Thermal control system for a set of electrochemical fuel cell devices

Abstract

A thermal control system for a set of at least two electrochemical devices (100a-100c), the system comprising a heat transfer fluid source (201), a heat exchanger (208), a heating unit (202), a pump (206a-206c), and two valves (209a-209c). The heat transfer fluid is supplied by the source (201) at a temperature below a low temperature. The pump (206a-206c) allows the heat transfer fluid to reach each of the heat exchange means associated with the two electrochemical devices (100a-100c), and each of the valves (209a-209c) allows the flow of heat transfer fluid to one of the electrochemical devices to be interrupted. The system includes a second heat transfer fluid source (203), the fluid in the second source (203) being heated by one of the two devices (100a-100c) to a high temperature, and one of the devices (100a-100c) being heated by the fluid in the second source (203). Figure 2

Description

Title of the invention: Thermal regulation system for a set of electrochemical devices with fuel cells. Technical field

[0001] The invention relates to the field of thermal management of systems generating or consuming heat, particularly electrochemical devices. More specifically, the invention relates to the thermal regulation of a system comprising multiple electrochemical devices with fuel cells. [BACKGROUND]

[0002] Electrochemical devices carry out a chemical reaction in connection with an exchange of electrical energy.

[0003] These systems can, for example, generate electrical energy through a specific electrochemical reaction, such as a redox reaction, as in fuel cells. Fuel cells, also called FCs, are electrochemical generators that produce electricity through a redox reaction between a fuel such as dihydrogen and an oxidant such as dioxygen.

[0004] Such systems produce heat during their operation following the exothermic electrochemical reaction. This heat must be dissipated to ensure optimal system operation and to prevent rapid wear of the various components.

[0005] Conversely, it may be necessary to consider heating the system. This allows, in particular, for the optimal temperature range to be reached quickly when starting up, or restarting, a system. This is referred to as preheating the system. Preheating helps to avoid significant thermal stresses when starting up such a system, for example, a cold fuel cell. Preheating also helps to mitigate the overconsumption of hydrogen and energy during this transient phase in a non-optimal operating mode.

[0006] In order to thermoregulate such an electrochemical device, it is known to use air or heat transfer fluids such as water in thermal circuits in contact with the electrochemical device. The fluid is heated or cooled to supply or remove heat from the electrochemical device, respectively.

[0007] Furthermore, a single architecture can comprise multiple electrochemical devices. The electrochemical devices are placed either in parallel or in series depending on the application requirements. Thus, cooling and heating become more complex for such architectures since each device electrochemical processes require the correct temperature to function optimally; the devices must be supplied correctly and independently with heat transfer fluid at a useful temperature.

[0008] CN115275264A proposes, for the thermal management of fuel cells, to cool a group of fuel cells using a cold water reservoir. The fuel cells are all connected to the cold water source and supplied by a single pump and a set of check valves. Valves connect the fuel cells to each other, as well as to a heat exchanger. When the water is heated after removing excess heat from the operating fuel cells, the water is returned to the heat exchanger to remove the heat and then returned to the cold water reservoir or, alternatively, the heat can be supplied to a nearby fuel cell. A heating unit (PCT = positive temperature coefficient heater) is present in the circuit between the pump and the fuel cells to heat the heat transfer fluid.The heat transfer fluid can then remove or supply heat to the fuel cells, either individually or through a linear order imposed by the architecture. Thus, a fuel cell communicates only with the next fuel cell, and not with a fuel cell further along the circuit.

[0009] Thus, such principles do not, however, allow for the simultaneous and independent supply of hot heat transfer fluid to some fuel cells and cold heat transfer fluid to others. Furthermore, since the heat transfer fluid must be heated before being sent to the fuel cells, a delay and a more or less significant increase in energy consumption can impact the supply of hot fluid to the fuel cells.

[0010] [FEATURES OF THE INVENTION AND ASSOCIATED ADVANTAGES]

[0011] To overcome all or part of the aforementioned drawbacks, the invention is a thermal control system for at least two electrochemical devices. The thermal control system comprises a first source of a heat transfer fluid, a heat exchanger, a heating unit for the heat transfer fluid, a pump for circulating the heat transfer fluid, and at least two valves, each connected to one of the electrochemical devices. The heat transfer fluid is supplied by the source at a temperature below a predetermined threshold temperature, referred to as the low temperature, and the heating unit supplies heat to the heat transfer fluid. The heat exchanger cools the heat transfer fluid by exchanging heat with a medium external to the control system, and the pump allows the heat transfer fluid to reach each of the two electrochemical devices.Each valve allows for the interruption of the flow of heat transfer fluid to one of the electrochemical devices.

[0012] Remarkably, the thermal regulation system further comprises a second heat transfer fluid source, the fluid of the second source being at a temperature above a second predetermined threshold temperature, referred to as the high temperature, the high temperature being higher than the low temperature. The fluid of the second source is further heated by one of the electrochemical devices through contact of the heat transfer fluid with the device, and one of the electrochemical devices is heated by the heat transfer fluid of the second fluid source.

