Computer-implemented method for operating fuel cell system in conjunction with start-up of fuel cell system

Abstract

The invention relates to a computer-implemented method for operating a fuel cell system in conjunction with a start-up of the fuel cell system, in particular to a fuel cell system and a method for operating the fuel cell system in conjunction with a start-up of the fuel cell system. The fuel cell system comprises: an anode volume and a cathode volume; a fluid flow assembly comprising a plurality of fluid conduits and a fluid flow control device wherein a recirculation loop is formed when a fluid connection between the anode volume and the cathode volume is enabled; a hydrogen supply device; the method comprises the following steps: controlling the hydrogen supply device to supply hydrogen; adjusting the fluid flow control device such that the anode volume is fluidly connected to the cathode volume; the recirculation device is controlled to recirculate the gas mixture in the fluid recirculation loop such that the supplied hydrogen reacts with residual oxygen during recirculation.

Description

Technical Field

[0001] The present disclosure generally relates to fuel cell vehicles. In particular aspects, the present disclosure relates to a computer-implemented method for operating a fuel cell system in conjunction with the startup of the fuel cell system. The present disclosure also relates to a fuel cell system, a computer system, a computer program product, and a non-transitory computer-readable storage medium. The present disclosure may be applicable to heavy vehicles such as trucks, buses, and construction equipment, as well as other vehicle types. Although the present disclosure may be described with respect to a particular vehicle, the present disclosure is not limited to any particular vehicle. Background Art

[0002] A fuel cell is an electrochemical cell that converts chemical energy into electrical energy. A fuel cell converts the chemical energy of a fuel (usually hydrogen) and an oxidant (usually oxygen) into electricity. Therefore, fuel cells can be used as a replacement or supplement to batteries. In recent years, fuel cells have been considered for use in powering electric vehicles.

[0003] A fuel cell includes an anode and an anode volume to which a fuel (usually hydrogen) is supplied, a cathode and a cathode volume to which an oxidant (usually air) is supplied, and an electrolyte disposed between the anode and the cathode. A catalyst provided at the anode causes an oxidation reaction of the fuel, thereby generating ions and electrons. The ions move from the anode to the cathode through the electrolyte. The electrons flow from the anode to the cathode through an external circuit, thereby generating electricity.

[0004] Fuel cell systems including one or more fuel cells are susceptible to degradation due to startup and shutdown of the system. Typically, degradation is caused by high, reverse or uneven voltage potentials, which are often the result of uneven or undesirable distribution of reactants. For example, degradation may also be caused by oxidation caused by residual oxidant in the fuel cell. Degradation may also be caused by residual fuel in the anode flow field when the fuel cell is shut down (which may contaminate the cathode flow field). When the fuel cell is started, the anode flow field and the cathode flow field may contain a mixture of fuel and oxidant, which can cause hot spots and high potentials, leading to degradation of the fuel cell.

[0005] Various strategies have been developed to mitigate degradation mechanisms during startup and shutdown of fuel cell systems. Among these strategies, a known solution is scavenging, which involves flushing the fuel cell system with an inert gas. The main purpose of this scavenging method is to expel residual oxidants from the fuel cell system as quickly as possible. However, the rapid nature of the process may result in significant gas concentration gradients, which poses potential challenges. In addition, the implementation of this scavenging method requires additional storage space for the inert gas, which further complicates the requirements of the system. In addition, hydrogen scavenging methods are used for rich air conditions, which can cause carbon corrosion and can cause waste of fuel. Using air as a scavenging gas to transition from a hydrogen-rich state may also dump fuel into the exhaust and may result in sudden or localized heat release.

[0006] Accordingly, efforts have been made to develop improved technologies related to fuel cell systems. Summary of the invention

[0007] According to a first aspect of the present invention, there is provided a computer system according to claim 1, comprising a processing circuit, the processing circuit being configured to operate a fuel cell system in conjunction with startup of the fuel cell system. The fuel cell system comprises: − a fuel cell stack, the fuel cell stack comprising an anode side and a cathode side, wherein the anode side comprises an anode volume and the cathode side comprises a cathode volume, a fluid flow assembly comprising a plurality of fluid conduits and fluid flow control means, wherein the fluid flow assembly is arranged to selectively enable a fluid connection between the anode volume and the cathode volume, wherein when the fluid connection between the anode volume and the cathode volume is enabled, a recirculation loop is formed, − Hydrogen supply, and − a recirculation device arranged on the recirculation loop and configured to recirculate a gas mixture of supplied hydrogen and residual gas in the recirculation loop, wherein the residual gas includes residual oxygen and residual nitrogen present in the fuel cell stack.

[0008] The processing circuit is configured to: − Control the hydrogen supply device to supply hydrogen to the fuel cell system, − adjusting the fluid flow control device so that the anode volume is fluidly connected to the cathode volume, and − controlling the recirculation device to recirculate the gas mixture in the fluid recirculation loop so that the supplied hydrogen reacts with the residual oxygen during the recirculation, thereby resulting in a reduction in the amount of residual oxygen in the fuel cell system.

[0009] A first aspect of the present disclosure may seek to avoid significant gas concentration gradients in a fuel cell system, for example, avoiding an unbalanced condition of an oxygen-rich environment on either the anode side or the cathode side. Specifically, it may seek to transform the fuel cell system from an air-rich condition to a condition that is favorable for startup without generating carbon corrosion conditions, significant concentration gradients, heat bursts, or uneven or undesirable voltage potentials. Technical advantages may include improved system uniformity.

[0010] This technical advantage is achieved by implementing a recirculation loop that enables continuous circulation of the gas mixture within the fuel cell system. During this recirculation process, the supplied hydrogen can react with the residual oxygen on both the anode side and the cathode side simultaneously. Therefore, no voltage difference is generated between the anode and cathode, which can effectively eliminate any potential difference between them. Another technical advantage can include stable and consistent voltage output and enhanced overall system stability.

[0011] Furthermore, during this process, it can generate heat and water as byproducts of the chemical reaction, which can occur in both the cathode volume and the anode volume. Therefore, it can allow for even distribution of heat and humidity throughout the fuel cell stack. This is particularly beneficial during cold starts, as it can effectively pre-condition and evenly humidify the fuel cell stack. As a result, the fuel cell system can be fully prepared for startup, thereby enhancing its overall performance and efficiency.

[0012] According to a second aspect of the present invention, there is provided a computer-implemented method according to claim 2 for operating a fuel cell system in conjunction with startup of the fuel cell system. The fuel cell system comprises: − a fuel cell stack, the fuel cell stack comprising an anode side and a cathode side, wherein the anode side comprises an anode volume and the cathode side comprises a cathode volume, a fluid flow assembly comprising a plurality of fluid conduits and fluid flow control means, wherein the fluid flow assembly is arranged to selectively enable a fluid connection between the anode volume and the cathode volume, wherein when the fluid connection between the anode volume and the cathode volume is enabled, a recirculation loop is formed, − Hydrogen supply, and − a recirculation device arranged on the recirculation loop and configured to recirculate a gas mixture of supplied hydrogen and residual gas in the recirculation loop, wherein the residual gas includes residual oxygen and residual nitrogen present in the fuel cell stack.

