Fuel cell system and aircraft

Abstract

This invention provides a fuel cell system and an aircraft, which prevents the exhaust drain valve in the fuel gas system from icing even at high altitudes. The fuel cell system, used in an aircraft, is characterized by comprising: a fuel cell; a fuel gas system for supplying fuel gas to the fuel cell; a cooling system for regulating the temperature of the fuel cell; an altitude sensor; a temperature sensor; and a control unit that, upon detecting an increase in altitude measured by the altitude sensor and when the temperature of the exhaust drain valve measured by the temperature sensor is less than a predetermined temperature, controls a three-way valve to circulate refrigerant in a heating path and drives a circulation pump and a water heater to heat the refrigerant, thereby raising its temperature.

Description

Technical Field

[0001] This disclosure relates to fuel cell systems and aircraft. Background Technology

[0002] A fuel cell (FC) consists of a single cell (hereinafter referred to simply as a cell) or a fuel cell stack (hereinafter referred to simply as a cell stack) composed of multiple stacked single cells. It is a power generation device that extracts electrical energy through the electrochemical reaction of fuel gas such as hydrogen and oxidant gas such as oxygen. In many cases, the fuel gas and oxidant gas actually supplied to the fuel cell are mixtures with gases that do not contribute to oxidation / reduction. Air, which includes oxygen, is particularly common as the oxidant gas.

[0003] In some cases, fuel gas and oxidant gas are not specifically distinguished and are simply referred to as "reaction gas" or "gas". Additionally, both single cells and fuel cell stacks composed of stacked single cells are sometimes referred to as fuel cells.

[0004] Various studies have been conducted on fuel cells.

[0005] For example, Patent Document 1 discloses an aircraft equipped with a fuel cell.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-081559

[0007] When fuel cells are mounted on aircraft, they generate electricity at higher altitudes and lower temperatures compared to when they are mounted on vehicles.

[0008] In a fuel gas system, if the altitude is high and the temperature is low, the temperature of the exhaust / drain valve will decrease, causing water to freeze and preventing exhaust / drainage. Because drainage is impossible, the nitrogen concentration increases, the hydrogen partial pressure decreases (local hydrogen deficiency), and hydrogen deficiency occurs in the fuel cell. This reduces the fuel cell's durability, necessitating output limiting and system shutdown. Summary of the Invention

[0009] This disclosure was made in view of the above-mentioned actual conditions, and its main purpose is to provide a fuel cell system that can prevent the exhaust drain valve in the fuel gas system from freezing even at high altitudes.

[0010] The fuel cell system disclosed herein is a fuel cell system for aircraft, characterized in that,

[0011] The above-mentioned fuel cell system has the following characteristics:

[0012] Fuel cells;

[0013] A fuel gas system supplies fuel gas to the aforementioned fuel cell;

[0014] The cooling system regulates the temperature of the aforementioned fuel cell;

[0015] Altitude sensor;

[0016] Temperature sensor; and

[0017] Control Department

[0018] The aforementioned fuel gas system includes: a fuel gas supply section; and an exhaust / drain valve, capable of discharging the fuel exhaust gas emitted from the aforementioned fuel cell to the outside.

[0019] The aforementioned cooling system includes: a refrigerant flow path for circulating refrigerant inside and outside the fuel cell; and a heating flow path branching from the refrigerant flow path and disposed near the exhaust / drain valve, wherein the refrigerant is circulated to heat the exhaust / drain valve.

[0020] The aforementioned heating flow path includes: a circulation pump for circulating the refrigerant within the heating flow path; a water heater for heating the refrigerant; and a three-way valve for controlling the supply of the refrigerant from the refrigerant flow path and enabling the refrigerant to circulate within the heating flow path.

[0021] When the height increase measured by the height sensor is detected, and when the temperature of the exhaust and drain valve measured by the temperature sensor is less than the specified temperature, the control unit controls the three-way valve to circulate the refrigerant in the heating flow path, and drives the circulation pump and the water heater to heat the refrigerant and raise its temperature.

[0022] The aircraft disclosed herein is equipped with the aforementioned fuel cell system.

[0023] According to the fuel cell system disclosed herein, icing of the exhaust drain valve in the fuel gas system can be prevented even at high altitudes. Attached Figure Description

[0024] Figure 1 This is a simplified structural diagram illustrating an example of a fuel cell system according to the present disclosure.

