Improved Fuel Cell System

Abstract

The invention relates to an assembly (24) formed by an air transport circuit (21) and a thermal control device (23) for the air transport circuit (21) for a fuel cell stack (6), the thermal control device (23) comprising a heat exchanger (4) mounted on the upstream air duct (21A) to regulate the air temperature and supplied with heat transfer fluid by a distribution element (8) selectively mixing the heat transfer fluid flows from the inlet (25A) of the fuel cell stack (6) to the outlet of another heat exchanger (9) and from the outlet (25B) of the fuel cell stack (6) to control the air temperature in the upstream air duct (21A). Figure for the abstract: Figure 2

Description

Title of the invention: Improved fuel cell system Technical field of the invention

[0001] The invention relates to the field of fuel cells such as proton exchange membrane fuel cells. More specifically, the invention relates to an assembly consisting of an air transport circuit and a thermal regulation device for a stack of fuel cells, a fuel cell system connected to such an assembly, a vehicle comprising such a fuel cell system, a method for thermally regulating such an assembly, a computer program and a computer-readable recording medium for implementing the steps of such a method. Technical background

[0002] A proton exchange membrane fuel cell (usually abbreviated as "PEMFC") typically comprises a membrane electrode arranged between two unipolar half-plates. A membrane electrode includes an electrolyte solution contained within a proton-conducting membrane located between an anode and a cathode. A collection of fuel cells forms what is commonly called a fuel cell stack. In a fuel cell stack, several fuel cells are mounted in parallel and are electrically connected in series so that the fuel cell stack produces sufficient electrical power.In a known manner, the anode is supplied with a gas rich in H2 (dihydrogen, commonly called hydrogen) and the cathode with a gas containing O2 (dioxygen, commonly called oxygen), such as air, in order to produce electricity and, notably, water at the cathode outlet. Water is a reaction product of every fuel cell. When air is used as the oxygen-containing gas, N2 (dinitrogen, commonly called nitrogen) is another product present at the anode outlet. In this case, the nitrogen from the air migrates from the cathode to the anode through the electrode membrane.

[0003] To obtain good efficiency from the fuel cell stack and minimize its degradation over time, each membrane of the fuel cell stack requires adequate humidification at all operating states of the fuel cell system, such as start-up, steady-state operation, dynamic load, and shutdown. Typically, the water produced at the cathode outlet can It can be used to humidify the oxygen-containing gas that powers the fuel cell stack. Furthermore, if the oxygen-containing gas is obtained from ambient air, the air's humidity already provides some moisture, meaning it contains water vapor, but this humidity is insufficient. Therefore, it is common practice to install a humidifier upstream of the fuel cell stack to increase the relative humidity of the oxygen-containing gas.

[0004] In order to obtain adequate humidification at each operating state of the fuel cell system, it is necessary that the humidity in the fuel cell stack be precisely controlled according to the operating pressure and temperature of the fuel cell system; in particular, the humidity must be adapted to the temperature of the fuel cell stack. Summary of the invention

[0005] The invention aims in particular to provide a fuel cell system that is reliable and robust regardless of the operating states of the fuel cell system.

[0006] To this end, the invention relates to an assembly formed by an air transport circuit and a thermal regulation device for the air transport circuit for a fuel cell stack comprising an anode and a cathode, the air transport circuit comprising at least one upstream air duct, called the cathode air inlet duct, intended to supply oxygen to the fuel cell stack, the thermal regulation device comprising a network of heat transfer fluid pipes cooled by a first heat exchanger, the network of heat transfer fluid pipes comprising at least one upstream heat transfer fluid pipe, called the fuel cell stack heat transfer fluid inlet pipe, intended to supply heat transfer fluid to the fuel cell stack and a downstream heat transfer fluid pipe, called the fuel cell stack heat transfer fluid outlet pipe,intended to receive the heat transfer fluid after heat exchange with the fuel cell stack coming from the upstream heat transfer fluid pipe, the first heat exchanger being mounted between the upstream heat transfer fluid pipe and the downstream heat transfer fluid pipe, characterized in that the thermal regulation device comprises a second heat exchanger mounted on the upstream air duct, upstream of a humidifier, in order to regulate the air temperature in the upstream air duct upstream of the humidifier by the heat transfer fluid pipe network and in that the second heat exchanger is supplied with heat transfer fluid by a distribution element selectively mixing the heat transfer fluid flows of the pipe, upstream of the heat transfer fluid at the outlet of the first heat exchanger and of the downstream heat transfer fluid pipe in order to control the air temperature in the upstream air duct.

[0007] Advantageously, thanks to the control device according to the invention, regardless of the operating states of the fuel cell system, the air temperature contained in the upstream air duct intended to supply oxygen to the fuel cell stack will be managed by a control unit of the control device in order to optimize the temperature and humidity conditions. It is understood in particular that the second heat exchanger is mounted upstream of the humidifier in order to ensure the proper functioning of the latter.By ensuring the proper functioning of the humidifier, its lifespan is increased, and the overall reliability and robustness of the fuel cell system are improved by adapting the humidity of the air supplied to the fuel cell stack, for example, based on the temperature of the fuel cell stack and / or the temperature measured by the temperature sensor. Of course, air is just one possible example of a gas containing oxygen. Alternatively, pure oxygen could be transported in the upstream section of the transport circuit.

