FUEL CELL MODULE AND AUXILIARY COMPONENT MODULES WITH ON-BOARD CONTROL LOGIC, SUITABLE FOR AERONAUTICAL USE

Abstract

The invention relates to a fuel cell device intended to be installed in aircraft and to be used in propulsive and non-propulsive applications. The device consists of an assembly incorporating one or more fuel cells (1) and all the auxiliary organ modules necessary to operate it, specifically the modules for hydrogen supply (2), air supply (3), cooling management (4), electricity (5) and control (6). The system converts hydrogen and air into direct current via the fuel cell. According to the invention, the system is modified and improved to be in compliance with all applicable aeronautical standards and thus meet the regulatory requirements for aviation safety. These modifications provide a significant change compared to existing devices to make the invention suitable for aeronautics.

Description

Title of the invention: FUEL CELL MODULE AND AUXILIARY COMPONENT MODULES WITH ON-BOARD CONTROL LOGIC, SUITABLE FOR AERONAUTICAL USES Technical field

[0001] The present invention relates to a fuel cell device producing electrical energy from a chemical reaction; and which is intended to be installed in aircraft and to be used for propulsive and non-propulsive applications for which it is suitable. State of the prior art

[0002] A fuel cell system has been proposed as a device for generating electricity in a clean, efficient and sustainable manner for stationary or mobile applications; particularly for land vehicles such as automobiles and trucks. These systems are specifically adapted to these applications.

[0003] An example of fuel cell system technology is a proton exchange membrane fuel cell (PEMFC). This fuel cell operates at low temperatures (LT-PEMFC) or high temperatures (HT-PEMFC).

[0004] A low temperature proton exchange membrane fuel cell (LT-PEMFC) system consists of an assembly incorporating one or more fuel cells, called the fuel cell module, and all other ancillary component modules necessary to operate it, more specifically the hydrogen supply, air supply, cooling, electrical and control modules.

[0005] According to the state of the art, high power fuel cell systems are optimized for terrestrial uses for which price and efficiency are favored at the expense of system mass and a high level of safety. For example, devices used for fuel cell vehicles are not qualified for the air environment, in other words, they are not designed to be operated at the temperatures and pressures experienced in flight. In another example, these devices do not include element redundancy and do not achieve reliability levels strictly acceptable for aviation.

[0006] The aim of the invention is therefore to propose means adapted to the aeronautical industry nautical for the introduction of safety devices by modifying the architecture of the conventional terrestrial system by adding specialized components and creating a new control method that accompanies them, in order to bring fuel cell systems into compliance with aeronautical standards and regulations. Statement of the invention

[0007] To do this, the device according to the invention allows significant changes to be made compared to existing devices to make the invention suitable for aeronautics while retaining the same intention. It incorporates modifications and improvements in accordance with the applicable aeronautical standards in order to meet the regulatory requirements of aviation safety.

[0008] In one aspect, the device is a fuel cell system comprising the following elements: - A fuel cell module; - A hydrogen supply module; - An air supply module; - A cooling module; - An electrical module; and - A control module.

[0009] In this manner, the fuel cell module consists of an assembly incorporating one or more low temperature proton exchange membrane fuel cells (LT-PEMFCs). Fuel cells are an assembly of elementary cells, bipolar plates, cooling plates, collectors and a support structure that converts, through an electrochemical process, hydrogen and air into direct current, heat and other reaction products. The elementary cell is the basic unit of a fuel cell and consists of an anode and cathode assembly, separated by an electrolyte, and placed between bipolar plates. For an LT-PEMFC system; the elementary cell is called a membrane-electrode assembly comprising an electrolyte membrane coated or not with a catalyst with gas diffusion layers on each side acting as electrodes.

[0010] In addition, the hydrogen supply module consists of all the elements necessary to supply the fuel cell with hydrogen at the appropriate pressure, temperature, humidity and flow rate. These elements are sized to operate in the temperature and pressure ranges encountered during a air operation by aircraft.

[0011] In addition, the air supply module consists of all the elements necessary to supply the fuel cell with air at the correct pressure, temperature, humidity and flow rate and to remove excess water. These elements are sized to operate in the temperature and pressure ranges encountered during flight operation by aircraft.