[0025] Figure 2 This is a flowchart illustrating an example of the control of a fuel cell system according to this disclosure. Explanation of reference numerals:

[0026] 10…Fuel cell; 20…Fuel gas supply unit; 21…Fuel gas supply path; 22…Fuel exhaust gas discharge path; 23…Exhaust drain valve; 24…Gas-liquid separator; 25…Circulation path; 26…Ejector; 31…Refrigerant supply unit; 32…Refrigerant path; 33…Radiator; 41…Heating path; 42…Circulation pump; 43…Water heater; 44…Three-way valve; 50…Control unit; 60…Height sensor; 70…Temperature sensor; 100…Fuel cell system. Detailed Implementation

[0027] The fuel cell system disclosed herein is a fuel cell system for aircraft.

[0028] The above-mentioned fuel cell system has the following characteristics:

[0029] Fuel cells;

[0030] A fuel gas system supplies fuel gas to the aforementioned fuel cell;

[0031] The cooling system regulates the temperature of the aforementioned fuel cell;

[0032] Altitude sensor;

[0033] Temperature sensor; and

[0034] Control Department

[0035] The aforementioned fuel gas system includes: a fuel gas supply section; and an exhaust / drain valve, capable of discharging the fuel exhaust gas emitted from the aforementioned fuel cell to the outside.

[0036] The aforementioned cooling system includes: a refrigerant flow path for circulating refrigerant inside and outside the fuel cell; and a heating flow path branching from the refrigerant flow path and disposed near the exhaust / drain valve, for circulating the refrigerant to heat the exhaust / drain valve.

[0037] The aforementioned heating flow path includes: a circulation pump for circulating the refrigerant within the heating flow path; a water heater for heating the refrigerant; and a three-way valve for controlling the supply of the refrigerant from the refrigerant flow path and enabling the refrigerant to circulate within the heating flow path.

[0038] When the height increase measured by the height sensor is detected and the temperature of the exhaust and drain valve measured by the temperature sensor is less than the specified temperature, the control unit controls the three-way valve to circulate the refrigerant in the heating flow path and drives the circulation pump and the water heater to heat the refrigerant to raise its temperature.

[0039] In this disclosure, fuel gas and oxidant gas are collectively referred to as reactant gases. The reactant gas supplied to the anode is the fuel gas, and the reactant gas supplied to the cathode is the oxidant gas. The fuel gas is a gas mainly containing hydrogen, and may also be hydrogen gas. The oxidant gas may be oxygen, air, dry air, etc.

[0040] The fuel cell system disclosed herein is used when mounted on an aircraft.

[0041] In addition, the fuel cell system disclosed herein can be mounted on aircraft that can also fly using electricity from secondary batteries.

[0042] The aircraft disclosed herein can be an aircraft. An aircraft can be an airplane, a vertical takeoff and landing (VTOL) aircraft, etc. A VTOL aircraft can be a helicopter, a drone, etc.

[0043] The aircraft may be equipped with the fuel cell system disclosed herein.

[0044] The fuel cell system disclosed herein includes a fuel cell.

[0045] A fuel cell can be a structure with only one single cell, or it can be a stack of multiple single cells, i.e., a fuel cell stack.

[0046] The number of layers in a single cell is not particularly limited; for example, it can be 2 to several hundred, or 2 to 600.

[0047] Fuel cell stacks can have end plates at both ends in the stacking direction of the individual cells.

[0048] Each cell of a fuel cell has at least a membrane electrode gas diffusion layer junction.

[0049] The membrane electrode gas diffusion layer assembly sequentially comprises an anode-side gas diffusion layer, an anode catalyst layer, an electrolyte membrane, a cathode catalyst layer, and a cathode-side gas diffusion layer.

[0050] The cathode (oxidant electrode) includes a cathode catalyst layer and a cathode-side gas diffusion layer.

[0051] The anode (fuel electrode) includes an anode catalyst layer and an anode-side gas diffusion layer.

[0052] The cathode catalyst layer and the anode catalyst layer are collectively referred to as the catalyst layer. Examples of anode and cathode catalysts include Pt (platinum) and Ru (ruthenium), while examples of substrate materials for supporting the catalyst and conductive materials include carbon materials such as carbon.

[0053] The gas diffusion layer on the cathode side and the gas diffusion layer on the anode side are collectively referred to as the gas diffusion layer.

[0054] The gas diffusion layer can be a breathable conductive component, etc.