[0008] Furthermore, the control unit's management of the distribution element's regulation device advantageously allows, according to the invention, for a wider range of temperatures controllable by the regulation device through selective control of the distribution element's state. Thus, depending on the characteristics of the air present in the upstream air duct, it may be preferable to heat the air (for example, very low air temperature upstream of the second heat exchanger) or, conversely, to cool the air (for example, very high air temperature upstream of the second heat exchanger), or even to maintain the air temperature.Indeed, it is preferable to have as many options as possible between the heat transfer fluid temperature at the outlet of the first heat exchanger, generally between ambient temperature and approximately 70°C (upstream heat transfer fluid line), and the heat transfer fluid temperature at the outlet of the fuel cell stack, generally between ambient temperature and approximately 85°C (downstream heat transfer fluid line). This also avoids having to oversize the second heat exchanger by providing the lowest possible temperature for the fuel cell system (upstream heat transfer fluid line), the highest possible temperature for the fuel cell system (downstream heat transfer fluid line), or a combination of both (upstream and downstream heat transfer fluid lines).The first heat exchanger is preferably connected to an existing cooling device in . the environment of the fuel cell system.

[0009] Finally, advantageously according to the invention, depending on the operating states of the fuel cell system, the control unit of the regulation device according to the invention makes it possible to dynamically control the desired air temperature in the upstream air duct.

[0010] The invention includes, as an alternative, one or more of the following optional features, taken alone or in combination.

[0011] The humidity for the humidifier can be supplied by a downstream air line of the air transport circuit, referred to as the cathode air outlet line, designed to receive air, after oxygen reduction in the air within the fuel cell stack, from the upstream air line, and a reaction product from the fuel cell stack. Indeed, oxygen reduction occurs at the cathode, yielding water as its main reaction product, which can advantageously be recycled to humidify the air circulating in the air transport circuit. Alternatively, a water source can be used to supply the humidifier.

[0012] The air transport circuit may include an ambient air compression device mounted on the upstream air line upstream of the second heat exchanger to supply air to the upstream air line. Thus, the compression device delivers air at a predetermined pressure higher than atmospheric pressure, controlled by the regulator's control unit, and also eliminates the need for a pressurized oxygen or air storage source. This is particularly advantageous for improving the compactness and weight of the fuel cell system when installed in a vehicle. Of course, as an alternative to the compression device, the air transport circuit could also provide for the use of a pressurized oxygen or air storage source without departing from the scope of the invention.

[0013] The heat transfer fluid piping network may include a heat transfer fluid flow generation element to force a movement of heat transfer fluid within the network. The heat transfer fluid flow generation element may, for example, be mounted on the downstream heat transfer fluid piping upstream of the first heat exchanger or on the upstream heat transfer fluid piping downstream of the first heat exchanger.

[0014] The heat transfer fluid piping network may include a heat transfer fluid flow bypass element in order to selectively either connect the downstream heat transfer fluid piping to the first heat exchanger, or connect the downstream heat transfer fluid piping to the upstream heat transfer fluid piping without going through the first heat exchanger, or both at the same time in order to control the heat transfer fluid temperature in the upstream heat transfer fluid piping. The heat transfer fluid flow bypass element can, for example, be mounted on the downstream heat transfer fluid line upstream of the first heat exchanger or on the upstream heat transfer fluid line downstream of the first heat exchanger. It is the mixing performed by the bypass element, controlled by the control unit, that brings the heat transfer fluid to the correct temperature at the inlet of the fuel cell stack.

[0015] The thermal regulation device may include a third heat exchanger mounted between the upstream and downstream heat transfer fluid piping. The inlet of the third heat exchanger is in fluidic communication with the outlet of the first heat exchanger in order to improve the cooling of the heat transfer fluid present in the heat transfer fluid piping network. The third heat exchanger is preferably connected to an existing cooling device in the environment of the fuel cell system.

[0016] The distribution element can be configured to be supplied by the heat transfer fluid flow from the downstream heat transfer fluid line and the heat transfer fluid flow exiting the third heat exchanger in order to provide a wider range of air temperature control in the upstream air line. Indeed, the third heat exchanger, as described above, lowers the temperature of the heat transfer fluid exiting the third heat exchanger to a maximum temperature of 60°C.

[0017] The heat transfer fluid piping network may include an auxiliary heat transfer fluid piping connecting the outlet of the third heat exchanger to the downstream heat transfer fluid piping in order to lower the heat transfer fluid temperature in the auxiliary heat transfer fluid piping. Typically, as explained above, components can thus be configured to be cooled by the heat transfer fluid flow from the auxiliary piping.