[0012] In addition, the cooling module consists of all the elements necessary to supply the fuel cell with refrigerant at the appropriate pressure, temperature and flow rate to remove excess heat from the system. These elements are sized to operate in the temperature and pressure ranges encountered during flight operation by aircraft.

[0013] In addition, the electrical module consists of all the elements necessary to supply the fuel cell module and the auxiliary components with electricity, to collect and distribute the electricity produced by the fuel cell, and to filter and transform the electrical energy. These elements are sized to operate in the temperature and pressure ranges encountered during an aerial operation by aircraft as well as according to the regulations applying to electrical networks on board aircraft.

[0014] In addition, the control module consists of all the elements necessary to control and communicate with the elements of each of the modules, and to monitor the status and performance of the system. It also includes a cell voltage measurement (CVM) device. These elements are sized to operate in the temperature and pressure ranges encountered during flight operation by aircraft as well as according to the regulations applying to electrical networks on board aircraft.

[0015] In a preferred embodiment, all modules are integrated together in an aircraft.

[0016] In another preferred embodiment, the modules are integrated separately into an aircraft, in whole or in part. Presentation of the drawings

[0017] The attached drawings illustrate the invention:

[0018] [Fig-1] describes in section the entire device of the invention.

[0019] [Fig.2] is a diagram which describes a representation of the fuel cell (1) and hydrogen supply (2) modules.

[0020] [Fig.3] illustrates the elements comprising the air supply module (3).

[0021] [Fig.4] illustrates the elements comprising the cooling module (4).

[0022] [Fig.5] illustrates the elements comprising the electrical module (5).

[0023] [Fig.6] illustrates the elements comprising the control module (6). Detailed description

[0024] The following description is provided by way of example only and is not intended to limit the present disclosure, application, or uses. It should also be understood that, in the drawings, corresponding reference numbers indicate similar or corresponding components and features. With respect to the disclosed methods, the disclosed steps are for illustrative purposes only and are therefore neither necessary nor critical. The embodiments are associated with various advantages and / or technical effects.

[0025] The device according to the invention introduces the new elements or modifies in order to allow its use in different types of aircraft.

[0026] As used herein, the term "regulatory requirements" refers to requirements arising from discussions and work between the aviation industry and aviation authorities that are not yet finalized.

[0027] As used herein, the term "ATEX" refers to European regulations relating to explosive atmospheres.

[0028] The fuel cell system comprises a fuel cell and associated auxiliary components that manage the properties of the chemical reactants as well as the thermal and electrical behavior of the system. The fuel cell system is composed of 6 different modules.

[0029] In one embodiment, the fuel cell module (1) is composed of a fuel cell (1a) and a cell voltage measuring device (or CVM) (1b). A fuel cell is an electrochemical device that converts the chemical energy of reactants into electrical energy. A fuel cell is composed of several elementary cells with different layers to maximize the reaction surface area between reactants and electrodes. The fuel cell uses low-temperature proton exchange membrane fuel cell technology. Oxygen from ambient air and hydrogen are the reactants and react in a redox reaction between oxygen and hydrogen. The cells that make up the fuel cell are electrically connected in series, so the fuel cell voltage is the sum of the cell voltages. The Cell Voltage Meter (or CVM) (lb) is the instrumentation device that measures cell voltage. The CVM (lb) includes multiple channels to measure different cell voltages. The CVM (lb) also contains an internal controller to monitor various parameters such as voltage and temperature, but also to perform specific and simple operations such as the minimum voltage channel for example. The CVM (1b) contains an external communication port to communicate with the rest of the system. This can be for example a CAN bus port to communicate via the CAN bus protocol.