[0055] Examples of conductive components include porous carbon materials such as carbon cloth and carbon paper, as well as porous metal materials such as metal mesh and foamed metal.

[0056] Electrolyte membranes can be solid polymer electrolyte membranes. Examples of solid polymer electrolyte membranes include fluorinated electrolyte membranes such as perfluorosulfonic acid membranes containing water, and hydrocarbon electrolyte membranes. Examples of electrolyte membranes include Nafion membranes (manufactured by DuPont).

[0057] A single cell may have two separators on both sides of the membrane electrode gas diffusion layer junction as needed. One of the two separators is the anode-side separator, and the other is the cathode-side separator. In this disclosure, the anode-side separator and the cathode-side separator are collectively referred to as separators.

[0058] The separator may have supply and discharge ports for allowing the reactant gases and refrigerant to flow along the stacking direction of the single cell. As a refrigerant, to prevent freezing at low temperatures, a mixture of ethylene glycol and water can be used, for example.

[0059] Examples of supply ports include fuel gas supply ports, oxidizer gas supply ports, and refrigerant supply ports.

[0060] Examples of discharge ports include fuel gas discharge ports, oxidizer gas discharge ports, and refrigerant discharge ports.

[0061] The baffle may have one or more fuel gas supply holes, one or more oxidant gas supply holes, one or more refrigerant supply holes, one or more fuel gas discharge holes, one or more oxidant gas discharge holes, and one or more refrigerant discharge holes.

[0062] The separator may have a reactive gas flow path on the surface in contact with the gas diffusion layer. Additionally, the separator may have a refrigerant flow path on the surface opposite to the surface in contact with the gas diffusion layer to maintain a constant temperature in the fuel cell.

[0063] When the partition is an anode-side partition, it may have one or more fuel gas supply holes, one or more oxidant gas supply holes, one or more refrigerant supply holes, one or more fuel gas discharge holes, one or more oxidant gas discharge holes, and one or more refrigerant discharge holes. The anode-side partition may have a fuel gas flow path on the surface in contact with the anode-side gas diffusion layer for fuel gas to flow from the fuel gas supply hole to the fuel gas discharge hole, and may have a refrigerant flow path on the surface opposite to the surface in contact with the anode-side gas diffusion layer for refrigerant to flow from the refrigerant supply hole to the refrigerant discharge hole.

[0064] When the partition is a cathode-side partition, it may have one or more fuel gas supply holes, one or more oxidant gas supply holes, one or more refrigerant supply holes, one or more fuel gas discharge holes, one or more oxidant gas discharge holes, and one or more refrigerant discharge holes. The cathode-side partition may have an oxidant gas flow path on the surface in contact with the cathode-side gas diffusion layer for oxidant gas to flow from the oxidant gas supply hole to the oxidant gas discharge hole, and may have a refrigerant flow path on the surface opposite to the surface in contact with the cathode-side gas diffusion layer for refrigerant to flow from the refrigerant supply hole to the refrigerant discharge hole.

[0065] The partition can be an airtight conductive component. Examples of conductive components include compressed carbon forming an airtight, dense carbon, and stamped metal sheets (such as iron, aluminum, and stainless steel). Furthermore, the partition can have a current-collecting function.

[0066] A fuel cell may have manifolds such as inlet manifolds connected to each supply port and outlet manifolds connected to each discharge port.

[0067] Examples of inlet manifolds include anode inlet manifolds, cathode inlet manifolds, and refrigerant inlet manifolds.

[0068] Examples of outlet manifolds include anode outlet manifolds, cathode outlet manifolds, and refrigerant outlet manifolds.

[0069] The fuel cell system is equipped with an altitude sensor.

[0070] Altitude sensors determine the altitude of the aircraft.

[0071] The altitude sensor is electrically connected to the control unit, which detects the altitude of the aircraft as determined by the altitude sensor.

[0072] The height sensor can use previously known altimeters, etc.

[0073] The fuel cell system is equipped with a temperature sensor.

[0074] A temperature sensor measures the temperature of the exhaust and drain valve.

[0075] The temperature sensor is electrically connected to the control unit, which detects the temperature of the exhaust and drain valve as measured by the temperature sensor.

[0076] The temperature sensor can use conventionally known thermometers, etc.

[0077] The fuel cell system has a fuel gas system.

[0078] The fuel gas system supplies fuel gas to the fuel cell.

