Fuel Cell Systems

Abstract

To provide a fuel cell system that can suppress heat spots while performing warm-up operation with a simple mechanism.SOLUTION: A fuel cell system includes a fuel cell, a fuel gas supply device, an oxidant gas supply device, a refrigerant supply device, a fuel cell temperature measurement device that measures the temperature of the fuel cell, and a control unit, and when the temperature of the fuel cell is lower than the target temperature, the control unit stops the supply of refrigerant and controls the supply amount of oxidant gas, such that power is generated by the fuel cell while cooling the fuel cell with oxidant gas, and a warm-up operation is performed to raise the temperature of the fuel cell to the target temperature.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present application discloses a fuel cell system. [Background technology]

[0002] A fuel cell system is a power generation device that generates electricity by supplying an oxidant gas and a fuel gas to a fuel cell. In order to increase the power generation efficiency, the fuel cell usually generates electricity at a predetermined target temperature. Therefore, when starting up a fuel cell at a low temperature, it is necessary to quickly raise the temperature of the fuel cell to the target temperature. This process is called warm-up operation. Warm-up operation is performed by the fuel cell generating electricity.

[0003] Methods for warming up a fuel cell system during startup at low temperatures are disclosed, for example, in Patent Documents 1 and 2. In Patent Documents 1 and 2, the rate of temperature rise is increased by adjusting the amount of coolant supplied to the fuel cell stack. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-216084 A [Patent Document 2] JP 2010-186599 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to increase the rate at which the fuel cell temperature rises during warm-up, it is conceivable to not supply any coolant to the fuel cell at all. However, if no coolant is supplied at all, heat spots will occur in the fuel cell, which can accelerate deterioration of the fuel cell.

[0006] On the other hand, adjusting the amount of refrigerant supplied as described in Patent Documents 1 and 2 can suppress the occurrence of heat spots to some extent, but it requires the installation of valves or the like in the refrigerant flow path, which may complicate the system and increase costs.

[0007] Therefore, a main object of the present disclosure is to provide a fuel cell system that can perform warm-up operation using a simple mechanism while suppressing heat spots. [Means for solving the problem]

[0008] The present disclosure provides a fuel cell system comprising: a fuel cell that generates electricity by being supplied with a fuel gas and an oxidant gas; a fuel gas supply device that supplies fuel gas to the fuel cell; an oxidant gas supply device that supplies oxidant gas to the fuel cell; a refrigerant supply device that supplies a refrigerant to the fuel cell; a fuel cell temperature measuring device that measures the temperature of the fuel cell; and a control unit, wherein when the temperature of the fuel cell is below a target temperature, the control unit stops the supply of refrigerant and controls the amount of oxidant gas supplied, thereby generating electricity using the fuel cell while cooling the fuel cell with the oxidant gas, and performs a warm-up operation to raise the temperature of the fuel cell to the target temperature.

[0009] In the above fuel cell system, the coolant may be a cooling gas. Effect of the Invention

[0010] According to the fuel cell system of the present disclosure, it is possible to suppress heat spots while performing warm-up operation with a simple mechanism. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram of a fuel cell system 100. [Diagram 2] 4 is an example of a flowchart of a warm-up operation control. [Diagram 3] FIG. 2 is a block diagram of a fuel cell system 200. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [Fuel cell system 100] The fuel cell system of the present disclosure will be described in detail using one embodiment of a fuel cell system 100. A block diagram of the fuel cell system 100 is shown in FIG.

[0013] As shown in FIG. 1, the fuel cell system 100 includes a fuel cell 10, a fuel gas piping section 20, an oxidizing gas piping section 30, a refrigerant piping section 40, and a control section 50.

[0014] <Fuel cell 10> The fuel cell 10 is formed by stacking a plurality of unit cells in series. The unit cell has an electrolyte membrane, an anode disposed on one side of the electrolyte membrane, and a cathode disposed on the other side of the electrolyte membrane. Specifically, catalyst layers are disposed on both sides of the electrolyte membrane, gas diffusion layers are disposed on the outside of the catalyst layers, and separators having fuel gas flow paths and oxidant gas flow paths are disposed on the outside of the gas diffusion layers. Such a unit cell has a general configuration. Here, in the unit cell, the catalyst layers and gas diffusion layers function as the anode or cathode.

