor while the discharge channel and the diversion channel are closed.

[0009] According to embodiment 2, water adhering to the second valve during power generation can be blown away by an oxidizing gas supplied from the air compressor after power generation has stopped.

[0010] According to embodiment 3, if fuel gas accumulates in the oxidizer gas inlet manifold while power generation is stopped, the fuel gas concentration in the oxidizer gas inlet manifold can be reduced by a fuel gas concentration reduction operation. This prevents high concentrations of fuel gas from being discharged from the fuel cell stack to the outside when power generation starts.

[0011] (Example 1) The fuel cell module 100 of Embodiment 1 shown in Figure 1 is mounted on a device that uses a fuel cell as a power source (for example, a fuel cell vehicle). The fuel cell module 100 has a fuel cell stack 10. The fuel cell module 100 supplies the electricity generated by the fuel cell stack 10 to a motor and the like.

[0012] The fuel cell stack 10 has a plurality of stacked fuel cell cells 12, an end plate 14, and an end plate 16. One end of the stack of fuel cell cells 12 is covered by the end plate 14, and the other end of the stack of fuel cell cells 12 is covered by the end plate 16. That is, the stack of fuel cell cells 12 is sandwiched between the end plate 14 and the end plate 16 in the stacking direction. In the following, the end face on the end plate 14 side of the fuel cell stack 10 will be referred to as the first end face 10a, and the end face on the end plate 16 side will be referred to as the second end face 10b.

[0013] As shown in Figure 1, an oxidant gas inlet manifold 20 is provided inside the fuel cell stack 10. The oxidant gas inlet manifold 20 extends through each fuel cell cell 12, end plate 14, and end plate 16, 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 opens on the first end face 10a. The oxidant gas outlet 20b opens on the second end face 10b. Oxidant gas (e.g., air) is supplied to the oxidant gas supply port 20a from a supply channel 22, which will be 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. Each fuel cell cell 12 is supplied with oxidant gas from the oxidant gas inlet manifold 20, as well as fuel gas (e.g., hydrogen) from a fuel gas manifold (not shown). Each fuel cell cell 12 generates electricity by reacting an oxidizer gas with a fuel gas.

[0014] The fuel cell module 100 includes a supply channel 22, an air compressor 24, an intercooler 26, and an inlet valve 28. The upstream end of the supply channel 22 is connected to an oxidant gas supply source (not shown). The downstream end of the supply channel 22 is connected to an oxidant gas supply port 20a. The supply channel 22 supplies oxidant gas to the oxidant gas inlet manifold 20.

[0015] The air compressor 24 is provided in the supply flow path 22. The air compressor 24 pressurizes the oxidant gas in the supply flow path 22 and sends it out to the downstream side.

[0016] The intercooler 26 is provided in the supply flow path 22, downstream of the air compressor 24. High-pressure and high-temperature oxidant gas supplied from the air compressor 24 flows through the intercooler 26. A coolant is supplied to the intercooler 26 from a cooling flow path (not shown). The intercooler 26 cools the oxidant gas with the coolant.

[0017] The inlet valve 28 is provided in the supply flow path 22, downstream of the intercooler 26. The inlet valve 28 adjusts the flow rate of the oxidant gas supplied from the supply flow path 22 to the oxidant gas inlet manifold 20 by adjusting the opening degree of the supply flow path 22.

[0018] As shown in FIG. 1, an oxidant gas outlet manifold 30 is provided inside the fuel cell stack 10. The oxidant gas outlet manifold 30 penetrates each fuel cell 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 discharge outlet 30a. The oxidant gas discharge outlet 30a opens to the second end face 10b. The oxidant gas that has passed through each fuel cell 12 flows through the oxidant gas outlet manifold 30.

[0019] The fuel cell module 100 has a discharge flow path 32 and a pressure regulating valve 34. The upstream end of the discharge flow path 32 is connected to the oxidant gas discharge outlet 30a. The oxidant gas flowing through the oxidant gas outlet manifold 30 is discharged to the outside of the fuel cell stack 10 through the discharge flow path 32. A pressure regulating valve 34 is provided in the discharge flow path 32. The pressure regulating valve 34 opens and closes the flow path of the discharge flow path 32. Further, by adjusting the opening degree of the pressure regulating valve 34, the pressure inside the oxidant gas outlet manifold 30 is adjusted.

