FUEL CELL SYSTEM INCLUDING A THERMOREGULATED HUMIDIFIER AND HUMIDIFICATION REGULATION METHOD

Abstract

The present invention relates to a fuel cell system for a vehicle comprising a thermoregulation system including at least a first and a second fluid loop of heat transfer fluid (5, 6, 7) intended for the thermal regulation of vehicle systems and fluid control means (801, 802, 803). The system includes a third fluid loop (8) fluidically connected with condensers (131, 221) and in which the fluid control means (801, 802, 803) are capable of regulating the flow rate and temperature of the heat transfer fluid of the third fluid loop (8) as a function of the flow rate and temperature of the heat transfer fluid of the first and second fluid loops (5, 6, 7) and as a function of a condensation requirement of each condenser (131, 221). Figure 2.

Description

Title of the invention: FUEL CELL SYSTEM COMPRISING A THERMOREGULATED HUMIDIFIER AND A METHOD FOR REGULATING HUMIDIFICATION

[0001] The field of the invention relates to a fuel cell system comprising thermoregulation means for humidifying the reactant gases and the membrane.

[0002] With growing concern about energy and environmental issues, fuel cell technology holds promise for many power systems. A fuel cell (also known as a fuel cell) is an electrochemical device that converts the chemical energy of a fuel (in this context: gaseous dihydrogen, hereafter referred to as H2) into electrical energy. Among the various types, the proton-exchange membrane fuel cell (PEMFC) has the greatest potential for application in electric and hybrid vehicles, thanks in particular to its high efficiency and low operating temperature.

[0003] Such a PEMFC employs an electrolytic membrane in the form of a solid polymer, permeable to protons but impermeable to electrons, on each side of which an anode and a cathode are arranged. More generally, the assembly of the membrane, the anode, and the cathode is designated as the MEA (Membrane Electrode Assembly).

[0004] Within a catalytic converter, H2 is supplied to the anode while air, in which dioxygen (O2) acts as an oxidant, is supplied to the cathode. Each H2 molecule is split into protons and electrons within a catalytic layer. The membrane transports protons from the anode to the cathode, while electrons reach the cathode via current-collecting plates and an external electrical circuit. At the cathode, the protons and electrons react with O2 from the air to generate water in an exothermic reaction.

[0005] Within the membrane, proton conduction is enabled by an adjusted degree of humidity. The FC system requires that the reacting gases, O2 from the air and H2, admitted respectively to the cathode and anode, be sufficiently hydrated to facilitate the chemical half-reactions at the anode and cathode, and above all to maintain reliable, durable, and efficient FC operation. In particular, the membrane must be saturated with water. Indeed, if the membrane is not sufficiently moistened, the proton conductivity is reduced or even zero, and the membrane is deteriorated by the appearance of hot spots. Conversely, excessive humidity (introduced by the reactant gases or produced in situ, particularly when the FC operates under a high current density) inhibits the access of protons and O2 to the catalytic sites, drastically reducing the FC's performance and efficiency. Thus, operating the PEMFC under optimal conditions requires precise management of membrane humidification, which must be regulated according to the FC's operating point, balancing the water produced by the membrane and the humidity supplied by an external humidifier.

[0006] Some known humidifiers used the FC's cooling fluid to reduce its volume and size. The hydration water was then taken from the cooling fluid. A conventional humidifier protects the FC's MEA from drying out by transferring water vapor from the exhaust gases to the incoming gases circulating in an intake circuit, rather than the vapor being directly discharged into the outside environment. By humidifying the former, an optimal level of MEA hydration is maintained. FC humidifiers are classified according to:

[0007] - The type of hydration, gas / gas or water / gas.

[0008] - The hydration method, which may be of the internal type by direct injection by Jet or spray, additional membrane, wicks, sponges, or porous plates. This type of hydration impacts the cell stack design. Other known methods are external to the FC (Fuel Cell) system, such as bubbling, membrane, or enthalpy wheel hydration, which rely on components added to the FC system. However, these techniques have drawbacks, depending on the design, such as slow response times, poor compatibility with rapid changes in MEA (Medium Enthalpy Area) humidity, or the risk of liquid water being present at the electrodes.

[0009] - The type of hydration, which can be by recirculation, with a flat membrane, with porous fiber membrane.

[0010] In practice, the hydration of dihydrogen is difficult to achieve, and the emphasis is often placed on the relative humidity of the air at the cathode. The humidifier must maintain stable and precise humidity and reactant flow levels at both the anode and cathode of the FC at all times. The response time, or the speed at which a desired humidity level can be reached, is also a factor to consider.

[0011] The performance and durability of a humidifier, and consequently of the FC itself, depend on the stability, accuracy, and capacity of the humidification system. The humidifier's accuracy in maintaining the required humidity level of the incoming gases affects the FC's performance. The same humidity level must be maintained for each cycle to achieve optimal performance. The humidifier capacity must be taken into account to match the FC capacity, without flow restriction between the humidifier and the FC.

[0012] The other criteria required for a fuel cell humidifier are temperature and thermal mass, with temperature being the parameter that most significantly impacts performance. The contact area between the hot gases entering the humidifier and the cold gases exiting affects the overall efficiency of the fuel cell, in trade-off with the pressure drop and the increased size of the system.

[0013] Moreover, the required relative humidity levels are not identical on the anode side (65 to 90%) and the cathode side (30 to 50%) and the gases that come out of them are not strictly at the same temperature.

[0014] Furthermore, US patent document B2-7267900 is known, describing a combustion engine (CE) system comprising two reactant gas humidification units. This system describes a first humidification unit comprising moisture transfer membranes from a reactant gas exhaust manifold to an intake manifold. It further comprises an arrangement of polymer separators for transferring heat from the CE cooling circuit to the intake manifolds. The humidity level depends on the arrangement of the separators and the dimensions of the membrane. This is a passive humidity control that is also highly dependent on the temperature conditions under which the CE operates. This first unit therefore does not allow for effective active humidity regulation.

[0015] This document further describes a second humidification unit comprising a condenser coupled to the exhaust manifold of the reaction gases and a second heat transfer fluid loop coupled to an engine cooling circuit and power electronics, enabling the condensation of moisture in a water tank. Injectors connected to the tank are controlled to regulate the humidity level of the intake manifolds based on the moisture recovered by this second humidification unit.

[0016] The taught solution poses a problem because pressure losses are generated on the gas side and the cooling circuit of the FC due to the plate arrangement.

[0017] Furthermore, to condense the water vapor contained in the reactant gases, a lower fluid temperature is required than the temperature of the gas whose vapor is to be condensed. However, the reactant gases from the FC are at approximately the same temperature as the FC itself, and the coolant from the stack is also at approximately the same temperature as the stack, so the coolant therefore has a low condensation potential. This solution therefore does not allow for temperature control of the humidifiers and consequently does not optimize the humidification of the reactant gases at the inlet.

[0018] Moreover, this architecture poses a problem of electrical conductivity of the cooling circuit and insulation resistance in the presence of a high-voltage electrical circuit, commonly used in electrified vehicles. Insulation resistance is generally determined as the resistance of the highest leakage current when the power battery is short-circuited to ground or the vehicle chassis. During operation, this value is continuously monitored, and if it drops to a certain level, the insulation fault alarm device will be triggered to send an alarm signal and disconnect the high-voltage power supply.However, in automotive applications, a decrease in the insulation resistance of a fuel cell can occur due to the generation of organic and inorganic ions from the plastic, rubber, and metallic components of the fuel cell's cooling circuit, and particularly from the aluminum in the brazing fluxes of the heat exchangers. Consequently, these ions, by increasing the electrical conductivity of the coolant, reduce the vehicle's insulation resistance. It is therefore necessary to reduce the volume of coolant, especially given its cost, and the number of heat exchangers to minimize the generation of aluminum ions within the fuel cell's cooling circuit.