[0030] The hydrogen supply module (2) is the unit responsible for supplying hydrogen and distributing it within the module. It transforms the hydrogen at the inlet of the module to the appropriate pressure level for the inlet of the fuel cell. The hydrogen shutoff valve (2b) allows or stops the flow of hydrogen in its circulation in the module (2) and to the fuel cell module (1). The injectors (2c) regulate the flow and pressure of hydrogen according to the operating conditions and the needs of the system. The ejector (2d) allows the mixing of hydrogen from the supply with that which is reinjected at the fuel cell outlet via the recirculation function. The ejector also contributes to the expansion of the hydrogen. A safety valve (2nd) is used to protect the fuel cell against overpressure. A water condenser (2g) separates liquid water and wet hydrogen gas at the fuel cell outlet. A level sensor (2j) is used to detect if the water level exceeds a certain threshold in order to protect the fuel cell against flooding. The liquid water is discharged through the drain valve (2h). Hydrogen gas is discharged through the hydrogen purge valve (2i). Pressure (2a) and temperature (2f) sensors are used to monitor gas conditions inside the module and communicate information to the control logic.

[0031] The air supply module (3) is the unit responsible for supplying air under the appropriate conditions to the fuel cell module (1). The air supply module (3) consists of an air inlet (3a). This air intake allows oxygen to be taken from the air while reducing the pressure drop. It also contains a filter which removes ambient pollutants which could damage the fuel cell (la). Another function of the air supply module is the air compression function (3b). The air compression function aims to increase the air pressure so as to respect the pressure envelope of the fuel cell, which may be different from the ambient air pressure in which the fuel cell system is located, particularly in an aircraft flying at high altitude. An example of this function can be a centrifugal air compressor (3bi), or a centrifugal air compressor with a bypass line (3bii) in order to achieve a higher pressure ratio with a lower mass flow rate, or a turbocharger architecture (3biii) with a turbine placed at the air exhaust of the fuel cell (la) which will draw part of the exhaust energy from the air to reduce the energy requirements of the centrifugal compressor, thus increasing the efficiency of the system. The air intercooler (3c) allows the air temperature to be reduced if necessary to respect the inlet temperature envelope of the fuel cell (la). It can be for example an air-coolant heat exchanger (3ci) in which the mass flow rate of the coolant can be varied to achieve a different heat removal rate.Another example might be a cryogenic air-hydrogen heat exchanger (3cii). The air humidifier (3d) allows the relative humidity of the incoming air to be regulated to match the input requirements of the fuel cell (la). This could be a passive humidifier (3di) that uses the higher relative humidity of the exhaust air to exchange water through a membrane. Another example could be the same humidifier with a bypass line (3dii) to allow more active regulation of the relative humidity of the air inlet. Another part of the air supply module (3) is the air exhaust part (3e) to discharge air and water into the atmosphere. The air supply module (3) also contains the air supply monitoring (3f) for monitoring all the various relevant parameters of the reactive air. Air pressure transmitters, air temperature transmitters, air relative humidity sensors, air mass flow meters are examples of monitoring devices that could be used in the air supply module (3). Finally, valves (3g) are used at various locations in the system to control, direct, or stop the flow of air in the system.

[0032] The cooling module (4) is the unit responsible for the thermal management of the system. The cooling module consists of pumps (4a) that allow coolant to circulate through the thermal management system and through all components that need to be cooled. The pumps (4a) are also powered to control the mass flow rate entering the fuel cell (la). A fuel cell heat exchanger (4b) is integrated to remove the coolant heat that has been captured in the fuel cell (1a) by the coolant flowing through the fuel cell. The fuel cell heat exchanger (4b) is an air-coolant heat exchanger dissement. It can be a passive heat exchanger, with the coolant flow controlled by the pump and air coming from the atmosphere. Another example can be this same radiator with the addition of electric fans to increase airflow through the heat exchanger. An electric heater (4c) is used in the system to warm the coolant to enable cold starting of the system. A filter (4d) is integrated into the system to remove particles and pollutants that could damage the fuel cell. A heat exchanger for auxiliary components (4e) is located in the system to remove heat generated by the operation of other modules that must be cooled by liquid. This heat exchanger can be an air-to-coolant heat exchanger. Another example can be a refrigerant-to-cryogenic hydrogen heat exchanger. This heat exchanger can be placed in the same cooling loop or in a different one relative to the heat exchanger for the fuel cell (4b). The cooling module (4) also contains cooling monitoring tools (4f) to monitor all relevant physical parameters of the coolant. Pressure, temperature, conductivity and mass flow sensors can be used to monitor the coolant. Finally, valves (4g) are used at various locations in the system to control, direct or stop the flow of coolant in the system.