[0018] The invention also relates to a fuel cell system comprising a stack of fuel cells connected to a hydrogen source, characterized in that the fuel cell system is connected to the assembly as described above, the stack of fuel cells being connected to the air transport circuit of the assembly in order to supply oxygen to the stack of fuel cells and to the heat transfer fluid piping network of the assembly in order to exchange heat with the stack of fuel cells.

[0019] The invention also relates to a vehicle comprising an electric powertrain and an electrical energy storage element, characterized in that the vehicle comprises a fuel cell system as presented above.

[0020] The invention also relates to a method for thermal regulation, preferably implemented by computer, of a fuel cell system such as presented above.

[0021] Finally, the invention also relates to a computer program comprising instructions which, when the program is executed by a computer, lead the latter to implement the steps of the process as presented above and a computer-readable recording medium comprising instructions which, when executed by a computer, lead the latter to implement the steps of the process as presented above. Brief description of the figures

[0022] Other features and advantages of the invention will become clear from the description given below, by way of example and not limitation, with reference to the accompanying drawings, in which:

[0023] [Fig.1] is a schematic top view of a vehicle comprising an example of a fuel cell system according to the invention;

[0024] [Fig.2] is a diagram of an example of a first embodiment of a fuel cell system according to the invention;

[0025] [Fig.3] is a diagram of an example of a second embodiment of a fuel cell system according to the invention. Detailed description

[0026] In the various figures, identical or similar elements bear the same reference numerals, possibly with an additional subscript. Therefore, the description of their structure and function is not systematically repeated.

[0027] In all that follows, the directions refer to the directions of the figures. In particular, the terms "upper," "lower," "left," "right," "above," "below," "forward," and "backward" generally refer to the direction in which the figures are represented. Furthermore, the terms "upstream" and "downstream" generally refer to the direction of pumping flow, that is, in particular, the direction of movement between an inlet and an outlet of the circuit or network.

[0028] In this description, to clarify the explanation of the invention, heat exchangers are arbitrarily referred to as a first heat exchanger, a second heat exchanger, etc. This is simply a nomenclature to differentiate and name non-identical elements. This nomenclature does not imply any priority of one heat exchanger over another, and such designations can easily be interchanged without departing from the scope of this description. Nor does this nomenclature imply any order; that is, a third heat exchanger could be used without a first and / or second heat exchanger being necessary for its operation. work of invention.

[0029] The invention applies to any type of fuel cell system 1 that can be used in a mobile manner such as, for example, mounted in a vehicle 31 (passenger car, industrial vehicles (utility vehicle, truck, etc.), transport vehicles (tram, metro, bus, etc.), agricultural vehicles (tractor, harvester, etc.), civil engineering vehicles (excavator, bulldozer, etc.), train, boat, aircraft, spacecraft, etc.) or in a stationary manner such as, for example, in power plants or generator sets.

[0030] In the example illustrated in [Fig. 1], a fuel cell system 1 is integrated into a vehicle 31. The vehicle 31 mainly comprises a powertrain 15, an electrical energy storage element 29, a cooling device 33, and the fuel cell system 1. In the example illustrated in [Fig. 1], the powertrain 15 is preferably of the electric type and comprises an electric motor and its power electronics, such as at least one DC-DC converter 14 (chopper) for reducing the electrical power supplied to the electrical energy storage element 29 (battery) of the vehicle 31 to that of the vehicle 31's on-board electrical system, and at least one DC-AC converter (inverter) for converting the DC electrical power supplied to the vehicle 31's on-board electrical system into AC electrical power to supply the electric motor.The cooling device 33 includes at least one heat exchanger such as a heat transfer fluid radiator (condenser) in order to use the movement of the vehicle 31 and the ambient air around the vehicle 31 to form the cold zone of the cooling device 33, i.e. the area where the heat transfer fluid is coldest.

[0031] The electrical energy storage element 29 is preferably designed to provide a direct current voltage, for example between 12 V and 800 V, and comprises, for example, electrical energy storage cells, i.e., any type of electrochemical accumulator capable of storing electrical energy and, reversibly, releasing the stored electrical energy, such as a rechargeable battery (for example, using an external power cable). The electrical energy storage element 29 will not be described further below as it is not central to the invention.

[0032] The fuel cell system 1 mainly comprises a stack 6 of fuel cells, an air transport circuit 21, a thermal control device 23, and a hydrogen source 27. The combination of the air transport circuit 21 and the thermal control device 23 forms an assembly 24. The fuel cell stack 6 is connected in a known manner, at its anode, to the hydrogen source 27 in order to supply hydrogen to the fuel cell stack 6 and, at Its cathode is connected to the air transport circuit 21 to supply oxygen to the fuel cell stack 6. Furthermore, the fuel cell stack 6 is connected in a known manner to a network 25 of heat transfer fluid pipes of the thermal control device 23 in order to exchange heat with the fuel cell stack 6.