[0013] The method comprises: − The processing circuit controls the hydrogen supply device to supply hydrogen to the fuel cell system. − the fluid flow control means are regulated by the processing circuit so that the anode volume is fluidly connected to the cathode volume, − The recirculation device is controlled by the processing circuit to recirculate the gas mixture in the fluid recirculation loop so that the supplied hydrogen reacts with the residual oxygen during the recirculation, thereby resulting in a reduction in the amount of residual oxygen in the fuel cell system.

[0014] The advantages and technical advantages of the second aspect of the present disclosure are largely similar to those of the first aspect of the present disclosure. It should also be noted that all examples of the second aspect of the present disclosure can be combined with all examples of the first aspect of the present disclosure, and vice versa.

[0015] Optionally, in some examples, including at least one preferred example, hydrogen is supplied to the fuel cell system by hydrogen injection at a controllable injection rate. The injection rate can be slow enough so that hydrogen can be supplied in a gentle manner, allowing residual oxygen to be gradually consumed. Technical advantages may include that significant gas concentration gradients can be avoided.

[0016] Optionally, in some examples, including in at least one preferred example, a catalytic device is provided at which the reaction of the supplied hydrogen and the residual oxygen is promoted, wherein the catalytic device is disposed separately from the fuel cell stack, and wherein the method further comprises: − The hydrogen supply device is controlled by the processing circuit to inject hydrogen into the catalytic device.

[0017] In this way, it can passivate the residual oxygen present in the fuel cell stack more effectively with respect to the newly supplied hydrogen at the separately provided catalytic device and thus protect the anode side and / or cathode side from corrosion. The catalytic device can be easily replaced and / or repaired if necessary without affecting the fuel cell stack. Technical advantages may include that the service life of the fuel cell system may be extended.

[0018] Optionally, in some examples, including in at least one preferred example, the method comprises: − the residual oxygen level in the gas mixture is estimated by the processing circuit, In response to the estimated remaining oxygen level being below a threshold, the processing circuit adjusts the fluid flow control device so that the anode volume is fluidly disconnected from the cathode volume, and the processing circuit controls the hydrogen supply device to terminate the supply of hydrogen to the fuel cell system.

[0019] In this way, the recirculation process can be terminated where appropriate, for example after residual oxygen has been completely removed.

[0020] Optionally, in some examples, including at least one preferred example, estimating the residual oxygen level in the gas mixture further comprises: − monitoring of the temperature at the catalyst and / or the gas mixture by the processing circuit, and − The residual oxygen level in the gas mixture is estimated by the processing circuit based on the monitored temperature.

[0021] The temperature at the catalytic device and / or the gas mixture is generally a good indicator of the ongoing chemical reaction process of the supplied hydrogen and residual oxygen, and may also be indicative of the residual oxygen level. By using temperature information to assess the residual oxygen level in the gas mixture, the need to use a dedicated and more expensive oxygen sensor for estimation may be eliminated. Technical advantages may include that the estimation may be performed using relatively simple and robust equipment.

[0022] Optionally, in some examples, including at least one preferred example, estimating the residual oxygen level in the gas mixture further comprises: − monitoring of the pressure of the catalyst and / or the gas mixture by the processing circuit, and − The residual oxygen level in the gas mixture is estimated by the processing circuit based on the monitored pressure.

[0023] After injecting hydrogen into the catalytic device, an initial pressure drop may occur due to the chemical interaction between hydrogen and residual oxygen. As the oxygen is gradually consumed in the reaction, a reversal of the pressure dynamics may be observed. The partial pressure of the supplied hydrogen may initially rise, subsequently resulting in a pressure increase. In this way, by monitoring the pressure change, the residual oxygen level in the gas mixture may be assessed. In this way, the need to use a dedicated and more expensive oxygen sensor for estimation may be eliminated. Technical advantages may include that the estimation may be performed using relatively simple and robust equipment.

[0024] Optionally, in some examples, including in at least one preferred example, the method further comprises: − in response to the anode volume being fluidly disconnected from the cathode volume, the processing circuit controls the hydrogen supply device to supply hydrogen to the anode volume, and the processing circuit controls the air supply device to supply air to the cathode volume, and − The fuel cell system is started by the processing circuit.

[0025] This is to ensure that any residual nitrogen present in the anode volume as well as in the cathode volume is purged, respectively. Thereafter, the fuel cell system is fully ready for start-up. Technical advantages may include that the fuel cell system is better prepared for start-up.

[0026] According to a third aspect of the present disclosure, there is provided a fuel cell system for supplying electric power according to claim 9. The fuel cell system comprises: − a fuel cell stack, the fuel cell stack comprising an anode side and a cathode side, wherein the anode side comprises an anode volume and the cathode side comprises a cathode volume, a fluid flow assembly comprising a plurality of fluid conduits and fluid flow control means, wherein the fluid flow assembly is arranged to selectively enable a fluid connection between the anode volume and the cathode volume, wherein when the fluid connection between the anode volume and the cathode volume is enabled, a recirculation loop is formed, − a hydrogen supply device configured to supply hydrogen to the fuel cell system, and − a recirculation device arranged on the recirculation loop and configured to recirculate a gas mixture of supplied hydrogen and residual gas in the recirculation loop, wherein the residual gas includes residual oxygen and residual nitrogen present in the fuel cell stack.

[0027] The fuel cell system further comprises a control unit, the control unit comprising a processing circuit, the processing circuit being configured to: − Control the hydrogen supply device to supply hydrogen to the fuel cell system, − adjusting the fluid flow control device so that the anode volume is fluidly connected to the cathode volume, and − controlling the recirculation device to recirculate the gas mixture in the fluid recirculation loop so that the supplied hydrogen reacts with the residual oxygen during the recirculation, thereby resulting in a reduction in the amount of residual oxygen in the fuel cell system.

[0028] The control unit is configured to control the above-mentioned device during the start-up of the fuel cell system, which can seek to avoid significant gas concentration gradients, for example, to avoid unbalanced conditions of an oxygen-rich environment on one side of the anode side or the cathode side. The advantages and technical advantages of the third aspect of the present disclosure are largely similar to the advantages and technical advantages of the first aspect and / or the second aspect of the present disclosure.

[0029] Optionally, in some examples, including at least one preferred example, the hydrogen supply device includes a fuel injector configured to supply hydrogen at a controllable injection rate. The injection rate can be slow enough so that hydrogen can be supplied in a gentle manner, thereby allowing residual oxygen to be gradually consumed. Technical advantages may include that significant gas concentration gradients can be avoided.

[0030] Optionally, in some examples, including at least one preferred example, the fuel cell system further comprises a catalytic device at which the reaction of the supplied hydrogen with the residual oxygen is promoted, wherein the catalytic device is arranged separately from the fuel cell stack. In this way, it can passivate the residual oxygen present in the fuel cell stack more effectively than the newly supplied hydrogen at the separately provided catalytic device, and thus protect the anode side and / or cathode side from corrosion. The catalytic device can be easily replaced and / or repaired when necessary without affecting the fuel cell stack. Technical advantages may include that the service life of the fuel cell system can be extended.

[0031] Optionally, in some examples, including in at least one preferred example, the fluid flow control device includes one or more three-way valves and / or one or more two-way valves. In some examples, the two-way valve is used to enable and / or disable the fluid connection between the anode volume and the cathode volume. In some other examples, a three-way valve is used, which can additionally control the air supply from the intake conduit to the cathode volume and from the cathode volume to the exhaust conduit.