[0015] The electrolyte membrane, catalyst layer, gas diffusion layer, and separator arranged in the single cell are not particularly limited, and known materials can be used. For example, the electrolyte membrane can be an ion exchange membrane made of a solid polymer material. The catalyst layer can be a platinum-based catalyst. The gas diffusion layer can be a porous material such as a carbon material. The separator can be a metal material such as stainless steel, or a carbon material such as a carbon composite material.

[0016] In the fuel cell 10, an electrochemical reaction occurs when a fuel gas is supplied to the anode and an oxidant gas is supplied to the cathode, generating electricity. If the fuel cell system 100 is installed in a vehicle, for example, the generated current is used to power a power load installed in the vehicle or is stored in a battery.

[0017] The fuel cell 10 may be selected to have a size and capacity that allows the occurrence of heat spots to be suppressed by cooling with oxidant gas during warm-up operation.

[0018] <Fuel gas piping section 20> The fuel gas piping section 20 is for supplying fuel gas to the anode of the fuel cell 10. The fuel gas piping section 20 includes a fuel gas supply source 21, an injector 22, an ejector 23, a gas-liquid separator 24, and an exhaust drain valve 25. The fuel gas piping section 20 also includes flow paths 20a-20f which are piping connected to these components. Furthermore, the fuel gas piping section 20 includes a fuel gas pressure measuring device P1 on the fuel gas inlet side of the fuel cell 10. The fuel gas piping section 20 may also include other components that are generally included in a fuel gas piping section.

[0019] The fuel gas supply source 21 may be composed of a high-pressure hydrogen tank or a hydrogen storage alloy that stores hydrogen gas. Alternatively, the fuel gas supply source 21 may be composed of a reformer that generates a hydrogen-rich reformed gas from a hydrocarbon fuel, and a high-pressure gas tank that pressurizes and stores the reformed gas generated by the reformer. Therefore, the fuel gas is hydrogen gas or reformed gas.

[0020] The flow path 20a is a pipe that connects the fuel gas supply source 21 and the injector 22, and serves to flow the fuel gas supplied from the fuel gas supply source to the injector 22. The flow path 20a may be provided with a shutoff valve that controls the opening and closing of the fuel gas supply source 21, and a regulator that controls the pressure of the fuel gas.

[0021] The injector 22 is a fuel gas supply device that supplies fuel gas to the fuel cell 10 and can control the amount of fuel gas supplied to the fuel cell 10. The amount of fuel gas supplied from the injector 22 is controlled by a control unit 50. Examples of the injector 22 include an on-off valve and a solenoid valve.

[0022] The flow passage 20b is a pipe that connects the injector 22 and the ejector 23, and serves to flow the fuel gas supplied from the injector 22 to the ejector 23.

[0023] The ejector 23 has a role of supplying the fuel gas supplied from the injector 22 to the fuel cell 10. The ejector 23 also has a role of supplying the circulating gas separated by the gas-liquid separator 24 to the fuel cell 10. The ejector 23 also has a role of supplying the fuel cell 10 with a mixed gas obtained by mixing the fuel gas supplied from the injector 22 with the circulating gas separated by the gas-liquid separator 24. Such an ejector 23 is publicly known.

[0024] The flow path 20c (fuel gas supply flow path) is a pipe that connects the fuel cell 10 and the ejector 23, and serves to flow the fuel gas supplied from the ejector 23 to the fuel cell 10.

[0025] The fuel gas pressure measuring device P1 is disposed in the flow path 20c, and measures the pressure of the fuel gas supplied to the fuel cell 10. The measurement result is transmitted to the control unit 50.

[0026] Flow path 20d (fuel gas discharge flow path) is a pipe that connects the fuel cell 10 and the gas-liquid separator 24, and serves to flow the fuel gas (fuel off-gas) discharged from the fuel cell 10 to the gas-liquid separator 24. The fuel off-gas contains liquid water produced by the electrochemical reaction of the fuel cell 10.