[0033] In the examples illustrated in Figures 2 and 3, the air transport circuit 21 comprises, from an inlet E to an outlet S, at least one upstream air line 21A, called the cathode air inlet line, intended to supply oxygen to the fuel cell stack 6 and a downstream air line 21B, called the cathode air outlet line, intended to receive air, after reduction of oxygen from the air in the fuel cell stack 6, coming from the upstream air line 21A, and any reaction product from the fuel cell stack 6 such as water.

[0034] In the examples illustrated in figures 2 and 3, the air transport circuit 21 includes an optional filter 2 intended to retain any pollution from the air drawn in at the inlet E, a compression device 3, a second heat exchanger 4, a temperature measuring element 7 such as a temperature sensor (thermistor of the NTC (Negative Temperature Coefficient) type or equivalent) and a humidifier 5.

[0035] The ambient air compression device 3 is mounted on the upstream air line 21A, upstream of the second heat exchanger 4, in order to supply air to the upstream air line 21A. Thus, the compression device 3 supplies air at a predetermined pressure higher than atmospheric pressure, controlled by a control unit 20 of the regulating device 23, such as an electronic control unit, and also avoids the use of a pressurized oxygen or pressurized air storage source. This is particularly advantageous for improving the compactness and weight of the fuel cell system 1, especially when mounted in the vehicle 31, as in the examples of Figures 1 to 3. By way of non-limiting example, the compression device 3 may include a compressor, such as an electric turbocharger.

[0036] Of course, air is only one possible example of a gas containing oxygen. Alternatively, oxygen alone, for example pure oxygen, could be transported in the upstream conduit 21A of the transport circuit 21. Furthermore, as an alternative to the compression device 3, the air transport circuit 21 could provide for the use of a (not shown) source of pressurized oxygen or pressurized air storage without departing from the scope of the invention.

[0037] To obtain good performance from the fuel cell stack 6 and minimize its degradation over time, each membrane of the fuel cell stack 6 requires adequate humidification at all operating states of the fuel cell system 1, such as start-up, operation stabilized operation, dynamic load and shutdown. In the examples in Figures 2 and 3, the humidifier 5 is mounted upstream of the fuel cell stack 6 in order to increase the relative humidity of the air moved in the air transport circuit 21.

[0038] In the examples in Figures 2 and 3, the humidity of the humidifier 5 is supplied by a downstream air duct 21B of the air transport circuit 21, referred to as the cathode air outlet duct. Indeed, the oxygen reduction that takes place at the cathode produces, as its main reaction product, water, which can advantageously be recycled to humidify the air circulating in the air transport circuit 21. Consequently, the water produced at the cathode outlet can be used to humidify the air moved in the air transport circuit 21, supplementing the humidity present in the ambient air drawn in through the inlet E.

[0039] Of course, alternatively or in addition, a water source can be used to supply the humidifier 5.

[0040] In the examples of Figures 2 and 3, the thermal regulation device 23 includes a network 25 of heat transfer fluid pipes cooled by the first heat exchanger 9. The network 25 of heat transfer fluid pipes includes at least one upstream heat transfer fluid pipe 25A, referred to as the heat transfer fluid inlet pipe of the fuel cell stack 6, intended to supply heat transfer fluid to the fuel cell stack 6 and a downstream heat transfer fluid pipe 25B, referred to as the heat transfer fluid outlet pipe of the fuel cell stack 6, intended to receive the heat transfer fluid after heat exchange with the fuel cell stack 6 coming from the upstream heat transfer fluid pipe 25A.In the examples in Figures 2 and 3, the first heat exchanger 9 is mounted between the upstream heat transfer fluid pipe 25A and the downstream heat transfer fluid pipe 25B, forming a closed loop moving heat transfer fluid between the fuel cell stack 6 and the first heat exchanger 9.

[0041] In the examples of Figures 2 and 3, the thermal control device 23 includes the second heat exchanger 4 mounted on the upstream air duct 21A in order to also regulate the air temperature in the upstream air duct 21A upstream of the humidifier 5 via the heat transfer fluid piping network 25. By way of non-limiting example, the second heat exchanger 4 may be a charge air cooler (also known by the English abbreviation "CAC").

[0042] More specifically, the second heat exchanger 4 is supplied with heat transfer fluid via the inlet pipe 25E of the second heat exchanger 4 by means of a distribution element 8 that selectively mixes the heat transfer fluid flows from the upstream pipe 25A and the heat transfer fluid at the outlet of the first heat exchanger 9 (directly in the first embodiment of [Fig. 2] and indirectly in the first embodiment of [Fig. 3]), and the downstream heat transfer fluid line 25B to control the air temperature in the upstream air line 21A. The second heat exchanger 4 includes an outlet line 25F connected to the downstream heat transfer fluid line 25B upstream of a flow generation element 10, such as a centrifugal pump. By way of non-limiting example, the distribution element 8 may be a three-way proportional valve having two heat transfer fluid inlets and one heat transfer fluid outlet that can be closed or opened.The output of the distribution element 8, when open, can be supplied, by control unit 20, either solely by the first input, or solely by the second input, or by a mixture of the two inputs in proportions managed by control unit 20, for example, according to a temperature measuring element such as the temperature measuring element 7 downstream of the second heat exchanger 4.