[0019] There is therefore a need to address the aforementioned problems. One objective of the invention is to provide a fuel cell system that optimizes the humidification of the MEA in order to improve energy efficiency.

[0020] More specifically, the invention relates to a fuel cell system for a vehicle comprising:

[0021] - a membrane electrode assembly,

[0022] - at least one inlet pipe for supplying reactant gas to an electrode of said assembly,

[0023] - at least one exhaust pipe to evacuate the gas from said electrode reacting,

[0024] - at least one humidifier through which the inlet pipe and the tubing pass exhaust and comprising a condenser capable of condensing moisture from the reactant gas circulating in the exhaust manifold and a first means for transferring the condensed moisture to the reactant gas circulating in the intake manifold,

[0025] - a thermoregulation system comprising at least a first and a second fluid loops of heat transfer fluid intended for the thermal regulation of vehicle systems and fluid control means configured to control the flow and temperature of the heat transfer fluid of each fluid loop.

[0026] According to the invention, the thermoregulation system comprises a third fluidic loop fluidically connected with each condenser and fluidic control means capable of regulating the flow rate and temperature of the heat transfer fluid of the third fluidic loop depending on the flow rate and temperature of the heat transfer fluid of the first and second fluidic loops and depending on a condensation need of each condenser.

[0027] The system according to the invention may include the following additional features, alone or in combination:

[0028] - The first fluidic loop is configured to regulate the fluid temperature heat transfer fluid in a first temperature range and the second fluid loop is configured to regulate the temperature of the heat transfer fluid in a second temperature range.

[0029] - The first means of transferring condensed moisture is a device by capillarity arranged on the surface of a wall of the inlet tubing passing through the humidifier and configured to humidify the reactant gas circulating in the inlet tubing.

[0030] - The exhaust manifold further comprises a desiccant arranged downstream of the humidifier and configured to separate moisture from the reactant gas, - and a second piloted means for transferring the separated moisture configured to humidify the reactant gas flowing in the inlet tubing upstream of the humidifier.

[0031] - The first fluidic loop is a heating circuit for the vehicle including a heater.

[0032] - The second fluidic loop is a thermal regulation circuit of a system electrical power for electric traction of the vehicle comprising a first thermal regulation circuit of power electronics and a second thermal regulation circuit of an energy storage system for the needs of electric traction.

[0033] - The system further comprises a fourth fluidic cooling loop of the membrane electrode assembly, arranged so that the first and fourth fluidic loops are configured for heat exchange.

[0034] - The fluid control means include a piloted hydraulic distributor connected fluidly by a first and second input to the first and second fluidic loops respectively and by an output to the third fluidic loop.

[0035] - The system further comprises a first heat exchanger arranged so as that the first fluidic loop is in heat exchange with the third fluidic loop and a second heat exchanger arranged so that the second fluidic loop is in heat exchange with the third fluidic loop, and the fluidic control means include a pilot-operated hydraulic distributor fluidically connected by a first and a second inlet to the first and the second heat exchangers respectively, and by an outlet to the third fluidic loop.

[0036] - The system comprises a single humidifier arranged in a gas circuit oxidant including the intake manifold and the exhaust manifold.

[0037] - The system comprises an oxidizing gas circuit including a first tube intake, a first exhaust manifold and a first humidifier, a fuel gas circuit comprising a second intake manifold, a second exhaust manifold and a second humidifier, and the fluidic control means are arranged to thermally regulate each condenser of the first and second humidifier, the thermal regulation being operated either individually within a temperature range specific to each condenser by a specific thermoregulation function, or jointly by a single thermoregulation function.

[0038] The invention provides for an electrified motor vehicle comprising a fuel cell system according to any one of the preceding embodiments.

[0039] A method for regulating the humidification of a reactant gas implemented by a fuel cell system as defined by any one of the preceding embodiments is also provided, comprising the following steps:

[0040] - the control of the flow rate and temperature of the heat transfer fluid of the first and the second fluidic loop,

[0041] - the control of fluidic control means to regulate flow and temperature of the heat transfer fluid of the third fluidic loop as a function of the flow rate and temperature of the heat transfer fluid of the first and second fluidic loops and as a function of a condensation requirement of each condenser.

[0042] The provided thermoregulation ensures adequate heat transfer within the condensers and thus optimizes the humidification of the reactant gases and the membrane-electrode assembly of the fuel cell system, which is crucial for optimal fuel cell operation. The system is suitable for high-power and / or long-term operating installations in dry outdoor environments.

[0043] Other features and advantages of the present invention will become more apparent upon reading the following detailed description, which includes embodiments of the invention given by way of non-limiting examples and illustrated by the accompanying drawings, in which:

[0044] [Fig. 1] schematically represents an embodiment of the fuel cell system according to the invention.

[0045] [Fig.2] schematically represents a first embodiment of the thermoregulation system of the FC system according to the invention comprising fluidic temperature regulation loops used as hot source and cold source and fluidically connected to the condenser regulation loop.

[0046] [Fig.3] schematically represents an embodiment of the thermoregulation system in which a cooling fluid loop of the MEA of the FC system is thermally coupled to the thermal regulation fluid loop of the passenger compartment of a vehicle.

[0047] [Fig.4] schematically represents a second embodiment of the thermoregulation system comprising fluidic temperature regulation loops connected fluidically and in which the regulation of the condensers is controlled individually.

[0048] [Fig.5] schematically represents a third embodiment of the thermoregulation system in which the fluidic loops forming the temperature sources are coupled by heat exchangers to the thermoregulation fluidic loop of the condensers.

[0049] [Fig.6] schematically represents a fourth embodiment of the thermoregulation system in which the fluidic loops forming the temperature sources are coupled by heat exchangers to the thermoregulation fluidic loop of the condensers and in which the regulation of the condensers is controlled individually.

[0050] [Fig.7] schematically represents the variant embodiment of the hot source fluidic loop coupled to the condenser control loop via a heat exchanger.

[0051] [Fig.8] schematically represents the variant embodiment of the cold source fluidic loop coupled to the condenser regulation loop via heat exchangers.

[0052] The fuel cell system according to the invention is applicable to vehicles comprising a powertrain that is at least partially electrified, and can also be extended to applications other than electromobility, for example, stationary applications and fuel cell cogeneration. The invention is applicable to electrified vehicles, preferably motor vehicles, but not exclusively, such as aircraft, trucks, tractors, bicycles, and ships.

[0053] In this description, it is understood that each fluid loop comprises fluid connections hydraulically linking one or more thermoregulation elements in series, and through which a heat transfer fluid circulates. The heat transfer fluid is moved within each fluid loop by suitable fluid control means. A fluid loop is a heat transfer fluid circulation circuit allowing The heat transfer system can be subdivided into parallel circuits. Depending on the function of each fluid loop, the temperature control elements may include an electric heater, an air heater, a radiator, a condenser, a chiller, an air heater, or any type of heat exchanger suitable for the intended temperature control function.

[0054] In a manner known per se, a heat exchanger can be made up of plate, tube and / or fin type elements adapted for heat transfer between fluids in different liquid / air, liquid / liquid, liquid / gas or gas / air states.

[0055] The fluid control means are actuators that can be selected from among the following types of actuators: flow and temperature control valves for the heat transfer fluid, thermoregulation valves, thermostatic valves, proportional valves, pilot-operated hydraulic distributors, or pumps, to perform the desired function. A heat transfer fluid can be any type of coolant used for this function, for example, water or glycol water with low electrical conductivity.

[0056] When two elements are arranged, coupled, configured in heat exchange, this means that they are in fluidic communication through links of the same heat transfer fluid, or that they are able to exchange heat through a heat exchanger connecting two fluidic loops of two heat transfer fluids put into circulation by fluidic control means specific to each loop.