[0027] The gas-liquid separator 24 has a function of separating gas components and liquid components from the fuel off-gas discharged from the fuel cell 10. The separated gas components are supplied to the flow path 20e. The separated liquid components are discharged to the flow path 20f via the exhaust drain valve 25. Here, the liquid components are water produced by the electrochemical reaction of the fuel cell 10, and may contain unavoidably contained impurities. The gas components are unreacted fuel gas, and may contain unavoidably contained impurities.

[0028] The flow path 20e (circulation flow path) is a pipe that connects the gas-liquid separator 24 and the ejector 23, and serves to flow the gas component (circulation gas) separated by the gas-liquid separator 24 to the ejector 23.

[0029] The exhaust / drain valve 25 controls the discharge of the liquid component separated by the gas / liquid separator 24. The exhaust / drain valve 25 may use the pressure of the gas component as a driving force to cause the liquid component to flow together with the gas component into the flow path 20f. The exhaust / drain valve 25 is controlled by the control unit 50.

[0030] Flow path 20f (exhaust / drainage flow path) is a pipe connected to exhaust / drainage valve 25, and is a flow path for discharging the liquid component separated by gas-liquid separator 24 to the outside of the system. Flow path 20f may be connected to flow path 30f. In this case, the discharged liquid component is discharged to the outside of the system via flow path 30f.

[0031] <Oxidant gas piping section 30> The oxidant gas piping section 30 is for supplying the oxidant gas to the cathode. The oxidant gas piping section 30 includes an air filter 31, an air compressor 32, an inlet valve 33, and an outlet valve 34. The oxidant gas piping section 30 also includes flow paths 30a-30f, which are piping connected to these members. The flow paths 30a-30d are oxidant gas supply flow paths, and the flow paths 30e-30f are oxidant gas discharge flow paths. The oxidant gas piping section 30 also includes an inlet-side oxidant gas temperature measuring device T1 and an oxidant gas pressure measuring device P2 on the oxidant gas inlet side of the fuel cell 10. The oxidant gas piping section 30 also includes an outlet-side oxidant gas temperature measuring device T2 on the oxidant gas outlet side of the fuel cell 10. The oxidant gas piping section 30 may also include other members that are generally included in an oxidant gas piping section.

[0032] The flow path 30a is a pipe connected to the air filter 31, and serves to flow the oxidizing gas to the air filter 31. When the oxidizing gas is air, the flow path 30a connects the outside air and the air filter 31.

[0033] The air filter 31 has a function of removing foreign matter contained in the oxidant gas. Such air filters are well known.

[0034] The flow path 30 b is a pipe that connects the air filter 31 and the air compressor 32 , and serves to flow the oxidant gas from which foreign matter has been removed by the air filter 31 to the air compressor 32 .

[0035] The air compressor 32 is an oxidant gas supply device that supplies oxidant gas to the fuel cell 10, and is capable of controlling the amount of oxidant gas supplied to the fuel cell 10. The amount of oxidant gas supplied from the air compressor 32 is controlled by a control unit 50.

[0036] The flow path 30 c is a pipe that connects the air compressor 32 and the inlet valve 33 , and serves to allow the oxidant gas supplied from the air compressor 32 to flow to the inlet valve 33 .

[0037] The inlet side oxidant gas temperature measuring device T1 and the oxidant gas pressure measuring device P2 are arranged in the flow path 30c. The inlet side oxidant gas temperature measuring device T1 measures the temperature of the oxidant gas supplied to the fuel cell 10. The oxidant gas pressure measuring device P2 measures the pressure of the oxidant gas supplied to the fuel cell 10. The measurement results of these devices are transmitted to the control unit 50.

[0038] The inlet valve 33 has a role of controlling the pressure and supply amount of the oxidant gas supplied from the air compressor 32. The inlet valve 33 is controlled by the control unit 50.

[0039] The flow path 30 d is a pipe that connects the inlet valve 33 and the fuel cell 10 , and serves to allow the oxidant gas adjusted by the inlet valve 33 to flow into the fuel cell 10 .

[0040] The flow path 30e is a pipe that connects the fuel cell 10 and the outlet valve 34, and serves to flow the oxidant gas (oxidant off-gas) discharged from the fuel cell 10 to the outlet valve 34. The oxidant off-gas contains liquid water produced by the electrochemical reaction of the fuel cell 10.