[0020] The fuel cell module 100 has a shunt flow path 40 and a shunt valve 42. The upstream end of the shunt flow path 40 is connected to the oxidant gas discharge port 20b. The downstream end of the shunt flow path 40 is connected to the discharge flow path 32 on the downstream side of the pressure regulating valve 34. A shunt valve 42 is provided in the shunt flow path 40. The shunt valve 42 opens and closes the flow path of the shunt flow path 40. When the shunt valve 42 is in the open state, a part of the oxidant gas flowing in the oxidant gas inlet manifold 20 flows into the shunt flow path 40. The oxidant gas in the shunt flow path 40 flows into the discharge flow path 32. When the opening degree of the shunt valve 42 is changed, the flow rate of the oxidant gas flowing into the shunt flow path 40 changes, so the flow rate of the oxidant gas flowing into each fuel cell 12 also changes. Therefore, the flow rate of the oxidant gas flowing into each fuel cell 12 can be adjusted by the shunt valve 42.

[0021] 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 shunt valve 42.

[0022] When the fuel cell module 100 generates electricity, the control device 50 opens the inlet valve 28, the pressure regulating valve 34 and the shunt valve 42. Further, the control device 50 drives the air compressor 24. Therefore, the oxidant gas is supplied from the supply flow path 22 to the oxidant gas inlet manifold 20. For this reason, the oxidant gas is supplied from the oxidant gas inlet manifold 20 to each fuel cell 12. Also, the control device 50 supplies the fuel gas to each fuel cell 12 by controlling the fuel gas supply system. Each fuel cell 12 generates electricity by reacting the oxidant gas and the fuel gas. The oxidant gas that has passed through each fuel cell 12 flows into the oxidant gas outlet manifold 30. The oxidant gas flows from the oxidant gas outlet manifold 30 into the discharge flow path 32. Also, a part of the oxidant gas in the oxidant gas inlet manifold 20 passes through the shunt flow path 40 and flows into the discharge flow path 32. The oxidant gas in the discharge flow path 32 is discharged to the outside of the fuel cell module 100.

[0023] Furthermore, when the oxidizer gas and fuel gas react in each fuel cell cell 12, generated water is produced. The generated water is discharged from each fuel cell cell 12 to the oxidizer gas inlet manifold 20 and the oxidizer gas outlet manifold 30. The generated water discharged to the oxidizer gas inlet manifold 20 flows through the diversion channel 40 together with the oxidizer gas and into the discharge channel 32. The generated water discharged to the oxidizer gas outlet manifold 30 flows into the discharge channel 32 together with the oxidizer gas. The generated water is then discharged from the discharge channel 32 to the outside of the fuel cell module 100.

[0024] As explained above, the oxidizer gas flowing through the diversion channel 40 bypasses each fuel cell cell 12 and flows to the discharge channel 32. Since both the oxidizer gas outlet 20b of the oxidizer gas inlet manifold 20 and the discharge channel 32 are located on the second end face 10b side, the diversion channel 40 connecting them can be shortened. In other words, the diversion channel 40 can be shortened compared to the case where the diversion channel is provided to connect the supply channel 22 and the discharge channel 32. Therefore, the fuel cell module 100 can be miniaturized.

[0025] During power generation, generated water may adhere to the diversion channel 40 and the diversion valve 42. In cold regions, the generated water adhering to the diversion valve 42 may freeze, which may cause the diversion valve 42 to deteriorate. Therefore, the control device 50 can perform an exhaust drainage operation to remove the generated water adhering to the diversion valve 42 after the fuel cell stack 10 stops generating power. The control device 50 selectively performs the exhaust drainage operation according to the flowchart in Figure 2.

[0026] In step S2, the control device 50 measures the ambient temperature using a temperature sensor (not shown). The control device 50 determines whether the ambient temperature is below the determination temperature T1 (for example, 0°C). If the ambient temperature is below the determination temperature T1, the control device 50 performs the exhaust drainage operation in step S4; if the ambient temperature is less than the determination temperature T1, it does not perform step S4 (i.e., the exhaust drainage operation).