[0057] In [Fig. 1], an embodiment of a fuel cell system according to the invention is shown, also referred to as the FC system. The system comprises intake and exhaust circuits for the reactant gases at the cathode 1 and the anode 2 of the MEA of the fuel cell. More specifically, a first air intake tube 100 extends at the inlet, upstream of the cathode 1, while a first air exhaust tube 110 extends at the outlet, downstream of the cathode 1. Similarly, a second H2 intake tube 200 extends at the inlet, upstream of the anode 2, while a second H2 exhaust tube 210 extends at the outlet, downstream of the anode 2.

[0058] The fuel cell employs an electrolytic membrane in the form of a solid polymer, permeable to protons but impermeable to electrons, on either side of which are arranged the anode 2 and the cathode 1, these elements forming the MEA assembly. Within the fuel cell, H2 is supplied to the anode while air, in which dioxygen O2 acts as an oxidant, is supplied to the cathode. Each H2 molecule is decomposed into protons and electrons within a catalytic layer. The membrane transports the protons from the anode to the cathode while the electrons reach the cathode via current-collecting plates and a circuit external electrical source. At the cathode, protons and electrons react with O2 from the air to generate water in an exothermic reaction.

[0059] Preferably, the second H2 exhaust pipe 210 opens into the first air exhaust pipe 110 before the venting to the atmosphere, i.e. the outlet to ambient air, and downstream of all the components located within the first air exhaust pipe 110. Alternatively, the second H2 exhaust pipe 210 has its own venting to the atmosphere, i.e. its own outlet to ambient air, independently and separately from that of the first air exhaust pipe 110. Air and H2 are supplied respectively to the cathode 1 and the anode 2 under superstoichiometric conditions in order to optimize efficiency.

[0060] Between the first air intake manifold 100 and the first air exhaust manifold 110 is arranged an intake air supercharging device 120, consisting of an air compressor 121 driven in rotation by an electric motor 122 controlled by an inverter 123 or DC / AC converter of direct current and voltage, supplied by a power energy storage system not shown in [Fig.1] or by the FC, in three-phase alternating current and voltage to drive the electric motor 122 in rotation. It is understood that this technology is not limiting and includes in this context any device capable of supplying the cathode 1 of the MEA with intake air at an air pressure at least equal to atmospheric pressure. According to a preferred variant, the intake air supercharging device 120 also includes a turbine 124 arranged on the first air exhaust manifold 110.Alternatively, turbine 124 is absent. Turbine 124 allows, by expanding the exhaust air from the cathode 1 and circulating in the first air exhaust pipe 110, the recovery of mechanical work which reduces the work required by the electric motor 122 for a given control of the inverter 123. In this way, the energy consumption of the supercharging device 120 is reduced and the overall efficiency of the FC system is improved.

[0061] The action of the electric motor 122 causes the compressor 121 to rotate, which draws outside air into the first air intake manifold 100 through a filter 101 and an air mass flow controller 102 positioned at the inlet of the first intake manifold 100. The flow controller 102 can optionally be a simple air flow meter.

[0062] Downstream of the flow controller 102 in the first pipe 100, the filtered air is discharged by the compressor 121 through a charge air cooler 103, also designated by the acronym RAS 103. This is an air-type heat exchanger of charge / outside air or preferably of charge air / coolant type. The RAS aims to cool the charge air previously heated by the compression performed by the compressor 121, in order to increase, for its admission to the cathode 1 of the MEA, the density of the air and therefore of the O2 gas it contains, with a limited impact on the charge pressure, thanks to an optimized pressure drop with its heat exchange performance.

[0063] In addition, a small portion of the filtered airflow, compressed by the compressor 121, is drawn from the outlet of the RAS 103 by a proportional valve 104 in order to cool and lubricate the bearings of the compressor 121 and the turbine 124 of the intake air supercharging device 120. Since this is an intake air supercharging device 120 for application to an FC system, oil lubrication of the bearings is prohibited in order to eliminate any risk of cathode 1 contamination.

[0064] Furthermore, cooling of the inverter 123, of the electric motor 122 and possibly the compressor housing 121 are also cooled, preferably by a coolant passage which will be described in more detail later. Any alternative method of cooling these components of the intake air boost device 120, for example by outside air, or by the boost air taken from the outlet of the RAS 103 by the valve 104, is conceivable.

[0065] In addition, downstream of the RAS 103, the first inlet pipe 100 includes a temperature sensor 105 and a pressure sensor 106 whose function is to perform the associated measurements on the air coming from the RAS 103, downstream of the air bypass by the valve 104 and upstream of a second air bypass, controlled by a second proportional valve 107. Alternatively, the temperature sensor 105 and the pressure sensor 106 can be arranged in a different order.

[0066] Furthermore, the valve 107 allows, if necessary, the air circulating in the first air intake manifold 100 to bypass the cathode 1 and flow into the first air exhaust manifold 110, and mainly to regulate, through the processing of information transmitted by the mass air flow controller 102 and the temperature 105 and pressure 106 sensors, the mass of air admitted to the cathode 1 by diverting the excess into the first air exhaust manifold 110.

[0067] In addition, the FC system includes a first humidifier 130 through which the incoming air passes, on one side of a wall lined with a capillary material, in order to be humidified before its admission to the cathode 1. Downstream of the first humidifier 130, a third proportional valve 108 regulates the air admitted to the cathode 1 of the MEA according to the processing of information transmitted by a third sensor 109 which measures the pressure, temperature and relative humidity of the air entering the cathode 1. Alternatively, this single sensor performing the three measurements can be replaced by three sensors arranged one after the other.

[0068] At the outlet of cathode 1, the air that has participated in the electrochemical process is conveyed to the outside by the first air exhaust pipe 110. A second temperature sensor 111 and a second pressure sensor 112 perform the associated measurements on the air coming from cathode 1, upstream of a valve 113 controlling the air flow exiting cathode 1. Alternatively, these two sensors can be replaced by a single sensor performing both measurements. The air from valve 113 then has two outlets depending on the positions of the proportional valve 114 bypassing the first humidifier 130 and the proportional valve 115 adjusting the back pressure at the outlet of the first humidifier 130. A first outlet through the first humidifier 130 via valve 115 and / or a second outlet bypassing the first humidifier 130 via valve 114.

[0069] More specifically, the air passing through the first humidifier 130 passes through a condenser 131 consisting of a heat exchanger between the air from the cathode 1, passing through it from the outside in one or more stages, and a coolant circulating inside the condenser 131. This coolant, not shown in [Fig.1], is part of a fluidic loop dedicated to the thermal regulation of the condenser 131 which will be described in more detail later in the description.

[0070] On the other side of the first humidifier 130, the intake air, directed towards the inlet of the cathode 1, passes through a wall lined with a capillary material. The capillary material causes the water vapor present in the air from the cathode 1, which condenses upon passing through the condenser 131, to be captured by the capillary material lining the inner wall of the first humidifier 130.

[0071] The dehumidified air, from the first humidifier 130, passes through the back pressure adjustment valve 115 and is first joined downstream of it by the portion of air still humid, having possibly bypassed the humidifier 130 by the action of the valve 114, then by the portion of intake air from the air intake tube 100 and bypassing the cathode 1 by the action of the valve 107.

[0072] The air then enters a desiccant 116, located within the first air exhaust pipe 110 downstream of the first humidifier 130, where it undergoes a final dehumidification. The primary function of the desiccant 116 is to separate the water vapor from the air, condense the water (with or without the addition of a possible supplementary condenser, not shown in [Fig. 1]), and remove it. Thus, one of the purposes of the desiccant 116 is to protect the turbine 124, and in particular the blades or vanes of its runner, from any droplets that could damage it. However, even in the absence of a turbine 124, a desiccant 116 may still be present within the first air exhaust pipe 110. The air in the first pipe The exhaust 110 finally passes through the turbine 124 of the supercharging device 120 and gives up its residual enthalpy, allowing the mechanical work to be done by the electric motor 122 to be reduced for a given control of the inverter 123.