[0032] Optionally, in some examples, including at least one preferred example, the recirculation device includes a blower, which is preferably arranged downstream of the anode volume. The blower can provide a stable circulating gas flow. In this way, the gas mixture can be recirculated within the recirculation loop at a stable and slow rate, so that the hydrogen reacts with the residual oxygen in both the anode volume and the cathode volume simultaneously. Technical advantages may include improved system uniformity.

[0033] Optionally, in some examples, including at least one preferred example, the recirculation device further comprises a turbocharger, preferably arranged downstream of the cathode volume, which can enhance the recirculation process. Technical advantages may include an enhanced recirculation process.

[0034] Optionally, in some examples, including at least one preferred example, the fuel cell system further comprises a humidifier configured to humidify the gas mixture before it enters the cathode volume. Generally speaking, an appropriate humidity level is required to ensure proton conductivity in the electrolyte and maintain a good condition of the membrane electrode assembly of the fuel cell system. Technical advantages may include that the service life of the fuel cell system can be extended.

[0035] Optionally, in some examples, including at least one preferred example, the humidifier is provided with one or more bypass valves configured to selectively bypass air flow from the humidifier.

[0036] According to a fourth aspect of the present disclosure, a computer program product is provided. The computer program product comprises a program code. When the program code is executed by a processing circuit, the method according to the second aspect of the present disclosure is performed.

[0037] According to a fifth aspect of the present disclosure, there is provided a non-transitory computer-readable storage medium comprising instructions, which, when executed by a processing circuit, cause the processing circuit to perform the method according to the second aspect of the present disclosure.

[0038] According to a sixth aspect of the present disclosure, a vehicle is provided, the vehicle comprising the fuel cell system according to the third aspect of the present disclosure.

[0039] Those skilled in the art will appreciate that the disclosed aspects, examples (including any preferred examples), and / or the accompanying claims may be appropriately combined with each other. Additional features and advantages are disclosed in the following description, claims, and drawings, and in part will be apparent to those skilled in the art or recognized by practicing the disclosure as described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Examples are described in more detail below with reference to the accompanying drawings.

[0041] Figure 1 is a schematic side view of a vehicle;

[0042] Figure 2a is a schematic diagram of a fuel cell system according to one example;

[0043] Figure 2b to Figure 2d is a schematic diagram of a fuel cell system according to other examples;

[0044] Figure 3 is a flow chart illustrating an operating method for operating a fuel cell system in conjunction with startup of the fuel cell system according to one example;

[0045] Figure 4a to Figure 4b It is shown Figure 3 Flowchart of optional steps of the method described in.

[0046] Figure 5 is a schematic diagram of an exemplary computer system for implementing the examples disclosed herein, according to one example. DETAILED DESCRIPTION

[0047] The detailed description set forth below provides information and examples of the disclosed technology in sufficient detail to enable those skilled in the art to practice the disclosure.

[0048] Fuel cell systems including one or more fuel cells are susceptible to degradation due to startup and shutdown of the system. Typically, degradation is caused by high, reverse or uneven voltage potentials, which are often the result of uneven or undesirable distribution of reactants. For example, degradation may also be caused by oxidation caused by residual oxidant in the fuel cell. Degradation may also be caused by residual fuel in the anode flow field when the fuel cell is shut down (which may contaminate the cathode flow field). When the fuel cell is started, the anode flow field and the cathode flow field may contain a mixture of fuel and oxidant, which can cause hot spots and high potentials, leading to degradation of the fuel cell.

[0049] Various strategies have been developed to mitigate degradation mechanisms during startup and shutdown of fuel cell systems. Among these strategies, one known solution is scavenging, which involves flushing the fuel cell system with an inert gas. The main purpose of this scavenging method is to expel the residual oxidants present from the fuel cell system as quickly as possible. However, the rapid nature of the process can result in significant gas concentration gradients, which poses potential challenges. In addition, implementing this scavenging method requires providing additional storage space for the inert gas, which further complicates the requirements of the system.

[0050] The present disclosure may seek to avoid significant gas concentration gradients, such as unbalanced conditions where an oxygen-rich environment occurs on one side, either the anode side or the cathode side. Specifically, it may seek to transition from air-rich conditions to conditions that are favorable for startup without creating carbon corrosion conditions, significant concentration gradients, heat bursts, or uneven or undesirable voltage potentials. Technical advantages may include improved system uniformity.

[0051] Figure 1 A side view of a vehicle 100 according to one example is depicted. The vehicle 100 is here a truck, more specifically a heavy truck for towing one or more trailers (not shown). Although a heavy truck 100 is shown, it should be noted that the present invention is not limited to this type of vehicle, but can be used for any other type of vehicle, such as buses, construction equipment (e.g., wheel loaders and excavators), and passenger cars. The present invention is also applicable to other applications not related to vehicles, as long as fuel cells are utilized.

[0052] The vehicle 100 includes a fuel cell system 110 according to one example. The fuel cell system 110 is used here to power one or more electric motors (not shown), which are used to generate propulsion for the vehicle 100. The fuel cell system 110 can be used in addition or alternatively to power other power consuming devices of the vehicle 100 (such as an electric motor for a refrigerator system, an electric motor for an air conditioning system, or any other power consuming function of the vehicle 100). The vehicle 100 may also include an energy storage system (not shown), which typically includes a high-voltage battery (not shown). The fuel cell system 110 is suitable for generating electricity, wherein the generated electricity can be fed to one or more electric motors (not shown), which are configured to provide propulsion power to drive the drive wheels 101 of the vehicle 100. The electricity generated by the fuel cell system 110 can also be used to charge the high-voltage battery of the energy storage system. The electricity stored in the high-voltage energy storage system can also be fed to one or more electric motors.

[0053] The vehicle 100 further includes a control unit 400, which may also be a computer system 400. The control unit 400 is used to control the fuel cell system 110. Although an onboard control unit 400 is shown, it should be understood that the control unit 400 may also be a remote control unit 400, i.e., an off-board control unit, or a combination of on-board and off-board control units. The control unit 200 may be configured to control the fuel cell system 110 by issuing control signals and by receiving status information related to the fuel cell system 110.

[0054] Figure 2a A schematic diagram of a fuel cell system 110 according to a first example is depicted. The fuel cell system 110 may be used, for example, as Figure 1 The illustrated vehicle 100. The illustrated fuel cell system 110 is a polymer electrolyte (PEM) fuel cell system configured to generate electrical current from a first reactant (in the form of an oxidant, such as air) and a second reactant (in the form of a fuel, such as hydrogen).

[0055] The fuel cell system 110 includes a fuel cell stack 120, which in turn includes a plurality of fuel cells (not shown), such as hundreds of fuel cells. The fuel cell stack 120 has a cathode side 121 including a cathode volume 122, and an anode side 123 including an anode volume 124. A cathode catalyst layer 121a and an anode catalyst layer 123a are disposed in the cathode volume 122 and the anode volume 124, respectively. Although not shown in detail, the cathode volume 122 includes a cathode and a cathode flow channel, which are typically made of a porous material coated with a catalyst material, and the anode volume 124 includes an anode and an anode flow channel, which are typically made of a porous material coated with a catalyst material. An electrolyte layer (such as a polymer membrane) is inserted between the cathode volume 122 and the anode volume 124 to form a membrane electrode assembly, which is configured to conduct protons while acting as an electronic insulator and a reactant barrier (e.g., to oxygen and hydrogen).