[0027] During exhaust drainage operation, the control device 50 closes the pressure regulating valve 34 and opens the inlet valve 28 and the flow diversion valve 42. The control device 50 also 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, no oxidant gas flows from the oxidant gas inlet manifold 20 to each fuel cell cell 12. Therefore, all oxidant gas supplied to the oxidant gas inlet manifold 20 is discharged to the discharge channel 32 via the flow diversion channel 40. As a result, during exhaust drainage operation, the flow rate of oxidant gas flowing through the flow diversion valve 42 increases compared to power generation operation. Therefore, any generated water adhering to the flow diversion valve 42 is blown away by the oxidant gas during exhaust drainage operation. As a result, the generated water is removed from the flow diversion valve 42. Thus, it is possible to prevent the generated water from freezing on the surface of the flow diversion valve 42 when power generation is stopped.

[0028] In Figure 2, the control device 50 performed the exhaust drainage operation when the ambient temperature was below the determination temperature T1. However, the control device 50 may also perform the exhaust drainage operation after power generation has stopped, regardless of the ambient temperature.

[0029] After the fuel cell stack 10 stops generating power, the fuel gas in the fuel gas manifold (not shown) flows through each fuel cell cell 12 into the oxidizer gas inlet manifold 20, which may increase the fuel gas concentration in the oxidizer gas inlet manifold 20. If power generation is started with a high fuel gas concentration in the oxidizer gas inlet manifold 20, the high-concentration fuel gas in the oxidizer gas inlet manifold 20 will be discharged to the outside of the fuel cell module 100. Therefore, the control device 50 can perform a fuel gas concentration reduction operation to lower the fuel gas concentration in the oxidizer gas inlet manifold 20 before the fuel cell stack 10 starts generating power. The control device 50 selectively performs the fuel gas concentration reduction operation according to the flowchart in Figure 3.

[0030] The control device 50 can measure the time elapsed since the fuel cell stack 10 stopped generating power (hereinafter referred to as elapsed time t1) using a timer (not shown). When 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 (for example, half a day). If the elapsed time t1 is equal to or greater than the predetermined time ta, the control device 50 executes a fuel gas concentration reduction operation in step S12, and does not execute step S12 (i.e., the fuel gas concentration reduction operation) if the time t1 is less than the predetermined time ta. The longer the elapsed time t1, the higher the fuel gas concentration in the oxidizer gas inlet manifold 20 becomes, so according to the determination in step S10, the fuel gas concentration reduction operation can be executed when the fuel gas concentration in the oxidizer gas inlet manifold 20 is high.

[0031] During the fuel gas concentration reduction operation, the control device 50 opens the inlet valve 28 and closes the pressure regulating valve 34 and the flow diversion valve 42. The control device 50 also repeatedly increases and decreases the pressure of the oxidizer gas in the oxidizer gas inlet manifold 20 by repeatedly driving and stopping the air compressor 24 in short cycles. As a result, the fuel gas spreads throughout the supply passage 22 downstream of the air compressor 24 and the entire oxidizer gas inlet manifold 20, and the fuel gas concentration in the oxidizer gas inlet manifold 20 decreases.

[0032] After performing a fuel gas concentration reduction operation, the control device 50 opens the pressure regulating valve 34 and the flow diversion valve 42 to start power generation. When power generation starts, the fuel gas and oxidizer gas in the oxidizer gas inlet manifold 20 are discharged to the outside of the fuel cell module 100 via the pressure regulating valve 34 and the flow diversion valve 42. Because the fuel gas concentration in the oxidizer gas inlet manifold 20 has been reduced by the fuel gas concentration reduction operation, it is prevented from discharging high-concentration fuel gas to the outside of the fuel cell module 100.