[0073] However, it is conceivable that the first exhaust manifold includes a proportional valve 117 located within an air duct, situated on either side of the turbine 124, allowing the bypass of all or part of the air flow in the exhaust manifold 110 from the desiccator 116. The valve 117 thus makes it possible to regulate and, if necessary, limit the mass flow rate of air passing through the turbine 124 and, if needed, to bypass it completely, depending on the processing of information transmitted by a sensor 118 which measures at least the relative humidity, and ideally also the pressure and temperature of the air at the inlet of the turbine 124. The valve 117 also makes it possible to regulate and, if necessary, limit the rotational speed of the turbine 124, and therefore of the electric motor 122 and the compressor 121, these elements being fixed to the same axis of rotation.At the outlet of the turbine 124 and / or, depending on the action of the valve 117, of its bypass duct, the air from the air exhaust pipe 110 is then discharged into the external environment.

[0074] The second H2 inlet pipe 200 and the second H2 outlet pipe 210, located respectively upstream and downstream of the anode 2, are now described. The H2 stored in at least one storage tank (not shown in [Fig. 1]) at high pressure (for example, at 350 or 700 bar) is depressurized during its release before passing through the second inlet pipe 200, so that the temperature of the H2 from at least one storage tank can fall below the outside ambient temperature and even reach temperatures as low as -20°C to -40°C depending on the ambient temperature of at least the storage tank and around the second inlet pipe 200 and depending on the flow rate of H2 released.

[0075] Preferably, but not necessarily, the second inlet pipe 200 includes a heat exchanger 201 whose function is to heat the H2 before its admission to the anode 2. By way of non-limiting example, it may be, as illustrated in [Fig. 2], a heat exchanger between the H2 and the FC coolant. Thus, the heat exchanger 201 makes it possible to transfer heat from the MEA cooling fluid loop, the temperature of which is, under nominal operating conditions, usually between 60 and 90°C, but also to take advantage of the low temperature of the H2 passing through the exchanger 201 to contribute to the cooling of the MEA, given the low temperature of the H2 passing through the heat exchanger 201. However, other solutions for heating the H2 are conceivable without departing from the scope of the invention.

[0076] Downstream of the heat exchanger 201, the H2 circulating in the inlet pipe 200 passes through a proportional valve 202 allowing precise metering, or even cutting off, of the H2 flow to the anode 2, and whose control is made possible thanks, in particular, to the information transmitted by a first pressure sensor 203 and by a second temperature sensor 204 of the H2 downstream of this valve 202. The H2 is then admitted as a primary fluid at a first inlet of an ejector 205 positioned downstream of the sensor 204 which, under the effect of a second flow of H2 from the anode 2 which presents itself as a secondary fluid at a second inlet of the ejector 205, discharges the gaseous mixture of H2. Thus, the H2 that has not reacted within the MEA is recycled in order to save the mass of H2 consumed, and is therefore reinjected from the second exhaust manifold 210 into the second intake manifold 200 of H2.

[0077] This gaseous mixture of H2 is discharged from the ejector, through a second humidifier 220 positioned downstream of the anode 2. The second humidifier is charged with moisture from the water vapor, condensed through a condenser 221, lost by the H2 from the anode 2. A second pressure sensor 206 performs the associated measurement on the H2 from the second humidifier 220, just at the inlet of the anode 2 of the MEA.

[0078] The H2 from the anode 2 passes through the second humidifier 220 to transfer its moisture to the H2 circulating in the second inlet pipe 200 and admitted to the anode 2. To this end, the H2 from the anode 2 passes through the condenser 221 consisting of a heat exchanger between the H2 passing through it from the outside in one or more stages, and a coolant circulating inside the condenser 221. This coolant, not shown in [Fig. 1], is part of a fluid loop dedicated to the thermal regulation of the condenser 221 which will be described in more detail later in the description.

[0079] More specifically, the H2 from anode 2 and the H2 admitted to anode 2 pass through the second humidifier 220 on either side of internal walls. The water vapor present in the H2 from anode 2 condenses as it passes through the condenser 221 and is captured by a capillary material lining the internal wall of the second humidifier 220.

[0080] In addition, at the outlet of the second humidifier 220, the second inlet pipe 210 includes a desiccator 207 through which the H2 from the anode 2 passes, the function of which is to separate the residual water vapor from the H2, to condense the water (with or without the addition of a possible additional condenser, not shown in [Fig.1]), and to eliminate it.

[0081] In addition, a valve 208 located on the second H2 exhaust pipe 210 ensures the purging of the anode 2 with H2. At the end of this purging valve 208, the second H2 exhaust pipe 210 extends directly to the open air through its own outlet to the ambient air, independently and separately from that of the air exhaust pipe (110); as mentioned above, the outlet of the H2 exhaust pipe (210) into the air exhaust pipe (110) before the opening to the open air, downstream of all the components located within the air exhaust pipe (110), constitutes an advantageous alternative.

[0082] The recovery and distribution network 3 for water from the water vapor separated or condensed by the dryers 116 and 207 is described in this paragraph. This network 3 is represented by dashed lines in [Fig. 1]. More specifically, a portion of the water vapor contained in the gases, air from cathode 1 and H2 from anode 2 in the first and second exhaust pipes 110 and 210, is directly used in the first and second humidifiers 130 and 220 to humidify the reactant gases at the inlet of cathode 1 and anode 2 respectively. The condensed water recovered from cathode 1 and anode 2 is stored in respective tanks 31 and 32 from which water pumps 33 and 34 respectively draw water to spray this water into droplets within the first and second humidifiers 130 and 220 in the reactant gases before their admission to cathode 1 and anode 2 respectively.Alternatively, a single water tank collects the water from the desiccants 116 and 207, and a single water pump draws the water from this tank. More specifically, the water spray within the first and second humidifiers 130 and 220 is also controlled, in addition to the water pumps 33 and 34, by water spray valves 35 and 36, or injectors, located immediately upstream of the humidifiers. The water tanks 31 and 32, or alternatively, the single water tank, are intentionally designed with a small capacity to limit their size and additional weight. Their function is to provide a buffer volume of water to manage load transients in the FC system when the humidification requirements of the reaction gases vary. Thus, a distributor 37 controls the distribution of water drawn from water tanks 31 and 32, alternatively, into the single water tank.A water drain from the distributor 37 is in fluidic communication with a water purge valve 38 which controls the discharge of the water passing through it into the air exhaust pipe 110 to the external environment, downstream of all the components located on this pipe 110 and downstream of any possible discharge from the H2 exhaust pipe 210 into the air exhaust pipe 110 before venting to the atmosphere. In normal operation, this valve 38 is kept closed.

[0083] In addition, the system provides that the temperature of the water stored in the water tank(s) is measured by a water temperature sensor located within each tank 31 and 32 (not shown in [Fig. 1]). Similarly, the ambient air temperature is measured by an air temperature sensor (not shown in [Fig. 1]), located, for example, at the inlet of filter 101. The probability of reaching a water temperature below a given threshold (for example, 3°C) in tanks 31 and 32 is also determined from the preceding information and from information from the vehicle's infotainment or navigation systems. Consequently, a purging function is activated if necessary to, where appropriate, control and carry out the purging of tank(s) 31 and 32 and the water lines of network 3.In this case, the water spray valves 35 and 36 (or injectors) are closed and the distributor 37 directs the water, drawn from the tanks 31 and 32 and through the water pipes upstream of the valves 35 and 36, through the valve 38 which is then open in order to allow the purging of water from the network 3 and to evacuate all the water still present in the network 3 to the external environment, via the air exhaust pipe 110. In a manner known per se, this purging of the network 3 is carried out simultaneously with the purging of water and reactant gases from the MEA, by consumption of the residual reactants and moisture, activated each time the FC system is deactivated and the final shutdown ("key off") and the electrical supply to the vehicle is cut off.