[0043] Advantageously, thanks to the control device 23 according to the invention, regardless of the operating states of the fuel cell system 1, the air temperature contained in the upstream air duct 21A, intended to supply oxygen to the fuel cell stack 6, will be managed by the control unit 20 of the control device 23 in order to optimize the temperature and, consequently, the humidity conditions. It is understood, in particular, that the second heat exchanger 4 is mounted upstream of the humidifier 5 to ensure the proper functioning of the latter.Indeed, by ensuring the proper functioning of the humidifier, we increase its lifespan on the one hand, and we make the overall operation of the fuel cell system 1 more reliable and robust on the other hand, by adapting the temperature and incidentally the humidity of the air supplied to the stack 6 of fuel cells, for example, according to the temperature of the stack 6 of fuel cells (given by a temperature sensor (not shown) mounted in the stack 6 of fuel cells and known in itself) and / or according to the temperature measured by the temperature measuring element 7.

[0044] Furthermore, the control unit 20's management of the distribution element 8's regulation device 23 advantageously allows, according to the invention, for a wider range of temperatures controllable by the regulation device 23 through selective control of the distribution element 8's state. Thus, depending on the characteristics of the air present in the upstream air duct 21A, it may be preferable to heat the air (for example, a very low air temperature upstream of the second heat exchanger 4), or conversely, to cool the air (for example, a very high air temperature upstream of the second heat exchanger 4), or even to maintain the air temperature. Indeed, it is preferable to have a maximum number of options. between the temperature of the heat transfer fluid at the outlet of the first heat exchanger 9 generally between the ambient temperature and about 70°C (upstream heat transfer fluid pipe 25A) and the temperature of the heat transfer fluid at the outlet of the fuel cell stack 6 generally between the ambient temperature and about 85°C (downstream heat transfer fluid pipe 25B).

[0045] This also makes it possible not to have to oversize the second heat exchanger 4 by providing the lowest possible temperature of the fuel cell system 1 (upstream heat transfer fluid pipe 25A) or the highest possible temperature of the fuel cell system 1 (downstream heat transfer fluid pipe 25B) or a mixture of the two (upstream heat transfer fluid pipe 25A and downstream heat transfer fluid pipe 25B).

[0046] Preferably, the first heat exchanger 9 can be directly connected, or indirectly connected via an intermediate circuit, to an existing radiator of the vehicle 31, such as that of the cooling device 33. The first heat exchanger 9 thus allows the (unused) heat produced by the fuel cell stack 6 to be dissipated into the ambient air. The first heat exchanger 9 is preferably sized so that the temperature of the heat transfer fluid at its outlet is always lower than the temperature at the inlet of the fuel cell stack 6.

[0047] Finally, advantageously according to the invention, depending on the operating states of the fuel cell system 1, the control unit 20 of the regulation device 23 according to the invention allows the desired air temperature in the upstream air duct 21A to be controlled dynamically.

[0048] In the examples of Figures 2 and 3, the heat transfer fluid network 25 preferably includes the heat transfer fluid flow generation element 10 in order to force a movement of heat transfer fluid within the network 25. In the examples of Figures 2 and 3, the heat transfer fluid flow generation element 10 is mounted on the downstream heat transfer fluid pipe 25B upstream of the first heat exchanger 9. Of course, alternatively, the heat transfer fluid flow generation element 10 could be mounted on the upstream heat transfer fluid pipe 25A downstream of the first heat exchanger 9 without departing from the scope of the invention.

[0049] Furthermore, in the examples of Figures 2 and 3, the heat transfer fluid piping network 25 preferably includes a heat transfer fluid flow bypass element 11 in order to selectively either connect the downstream heat transfer fluid piping 25B to the first heat exchanger 9, or connect the downstream heat transfer fluid piping 25B to the upstream heat transfer fluid piping 25A without passing through the first heat exchanger 9, or both simultaneously in order to control the temperature The temperature of the heat transfer fluid in the upstream heat transfer fluid pipe 25A is determined by the following: In the examples shown in Figures 2 and 3, the heat transfer fluid flow bypass element 11 is mounted on the downstream heat transfer fluid pipe 25B upstream of the first heat exchanger 9 and downstream of the flow generation element 10. It is the mixing performed by the bypass element 11, controlled by the control unit 20, that brings the heat transfer fluid to the correct temperature at the inlet of the fuel cell stack 6. Of course, the heat transfer fluid flow bypass element 11 could also be mounted on the upstream heat transfer fluid pipe 25A downstream of the first heat exchanger 9 without departing from the scope of the invention.