[0056] The fuel cell system 110 also includes a fluid flow assembly 111, which includes a plurality of fluid conduits 111a to 111d and a pair of multi-way valves 113a, 113b, such as a pair of three-way valves 113a, 113b. A pair of three-way valves 113a, 113b is configured to control the fluid connection between the cathode volume 122 and the anode volume 124. In addition, the three-way valves 113a, 113b can adjust the air supply from the intake conduit (not shown) to the cathode volume 121 and from the cathode volume 121 to the exhaust conduit (not shown), as indicated by the arrows at the valves 113a, 113b. The valves 113a, 113b can also be adjusted to allow a small amount of air to enter the fuel cell system 100. This may help to avoid insufficient pressure and / or increase the temperature when necessary. When the three-way valves 113a, 113b are adjusted so that the cathode volume 122 and the anode volume 124 are fluidly connected, a closed loop 112 is formed, and any gas present in the fuel cell system 110 can be recirculated in the closed loop, preferably with the help of a blower 140. The fuel cell system 110 also includes a hydrogen supply 130, which may include a fuel injector (as shown) and a hydrogen storage tank (not shown). The fuel injector can inject hydrogen supplied from the hydrogen storage tank into the fuel cell system 110 at a certain injection rate.

[0057] Figure 1The control unit 400 shown can be used to control the fuel cell system 110, for example during startup. The control unit 400 can be configured to regulate the opening and closing of a pair of valves 113a, 113b to enable or disable the fluid connection between the cathode volume 122 and the anode volume 124. The control unit 400 can be configured to control the hydrogen supply device 130 and regulate the injection rate of the injected hydrogen. The control unit 400 can also be configured to control the operation of the blower 140. These devices and the control of the fuel cell system 110 during the startup process will be described in detail with reference to Figure 4, which shows the steps of a method for operating the fuel cell system 110 in conjunction with the startup of the fuel cell system 110.

[0058] Figure 2b to Figure 2d Several fuel cell systems 210 according to other examples are shown. The fuel cell systems 210 in these examples include a fuel cell stack 220 that is the same as the first example, the fuel cell stack having a cathode side 221 with a cathode volume 222 and a cathode side 223 with a cathode volume 224, wherein catalyst layers 221a, 223a are disposed in the corresponding volumes 222, 224. The fuel cell system 200 also includes a fluid flow assembly 211, which includes a plurality of fluid conduits and a pair of two-way valves 213a, 213b for controlling the fluid connection between the cathode volume 222 and the anode volume 224. When the valves 213a, 213b are in an open state, a closed loop 212 can be formed so that the gas in the fuel cell system 210 can be recirculated within the loop. The fuel cell system 210 also includes a blower 240 and a hydrogen supply 230, the blower being configured to recirculate the gas in the fuel cell system 210 when necessary.

[0059] exist Figure 2bIn the example shown, the fuel cell system 210 also includes a catalytic device 270 that is separately arranged from the fuel cell stack 220. In some examples, the catalytic device 270 includes a catalytic membrane or a catalytic mesh. The catalytic mesh can be, for example, a metal wire mesh coated with platinum, such as a rolled, pleated or wavy sheet form. As required, the catalytic membrane can form a boundary that fluidly isolates the two sides of the catalytic device from each other. The catalytic membrane can be, for example, a proton conductive polymer electrolyte membrane coated with a catalyst, such as a membrane used in a PEM fuel cell. As another non-limiting example, the catalytic device 270 is a catalytic heat exchanger, such as a catalytic heat exchanger of a cabin heater of a vehicle in which the fuel cell system 210 is provided. The heat exchanger can be, for example, a catalytic hydrogen heater. Such a heater can be provided for other reasons and used to at least partially passivate reactants, such as air, as required. Using a catalytic heat exchanger, the heat and / or pressure response changes generated when the fuel and / or oxidant supply to the fuel cell stack is started can be used to check whether the oxidant-fuel ratio (λ value) is acceptable. In some examples, a catalytic heater may be located on the cathode side and may incorporate a blower that may provide the functionality of blower 240. Figure 2b As shown, the hydrogen supply device 230 is arranged upstream of the catalytic device 270. In some other examples, the hydrogen supply device 230 is arranged at the catalytic device 270. During the startup process, hydrogen can be injected from the upstream of the catalytic device 270 or directly injected into the catalytic device 270, and then the injected hydrogen can move to the cathode volume 222 and the anode volume 224 as indicated by the arrows, and circulate with the residual oxygen in the cathode volume 222 and the anode volume 224, thereby causing a chemical reaction between the hydrogen and the residual oxygen. Once the gas mixture reaches the catalytic device 270, the reaction can be further promoted within the catalytic device 270.

[0060] In the illustrated example, the fuel cell system 210 may also include a plurality of two-way valves 214 a , 214 b configured to regulate air entering and / or leaving the cathode volume 222 .

[0061] exist Figure 2c In the example shown, the fuel cell system 210 also includes a humidifier 280 disposed upstream of the cathode volume 222. The humidifier 280 is configured to humidify the gas mixture before it enters the cathode volume 222. Figure 2cThe humidifier 280 is depicted as being disposed upstream of the cathode volume 222, but it is contemplated that the humidifier 280 may be disposed at any suitable location in the fuel cell system 210. In the illustrated example, the fuel cell system 210 may also include: a pair of two-way valves 214a, 214b configured to regulate air entering and / or leaving the cathode volume 222; and a plurality of bypass valves 215a-215c for balancing airflow in the fuel cell system 210.

[0062] exist Figure 2d In the example shown, the fuel cell system 210 also includes a turbocharger 290 having a compressor 290b and a turbine 290a, wherein the compressor 290b is driven by the turbine 290a. During the startup process, the turbocharger 280 can further enhance the recirculation process.

[0063] Figure 3 is a flow chart showing a method for operating the fuel cell system 210 in conjunction with the start-up of the fuel cell system according to one example. Figure 2b The method is explained using the second example of the fuel cell system 210 shown in FIG. It should be noted that the method is also applicable to Figure 2a The fuel cell system 110 is shown. The method is executed by the processing circuit of the control unit 400 and comprises the steps listed below, which may be performed in any suitable order unless otherwise indicated.

[0064] S1: Control the hydrogen supply device 230 to supply hydrogen to the fuel cell system 210. As an example only, for every 34.3 grams of residual air present in the fuel cell system 210, 1 gram of hydrogen may be required to neutralize the residual oxygen in the air. As another example, 2.39 liters of air may require 1 liter of hydrogen to be injected. In some examples, excess hydrogen may be added beyond what is required. The excess hydrogen can, for example, be used to purge oxygen-free air on the anode side. Use Figure 2b In the example where the fuel cell system 210 includes a catalytic device 270, the method further includes optional steps such as Figure 4a As shown, S1-1: Control the hydrogen supply device 230 to inject hydrogen into the catalytic device 270. In this example, the hydrogen supply device 230 may include a fuel injector (not shown) configured to inject hydrogen at a controllable rate. The injection rate may be slow enough so that hydrogen can be supplied in a gentle manner. In this way, the oxygen in the residual air can be gradually consumed.