[0084] Before describing in more detail the thermal regulation system of the FC system implemented by the invention for the thermal regulation of the condenser of each first humidifier, it is recalled the action of the half-reactions at the anode and cathode of an FC taking place according to the operating principle of the FC system and the importance of the regulation of the hydration of such a system.

[0085] Protons (H+) are transported via water molecules to form hydronium ions, and hydration is a necessary condition for the development of both half-reactions and the final overall reaction. The protons formed at the anode are hydrated by a water molecule and transported as hydronium ions from the anode to the cathode through the water-filled pores of the membrane, primarily due to the potential difference induced between the cathode and anode. Multiple transport phenomena occur in the membrane: diffusion from the cathode to the anode, electro-osmosis from the anode to the cathode (hydronium ions), and the crossing and transport of H2 and O2. Membrane hydration is essential for proton transport, enabling and promoting hydraulic permeation across the membrane, vehicular diffusion (of protons via water molecules), and electro-osmotic diffusion (EOD).The water concentration in the MEA is determined by the balance of two driving forces, namely the back-diffusion of water and electro-osmotic diffusion. The back-diffusion of water occurs in the anode by a reaction. The electro-osmotic force (EOD) increases the water concentration at the anode and is determined by the concentration difference between the anode and cathode. This force arises from the voltage difference between the anode and cathode during an electrochemical reaction. The potential difference causes hydrogen cations (H+) to migrate with water molecules (and therefore hydronium ions) from the anode to the cathode. The combination of the EOD of water and backdiffusion from the cathode to the anode determines the water balance. Furthermore, the EOD is proportional to the current densities in the free current (FC), so the EOD can become dominant, leading to membrane desiccation and significant ohmic loss near the anode.To overcome potential dehydration on the anode side, supplying sufficient water to the anode side of the membrane (via airflow) and reducing water evaporation on the cathode side (by maintaining the temperature below a given threshold) helps keep the fuel cell humidified. Furthermore, the membrane's resistance to ion transport, directly related to its hydration, also directly determines its ohmic loss and associated Joule heating.

[0086] Figure 2 schematically represents a first embodiment of the loops fluidics of the thermoregulation system of the FC system according to the invention allowing the condensation of each condenser 131, 221 to be regulated from at least two fluidic loops used as hot and cold temperature sources.

[0087] More specifically, the thermoregulation system comprises a first fluidic loop 5 for thermal regulation of a vehicle passenger compartment, a second fluidic loop, referenced 6 and 7, for thermal regulation of an electrical power system for the electric traction of the vehicle comprising, in this non-limiting example, two heat transfer fluid circuits 6 and 7 arranged fluidically in parallel, and a third fluidic loop 8 fluidically connected with each condenser 131, 221 and in which fluidic control means are capable of regulating the flow and temperature of the heat transfer fluid of the third fluidic loop 8 as a function of the flow and temperature of the heat transfer fluid of the first and second fluidic loops 5, 6, 7 and as a function of a condensation requirement of each condenser 131 and 221.

[0088] More specifically, the first fluid loop 5 of coolant can be the vehicle's passenger compartment heating circuit. A pump 501 propels a glycol-water type coolant through a heater 502 or heat exchanger between this liquid and the air entering the passenger compartment. Upstream of this heater are arranged a heater 503, for example of the electric type, activated to heat the passenger compartment in cold ambient conditions, possibly assisting a heat pump (not shown), and a heat exchanger 408 between the coolant of the MEA and the coolant of the first fluid loop 5. As alternatives or additions, the fluid loop 5 can be part or all of a thermoregulation circuit of an electrochemical storage system for the powertrain. Alternatively, the heater 503 can be replaced by an air heater located in the vehicle's air conditioning unit or in an air duct opening into the vehicle's passenger compartment. Arrows 504 and 505 represent the supply and return branches, respectively, from the first fluid loop 5 to the third fluid loop 8 of the humidifiers. The outlet 504 is preferentially located downstream of the heater 503 and the exchanger 408, so that these, depending on the operating mode of the fluidic loop 5, can constitute a hot source for the third fluidic loop 8, and in parallel with the air heater 502 in order to limit the impact on the heating of the passenger compartment.The return 505 is preferentially made upstream of the exchanger 408 and the pump 501, in order to optimize the pressure drop between the interfaces 504 and 505 within the third fluid loop 8 and the provision of heat at the outlet 504 from the exchanger 408 and the heater 503. .

[0089] More specifically, circuit 6 of the second fluid loop constitutes a first cold or low-temperature source relative to the temperature of the exhaust pipes of the reaction gases of the FC system. In this example, circuit 6 is the cooling circuit of the electric traction 601, that is, the assembly consisting of an electric machine, its inverter, and a gearbox, which converts the electrical energy supplied by the FC system and / or an energy storage system 701 into mechanical energy that propels the vehicle. This circuit 6 has a pump 602 that propels a coolant through a radiator 603 assisted by a motor-fan assembly 604.This circuit 6 also provides thermoregulation for electrical systems preferably arranged on parallel branches of the circuit, fluidically connected by suitable fluid control means, for example a proportional valve. However, other variants are conceivable without departing from the scope of the invention. These electrical systems may be the RAS, the air intake manifold boost device, a DC / DC converter for the FC system, a DC / DC converter for the traction chain, or the electrochemical energy storage system 701.

[0090] Circuit 7 of the second fluidic loop constitutes a second cold or low-temperature source relative to the temperature of the exhaust pipes of the reaction gases of the FC system. This circuit 7 includes the electrochemical energy storage system 701. This circuit 7 has a pump 702 which propels a coolant through three branches preferably arranged in parallel and connected to each other by a thermoregulation valve 703 for circuit 7. A first branch includes the electrochemical energy storage system 701 and the pump 702. A second branch includes a heater 704, preferably of the electric type. A third branch includes a chiller 705 forming a heat exchanger between the coolant circulating within circuit 7 and the refrigerant of the vehicle's air conditioning system.

[0091] Valve 703, located between circuits 6 and 7, provides the fluid connection between these two circuits. Valve 703 is controlled in different positions depending on the thermoregulation requirements of the electrochemical energy storage system 701. More specifically, depending on the electrical load applied to the electrochemical energy storage system 701, including charge and discharge currents, energy exchanged, state of charge, state of health, and / or depending on the ambient temperature and the temperature of the storage system 701, valve 703 can be controlled in positions such that circuit 7 can remain connected to circuit 6, if the radiator 603, possibly assisted by the fan-motor unit 604, allows the thermoregulation of the storage system 701 to its setpoint temperature, or be disconnected from circuit 6 otherwise.The thermoregulation of the storage system 701 is then ensured by a bypass of the vehicle's refrigerant circuit via the chiller 705, within which the coolant circulates via the pump 702 thanks to the configuration then taken by the valve 703, which, in one position, also closes the passage of the coolant through the heater 704. If the storage system 701 requires heating, its heating is then ensured by the heater 704, within which the coolant circulates via the pump 702 thanks to the configuration then taken by the valve 703, which, in another position, also closes the passage of the coolant through the chiller 705.

[0092] In addition, two conduits 608 and 706 emerge respectively from the radiator 603 and the storage system 701 to enter a degassing box 609 preferably in an aerial position, that is to say above the maximum level of coolant in the degassing box 609, from which the return of the coolant into the circuit 6 is carried out immediately upstream of the pump 602 in order to ensure its pressurization.

[0093] More specifically, the coolant circulates through the condensers 131 and 221 under the action of a coolant pump 801, which draws the coolant from the outlet of a pilot-operated hydraulic distributor 802. A first inlet of the hydraulic distributor 802 is directly supplied by the coolant drawn from the fluid loop 5 through the outlet 504. In particular, the coolant reaching the first inlet of the hydraulic distributor 802 constitutes a hot source at the suction of the pump 801.