[0041] The outlet valve 34 has a role of controlling the discharge to the outside of the system of the oxidant off-gas discharged from the fuel cell 10. The outlet valve 34 is controlled by the control unit 50.

[0042] Flow path 30f is a pipe connected to outlet valve 34, and is a flow path for discharging to the outside of the system the oxidant off-gas discharged from outlet valve 34. Flow path 20h (exhaust drainage flow path) may be connected to the middle of flow path 30f, and liquid and gas components discharged from flow path 20f (exhaust drainage flow path) together with the oxidant off-gas may be discharged to the outside of the system.

[0043] The outlet side oxidant gas temperature measuring device T2 is disposed in the flow path 30f, and measures the temperature of the oxidant gas discharged from the fuel cell 10. The measurement results are appropriately transmitted to the control unit 50. During warm-up operation, the temperature of the fuel cell 10 is estimated based on the measurement results of the outlet side oxidant gas temperature measuring device T2. Therefore, during warm-up operation, the outlet side oxidant gas temperature measuring device T2 is the fuel cell temperature measuring device.

[0044] <Refrigerant piping section 40> The refrigerant piping section 40 is for supplying a cooling gas (refrigerant) for cooling the fuel cell 10. The refrigerant piping section 40 includes an air filter 41 and a fan 42. The refrigerant piping section 40 also includes flow paths 40a-40d, which are pipes connected to these components. The refrigerant piping section 40 also includes an inlet-side refrigerant temperature measuring device T3 and an outlet-side refrigerant temperature measuring device T4 on the refrigerant inlet and outlet sides of the fuel cell 10, respectively. The refrigerant piping section 40 may also include other components that are generally included in the refrigerant piping section 40. The cooling gas is, for example, cooling air.

[0045] The flow path 40a is a pipe connected to the air filter 41, and serves to flow the cooling gas to the air filter 41. When the cooling gas is air, the flow path 40a connects the outside air and the air filter 41.

[0046] The air filter 41 serves to remove foreign matter contained in the cooling gas supplied to the fuel cell 10. Such air filters are well known.

[0047] The flow path 40b is a pipe that connects the air filter 41 and the fuel cell 10, and serves to pass the cooling gas from which foreign matter has been removed by the air filter 41 to the fuel cell 10.

[0048] The inlet side coolant temperature measuring device T3 is disposed in the flow path 40b, and measures the temperature of the coolant supplied to the fuel cell 10. The measurement results are sent to the control unit 50 as appropriate.

[0049] The flow path 40c is a pipe that connects the fuel cell 10 and the fan , and serves to direct the cooling gas discharged from the fuel cell 10 to the fan .

[0050] The outlet side coolant temperature measuring device T4 is disposed in the flow path 40c, and measures the temperature of the coolant discharged from the fuel cell 10. The measurement results are appropriately transmitted to the control unit 50. During normal operation, the temperature of the fuel cell 10 is estimated based on the measurement results of the outlet side coolant temperature measuring device T4. Therefore, during normal operation, the outlet side coolant temperature measuring device T4 is the fuel cell temperature measuring device.

[0051] The fan 42 is a power source for circulating the cooling gas through the cooling piping section 40, and can be said to be a refrigerant supply device that supplies the cooling gas to the fuel cell 10. The amount of cooling gas supplied by the fan 42 is controlled by the control section 50.

[0052] The flow path 40d is a pipe connected to the fan 42. When the cooling gas is air, the flow path 40d connects the fan 42 with the outside air.

[0053] <Control unit 50> The control unit 50 is a computer system including a CPU, a ROM, a RAM, an input / output interface, and the like, and is capable of controlling each part of the fuel cell system 100.

[0054] The fuel cell system 100 uses a cooling gas as a refrigerant for cooling the fuel cell 10. In other words, the fuel cell system 100 is an air-cooled system.

[0055] When the temperature of the fuel cell 10 is lower than the target temperature after startup (low-temperature startup), the fuel cell system 100 needs to quickly raise the temperature of the fuel cell 10 to the target temperature in order to increase the power generation efficiency of the fuel cell 10. This is called warm-up operation. In warm-up operation, in order to increase the rate at which the temperature of the fuel cell 10 is raised, it is conceivable to perform power generation without supplying any coolant to the fuel cell 10. However, if no coolant is supplied at all, heat spots will occur in the fuel cell 10, which will accelerate the deterioration of the fuel cell.