[0065] S2: Adjust the fluid flow control devices 213a, 213b so that the anode volume 224 is fluidically connected to the cathode volume 222. In this way, a closed loop 212 is formed, in which any gas present in the fuel cell system 210 can be recirculated. The closed loop here can also be understood as a recirculation loop 212 formed by the fluid flow component 211.

[0066] S3 : Controlling the recirculation device 240 to recirculate the gas mixture in the fluid recirculation loop 212 , so that the supplied hydrogen reacts with the residual oxygen during the recirculation, thereby resulting in a reduction in the amount of residual oxygen in the fuel cell system 210 .

[0067] After the hydrogen is injected into the catalytic device 270, the hydrogen may move to the cathode volume 222 and the anode volume 224 as indicated by the arrows. Thereafter, the hydrogen may circulate with the residual oxygen present in the cathode volume 222 and the anode volume 224, thereby causing a chemical reaction therebetween. Once the gas mixture reaches the catalytic device 270, the reaction may be further promoted within the catalytic device 270. During the recirculation process, the hydrogen may react with the residual oxygen at a relatively slow rate, and the oxygen is gradually consumed. During this process, it may generate heat and water as byproducts of the chemical reaction, which may occur in both the cathode volume 222 and the anode volume 224. The hydrogen may also react with the oxygen in the anode volume 222 and the cathode volume 224, in which the catalytic layers 221a, 223a are disposed. Thus, it may allow for a uniform distribution of heat and humidity throughout the fuel cell stack 220. In this way, the fuel cell stack 220 may be effectively preheated and humidified, and thus the fuel cell system 210 may be fully prepared for startup.

[0068] In some examples, the method further includes the following optional steps: S4: estimating the residual oxygen level in the gas mixture, and In some examples, step S4 may be performed at the beginning of the startup process. For example, if the estimated oxygen level is higher than the threshold level, the processing circuit 402 of the control unit 400 may control the fuel cell system 270 to start executing the method starting from S1. S5 : In response to the estimated remaining oxygen level being lower than the threshold, the hydrogen supply device 240 is controlled to terminate the supply of hydrogen to the fuel cell system 220 , and the fluid flow control devices 213 a , 213 b are adjusted so that the anode volume 224 is fluidly disconnected from the cathode volume 222 .

[0069] In some examples, such as Figure 4b As shown, step S4 may also include the following sub-steps: S4-1: monitoring the temperature of the catalyst 270 and / or the gas mixture, and S4-2: Estimating a residual oxygen level in the gas mixture based on the monitored temperature.

[0070] The temperature at the catalyst 270 and / or the gas mixture is generally a good indicator of the ongoing chemical reaction process of the supplied hydrogen and residual oxygen, and may also be an indication of the residual oxygen level.

[0071] In some other examples, the pressure may be used to assess the residual oxygen level, and step S4 may further include the following sub-steps: S4-3: The processing circuit monitors the pressure of the catalyst device 270 and / or the gas mixture, S4-4: Estimate a residual oxygen level in the gas mixture based on the monitored pressure.

[0072] After hydrogen is injected into the catalytic device 270, an initial pressure drop may occur due to the chemical interaction between hydrogen and residual oxygen. As oxygen is gradually consumed during the reaction, a reversal of the pressure dynamics may be observed. The partial pressure of the supplied hydrogen may initially rise, subsequently resulting in a pressure increase. Thus, by monitoring the pressure change, the residual oxygen level in the gas mixture may be assessed.

[0073] In some examples, the method further includes the following optional steps: S6: In response to the anode volume 224 being fluidly disconnected from the cathode volume 222, the hydrogen supply device 230 is controlled to supply hydrogen to the anode volume 224, and the air supply device (not shown) is controlled to supply air to the cathode volume 222. This is to ensure that the residual nitrogen present in the anode volume 224 and the cathode volume 222 are purged, respectively. Thereafter, the fuel cell system is fully ready for startup. S7: Start the fuel cell system 200.

[0074] Figure 5. A computer system 400 is shown, which can be viewed as a control unit 400 of the vehicle 100 and / or the fuel cell system 110. The computer system 400 is adapted to execute instructions from a computer-readable medium to perform these and / or any of the functions or processes described herein. The computer system 400 can be connected (e.g., networked) to other machines in a LAN, an intranet, an extranet, or the Internet. Although only a single device is shown, the computer system 400 may include any collection of devices that execute an instruction set (or multiple instruction sets) individually or jointly to perform any one or more of the methods discussed herein. Therefore, any reference to a computer system, a computing system, a computer device, a computing device, a control system, a control unit, an electronic control unit (ECU), a processor device, a processing circuit, etc. in the present disclosure and / or claims includes a reference to one or more such devices for executing an instruction set (or multiple instruction sets) individually or jointly to perform any one or more of the methods discussed herein. For example, the control system may include a single control unit or multiple control units connected to each other or otherwise communicatively coupled, so that any executed functions can be distributed between the control units as needed. Additionally, such devices may communicate with each other or other devices through various system architectures, such as directly or via a Controller Area Network (CAN) bus, etc.

[0075] Computer system 400 may include at least one computing device or electronic device that can include firmware, hardware and / or execute software instructions to implement the functionality described herein. Computer system 400 may include processing circuitry 402 (e.g., a processing circuit that includes one or more processor devices or control units), memory 404, and system bus 406. Computer system 400 may include at least one computing device with processing circuitry 402. System bus 406 provides interfaces for system components including, but not limited to, memory 404 and processing circuitry 402. Processing circuitry 402 may include any number of hardware components for performing data or signal processing or for executing computer code stored in memory 404. Processing circuitry 402 may include, for example, a general-purpose processor, a special-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a circuit containing a processing component, a group of distributed processing components, a group of distributed computers configured for processing, or other programmable logic devices designed to perform the functions described herein, discrete gate or transistor logic, discrete hardware components, or any combination thereof. Processing circuitry 402 may also include computer executable code that controls the operation of a programmable device.

[0076] The system bus 406 can be any of several types of bus structures, which can also be interconnected to a memory bus (with or without a memory controller), a peripheral bus, and / or a local bus using any of a variety of bus architectures. Memory data 404 can be one or more devices for storing and / or computer code to complete or facilitate the methods described herein. Memory 404 can include a database component, an object code component, a script component, or other types of information structures for supporting various activities herein. Any distributed or local memory device can be utilized with the systems and methods of the present specification. Memory 404 can be communicatively connected to processing circuit 402 (e.g., via a circuit or any other wired, wireless, or network connection) and can include computer code for performing one or more processes described herein. The memory 404 may include nonvolatile memory 408 (e.g., read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.) and volatile memory 410 (e.g., random access memory (RAM)) or any other medium that can be used to carry or store desired program code in the form of machine-executable instructions or data structures and accessed by a computer or other machine having the processing circuit 402. A basic input / output system (BIOS) 412 may be stored in the nonvolatile memory 408 and may include the basic routines that help to transfer information between elements within the computer system 400.