[0094] In addition, the thermoregulation system includes a supply 610 and a return 611 constituting branches, preferably in parallel, from the circuit 6 to the third fluidic loop 8.

[0095] The outlet 610 is preferably located at the outlet of the radiator 603 so that the latter can constitute a source of cold coolant for the third fluid loop 8. The return 611 on the circuit 6 is preferably located downstream of the valve 703 and upstream of the pump 602, in order to have this part of the fluid loop 8 in parallel with the other branches of the circuit 6.

[0096] Similarly, the thermoregulation system includes a supply 707 and a return 708 constituting branches from the circuit 7 to the third fluid loop 8. Preferably, the supply 707 and the return 708 between the circuit 7 and the third fluid loop 8 are arranged on either side, i.e. immediately downstream and upstream, of the pump 702, so as not to impact the thermoregulation of the storage system 701. Depending on the thermoregulation mode (heating or cooling) of the storage system 701, a second source of hot coolant is available from the heater 704 and a second source of cold coolant is available from the chiller 705, the latter at a temperature potentially lower than that of the cold coolant source supplied at the outlet of the radiator 603 from the supply 610.

[0097] Thus, the coolant is supplied by circuit 7 via outlet 707 and the coolant is supplied by circuit 6 via outlet 610. These two circuits 6 and 7 join at the inlet of a valve 803 which places the resulting mixture at a second inlet of the hydraulic distributor 802. This valve 803 can consist of a thermostatic valve or a proportional valve adopting several intermediate positions suitable for regulating a precise temperature of the coolant at its outlet, towards the second inlet of the hydraulic distributor 802, according to the temperatures and flow rates arriving at its inlets.

[0098] Furthermore, the hydraulic distributor 802 is actuated to regulate the temperature and flow rate of the coolant at its outlet according to the flow rate and temperature of the coolant at its inlets and according to the condensation requirements at the condensers 131 and 221. The hydraulic distributor 802 can be actuated to a position in which coolant in heat exchange with the first fluid loop 5 is supplied to the first inlet at values ​​within a first warm temperature range, and in which coolant in heat exchange with the second fluid loops 6 and 7 is supplied to the second inlet at values ​​within a second cold temperature range, described in more detail below. The hydraulic distributor 802 can be operated in extreme positions alternately closing one or the other or both of its inlets simultaneously, while the valve 803 provides initial thermal regulation of the coolant temperature at the second inlet of the hydraulic distributor 802.

[0099] As described previously, the first fluidic loop 5 is a heating circuit for the vehicle's passenger compartment and consequently the heat transfer fluid 504 supplied to the first inlet of the hydraulic distributor 802 can be at values ​​in a range between 60°C and 100°C, up to a temperature that can reach 110°C possibly.

[0100] More specifically, the valve 803 can be piloted in a shut-off position of the outlet 707 so as to supply the second inlet of the hydraulic distributor 802 with low-temperature coolant, usually in a range between 50°C and 65°C, up to a temperature that may reach possibly 70°C taken from the outlet 610 at the outlet of the radiator 603.

[0101] The valve 803 can be operated in a closed position of the outlet 610 so as to supply the second inlet of the hydraulic distributor 802 with low-temperature coolant, usually in a temperature range of 30°C to 45°C depending on the current thermoregulation mode of the electrochemical energy storage system 701, up to a temperature of up to 60°C taken from the outlet 707 at the discharge of the pump 707. The coolant of the circuit 7 can be brought to this temperature range in cooling mode of the energy storage system 701 by the chiller 705.

[0102] However, in another operating mode of the circuit 7, the coolant can be brought to a higher temperature range, up to 80°C, in the heating mode of the storage system 701 when the heater 704 is activated. This latter mode is controlled, for example, if the first fluid loop 5 is inoperative, the pump 501 being deactivated, or if the valve 409 inhibits the circulation of the heat transfer fluid within the heat exchanger 408, or if the heater 503 is inactive.

[0103] Thus, the thermal management system 8 is configured to supply the condensers 131 and 221 with coolant at the optimal temperature and flow rate. The portions of coolant that have passed through the condensers 131 and 221 are then returned, via the returns 505, 611 and 708, to the respective circuits 5, 6, 7. Preferably, the thermal control system includes a valve 804 positioned at the coolant outlet of the condensers 131 and 221 in order to distribute, according to its temperature, the coolant between the returns 611 in circuit 6 and 708 in circuit 7.

[0104] The thermal regulation of the condensers 131 and 221 is operated by a control unit 800 of the fuel cell system implementing a thermoregulation function 805 configured to control the pump 801, the valve 802 and the valve 803, in particular, according to the flow rate and temperature of the heat transfer fluid of the first and second fluid loops 5, 6 and 7 and the condensation requirement of the condensers. The control of other fluid control means of the thermoregulation system is possible to operate this function.Based on the condensation requirement, determined from measurements including temperature, pressure, and humidity at the inlet and outlet of the intake and exhaust manifolds and internally within the MEA, function 805 determines a temperature setpoint and specific setpoints for the fluid control means (represented by dashed arrows) to maintain the temperature setpoint. The orders of magnitude of the required relative humidity levels are approximately 65 to 90% on the anode side and approximately 30 to 50% on the cathode side.

[0105] Figure 3 more specifically illustrates a preferred embodiment of the first fluid loop 5 intended to act as the hot temperature source operating in the first temperature range. This first fluid loop is preferably arranged in heat exchange with a fourth fluid loop 4 for cooling the FC system according to the invention, in order to transfer heat from the MEA to the first fluid loop 5. Thus, the fluid loop 4 can provide additional heat for temperature control of the condensers 131 and 221.

[0106] More specifically, the first fluidic loop 5 and the fourth fluidic loop 4 are arranged in heat exchange through the heat exchanger 408. This heat exchanger separates the fluidic connections between the two loops 4 and 5 in order in particular to ensure electrical isolation.

[0107] Furthermore, the fluid loop 4 is the designated high-temperature cooling circuit of the MEA 401, driven by a pump 402 which propels a coolant of a different nature (for example, glycol water with very low electrical conductivity) than that used in the first and second fluid loops 5, 6, and 7. This cooling circuit 4 also includes a radiator 403 assisted by a fan motor 404, as well as a bypass duct 405 for the radiator 403. A valve 406 distributes the flow of the coolant between the radiator 403 and its bypass duct 405. Another branch 407 of the fourth fluid loop 4, arranged parallel to the bypass duct 405 and the radiator 403, carries the heat exchanger 408 between the coolant of the MEA and the coolant of the first fluid loop 5, and is controlled by a valve 409. which inhibits or permits, totally or partially, the circulation of coolant through the exchanger 408.

[0108] A conduit 410 and a conduit 411 emerge from the MEA 401 and the radiator 403, respectively, and terminate in a degassing box 412. Conduit 410 opens into the degassing box 412 preferably above ground: above the maximum coolant level. Conduit 411 opens into the degassing box 412 preferably below ground, below the minimum coolant level, or possibly also above ground. The degassing box 412 incorporates the functions of a deionizer and a particulate filter for the coolant. Alternatively, these three functions can be separated from one another. The return of the coolant from the degassing box 412 into the fluid loop 4 occurs immediately upstream of the pump 402 to ensure its pressurization.Another branch 413 of the fluidic loop 4, arranged in parallel with the bypass conduit 405 and the radiator 403, carries the heat exchanger 201 between the coolant and the H2 before its admission to the anode 2.