[0050] By way of non-limiting example, the heat transfer fluid flow bypass element 11 may be a three-way proportional valve having a heat transfer fluid inlet that can be closed or opened and two heat transfer fluid outlets. In the examples of Figures 2 and 3, the inlet of the bypass element 11, when open, may supply, via control unit 20, either only the first outlet to a bypass pipe 25D to the upstream heat transfer fluid pipe 25A, or only the second outlet to the first heat exchanger 9, or a mixture of the two outlets in proportions controlled by the control unit 20, for example, based on a temperature measurement element of the fuel cell stack 6.

[0051] In the first embodiment illustrated in the example in [Fig. 2], the distribution element 8 is directly connected to the upstream heat transfer fluid pipe 25A at the outlet of the first heat exchanger 9. Specifically, the second inlet pipe 25H of the distribution element 8 is mounted directly at the outlet of the first heat exchanger 9 on the upstream heat transfer fluid pipe 25A. Furthermore, in the example shown in [Fig. 2], the first inlet pipe 25G of the distribution element 8 is mounted directly at the outlet of the flow generation element 10 (and upstream of the flow bypass element 11) on the downstream heat transfer fluid pipe 25B.Advantageously, according to the invention, the second heat exchanger 4 is thus supplied with heat transfer fluid by the distribution element 8 by selectively mixing the heat transfer fluid flows from the upstream pipe 25A directly at the outlet of the first heat exchanger 9 and from the downstream pipe 25B in order to control the air temperature in the upstream air duct 21A, which makes it possible to maximize the range of temperatures controllable by the regulation device 23 by selectively controlling the state of the distribution element 8 between the two theoretically coldest and hottest zones respectively.

[0052] In the second embodiment illustrated in the example in [Fig. 3], the The thermal regulation device 23 includes a third heat exchanger 12 mounted on an auxiliary heat transfer fluid pipe 25C between the upstream heat transfer fluid pipe 25A and the downstream heat transfer fluid pipe 25B. The inlet of the third heat exchanger 12 is in fluidic communication with the outlet of the first heat exchanger 9 in order to improve the cooling of the heat transfer fluid present in the network 25 of heat transfer fluid pipes. Preferably, the third heat exchanger 12 can be directly connected, or indirectly connected via an intermediate circuit, to an existing radiator of the vehicle 31 such as that of the cooling device 33. In the example of [Fig.3], the third heat exchanger 12 thus allows the (unused) heat produced by other components in the environment of the fuel cell stack 6, such as the DC-DC converter 14 (chopper) and the powertrain 15, to be evacuated into the ambient air.

[0053] Of course, said components can be other electronic power elements such as a converter (chopper, inverter, dimmer or rectifier) ​​connected to an electrical energy storage element 29 such as a battery or to an actuator such as an electric motor. The auxiliary conduit 25C can also be used for a component of the fuel cell system 1.

[0054] In the second embodiment illustrated in the example of [Fig.3], the distribution element 8 is therefore indirectly connected to the upstream heat transfer fluid pipe 25A at the outlet of the first heat exchanger 9 in order to use the coldest area of ​​the heat transfer fluid pipe network 25, which is no longer at the outlet of the first heat exchanger 9 but at the outlet of the third heat exchanger 12. In the example of [Fig.3], the auxiliary heat transfer fluid pipe 25C is connected at the outlet of the first heat exchanger 9 to the upstream heat transfer fluid pipe 25A and opens into the downstream heat transfer fluid pipe 25B.The auxiliary heat transfer fluid pipe 25C thus includes, depending on the direction of flow of the heat transfer fluid, the third heat exchanger 12, another flow generation element 13 intended in particular to compensate for the pressure losses of the passage of the heat transfer fluid through the components 14 and then 15 downstream of the other flow generation element 13.

[0055] In the example of [Fig. 3], the distribution element 8 is thus supplied by the heat transfer fluid flow from the downstream heat transfer fluid line 25B, via the first inlet line 25G of the distribution element 8 connected between the flow generation element 10 and the flow bypass element 11, and the heat transfer fluid flow exiting the third heat exchanger 12, via the second inlet line 25H' of the distribution element 8 connected between the other flow generation element 13 and the component 14, in order to offer a wider control range of air temperature in the upstream air duct 21A. Indeed, the third heat exchanger 12 as described in the example of [Fig.3] lowers the temperature of the heat transfer fluid at the outlet of the third heat exchanger 12 to a maximum temperature of 60°C.

[0056] The invention also relates to a method for thermal regulation, preferably implemented by computer, of the assembly 24 formed by the air transport circuit 21 and the thermal regulation device 23 of the air transport circuit 21 comprising the following steps:

[0057] - Measure the air temperature at the outlet of the second heat exchanger 4;

[0058] - Compare the temperature measured at the outlet of the second heat exchanger 4 with a predetermined target temperature;

[0059] - Selectively modify the state of the distribution element 8 in order to bring the temperature at outlet of the second heat exchanger 4 of said target temperature when the comparison value exceeds a predetermined threshold.