[0077] The computer system 400 may also include or be coupled to non-transitory computer-readable storage media such as storage device 414, which may include, for example, an internal or external hard disk drive (HDD) (e.g., Enhanced Integrated Drive Electronics (EIDE) or Serial Advanced Technology Attachment (SATA)), a HDD for storage (e.g., EIDE or SATA), flash memory, etc. The storage device 414 and other drives associated with computer-readable and computer-usable media may provide non-volatile storage of data, data structures, computer-executable instructions, etc.

[0078] The hard-coded or soft-coded computer code may be provided in the form of one or more modules. The module may be implemented as software and / or hard-coded in a circuit to implement the functionality described herein in whole or in part. The module may be stored in a storage device 414 and / or in a volatile memory 410 that may include an operating system 416 and / or one or more program modules 418. All or part of the examples disclosed herein may be implemented as a computer program 420 stored on a temporary or non-temporary computer-available or computer-readable storage medium (e.g., a single medium or multiple media) such as a storage device 414, which includes complex programming instructions (e.g., complex computer-readable program code) that cause the processing circuit 402 to perform the actions described herein. Therefore, the computer-readable program code of the computer program 420 may include software instructions for implementing the functionality of the examples described herein when executed by the processing circuit 402. In some examples, storage device 414 may be a computer program product (e.g., a readable storage medium) on which computer program 420 is stored, wherein at least a portion of computer program 420 may be loadable (e.g., loadable into a processor) for implementing the functionality of the examples described herein when executed by processing circuit 402. Processing circuit 402 may serve as a controller or control system of computer system 400 for implementing the functionality described herein.

[0079] The computer system 400 may include an input device interface 422 configured to receive input and selections to be communicated to the computer system 400 when executing instructions, such as from a keyboard, mouse, touch-sensitive surface, etc. Such input devices may be connected to the processing circuit 402 through an input device interface 422 coupled to the system bus 406, but may be connected through other interfaces such as a parallel port, an Institute of Electrical and Electronics Engineers (IEEE) 1394 serial port, a universal serial bus (USB) port, an IR interface, etc. The computer system 400 may include an output device interface 424 configured to forward output to a display, a video display unit (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)). The computer system 400 may include a communication interface 426 suitable for communicating with a network as appropriate or as needed.

[0080] The operational actions described in any of the exemplary aspects of this article are described to provide examples and discussions. These actions can be performed by hardware components, can be embodied in machine executable instructions so that a processor performs these actions, or can be performed by a combination of hardware and software. Although a specific order of method actions can be shown or described, the order of actions can be different. In addition, two or more actions can be performed simultaneously or partially simultaneously.

[0081] Furthermore, the present disclosure may be illustrated by any one of the following examples and combinations of the examples.

[0082] Example 1: A computer system (400) comprising a processing circuit (402) configured to operate the fuel cell system (110, 210) in conjunction with startup of the fuel cell system (110, 210), the fuel cell system (110, 210) comprising: − a fuel cell stack (120, 220), the fuel cell stack comprising an anode side (121, 221) and a cathode side (123, 223), wherein the anode side (121, 221) comprises an anode volume (124, 224) and the cathode side (123, 223) comprises a cathode volume (122, 222), a fluid flow assembly (111, 211) comprising a plurality of fluid conduits (111a to 111d) and fluid flow control means (113a, 113b, 213a, 213b), wherein the fluid flow assembly (111, 211) is arranged to selectively enable a fluid connection between the anode volume (124, 224) and the cathode volume (122, 222), wherein when the fluid connection between the anode volume (124, 224) and the cathode volume (122, 222) is enabled, a recirculation loop (112, 212) is formed, − Hydrogen supply device (130, 230), and − a recirculation device (140, 240) arranged on the recirculation loop (112, 212) and configured to recirculate a gas mixture of supplied hydrogen and residual gas in the recirculation loop (112, 212), wherein the residual gas includes residual oxygen and residual nitrogen present in the fuel cell stack (120, 220), The processing circuit is configured to: − controlling the hydrogen supply device (130, 230) to supply the hydrogen to the fuel cell system (110, 210), − adjusting the fluid flow control means (113a, 113b, 213a, 213b) such that the anode volume (124, 224) is fluidly connected to the cathode volume (122, 222), and − controlling the recirculation device (140, 240) to recirculate the gas mixture in the fluid recirculation loop (112, 212), so that the supplied hydrogen reacts with the residual oxygen during the recirculation, thereby reducing the amount of residual oxygen in the fuel cell system (110, 210).

[0083] Example 2: A computer-implemented method for operating a fuel cell system (110, 210) in conjunction with startup of the fuel cell system (110, 210), the fuel cell system (110, 210) comprising: − a fuel cell stack (120, 220), the fuel cell stack comprising an anode side (121, 221) and a cathode side (123, 223), wherein the anode side (121, 221) comprises an anode volume (124, 224) and the cathode side (123, 223) comprises a cathode volume (122, 222), − a fluid flow assembly (111, 211) comprising a plurality of fluid conduits and fluid flow control means (113a, 113b, 213a, 213b), wherein the fluid flow assembly (111, 211) is arranged to selectively enable a fluid connection between the anode volume (124, 224) and the cathode volume (122, 222), wherein when the fluid connection between the anode volume (124, 224) and the cathode volume (122, 222) is enabled, a recirculation loop (112, 212) is formed, − Hydrogen supply device (130, 230), and − a recirculation device (140, 240) arranged on the recirculation loop (112, 212) and configured to recirculate a gas mixture of supplied hydrogen and residual gas in the recirculation loop (112, 212), wherein the residual gas includes residual oxygen and residual nitrogen present in the fuel cell stack (120, 220). The method comprises: − the processing circuit controls (S1) the hydrogen supply device (130, 230) to supply the hydrogen to the fuel cell system (110, 210), − regulating (S2) the fluid flow control device (113a, 113b, 213a, 213b) by the processing circuit so that the anode volume (124, 224) is fluidically connected to the cathode volume (122, 222), The processing circuit controls (S3) the recirculation device (140, 240) to recirculate the gas mixture in the fluid recirculation loop (112, 212), so that the supplied hydrogen reacts with the residual oxygen during the recirculation, thereby reducing the amount of residual oxygen in the fuel cell system (110, 210).

[0084] Example 3: The method according to Example 2, wherein the hydrogen is supplied to the fuel cell system (110, 210) by hydrogen injection at a controllable injection rate.

[0085] Example 4: The method according to Example 3, wherein the fuel cell system (110, 210) further comprises a catalytic device (270) at which a reaction of the supplied hydrogen and the residual oxygen is promoted, wherein the catalytic device (270) is disposed separately from the fuel cell stack (120, 220), and wherein the method further comprises: − The processing circuit controls (S1-1) the hydrogen supply device (130, 230) to inject the hydrogen into the catalytic device (270).

[0086] Example 5: The method according to any one of Examples 2 to 4, further comprising: − estimating (S4) by said processing circuit a residual oxygen level in said gas mixture, − In response to the estimated remaining oxygen level being lower than a threshold value, the processing circuit adjusts the fluid flow control device (113a, 113b, 213a, 213b) so that the anode volume (124, 224) is fluidly disconnected from the cathode volume (122, 222), and the processing circuit controls (S5) the hydrogen supply device (130, 230) to terminate the supply of hydrogen to the fuel cell system (110, 210).