[0109] Figure 4 represents a second embodiment of the FC system in which The thermoregulation system includes fluidic control means arranged to thermally regulate each condenser 131 and 221 of the first and second humidifiers, and in which thermal regulation is operated individually by the control unit 800 of the FC system within a temperature range specific to each condenser 131 and 221. More specifically, each condenser 131 and 221 is thermally regulated according to a specific regulation function 805a and 805b, each managed by a dedicated hydraulic distributor 802a and 802b. This provision can be justified by the need for personalized thermal regulation of the condensers 131 and 221, when the conditions of entry of the reactant gases into their respective humidifiers 130 and 220, at the inlet and outlet of the cathode 1 and the anode 2, are very different and therefore require an adaptation of the thermal conditions of condensation.It is worth noting that the orders of magnitude of relative humidity levels required are approximately 65 to 90% on the anode side and approximately 30 to 50% on the cathode side.

[0110] To this end, all the elements of the fluidic loop 8 described in [Fig. 2] are duplicated to allow each of the condensers 131 and 221 to have its own personalized supply of coolant, from the outlets 504, 610 and 707 of circuits 5, 6 and 7 respectively, at the exit of which the hydraulic distributors 802a and 802b are connected in parallel. Thus, the first inlets of the hydraulic distributors 802a and 802b are directly supplied, in parallel with each other, by the coolant drawn from the fluidic loop 5 via outlet 504. Similarly, valves 803a and 803b are arranged in parallel, at the outlet of the coolant drawn from circuit 7 via outlet 707 and from circuit 6 via outlet 610, and create their own resulting mixture, potentially different from each other, at each of the second inlets of the hydraulic distributors 802a and 802b. These distributors can be controlled in a specific position depending on the inlet and outlet conditions, and supply the coolant under optimized conditions specific to each condenser 131 and 221 at the suction of each of the pumps 801a and 801b. The control of each pump is specific to each branch of the fluid loop 8. For simplicity, not all operating modes and configurations potentially adopted by the third fluid loop 8a are shown, but they will be readily accessible to those skilled in the art.

[0111] In [Fig.5] a third embodiment of the FC system is shown schematically. It differs from the first embodiment in that the first and second fluid loops 5, 6 and 7 are arranged in heat exchange with the third fluid loop 8 via a heat exchanger 506 for the first fluid loop 5, and heat exchangers 612 and 709 for the second fluid loops 6 and 7. This configuration has the advantage of not mixing, within the third fluid loop 8, the cooling liquids from the heat transfer circuits of the first and second fluid loops 5, 6 and 7.

[0112] Similar to the third fluid loop 8 described in [Fig. 2], the third fluid loop 8b of the humidifiers uses a coolant pump 801c which delivers the coolant from the hydraulic distributor 802c through the condensers 131 and 221. A first inlet of the hydraulic distributor 802c is fluidically connected to the heat exchanger 506. The first inlet is therefore directly supplied by the coolant from the heat exchanger 506, which constitutes a source of hot coolant at the suction of the pump 801c via the hydraulic distributor 802c.

[0113] Furthermore, the heat exchangers 612 and 709 are arranged in parallel with each other, at the outlet of the condensers 131 and 221, and the fluid connections having passed through the exchangers 612 and 709 are fluidly connected at the inlet of a valve 803c which itself is fluidly connected to a second inlet of the hydraulic distributor 802c and thus ensures thermal regulation of the temperature of the coolant at the second inlet of the hydraulic distributor 802c. This second inlet is used as a cold source or a hot source.

[0114] Similar to actuators 803, 803a and 803b, this valve 803c may consist of a thermostatic valve or a proportional valve, so as to regulate a precise temperature of the coolant at its outlet, towards the second inlet of the hydraulic distributor 802c. The hydraulic distributor 802c then adopts a position suitable for regulating the temperature and flow of coolant at its outlet according to its inlets and according to the condensation requirement at the condensers 131,221.

[0115] The temperature control of condensers 131 and 221 is operated by the fuel cell system's control unit 800, which implements a temperature control function 805c configured to control pump 801c, valve 802c, and valve 803c, among other things, based on the flow rate and temperature of the heat transfer fluid in the first and second fluid loops 5, 6, and 7, and the condensation requirements of the condensers. Thus, the third fluid loop is designed to supply condensers 131 and 221 with coolant at the optimal temperature and flow rate. The fluids that have passed through condensers 131 and 221 are then returned to the inlets of heat exchangers 506, 612, and 709 so that these fluids mix upstream of these heat exchangers.Not all operating modes and configurations potentially adopted by the third fluidic loop 8b are represented, for simplicity, but they will be easily accessible to those skilled in the art.

[0116] In [Fig. 6] a fourth embodiment of the FC system is schematically represented and differs from the third embodiment in that each condenser 131 and 221 has specific thermal regulation, similar to the second embodiment, each being managed by a dedicated hydraulic distributor 802d and 802e. More precisely, each condenser 131 and 221 is thermally regulated according to a specific control function 805d and 805e implemented by the control unit 800, each managed by a dedicated hydraulic distributor 802d and 802e.

[0117] The first inlets of the hydraulic distributors 802d and 802e are fluidically connected, in parallel, to the outlet of the heat exchanger 506. Furthermore, at the outlet of each of the parallel heat exchangers 612 and 709, the fluid connections that have passed through the exchangers 612 and 709 converge at the inlet of each of the parallel valves 803d and 803e. The valves 803d and 803e each prepare their own coolant mixture, potentially different from one another, supplied to the second inlets of the hydraulic distributors 802d and 802e. These can be controlled in a specific position depending on the inlet and outlet conditions, and supply the coolant under optimized conditions specific to each condenser 131 and 221 at the suction of each of the pumps 801e and 80Id.The control of each pump is specific to each branch of the fluid loop 8. All modes of . The operation and configurations potentially adopted by the third fluidic loop 8c are not represented, for simplicity, but they will be easily accessible to the person skilled in the art.

[0118] Furthermore, for this third and fourth embodiment, the first fluid loop 5 and the second fluid loops 6 and 7 are similar to those of the first and second embodiments, respectively, and already described in [Fig. 2] and [Fig. 3]. They differ in that the supply and return connections 504 and 505 for the first fluid loop 5 and the supply and return connections 610, 611, 707, and 708 for circuits 6 and 7, respectively, are absent. These fluid connections are replaced by the heat exchangers 506, 612, and 709 and their associated fluid connections with the third fluid loop 8 to ensure heat transfer. The fluid loops 5, 6, and 7 form independent loops, thermally coupled to the third fluid loop 8 through the heat exchangers 506, 612, and 709, respectively.

[0119] For the sake of brevity, and having already been described in detail in [Fig. 2] and [Fig. 3], the first and second fluidic loops 5, 6, and 7 will not be described again in detail. The reference numerals used in Figures 2 and 3 are retained to identify identical elements.

[0120] Figure 7 schematically represents an alternative embodiment of the first fluid loop 5a associated with the fourth fluid loop 4 for cooling the MEA. This alternative is similar to the fluid loop described in Figure 3. The heat exchanger 506 is preferably of a different nature than the heat exchanger 408, the heat exchanger 506 being arranged for heat exchange between the coolant of the MEA and the coolant of the fluid loop 5a because the coolant circulating within the third loop 8b and 8c is of a different nature than the coolant circulating within the fourth fluid loop 4 for cooling the MEA.A conduit 507 is arranged in parallel with the heat exchanger 506, that is, between its inlet and outlet of coolant within the fluid loop 5a, in order to allow the coolant circulating within the fluid loop 5a to bypass the heat exchanger 506 at least partially, and a valve 508 ensures the regulation of the flow of coolant from the fluid loop 5a through the heat exchanger 506. The valve 508 can occupy a fully open and fully closed position as well as all intermediate positions between these two extremes.