[0079] The fuel gas system includes: a fuel gas supply section; and an exhaust / drain valve that can discharge fuel exhaust gas from the fuel cell to the outside.

[0080] The fuel gas system may also include a fuel gas supply path, an injector, a circulation path, a gas-liquid separator, and a fuel exhaust gas discharge path.

[0081] The fuel gas supply unit supplies fuel gas to the anode of the fuel cell.

[0082] As a fuel gas supply unit, examples include fuel tanks, and more specifically, liquid hydrogen tanks and compressed hydrogen tanks.

[0083] The fuel gas supply unit is electrically connected to the control unit. The supply of fuel gas to the fuel cell can be controlled by opening and closing the main check valve of the fuel gas supply unit according to control signals from the control unit.

[0084] The fuel gas supply path connects the fuel gas supply unit to the fuel gas inlet of the fuel cell. The fuel gas supply path enables the supply of fuel gas to the anode of the fuel cell. The fuel gas inlet can be a fuel gas supply port, an anode inlet manifold, etc.

[0085] An injector can be configured in the fuel gas supply path.

[0086] The injector can be configured, for example, at the confluence of the fuel gas supply path and the recirculation path. The injector supplies a mixture of fuel gas and recirculation gas to the anode of the fuel cell. Conventionally known injectors can be used as injectors.

[0087] A pressure regulating valve and a medium-pressure hydrogen sensor can be installed in the area between the fuel gas supply section and the injector in the fuel gas supply flow path.

[0088] The pressure regulating valve regulates the pressure of the fuel gas supplied from the fuel gas supply section to the injector.

[0089] The pressure regulating valve is electrically connected to the control unit. By controlling the opening and closing of the pressure regulating valve and its opening degree, the pressure of the fuel gas supplied to the injector can be adjusted.

[0090] The medium-pressure hydrogen sensor is electrically connected to the control unit. The control unit detects the pressure of the fuel gas measured by the medium-pressure hydrogen sensor and adjusts the pressure of the fuel gas supplied to the injector by controlling the opening and closing of the pressure regulating valve and the opening degree based on the detected pressure.

[0091] The fuel exhaust path connects the fuel gas outlet of the fuel cell to the external environment of the fuel cell system.

[0092] In the fuel exhaust flow path, a gas-liquid separator can be configured in the area between the fuel gas outlet and the outside of the fuel cell system.

[0093] The fuel exhaust gas discharge path can branch off from the circulation path via a gas-liquid separator.

[0094] The fuel exhaust path discharges the fuel exhaust gas from the fuel gas outlet of the fuel cell to the outside of the fuel cell system. The fuel gas outlet can be a fuel gas outlet port, an anode outlet manifold, etc.

[0095] The exhaust drain valve (fuel exhaust gas discharge valve) can be configured in the fuel exhaust gas discharge path. The exhaust drain valve is configured downstream of the gas-liquid separator in the fuel exhaust gas discharge path.

[0096] The exhaust drain valve can discharge fuel exhaust gases and moisture to the outside (outside the system). The outside can be the outside of the fuel cell system or the outside of the aircraft.

[0097] The exhaust drain valve is electrically connected to the control unit. By controlling the opening and closing of the exhaust drain valve, the flow rate of fuel exhaust gas discharged to the outside and the flow rate of water (liquid water) drained can be adjusted. In addition, the fuel gas pressure (anode pressure) supplied to the anode of the fuel cell can be adjusted by adjusting the opening degree of the exhaust drain valve.

[0098] Fuel exhaust gases may include unreacted fuel gases that pass directly through the anode, as well as water generated at the cathode that reaches the anode. There may also be corrosive substances generated in the catalyst layer and electrolyte membrane, and oxidant gases that can be supplied to the anode during scavenging.

[0099] The recirculation path can connect the fuel gas outlet of the fuel cell to the injector.

[0100] The recirculation path can branch off from the fuel exhaust path and merge with the fuel gas supply path by connecting to an injector configured in the fuel gas supply path.

[0101] The circulating flow path can branch off from the fuel exhaust flow path via a gas-liquid separator and merge with the fuel gas supply flow path by connecting to an injector configured in the fuel gas supply flow path.

[0102] The recirculation path can recover the fuel gas, i.e. fuel exhaust gas, discharged from the fuel gas outlet of the fuel cell and supply it to the fuel cell as recirculation gas.