[0087] Example 6: The method according to example 4 and example 5, wherein estimating (S4) the residual oxygen level in the gas mixture further comprises: − monitoring (S4-1) by the processing circuit the temperature of the catalytic device (270) and / or of the gas mixture, − estimating (S4-2) the residual oxygen level in the gas mixture by the processing circuit based on the monitored temperature.

[0088] Example 7: The method of Examples 4 and 5, wherein estimating the residual oxygen level in the gas mixture further comprises: − monitoring (S4-3) by the processing circuit the pressure of the catalytic device (270) and / or the gas mixture, − estimating (S4-4) the residual oxygen level in the gas mixture by the processing circuit based on the monitored pressure.

[0089] Example 8: The method according to any one of Examples 5 to 7, further comprising: − in response to the anode volume (124, 224) being fluidically disconnected from the cathode volume (122, 222), the processing circuit controls (S6) the hydrogen supply device (130, 230) to supply hydrogen to the anode volume (124, 224), and the processing circuit controls the air supply device to supply air to the cathode volume (122, 222), and The fuel cell system (110, 210) is started (S7) by the processing circuit.

[0090] Example 9: A fuel cell system (110, 210) for supplying electric power, comprising: − a fuel cell stack (120, 220), the fuel cell stack comprising an anode side (121, 221) and a cathode side (123, 223), wherein the anode side (121, 221) comprises an anode volume (124, 224) and the cathode side (123, 223) comprises a cathode volume (122, 222), − a fluid flow assembly (111, 211) comprising a plurality of fluid conduits and fluid flow control means (113a, 113b, 213a, 213b), wherein the fluid flow assembly (111, 211) is arranged to selectively enable a fluid connection between the anode volume (124, 224) and the cathode volume (122, 222), wherein when the fluid connection between the anode volume (124, 224) and the cathode volume (122, 222) is enabled, a recirculation loop (112, 212) is formed, − a hydrogen supply device (130, 230), the hydrogen supply device being configured to supply hydrogen to the fuel cell system (110, 210), and − a recirculation device (140, 240) arranged on the recirculation loop (112, 212) and configured to recirculate a gas mixture of supplied hydrogen and residual gas in the recirculation loop (112, 212), wherein the residual gas includes residual oxygen and residual nitrogen present in the fuel cell stack (120, 220), and A control system (400), the control system comprising a processing circuit, the processing circuit being configured to: − controlling the hydrogen supply device (130, 230) to supply the hydrogen to the fuel cell system (110, 210), − adjusting the fluid control device (113a, 113b, 213a, 213b) so that the anode volume (124, 224) is fluidically connected to the cathode volume (122, 222), and − controlling the recirculation device (140, 240) to recirculate the gas mixture in the fluid recirculation loop (112, 212), so that the supplied hydrogen reacts with the residual oxygen during the recirculation, thereby reducing the amount of residual oxygen in the fuel cell system (110, 210).

[0091] Example 10: The fuel cell system (110, 210) according to Example 9, wherein the hydrogen supply device (130, 230) includes a fuel injector configured to supply the hydrogen at a controllable injection rate.

[0092] Example 11: A fuel cell system (110, 210) according to any one of Examples 9 to 10, further comprising a catalytic device (270) for promoting a reaction between the supplied hydrogen and the residual oxygen, wherein the catalytic device (270) is separately arranged from the fuel cell stack (120, 220).

[0093] Example 12: A fuel cell system (110, 210) according to any one of Examples 9 to 11, wherein the fluid flow control device (113a, 113b, 213a, 213b) includes one or more three-way valves (113a, 113b) and / or one or more two-way valves (213a, 213b).

[0094] Example 13: A fuel cell system (110, 210) according to any one of Examples 9 to 12, wherein the recirculation device (140, 240) includes a blower (140, 240), which is preferably arranged downstream of the anode volume (124, 224).

[0095] Example 14: The fuel cell system (110, 210) according to Example 13, wherein the recirculation device (140, 240) further includes a turbocharger (290), which is preferably arranged downstream of the cathode volume (122, 222).

[0096] Example 15: The fuel cell system (110, 210) according to any one of Examples 1 to 11, further comprising a humidifier (280) configured to humidify the gas mixture before it enters the cathode volume (222).

[0097] Example 16: A fuel cell system (110, 210) according to Example 15, wherein the humidifier (280) is provided with one or more bypass valves (215a to 215c), and the one or more bypass valves are configured to selectively bypass the airflow from the humidifier.

[0098] Example 17: A computer program product comprising program code, which, when executed by a processing circuit, performs the method according to any one of Examples 1 to 8.

[0099] Example 18: A non-transitory computer-readable storage medium comprising instructions that, when executed by a processing circuit, cause the processing circuit to perform the method according to any one of Examples 1 to 8.

[0100] Example 19: A vehicle (100) comprising a fuel cell system (110, 210) according to any one of Examples 9 to 12.

[0101] The terms used herein are only for the purpose of describing specific aspects and are not intended to limit the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms "a" and "the" are intended to include the plural forms as well. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It should also be understood that the term "comprises / comprising / includes and / or including" when used herein indicates the presence of stated features, integers, actions, steps, operations, elements and / or parts, but does not exclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, parts and / or their groups.

[0102] It should be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0103] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe the relationship of one element to another element, as shown in the figures. It should be understood that these terms and those discussed above are intended to cover different device orientations in addition to the orientations depicted in the figures. It should be understood that when an element is referred to as being "connected" or "coupled" to another element, the element may be directly connected or coupled to the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements.

[0104] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the present disclosure belongs. It should also be understood that, unless otherwise clearly defined herein, the terms used herein should be interpreted as meanings consistent with their meanings in the context of this specification and the relevant art, and should not be interpreted in an idealized or overly formal sense.

[0105] It should be understood that the present disclosure is not limited to the aspects described above and shown in the accompanying drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and the appended claims. In the drawings and description, various aspects have been disclosed for illustrative purposes only and not for limiting purposes, and the scope of the disclosure is set forth in the appended claims.

Claims

1. A computer system (400) comprising a processing circuit (402) configured to operate a fuel cell system (110, 210) in conjunction with startup of the fuel cell system (110, 210), the fuel cell system (110, 210) comprising: − a fuel cell stack (120, 220), the fuel cell stack comprising an anode side (121, 221) and a cathode side (123, 223), wherein the anode side (121, 221) comprises an anode volume (124, 224) and the cathode side (123, 223) comprises a cathode volume (122, 222), a fluid flow assembly (111, 211) comprising a plurality of fluid conduits (111a to 111d) and fluid flow control means (113a, 113b, 213a, 213b), wherein the fluid flow assembly (111, 211) is arranged to selectively enable a fluid connection between the anode volume (124, 224) and the cathode volume (122, 222), wherein when the fluid connection between the anode volume (124, 224) and the cathode volume (122, 222) is enabled, a recirculation loop (112, 212) is formed, − Hydrogen supply device (130, 230), and − a recirculation device (140, 240) arranged on the recirculation loop (112, 212) and configured to recirculate a gas mixture of supplied hydrogen and residual gas in the recirculation loop (112, 212), wherein the residual gas includes residual oxygen and residual nitrogen present in the fuel cell stack (120, 220), The processing circuit is configured to: − controlling the hydrogen supply device (130, 230) to supply the hydrogen to the fuel cell system (110, 210), − adjusting the fluid flow control means (113a, 113b, 213a, 213b) such that the anode volume (124, 224) is fluidly connected to the cathode volume (122, 222), and − controlling the recirculation device (140, 240) to recirculate the gas mixture in the fluid recirculation loop (112, 212), so that the supplied hydrogen reacts with the residual oxygen during the recirculation, thereby reducing the amount of residual oxygen in the fuel cell system (110, 210).