[0056] On the other hand, the occurrence of heat spots can be suppressed to some extent by adjusting the amount of coolant supplied as described in Patent Documents 1 and 2. However, it is necessary to install a valve or the like in the coolant flow path to adjust the amount of coolant supplied, which may complicate the system and increase costs. In addition, in the case of air-cooled systems, the heat capacity of the cooling gas is small, making heat spots more likely to occur.

[0057] Therefore, in the fuel cell system 100, the supply of the coolant is stopped and the supply amount of the oxidant gas is controlled to perform a warm-up operation during low temperature startup. That is, in the fuel cell system 100, when the temperature of the fuel cell 10 is below the target temperature, the control unit 50 stops the supply of the cooling gas and controls the supply amount of the oxidant gas to perform a warm-up operation in which the fuel cell 10 generates power while cooling the fuel cell 10 with the oxidant gas and raises the temperature of the fuel cell 10 to the target temperature.

[0058] As a result, during warm-up operation, the generation of heat spots can be suppressed with a simple mechanism without installing additional valves, etc., and the warm-up operation can be completed quickly. Furthermore, by completing the warm-up operation quickly, the power generation efficiency of the fuel cell 10 can be improved. Furthermore, during warm-up operation, flooding can be suppressed by controlling the supply amount of oxidant gas.

[0059] The amount of oxidant gas supplied during warm-up operation may be appropriately controlled depending on the temperature and temperature rise rate of the fuel cell 10. For example, the amount of oxidant gas supplied may be reduced or increased compared to normal operation, but may be increased from the viewpoint of cooling the fuel cell 10. The amount of oxidant gas supplied may be controlled based on the temperature of the oxidant gas (measurement result by the inlet side oxidant gas temperature measuring device T1). Furthermore, the amount of oxidant gas supplied may be controlled based on the results of a prior experiment or simulation so as to suppress heat spots.

[0060] For example, the amount of oxidant gas supplied during warm-up operation may be in the range of 0.5 to 10 times, or may be in the range of 2 to 10 times, of that during normal operation. This makes it possible to further suppress heat spots. Also, the amount of fuel gas supplied during warm-up operation may be in the range of 0.5 to 10 times, or may be in the range of 2 to 10 times, of that during normal operation. This makes it possible to quickly raise the temperature of the fuel cell 10.

[0061] The temperature of the fuel cell 10 is normally estimated from the measurement results of the outlet side coolant temperature measuring device T4, but since the supply of coolant is stopped during warm-up operation, it cannot be estimated based on the measurement results of the outlet side coolant temperature measuring device T4. Therefore, during warm-up operation, the temperature of the fuel cell 10 is estimated from the measurement results of the outlet side oxidant gas temperature measuring device T2. The temperature rise rate of the fuel cell 10 is calculated from the estimated change in the temperature of the fuel cell 10 over time. The target temperature of the fuel cell 10 is a temperature suitable for power generation by the fuel cell, and is set appropriately depending on the configuration of the fuel cell 10.

[0062] The warm-up operation may be controlled using not only the measurement results from the outlet side refrigerant temperature measuring device T4 but also the measurement results from other measuring devices. For example, the measurement results from the fuel gas pressure measuring device P1 and the oxidant gas pressure measuring device P2 may be used to control the power generation amount of the fuel cell 10.

[0063] FIG. 2 shows an example of a flowchart for determining whether or not to perform a warm-up operation. As shown in FIG. 2, for example, at start-up, it is determined whether or not the temperature of the fuel cell 10 is below a target temperature. If the temperature of the fuel cell 10 is below the target temperature, a warm-up operation is performed. The above-mentioned control method is adopted for the warm-up operation. Then, if the temperature of the fuel cell 10 becomes equal to or higher than the target temperature as a result of the warm-up operation, the warm-up operation is stopped and normal operation is performed. The normal operation is an operation using a cooling gas.

[0064] By carrying out the warm-up operation according to this flow, the temperature of the fuel cell 10 can be raised quickly to the target temperature.