[0103] A gas circulation pump can be configured in the circulation path. The gas circulation pump circulates the fuel exhaust gas as circulating gas. The gas circulation pump is electrically connected to the control unit, and the flow rate of the circulating gas can be adjusted by controlling the on / off state of the gas circulation pump drive and its speed, etc., by the control unit.

[0104] A gas-liquid separator (anode gas-liquid separator) can be configured in the circulating flow path.

[0105] The gas-liquid separator can be configured at the branch point of the fuel exhaust gas discharge path and the circulation path. Therefore, the flow path from the fuel gas outlet to the gas-liquid separator can be either the fuel exhaust gas discharge path or the circulation path.

[0106] The gas-liquid separator is positioned upstream of the exhaust drain valve in the fuel exhaust gas discharge path.

[0107] The gas-liquid separator separates the fuel gas, i.e., fuel exhaust gas, discharged from the fuel gas outlet from moisture (liquid water). This allows the fuel exhaust gas to be returned to the circulation path as recirculated gas, and the exhaust drain valve in the fuel exhaust path can be opened to discharge unwanted gases and moisture to the outside. Furthermore, because the gas-liquid separator can suppress excess moisture from flowing into the circulation path, it can prevent the formation of ice in the circulation pump and other components caused by this moisture.

[0108] The fuel cell system has a cooling system for the fuel cell.

[0109] The cooling system regulates the temperature of the fuel cell.

[0110] The cooling system has a refrigerant flow path and a heating flow path.

[0111] The refrigerant flow path allows the refrigerant to circulate inside and outside the fuel cell. The refrigerant flow path is connected to the refrigerant supply port and refrigerant discharge port located in the fuel cell, enabling the refrigerant to circulate inside and outside the fuel cell.

[0112] A refrigerant supply unit can be provided in the refrigerant flow path. The refrigerant supply unit is electrically connected to the control unit. The refrigerant supply unit is driven according to the control signal from the control unit. The flow rate of refrigerant supplied from the refrigerant supply unit to the fuel cell is controlled by the control unit. As a result, the temperature of the fuel cell can be controlled. Examples of refrigerant supply units include, for example, a cooling water pump.

[0113] A radiator can be installed in the refrigerant flow path to dissipate heat from the cooling water.

[0114] A storage tank for storing refrigerant can be installed in the refrigerant flow path.

[0115] The heating flow path branches off from the refrigerant flow path and is positioned near the exhaust / drain valve, enabling refrigerant circulation to heat the exhaust / drain valve. The positioning of the heating flow path near the exhaust / drain valve is not particularly limited, as long as it allows the refrigerant temperature to be transferred from the heating flow path to the exhaust / drain valve for heating. The heating flow path can either cover the area around the exhaust / drain valve in direct contact with it, or it can be positioned around the exhaust / drain valve with a predetermined gap.

[0116] The heating flow path includes a circulating pump, a water heater, and a three-way valve.

[0117] A circulation pump circulates the refrigerant within the heating flow path. The circulation pump is electrically connected to a control unit. The circulation pump is driven by a control signal from the control unit, which controls the flow rate of the refrigerant circulating in the heating flow path. This allows for control of the temperature of the exhaust and drain valves. Examples of circulation pumps include cooling water pumps.

[0118] The water heater heats the refrigerant. The water heater is electrically connected to the control unit. The water heater is switched on and off according to control signals from the control unit, which controls the temperature of the refrigerant circulating in the heating path.

[0119] The three-way valve controls the supply of refrigerant from the refrigerant flow path and allows the refrigerant to circulate within the heating flow path. Therefore, the refrigerant flow path can be connected to one of the three valves of the three-way valve, and the heating flow path can be connected to the remaining two valves of the three-way valve, branching off from the refrigerant flow path via the three-way valve. Two valves of the three-way valve can be used as inlet and outlet valves, respectively, and the heating flow path can be connected to these valves to form a loop that allows refrigerant circulation. The three-way valve is electrically connected to a control unit. For the three-way valve, the opening and closing of each valve is controlled according to a control signal from the control unit. The three-way valve can supply refrigerant from the refrigerant flow path to the heating flow path by opening at least one of the two valves on the refrigerant flow path side (the valve on the refrigerant flow path side) and the inlet and outlet valves on the heating flow path side (the valve on the heating flow path side). The three-way valve can also allow refrigerant to circulate within the heating flow path by closing the valve on the refrigerant flow path side and opening the inlet and outlet valves on the heating flow path side (the valve on the heating flow path side).