[0033] The electrical module (5) is the unit responsible for converting and distributing energy in the system. This electrical energy can be manifested under different voltage levels: high voltage or low voltage. The fuel cell produces a variable voltage so requires a high voltage DC to high voltage DC converter (5a) to stabilize the voltage before feeding it to the high voltage battery (5c). To power low voltage equipment, a high voltage DC to low voltage DC converter (5b) is required. A distribution box (5e) contains fuses (5d) and distributes the power to all the different consumers.

[0034] The control module (6) is the unit responsible for controlling the fuel cell system. The control module (6) is composed of controllers (6a) which ensure the performance of the entire system. The communication module (6b) is the main communication link between the system and the rest of the aircraft via a dedicated communication link. An example of a communication link may be a CAN bus port respecting the ARINC 825 protocol. The control module (6) also provides safety protections to protect the system and the aircraft.

[0035] The system includes modifications and improvements over standard systems used for land vehicles. These improvements are necessary to comply with aeronautical requirements, constitute an inventive activity and allow for an innovative application of existing technology.

[0036] The fuel cell module (1) has separate channels and seals for the air (3), hydrogen (2) and coolant (4) inlets and outlets of the cell. This ensures a high level of safety, because in the event of a leak from one of the channels, the escaped fluid will not be able to come into contact with the other fluids.

[0037] The fuel cell is equipped with a separate hydrogen purge and an exhaust for water discharge, as opposed to a single exhaust for both fluids. The hydrogen is purged and directed upwards while the water is discharged downwards. This is done to avoid the potential formation of ice in the hydrogen purge line in cold conditions. This could cause an additional safety risk if hydrogen builds up in the exhaust.

[0038] The fuel cell does not contain polyphenylene sulfide (PPS) plastic components (e.g., end plate) external to the fuel cell to reduce flammability. These components are replaced with non-flammable metallic materials compatible with hydrogen and glycol coolant. Only necessary components made from flammable materials for their intrinsic function do not require material changes (e.g., fuel cell membranes and seals).

[0039] A safety valve is introduced after the hydrogen expansion step (e.g. injectors) to avoid overpressure at the anode inlet. A failure in the pressure control before the fuel cell can lead to overpressure that can severely damage the cell and cause a safety risk. Detecting this overpressure using pressure transmitters and, consequently, performing a rapid shutdown of the system can avoid the safety risk but will not save the cell from damage. Moreover, the latter is an active monitoring and control protocol that can also fail. Thus, having a safety valve that would release the excess pressure before the anode inlet solves these problems.

[0040] In aviation, high pitch and roll angles can be achieved, and the fuel cell must be able to operate under these conditions and handle water accumulation. Failure to do so could result in hydrogen starvation via these two problems: • Recirculation of water into the fuel cell from the condenser through the ejector; or • Accumulation of water in the hydrogen collectors. To avoid this, three solutions are proposed: • Replace the ejector (2ei) (passive component) with a recirculation pump / blower (2eii) (active component), with which the correct water suction can be ensured under all the above-mentioned operating conditions. • Retain ejector (2ei) with special design of water condenser and more frequent purging of gas and water through the anode. • Replace the ejector with a hybrid solution (2eiii) using a low-current recirculation pump / blower and a passive high-current ejector-based system.

[0041] The hydrogen supply unit is adapted so that the fuel cell system is capable of operating in a vertical configuration. By vertical configuration, it is meant that the plane of the cells of the fuel cell is normal to the Z axis (gravity). The hydrogen supply unit will allow the change of direction of the water flow, in particular the water condenser. The vertical orientation is useful when space is limited in the X axis of the aircraft.