2. A computer-implemented method for operating a fuel cell system (110, 210) in conjunction with startup of the fuel cell system (110, 210), the fuel cell system (110, 210) comprising: − a fuel cell stack (120, 220), the fuel cell stack comprising an anode side (121, 221) and a cathode side (123, 223), wherein the anode side (121, 221) comprises an anode volume (124, 224) and the cathode side (123, 223) comprises a cathode volume (122, 222), − a fluid flow assembly (111, 211) comprising a plurality of fluid conduits and fluid flow control means (113a, 113b, 213a, 213b), wherein the fluid flow assembly (111, 211) is arranged to selectively enable a fluid connection between the anode volume (124, 224) and the cathode volume (122, 222), wherein when the fluid connection between the anode volume (124, 224) and the cathode volume (122, 222) is enabled, a recirculation loop (112, 212) is formed, − Hydrogen supply device (130, 230), and − a recirculation device (140, 240) arranged on the recirculation loop (112, 212) and configured to recirculate a gas mixture of supplied hydrogen and residual gas in the recirculation loop (112, 212), wherein the residual gas includes residual oxygen and residual nitrogen present in the fuel cell stack (120, 220). The method comprises: − the processing circuit controls (S1) the hydrogen supply device (130, 230) to supply the hydrogen to the fuel cell system (110, 210), − regulating (S2) the fluid flow control device (113a, 113b, 213a, 213b) by the processing circuit so that the anode volume (124, 224) is fluidically connected to the cathode volume (122, 222), The processing circuit controls (S3) the recirculation device (140, 240) to recirculate the gas mixture in the fluid recirculation loop (112, 212), so that the supplied hydrogen reacts with the residual oxygen during the recirculation, thereby reducing the amount of residual oxygen in the fuel cell system (110, 210).

3. The method according to claim 2, wherein the hydrogen is supplied to the fuel cell system (110, 210) by hydrogen injection at a controllable injection rate.

4. The method according to claim 3, wherein the fuel cell system (110, 210) further comprises a catalytic device (270) at which a reaction of the supplied hydrogen and the residual oxygen is promoted, wherein the catalytic device (270) is disposed separately from the fuel cell stack (120, 220), and wherein the method further comprises: − The processing circuit controls (S1-1) the hydrogen supply device (130, 230) to inject the hydrogen into the catalytic device (270).

5. The method according to any one of claims 2 to 4, further comprising: − estimating (S4) by said processing circuit a residual oxygen level in said gas mixture, − In response to the estimated remaining oxygen level being lower than a threshold value, the processing circuit adjusts the fluid flow control device (113a, 113b, 213a, 213b) so that the anode volume (124, 224) is fluidly disconnected from the cathode volume (122, 222), and the processing circuit controls (S5) the hydrogen supply device (130, 230) to terminate the supply of hydrogen to the fuel cell system (110, 210).

6. The method according to claim 4 and claim 5, wherein estimating (S4) the residual oxygen level in the gas mixture further comprises: − monitoring (S4-1) by the processing circuit the temperature of the catalytic device (270) and / or of the gas mixture, − estimating (S4-2) the residual oxygen level in the gas mixture by the processing circuit based on the monitored temperature.

7. The method of claim 4 and claim 5, wherein estimating the residual oxygen level in the gas mixture further comprises: − monitoring (S4-3) by the processing circuit the pressure of the catalytic device (270) and / or the gas mixture, − estimating (S4-4) the residual oxygen level in the gas mixture by the processing circuit based on the monitored pressure.

8. The method according to any one of claims 5 to 7, further comprising: − in response to the anode volume (124, 224) being fluidically disconnected from the cathode volume (122, 222), the processing circuit controls (S6) the hydrogen supply device (130, 230) to supply hydrogen to the anode volume (124, 224), and the processing circuit controls the air supply device to supply air to the cathode volume (122, 222), and The fuel cell system (110, 210) is started (S7) by the processing circuit.

9. A fuel cell system (110, 210) for supplying electric power, comprising: − a fuel cell stack (120, 220), the fuel cell stack comprising an anode side (121, 221) and a cathode side (123, 223), wherein the anode side (121, 221) comprises an anode volume (124, 224) and the cathode side (123, 223) comprises a cathode volume (122, 222) − a fluid flow assembly (111, 211) comprising a plurality of fluid conduits and fluid flow control means (113a, 113b, 213a, 213b), wherein the fluid flow assembly (111, 211) is arranged to selectively enable a fluid connection between the anode volume (124, 224) and the cathode volume (122, 222), wherein when the fluid connection between the anode volume (124, 224) and the cathode volume (122, 222) is enabled, a recirculation loop (112, 212) is formed, − a hydrogen supply device (130, 230), the hydrogen supply device being configured to supply hydrogen to the fuel cell system (110, 210), and − a recirculation device (140, 240) arranged on the recirculation loop (112, 212) and configured to recirculate a gas mixture of supplied hydrogen and residual gas in the recirculation loop (112, 212), wherein the residual gas includes residual oxygen and residual nitrogen present in the fuel cell stack (120, 220), and A control system (400), the control system comprising a processing circuit, the processing circuit being configured to: − controlling the hydrogen supply device (130, 230) to supply the hydrogen to the fuel cell system (110, 210), − adjusting the fluid control device (113a, 113b, 213a, 213b) so that the anode volume (124, 224) is fluidically connected to the cathode volume (122, 222), and − controlling the recirculation device (140, 240) to recirculate the gas mixture in the fluid recirculation loop (112, 212), so that the supplied hydrogen reacts with the residual oxygen during the recirculation, thereby reducing the amount of residual oxygen in the fuel cell system (110, 210).

10. The fuel cell system (110, 210) according to claim 9, wherein the hydrogen supply device (130, 230) comprises a fuel injector configured to supply the hydrogen at a controllable injection rate.

11. A fuel cell system (110, 210) according to any one of claims 9 to 10, further comprising a catalytic device (270) for promoting a reaction between the supplied hydrogen and the residual oxygen, wherein the catalytic device (270) is separately arranged from the fuel cell stack (120, 220).

12. The fuel cell system (110, 210) according to any one of claims 9 to 11, wherein the recirculation device (140, 240) comprises a blower, which is preferably arranged downstream of the anode volume (124, 224).

13. A computer program product comprising a program code which, when executed by a processing circuit, performs the method according to any one of claims 1 to 8.

14. A non-transitory computer-readable storage medium comprising instructions which, when executed by a processing circuit, cause the processing circuit to perform the method of any one of claims 1 to 8.

15. A vehicle comprising the fuel cell system (110, 210) according to any one of claims 9 to 12.

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