[0033] In the fuel gas concentration reduction operation described above, the pressure of the oxidizer gas in the oxidizer gas inlet manifold 20 was repeatedly increased and decreased by repeatedly starting and stopping the air compressor 24 in short cycles. However, the air compressor 24 may also be driven in the surge generation region during the fuel gas concentration reduction operation. When the air compressor 24 is driven in the surge generation region, the flow rate of the oxidizer gas discharged from the air compressor 24 oscillates between positive and negative values. Therefore, the pressure of the oxidizer gas in the oxidizer gas inlet manifold 20 can be repeatedly increased and decreased.

[0034] In the above-described embodiment 1, the control device 50 performed a fuel gas concentration reduction operation when the elapsed time t1 was equal to or greater than a predetermined time ta. In contrast, as shown in the flowchart of Figure 4, the control device 50 may also perform a fuel gas concentration reduction operation when the pressure value P1 of the fuel gas in the fuel gas flow path (not shown) is less than or equal to the reference pressure value Pa. Furthermore, as shown in the flowchart of Figure 5, the fuel gas concentration reduction operation may also be performed when the fuel gas concentration C1 in the flow diversion flow path 40 upstream of the flow diversion valve 42 is equal to or greater than the reference fuel gas concentration Ca. In the configurations of Figures 4 and 5, the fuel gas concentration reduction operation can also be performed when the fuel gas concentration in the oxidizer gas inlet manifold 20 is high. In addition, the control device 50 may perform a fuel gas concentration reduction operation before the start of power generation regardless of the fuel gas concentration in the oxidizer gas inlet manifold 20.

[0035] Oxidizer gas outlet 20b is an example of a "first oxidizer gas outlet." Oxidizer gas outlet 30a is an example of a "second oxidizer gas outlet."

[0036] The pressure regulating valve 34 is an example of a "first valve." The flow diversion valve 42 is an example of a "second valve."

[0037] Although embodiments have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness. [Explanation of symbols]

[0038] 10: Fuel cell stack, 10a: First end face, 10b: Second end face, 12: Fuel cell cell, 20: Oxidizer gas inlet manifold, 20a: Oxidizer gas supply port, 20b: Oxidizer gas outlet, 22: Supply channel, 24: Air compressor, 30: Oxidizer gas outlet manifold, 30a: Oxidizer gas outlet, 32: Outlet channel, 34: Pressure regulating valve, 40: Flow diversion channel, 42: Flow diversion valve, 50: Control device, 100: Fuel cell module

Claims

1. It is a fuel cell module, A fuel cell stack comprising a plurality of stacked fuel cell cells, wherein the plurality of fuel cell cells have a first end face on one side in the stacking direction and a second end face on the other side in the stacking direction, An oxidant gas inlet manifold extending along the stacking direction inside the fuel cell stack, having an oxidant gas supply port for receiving oxidant gas at its first end face and a first oxidant gas outlet at its second end face, configured such that oxidant gas flows from the oxidant gas inlet manifold to each of the fuel cell cells, An oxidizer gas outlet manifold extends inside the fuel cell stack along the stacking direction and is configured to allow the oxidizer gas that has passed through each fuel cell to flow through it, and has a second oxidizer gas outlet on its second end face, A discharge channel is connected to the second oxidizing gas outlet and discharges the oxidizing gas from the oxidizing gas outlet manifold, A diversion channel connecting the first oxidizing gas outlet and the discharge channel, A fuel cell module equipped with the following features.

2. An air compressor that supplies oxidizing gas from the oxidizing gas supply port to the oxidizing gas inlet manifold, A first valve that opens and closes the discharge channel upstream of the connection point between the discharge channel and the diversion channel, A second valve that opens and closes the aforementioned diversion channel, A control device that, after the power generation of the fuel cell stack is stopped, closes the first valve and opens the second valve, and then, with the air compressor, performs an exhaust drainage operation to supply oxidizer gas to the oxidizer gas inlet manifold. The fuel cell module according to claim 1, further comprising:

3. An air compressor that supplies oxidizing gas from the oxidizing gas supply port to the oxidizing gas inlet manifold, A control device that, before the start of power generation of the fuel cell stack, performs a fuel gas concentration reduction operation by repeatedly increasing or decreasing the pressure of the oxidizer gas in the oxidizer gas inlet manifold using the air compressor while the discharge channel and the diversion channel are closed. The fuel cell module according to claim 1, further comprising:

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