[0120] Fuel cell systems can include an oxidant gas system.

[0121] An oxidant gas system may include an oxidant gas supply unit, an oxidant gas supply path, an oxidant exhaust gas discharge path, an oxidant gas bypass path, a bypass valve, and an oxidant gas flow sensor.

[0122] The oxidant gas supply unit supplies oxidant gas to the fuel cell. Specifically, the oxidant gas supply unit supplies oxidant gas to the cathode of the fuel cell.

[0123] As an oxidant gas supply unit, an air compressor can be used, for example.

[0124] The oxidant gas supply unit is electrically connected to the control unit. The oxidant gas supply unit is driven according to a control signal from the control unit. The oxidant gas supply unit can be controlled by the control unit to select at least one of a group consisting of the flow rate and pressure of the oxidant gas supplied from the oxidant gas supply unit to the cathode.

[0125] The oxidant gas supply path connects the oxidant gas supply unit to the oxidant gas inlet of the fuel cell. The oxidant gas supply path enables the supply of oxidant gas from the oxidant gas supply unit to the cathode of the fuel cell. The oxidant gas inlet can be an oxidant gas supply port, a cathode inlet manifold, etc.

[0126] The oxidant exhaust gas discharge path is connected to the oxidant gas outlet of the fuel cell. This path allows the oxidant gas, i.e., the oxidant exhaust gas, to be discharged from the cathode of the fuel cell to the outside. The oxidant gas outlet can be an oxidant gas discharge port, a cathode outlet manifold, etc.

[0127] An oxidant gas pressure regulating valve can be installed in the oxidant exhaust gas discharge path.

[0128] The oxidant gas pressure regulating valve is electrically connected to the control unit. By opening the valve through the control unit, the reacted oxidant gas, i.e., the oxidant waste gas, is discharged to the outside through the oxidant waste gas discharge path. Furthermore, the pressure of the oxidant gas supplied to the cathode (cathode pressure) can be adjusted by changing the opening degree of the oxidant gas pressure regulating valve.

[0129] The oxidant gas bypass flow path branches off from the oxidant gas supply flow path, bypasses the fuel cell, and connects the branch of the oxidant gas supply flow path to the confluence of the oxidant exhaust flow path.

[0130] A bypass valve is provided in the oxidant gas bypass flow path.

[0131] The bypass valve is electrically connected to the control unit. By opening the bypass valve through the control unit, the oxidant gas can be bypassed from the fuel cell and discharged to the outside through the oxidant exhaust gas discharge path without the need for the supply of oxidant gas to the fuel cell.

[0132] An oxidant gas flow sensor is configured in the oxidant gas supply path.

[0133] An oxidant gas flow sensor detects the flow rate of oxidant gas within the oxidant gas system. The oxidant gas flow sensor is electrically connected to the control unit. The control unit can infer the air compressor speed based on the oxidant gas flow rate detected by the oxidant gas flow sensor. The oxidant gas flow sensor is positioned upstream of the oxidant gas supply section in the oxidant gas supply path.

[0134] Oxidant gas flow sensors can utilize conventionally known flow meters, etc.

[0135] Fuel cell systems can have secondary batteries.

[0136] A secondary battery (rechargeable battery) only needs to be capable of charging and discharging; examples include conventionally known secondary batteries such as nickel-metal hydride batteries and lithium-ion batteries. Furthermore, a secondary battery may include energy storage elements such as double-layer capacitors. A secondary battery can be a structure consisting of multiple batteries connected in series. The secondary battery supplies power to motors and oxidant gas supply units. The secondary battery can be charged, for example, from an external power source of the aircraft. The secondary battery can be charged by the output of a fuel cell. The charging and discharging of the secondary battery can be controlled by a control unit.

[0137] Physically, the control unit includes, for example, a processing unit such as a CPU (Central Processing Unit), a storage unit such as ROM (Read-Only Memory) storing the control program and control data processed by the CPU, and RAM (Random Access Memory) used primarily for various operating areas for control processing, as well as input / output interfaces. Alternatively, the control unit may be, for example, a control device such as an Electronic Control Unit (ECU).

[0138] The control unit can be electrically connected to a switch that can be mounted on an aircraft. The control unit can be configured to operate with the aid of an external power source even when the switch is turned off.