[0042] The hydrogen supply module is ATEX compliant, meaning that all components that transmit signals are at least ATEX II 2G Ile T6 classified. These components present a risk of causing an electrical spark that could potentially ignite the surrounding environment (under specific conditions). To prevent this, the electrical connectors of the transmitters are covered with a specific insulating material that would contain this spark. In terms of temperature classification, the surface of these components will not exceed 135°C (T4). If an individual transmitter component is not ATEX labeled, either its surrounding environment is degraded by the ATEX protection, or increased intrinsic safety of the system (potting, PTFE sleeves, etc.) is implemented.

[0043] The communication protocol of the anode control system follows the ARINC 825 standards which interacts via the CAN bus for the operation and protection of the fuel cell system. The control module receives a target air pressure and an operating mode. Based on this information, it controls the hydrogen supply loop and monitors risks.

[0044] According to a variant not illustrated, the fuel cell module can be composed of several fuel cells.

[0045] According to another variant not illustrated, the whole of the device or a part can be inclined relative to the horizontal axis of the aircraft to allow the flow of water in a manner beneficial to the operation of the system in the different attitudes of the flight.

[0046] The device according to the invention is particularly intended for electricity generation systems on board aircraft. List of reference signs

[0047] With reference to these drawings, the device comprises the following articles: 1. Fuel cell module; 2. Hydrogen supply module; 3. Air supply module; 4. Cooling module; 5. Electrical module; 6. Control module.

[0048] 1. Fuel cell module: the unit producing electrical energy comprising: a. A low-temperature proton exchange membrane fuel cell (LT-PEMFC); 1b. A cell voltage measuring device (CVM). As illustrated in [Fig.2].

[0049] 2. Hydrogen supply module: the unit responsible for supplying of hydrogen and its distribution which may include: 2a. Temperature transmitters (1 unit); 2b. Pressure transmitters (3 units); 2c. A hydrogen supply shut-off valve (SOV); 2d. Hydrogen injectors (4 units); 2nd. A recirculation module; i. An ejector ii. A recirculation pump / blower; iii. A hybrid solution using a recirculation pump / blower and an ejector. 2f. A safety valve for hydrogen; 2g. A water condenser; 2h. A water purge valve; 2i. A water level sensor; and 2d. A hydrogen purge valve. As illustrated in [Fig.2].

[0050] 3. Air supply module: the unit responsible for supplying air into the conditions appropriate to the fuel cell module which may include: 3a. An air inlet and filtering; 3b. An air compression module; i. A centrifugal air compressor; ii. A centrifugal air compressor with bypass line; or iii. A turbocharger. 3c. An intermediate exchanger; i. An air-to-coolant heat exchanger; or ii. A cryogenic air-hydrogen heat exchanger 3d. A humidification module; i. A simple humidifier; or ii. A humidifier with bypass controlled by a solenoid valve. 3rd. An air escape; 3f. Air monitoring devices; 3g. Valves. As illustrated in [Fig.3].

[0051] 4. Cooling module: the unit responsible for the thermal management of the system which may include: 4a. A pump; 4b. A heat exchanger for the fuel cell; 4c. A heater for the coolant; 4d. A filter; 4th. A heat exchanger for auxiliary organs; 4f. Cooling monitoring devices; 4g. Valves. As illustrated in [Fig.4].

[0052] 5. Electrical module: the unit responsible for the conversion and distribution of the energy in the system which can include: 5a. A high voltage direct current to low voltage direct current converter; 5b. A high voltage direct current to high voltage direct current converter; 5c. A high voltage auxiliary battery; 5d. Distribution boxes with fuses. As illustrated in [Fig.5].

[0053] 6. Control module: the unit responsible for controlling the system which can understand : 6a. A controller; 6b. A communication module. As illustrated in [Fig.6].

Claims

Claims

1. Fuel cell device for generating electrical energy from hydrogen and air and distributing it to the on-board network of an aircraft; said device comprising: a fuel cell module (1); a hydrogen supply module (2); an air supply module (3); a cooling module (4); an electrical module (5); and a control module (6); and characterized in that it incorporates modifications for greater lightness and a higher level of safety compared to a system designed for terrestrial applications; and that it is adapted to aeronautical standards and requirements by being qualified according to the requirements of standards DO-160 and DO-178.

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