[0065] [Fuel cell system 200] In the fuel cell system 100, a cooling gas is used as a refrigerant, but the refrigerant that can be used in the fuel cell system of the present disclosure is not limited to this, and cooling water may be used. Even in a form that uses cooling water (water-cooled type), the effects of the present disclosure can be achieved.

[0066] A fuel cell system 200 according to an embodiment, which uses cooling water as the refrigerant, will be described below. A block diagram of the fuel cell system 200 is shown in FIG.

[0067] The fuel cell system 200 is a system in which the refrigerant piping section 40 of the fuel cell system 100 has been replaced with a refrigerant piping section 140. Since the rest of the configuration is the same, a description thereof will be omitted here.

[0068] <Refrigerant piping section 140> The refrigerant piping section 140 is for supplying cooling water (refrigerant) for cooling the fuel cell 10. As shown in FIG. 3, the refrigerant piping section 140 is used by circulating the cooling water. The refrigerant piping section 140 includes a pump 141 and a radiator 142. The refrigerant piping section 140 also includes flow paths 140a-40c which are piping connected to these components. Furthermore, similar to the fuel cell system 100, the refrigerant piping section 140 includes an inlet side refrigerant temperature measuring device T3 and an outlet side refrigerant temperature measuring device T4 on the refrigerant inlet side and outlet side of the fuel cell 10, respectively. The refrigerant piping section 140 may also include other components that are generally included in the refrigerant piping section 40.

[0069] The pump 141 drives the cooling water circulating through the cooling water piping section 140 , and can be said to be a cooling water supply device that supplies the cooling water to the fuel cell 10 .

[0070] The flow path 140a is a pipe connected to the pump 141 and the fuel cell 10, and allows the cooling water supplied from the pump 141 to flow.

[0071] The flow path 140b is a pipe connected to the fuel cell 10 and the radiator 142, through which the cooling water discharged from the fuel cell 10 flows.

[0072] The radiator 142 exchanges heat between the coolant and the outside air to cool the coolant.

[0073] The flow path 140c is a pipe connected to the radiator 142 and the pump 141, through which the cooling water cooled by the radiator 142 flows.

[0074] The fuel cell system of the present disclosure has been described above using the fuel cell systems 100 and 200 as embodiments. According to the fuel cell system of the present disclosure, it is possible to suppress heat spots while performing a warm-up operation with a simple mechanism. [Explanation of symbols]

[0075] 10 fuel cell 20 Fuel gas piping section 20a~20f Flow path 21 Fuel gas supply source 22 Injector 23 Ejector 24 Gas-liquid separator 25 Exhaust drain valve P1 Fuel gas pressure measuring device 30 Oxidant gas piping section 30a~30f Flow path 31 Air Filter 32 Air Compressor 33 Inlet valve 34 Outlet valve P2 Oxidant gas pressure measuring device T1 Inlet side oxidant gas temperature measuring device T2 Outlet oxidant gas temperature measuring device 40 Refrigerant piping section 41 Air Filter 42 Fans Flow paths 40a to 40d T3 Inlet side refrigerant temperature measuring device T4 Outlet side refrigerant temperature measuring device 50 Control section 100 Fuel Cell System 140 Refrigerant piping section 141 Pump 142 Radiator 140a~140c Flow path 200 Fuel Cell System

Claims

1. a fuel cell that generates electricity by being supplied with a fuel gas and an oxidant gas; a fuel gas supply device for supplying a fuel gas to the fuel cell; an oxidant gas supply device for supplying an oxidant gas to the fuel cell; a coolant supply device for supplying a coolant to the fuel cell; a fuel cell temperature measuring device for measuring the temperature of the fuel cell; A control unit, when the temperature of the fuel cell is lower than a target temperature, the control unit stops the supply of the coolant and controls the supply amount of the oxidant gas to generate power using the fuel cell while cooling the fuel cell with the oxidant gas, and performs a warm-up operation to raise the temperature of the fuel cell to the target temperature; the supply amount of the oxidant gas during the warm-up operation is set to be between 2 and 10 times that during normal operation for the purpose of cooling the fuel cell, and the supply amount of the fuel gas is set to be between 2 and 10 times that during normal operation for the purpose of raising the temperature of the fuel cell. Fuel cell system.

2. 2. The fuel cell system of claim 1, wherein the coolant is a cooling gas.

Images