[0139] When the height sensor detects an increase in height and the temperature sensor detects that the exhaust and drain valve temperature is less than the specified temperature, the control unit controls the three-way valve to circulate the refrigerant in the heating flow path and drives the circulation pump and water heater to heat the refrigerant and raise its temperature.

[0140] In this disclosure, when the altitude is high, the enhanced heat preservation control achieved by the water heater in the enhanced cooling system can prevent the exhaust drain valve in the fuel gas system from freezing.

[0141] The specified temperature for the exhaust drain valve can be the temperature at which droplets adhere to the exhaust drain valve and freeze, or it can be appropriately set considering factors such as fuel efficiency.

[0142] For controlling a three-way valve to circulate refrigerant within the heating flow path, specifically, it can be used to control the three-way valve to close the valve on the refrigerant flow path side and open the inlet and outlet valves on the heating flow path side.

[0143] Figure 1 This is a simplified structural diagram illustrating an example of a fuel cell system according to the present disclosure.

[0144] Figure 1 The fuel cell system 100 shown includes a fuel cell 10, a fuel gas supply unit 20, a fuel gas supply path 21, a fuel exhaust gas discharge path 22, an exhaust and drain valve 23, a gas-liquid separator 24, a circulation path 25, an injector 26, a refrigerant supply unit 31, a refrigerant path 32, a radiator 33, a heating path 41, a circulation pump 42, a water heater 43, a three-way valve 44, a control unit 50, a height sensor 60, and a temperature sensor 70. Furthermore, in Figure 1 The diagram only shows the fuel gas system and cooling system, omitting diagrams of other oxidizer gas systems, etc.

[0145] Figure 2 This is a flowchart illustrating an example of the control of a fuel cell system according to the present disclosure.

[0146] First, the altitude sensor measures the aircraft's altitude, and the temperature sensor measures the temperature of the exhaust drain valve.

[0147] Furthermore, when the height sensor detects an increase in height and the temperature of the exhaust and drain valve measured by the temperature sensor is less than the specified temperature, the control unit controls the three-way valve to circulate the refrigerant in the heating flow path, drives the circulation pump and water heater to heat the refrigerant to raise its temperature, and then terminates the control.

[0148] On the other hand, when no increase in altitude is detected as measured by the altitude sensor, or when the temperature of the exhaust drain valve measured by the temperature sensor is above a predetermined temperature, the control unit may terminate control, or stop the operation of at least one of the circulation pump and the water heater. For example, the absence of detected altitude increase could be conceived as the aircraft flying horizontally at a predetermined altitude. In such a case, the temperature fluctuation of the exhaust drain valve is minimal, and the possibility of icing is low. Therefore, from the viewpoint of improving fuel efficiency, the operation of at least one of the circulation pump and the water heater can be stopped in such a situation.

Claims

1. A fuel cell system for use in an aircraft, characterized in that it comprises: Fuel cells; A fuel gas system supplies fuel gas to the fuel cell; The cooling system regulates the temperature of the fuel cell; Altitude sensor; Temperature sensor; and Control Department The fuel gas system includes: a fuel gas supply section; and an exhaust / drain valve capable of discharging fuel exhaust gas from the fuel cell to the outside. The cooling system includes: a refrigerant flow path for circulating refrigerant inside and outside the fuel cell; and a heating flow path branching from the refrigerant flow path and disposed near the exhaust / drain valve, wherein the refrigerant is circulated to heat the exhaust / drain valve. The heating flow path includes: a circulation pump for circulating the refrigerant within the heating flow path; a water heater for heating the refrigerant; and a three-way valve for controlling the supply of refrigerant from the refrigerant flow path and enabling the refrigerant to circulate within the heating flow path. The heating flow path is positioned near the exhaust drain valve so that the temperature of the refrigerant is transferred from the heating flow path to the exhaust drain valve, thereby heating the exhaust drain valve. When the height sensor detects an increase in height, and the temperature measured by the temperature sensor for the exhaust / drain valve is lower than a predetermined temperature, the control unit controls the three-way valve to circulate the refrigerant within the heating path, and drives the circulation pump and the water heater to heat the refrigerant, thereby raising its temperature. If no increase in height is detected as measured by the height sensor, or if the temperature of the exhaust drain valve measured by the temperature sensor is above a specified temperature, the control unit stops driving at least one of the circulating pump and the water heater.

2. An aircraft, characterized in that, The fuel cell system as described in claim 1 is provided.

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