[0060] Advantageously, the control unit 20 applies the method according to the invention to enable the control device 23, regardless of the operating states of the fuel cell system 1, to optimize the temperature and humidity conditions of the air contained in the upstream air duct 21A intended to supply oxygen to the fuel cell stack 6. It is understood, in particular, that the proper functioning of the humidifier 5 is guaranteed and thus makes the overall operation of the fuel cell system 1 more reliable and robust by adapting the temperature and humidity of the air supplied to the fuel cell stack 6. Furthermore, by guaranteeing the proper functioning of the humidifier 5, its service life is increased.The temperature of the fuel cell stack 6 can also be used to fine-tune the control of the distribution element 8 in addition to the temperature measured by the temperature measurement element 7 at the outlet of the second heat exchanger 4. Thus, depending on the characteristics of the air present in the upstream air duct 21A, it may be preferable to heat the air (supply via the downstream preferred heat transfer fluid duct 25B) or, conversely, to cool the air (supply via the upstream (or auxiliary) heat transfer fluid duct 25A) or even to not change the air temperature (maintaining the supply with the current state of the distribution element 8).

[0061] The comparison step is preferably implemented by a calculation module of the control unit 20 of the thermal regulation device 23. The predetermined target temperature can be between 60°C and 95°C. Indeed, it has been observed that above these temperatures the humidifier 5 can be damaged. The predetermined target temperature can, for example, be determined according to the operating state of the fuel cell system 1, in particular, according to of the operating state of the humidifier 5. Indeed, the predetermined target temperature must be chosen so that, regardless of the temperature of the air exiting the compression device 3, the humidifier 5 always provides enough humidity to the air entering the fuel cell stack 6.

[0062] The control step, i.e., the modification of the state, of the distribution element 8 is preferably managed by the control unit 20 of the thermal regulation device 23 in order to bring the air temperature at the outlet of the second heat exchanger 4 closer to the target temperature. To simplify the control process, a predetermined threshold is preferably provided to change the control of the distribution element 8 when the comparison value determined by the calculation module exceeds said predetermined threshold. The predetermined threshold can be ± 2°C between the air temperature measured at the outlet of the second heat exchanger 4 and the predetermined target temperature.Typically, as explained above, the distribution element 8 can be driven from a pre-parameterized data table or, possibly, from a calculation, for example, by linear interpolation, in the event of a match between two data points in said pre-parameterized table.

[0063] Finally, the invention also relates to a computer program comprising instructions which, when the program is executed by a computer, lead the latter to implement the steps of the process as presented above and a computer-readable recording medium comprising instructions which, when executed by a computer, lead the latter to implement the steps of the process as presented above.

[0064] The invention is not limited to the embodiments and variants presented, and other embodiments and variants will be obvious to those skilled in the art. Thus, the embodiments and variants can be combined with each other without departing from the scope of the invention. By way of no limitation, it is possible that the distribution element 8 can be supplied by the heat transfer fluid flow from the downstream heat transfer fluid line 25B, by the first inlet line 25G of the distribution element 8 connected between the flow generation element 10 and the flow bypass element 11, and the heat transfer fluid flow exiting the first heat exchanger 9, by the second inlet line 25H of the distribution element 8 mounted directly at the outlet of the first heat exchanger 9 as in [Fig. 2], even if the auxiliary line 25C of [Fig. 3] is used. List of references

[0065] 1: fuel cell system 2: filter 3: Compression device 4: second heat exchanger 5: humidifier 6: Fuel cell stack 7: Temperature measuring element 8: distribution element 9: first heat exchanger 10: Flow generation element 11: Flow bypass element 12: third heat exchanger 13: another element of flow generation 14: chopper 15: Powertrain 20: control unit 21: Air transport circuit 21A: Upstream air duct 21B: Downstream air duct 23: thermal regulation device 24: assembly of air transport circuit 21 and thermal regulation device 23 25: Heat transfer fluid piping network 25A: Upstream heat transfer fluid pipe 25B: downstream heat transfer fluid pipe 25C: Auxiliary heat transfer fluid pipe 25D: Bypass pipeline 25E: Inlet pipe of the second heat exchanger 4 25F: outlet pipe of the second heat exchanger 4 25G: First inlet pipe of distribution element 8 25H: second inlet pipe of distribution element 8 (first embodiment) 25H': second inlet pipe of distribution element 8 (second embodiment) 27: hydrogen source 29: electrical energy storage element 31: vehicle 33: Vehicle cooling system 31 E: air intake S: air outlet