[0121] Figure 8 schematically represents an alternative embodiment of the second fluidic loop comprising circuits 6a and 7a. This alternative is similar to the fluidic loop described in Figure 2, except that it includes, within circuit 6a and in parallel with the other branches constituting it, an additional branch. carrying the heat exchanger 612 between the coolant circulating within the fluid loop 6a and the coolant circulating within the third fluid loop 8b and 8c, and a valve 613 which regulates the flow of coolant from the fluid loop 6a through the heat exchanger 612. Similar to the heat exchanger 506, the heat exchanger 612 will preferably be of a different nature than the heat exchanger 408. The valve 613 can occupy a fully open and fully closed position as well as all intermediate positions between these two extremes.

[0122] More specifically, the circuit 7a includes the heat exchanger 709 between the coolant circulating within the fluidic loop 7a and the coolant circulating within the third fluidic loop 8b and 8c. Similar to heat exchangers 506 and 612, heat exchanger 709 is preferably of a different nature than heat exchanger 408. Heat exchanger 709 is arranged in parallel with the fluid connection linking the coolant outlet of the energy storage system 701 to the inlet of pump 702. A valve 710 is located on the fluid connection carrying heat exchanger 709, either upstream or downstream of it, and regulates the flow of coolant from the fluid loop 7a through heat exchanger 709. Valve 710 can occupy a fully open and fully closed position, as well as all intermediate positions between these two extremes.

[0123] Furthermore, other embodiments of the FC system are envisaged where only the O2 oxidizing gas circuit includes a humidifier coupled to the intake manifold and the exhaust manifold, unlike the previous embodiments where the oxidizing gas circuit and the fuel gas circuit are each equipped with a humidifier.

[0124] Furthermore, the control unit 800 of the temperature control system is equipped with an integrated circuit computer and electronic memories, the computer and the memories being configured to perform a temperature control process according to the invention. The computer is the computer of the FC system or the vehicle monitoring computer. The computer may itself be arranged as a dedicated computer including optional dedicated software, for example. The control unit, according to the invention, may be implemented in the form of software modules, electronic circuits, or a combination of electronic circuits and software modules.

[0125] More specifically, the process comprises the following steps:

[0126] - the control of the flow rate and temperature of the heat transfer fluid of the first loop fluidic and the second fluidic loop comprising circuits 6 and 7,

[0127] - the control of the fluidic control means 801, 802 and 803, with reference to the [Fig. 2], to regulate the flow rate and temperature of the heat transfer fluid in the third fluid loop 8 as a function of the flow rate and temperature of the heat transfer fluid in the first and second fluid loops 5, 6, and 7, and as a function of the condensation requirement of each condenser 131 and 221. The condensation requirement is determined from measurements including temperature, pressure, and humidity at the inlet and outlet of the intake and exhaust manifolds and internally within the MEA. Function 805 determines a temperature setpoint and specific setpoints for the fluid control means to maintain the temperature setpoint. The orders of magnitude of the required relative humidity levels are approximately 65 to 90% on the anode side and approximately 30 to 50% on the cathode side.

[0128] Furthermore, according to this method, thermal regulation can be operated individually within a temperature range specific to each condenser 131 and 221 by a specific thermoregulation function, as described in [Fig. 4] and [Fig. 6] by functions 805a and 805b, and respectively functions 805d and 805e. Alternatively, thermal regulation is operated jointly by a single thermoregulation function 805 or 805c according to the embodiments described in [Fig. 2] and [Fig. 5].

[0129] The invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different variant embodiments of the invention by combining, for example, the different features above taken alone or in combination, without departing from the scope of the invention.

Claims

Demands

1. A fuel cell system for a vehicle comprising: - a membrane-electrode assembly (1, 2, 401), - at least one inlet pipe (100, 200) for supplying reactant gas to an electrode (1, 2) of said assembly, - at least one exhaust pipe (110, 210) for removing reactant gas from said electrode (1, 2), - at least one humidifier (130, 220) through which the inlet pipe (100, 200) and the exhaust pipe (110, 210) pass, and comprising a condenser (131, 221) capable of condensing moisture from the reactant gas circulating in the exhaust pipe (110, 210), and a first means for transferring the condensed moisture to the reactant gas circulating in the intake manifold (100, 200), - a thermoregulation system comprising at least one first and one second fluidic loop of heat transfer fluid (5, 6, 7) intended for the thermal regulation of vehicle systems and fluidic control means (501, 602, 702, 801, 802,803) configured to control the flow rate and temperature of the heat transfer fluid in each fluid loop, the system being characterized in that the thermoregulation system comprises a third fluid loop (8) fluidically connected with each condenser (131, 221) and the fluid control means (801, 802, 803) are capable of regulating the flow rate and temperature of the heat transfer fluid in the third fluid loop (8) as a function of the flow rate and temperature of the heat transfer fluid in the first and second fluid loops (5, 6, 7) and as a function of a condensation requirement of each condenser (131, 221).

2. Fuel cell system according to claim 1 wherein the first fluidic loop (5) is configured to regulate the temperature of the heat transfer fluid in a first temperature range and the second fluidic loop (6, 7) is configured to regulate the temperature of the heat transfer fluid in a second temperature range.

3. A fuel cell system according to claim 1 or 2, wherein the first means for transferring condensed moisture is a capillary device arranged on the surface of a wall of the inlet tube (100, 200) passing through the humidifier and configured to humidify the reactant gas circulating in the intake manifold (100, 200).

4. Fuel cell system according to any one of claims 1 to 3 wherein the exhaust pipe further comprises: - a desiccator (116, 207) arranged downstream of the humidifier (130, 220) and configured to separate moisture from the reactant gas, - and a second controlled transfer means (32, 33, 34, 35, 36) for the separated moisture configured to humidify the reactant gas flowing in the intake pipe (100, 200) upstream of the humidifier (130, 220).

5. Fuel cell system according to any one of claims 1 to 4 wherein the first fluidic loop (5) is a heating circuit for the vehicle comprising a heater (503).

6. Fuel cell system according to any one of claims 1 to 5 wherein the second fluidic loop (6, 7) is a thermal regulation circuit of an electrical power system (601, 122, 606, 701) for electric traction of the vehicle comprising a first thermal regulation circuit (6) of power electronics (601, 606, 607) and a second thermal regulation circuit (7) of an energy storage system (701) for the needs of electric traction.

7. Fuel cell system according to any one of claims 1 to 6 further comprising a fourth fluidic loop (4) for cooling the membrane electrode assembly (401) arranged so that the first (5) and fourth (4) fluidic loops are configured in heat exchange.

8. Fuel cell system according to any one of claims 1 to 7 wherein the fluidic control means (801, 802, 803) comprise a piloted hydraulic distributor (802) fluidically connected by a first and a second inlet to the first (5) and second (6, 7) fluidic loops respectively and by an outlet to the third fluidic loop (8).

9. Fuel cell system according to any one of claims 1 to 7, in that it further comprises a first heat exchanger (506) arranged such that the first fluid loop (5) is in heat exchange with the third loop

10. fluidic (8) and a second heat exchanger (612, 709) arranged such that the second fluidic loop (6, 7) is in heat exchange with the third fluidic loop (8), and in that the fluidic control means (501, 602, 702, 801, 802, 803) comprise a pilot-operated hydraulic distributor (802) fluidically connected by a first and a second inlet to the first (506) and second (612, 709) heat exchangers respectively, and by an outlet to the third fluidic loop (8). A method for regulating the humidification of a reactant gas implemented by a fuel cell system as defined by any one of claims 1 to 9, the method being characterized in that it comprises the following steps: - control of the flow rate and temperature of the heat transfer fluid in the first and second fluid loops (5, 6, 7), - the control of the fluid control means (501, 602, 702, 801, 802, 803) to regulate the flow and temperature of the heat transfer fluid of the third fluid loop (8) according to the flow and temperature of the heat transfer fluid of the first and second fluid loops (5, 6, 7) and according to a condensation need of each condenser (131, 221).

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