Claims

Claims

1. Assembly (24) formed by an air transport circuit (21) and a device (23) for thermal regulation of the air transport circuit (21) for a stack (6) of fuel cells comprising an anode and a cathode, the air transport circuit (21) comprising at least one upstream air pipe (21A), called the cathode air inlet pipe, intended to supply oxygen to the stack (6) of fuel cells, the thermal regulation device (23) comprising a network (25) of heat transfer fluid pipes cooled by a first heat exchanger (9), the network (25) of heat transfer fluid pipes comprising at least one upstream heat transfer fluid pipe (25A), called the heat transfer fluid inlet pipe of the stack (6) of fuel cells, intended to supply heat transfer fluid to the stack (6) fuel cells and a downstream heat transfer fluid pipe (25B),said heat transfer fluid outlet pipe of the stack (6) of fuel cells, intended to receive the heat transfer fluid after heat exchange with the stack (6) of fuel cells coming from the upstream heat transfer fluid pipe (25A), the first heat exchanger (9) being mounted between the upstream heat transfer fluid pipe (25A) and the downstream heat transfer fluid pipe (25B), characterized in that the thermal regulation device (23) comprises a second heat exchanger (4) mounted on the upstream air pipe (21A), upstream of a humidifier (5),in order to regulate the air temperature in the upstream air pipe (21A) upstream of the humidifier (5) by the network (25) of heat transfer fluid pipes and in that the second heat exchanger (4) is supplied with heat transfer fluid by a distribution element (8) selectively mixing the heat transfer fluid flows from the upstream heat transfer fluid pipe (25A) at the outlet of the first heat exchanger (9) and from the downstream heat transfer fluid pipe (25B) in order to control the air temperature in the upstream air pipe (21A).,

2. Assembly (24) according to the preceding claim, in which the humidity of the humidifier (5) is supplied by a downstream air pipe (21B) of the air transport circuit (21), called the cathode air outlet pipe, intended to receive the air, after reduction of the oxygen in the air in the stack (6) of fuel cells, coming from the upstream air pipe (21A), and a reaction product of the stack (6) of fuel cells fuel.

3. Assembly (24) according to any one of the preceding claims, in which the air transport circuit (21) comprises a device (3) for compressing ambient air mounted on the upstream air pipe (21A) upstream of the second heat exchanger (4) in order to supply air to the upstream air pipe (21A).

4. An assembly (24) according to any preceding claim, wherein the heat transfer fluid pipe network (25) comprises a heat transfer fluid flow generating element (10) for forcing heat transfer fluid movement in the heat transfer fluid pipe network (25).

5. An assembly (24) according to any one of the preceding claims, wherein the network (25) of heat transfer fluid pipes comprises a heat transfer fluid flow bypass element (11) in order to selectively either connect the downstream heat transfer fluid pipe (25B) to the first heat exchanger (9), or connect the downstream heat transfer fluid pipe (25B) to the upstream heat transfer fluid pipe (25A) without passing through the first heat exchanger, or both at the same time in order to control the heat transfer fluid temperature in the upstream heat transfer fluid pipe (25A).

6. Assembly (24) according to any one of the preceding claims, in which the thermal regulation device (23) comprises a third heat exchanger (12) mounted between the upstream heat transfer fluid pipe (25A) and the downstream heat transfer fluid pipe (25B) in order to improve the cooling of the heat transfer fluid present in the network (25) of heat transfer fluid pipes.

7. Assembly (24) according to the preceding claim, in which the distribution element (8) is configured to be supplied by the flow of heat transfer fluid from the downstream heat transfer fluid pipe (25B) and the flow of heat transfer fluid leaving the third heat exchanger (12) in order to offer a wider range of air temperature control in the upstream air pipe (21 A).

8. An assembly (24) according to claim 6 or 7, wherein the heat transfer fluid pipe network (25) comprises an auxiliary heat transfer fluid pipe (25C) connecting the outlet of the third heat exchanger (12) to the downstream heat transfer fluid pipe (25B) in order to lower the heat transfer fluid temperature in the auxiliary heat transfer fluid pipe (25C).

9. Assembly (24) according to the preceding claim, in which members are configured to be cooled by the flow of heat transfer fluid from the auxiliary pipe.

10. Fuel cell system (1) comprising a stack (6) of fuel cells connected to a hydrogen source, characterized in that the fuel cell system (1) is connected to the assembly (24) according to any one of the preceding claims, the stack (6) of fuel cells being connected to the air transport circuit (21) of the assembly in order to supply oxygen to the stack (6) of fuel cells and to the network (25) of heat transfer fluid pipes of the assembly in order to exchange heat with the stack (6) of fuel cells.

11. Vehicle (31) comprising an electric powertrain (15) and an electrical energy storage element (29), characterized in that the vehicle (31) comprises a fuel cell system (1) according to the preceding claim.

12. Method for thermal regulation of the assembly according to any one of claims 1 to 9 comprising the following steps: - measuring the air temperature at the outlet of the second heat exchanger (4); - comparing the temperature measured at the outlet of the second heat exchanger (4) with a predetermined target temperature; - selectively modifying the state of the distribution element (8) in order to bring the temperature at the outlet of the second heat exchanger (4) closer to said target temperature when the comparison value exceeds a predetermined threshold.

13. A computer program comprising instructions which, when the program is executed by a computer, cause the latter to implement the steps of the method according to the preceding claim.

14. A computer-readable recording medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method of claim 12.

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