[0013] The electrochemical devices are thus supplied individually and without waiting with hot or cold heat transfer fluid as needed. This allows for efficient cooling of the heat-generating devices in operation and heating of devices during a cold start-up phase. The devices can then operate within their optimal temperature range more quickly and therefore consume less fuel. In addition, the electrochemical devices generate heat and help maintain the second heat source at a high temperature.

[0014] In one embodiment the valves are three-way valves connecting the electrochemical devices and the respective pumps either to the first or to the second source and switching between the two sources of heat transfer fluid.

[0015] It is therefore possible to choose to remove or supply heat to the electrochemical devices individually.

[0016] In one embodiment, the electrochemical devices are fuel cells.

[0017] Fuel cells are electrochemical devices that generate heat during their operation, and this heat must be dissipated. However, these devices also require a temperature within an optimal range to preserve their components and maximize their efficiency. The invention allows for the proper management of heat input and dissipation from such a device.

[0018] In one embodiment, the three-way valves are automatically controlled electrically or by a mechanical system.

[0019] This automatic electrical or mechanical control, such as a pneumatic system, allows for a rapid switchover between the supply of hot and cold heat transfer fluid. This makes the system responsive and provides additional safety in the event of a rapid temperature increase in one of the devices.

[0020] The rapid supply of hot heat transfer fluid also allows for the rapid start-up of an electrochemical system within its optimal temperature range. When such electrochemical systems are energy sources for a heavy transport vehicle For example, the transitional phase is reduced, which is particularly advantageous for the means of transport in question.

[0021] In one embodiment, at least one of the two heat transfer fluid sources is a storage tank.

[0022] Thus, the storage tank makes it possible to maintain the high or low temperature of the source more effectively.

[0023] In one embodiment, the system includes at least one thermometer for measuring the temperature of the electrochemical devices, the measured temperature being transmitted to a control unit for operating the three-way valves. Advantageously, there is one thermometer per electrochemical device and as many measured temperature values ​​are transmitted to the control unit for operation.

[0024] The system can thus regulate the temperature of each electrochemical device individually via thermometers and control units. This makes it possible to obtain a responsive system for rapidly cooling or heating the electrochemical devices.

[0025] In one embodiment, at least two electrochemical devices are individually connected to the heat transfer fluid sources, in a parallel configuration.

[0026] The devices are thus independent of each other and form a more fault-tolerant system. Indeed, when one device is no longer operational, the others can be quickly brought into operation, by preheating at startup, in order to replace the failed device. Because they are independent, the failure of one device does not affect the thermal management efficiency of the other devices.

[0027] In one embodiment, the fluid from the first fluid source is further cooled by a cooling system or by a third fluid source to a temperature lower than the low temperature.

[0028] The first fluid source is then maintained at a low temperature using a cooling system, for example air conditioning or any other heat dissipation system, or by a third fluid source. This third fluid source is at a temperature lower than the low temperature and allows the first source to be efficiently cooled.

[0029] In one embodiment, the heating unit is an electric resistance or a coiled tubular heater, or a heat exchanger, with a dedicated or captured heat source.

[0030] The invention further comprises a thermal regulation method implementing the thermal regulation system described above, such as during circulation of the heat transfer fluid from the second source to at least one electrochemical devices, the electrochemical device concerned is or the electrochemical devices concerned are stopped and at a temperature below a predetermined temperature known as the nominal operating temperature.

[0031] Thus, in this case, the devices are preheated to a temperature lower than their nominal operating temperature, and this preheating reduces the start-up time during which the electrochemical device consumes more energy and / or reagents to operate. This preheating therefore makes a device quickly available for optimal use at its nominal operating temperature.

[0032] The second heat transfer fluid source is further heated by the electrochemical devices during circulation of the heat transfer fluid, the purpose of which is to remove the heat emitted by said devices or at least one of them. The second fluid source, comprising the hot heat transfer fluid, can therefore be maintained at a high temperature by at least one of the heat-generating electrochemical devices. This heat removed from the electrochemical devices is thus utilized by the second fluid source, and the entire system therefore provides thermal regulation with a lower energy cost, since the heat input from the devices is reused by the second fluid source. Brief description of the drawings

[0033] The invention will be better understood and other advantages, details and features will become apparent from the following explanatory description, given by way of example and with reference to the figures, among which: - [Fig.1] is a diagram of a fuel cell system comprising a fuel cell and its thermal management circuit, according to the prior art; - Figures 2A and 2B are diagrams of thermal management systems according to two embodiments of the invention; - Fig. 3 and Fig. 4 are flowcharts representing the thermal management process according to two embodiments of the invention. Description of the implementation methods

[0034] [Fig. 1] Figure 1 is a diagram of a fuel cell system 100 comprising a fuel cell 101 and its thermal management circuit, according to the prior art. The thermal management system includes a pump 102, a heat exchanger 103 for removing or supplying heat to the thermal management circuit, a three-way valve 104 that can switch between several lines, and a thermometer 107. A heat transfer fluid circulates in the thermal circuit and allows the heat produced by the fuel cell 101 to be removed.

[0035] The pump 102 circulates the heat transfer fluid in the circuit. The inward arrow 105 and the outward arrow 106 of the heat exchanger 103 allow visualization of heat exchange with an external element or environment.

[0036] The heat transfer fluid circulates in the thermal management circuit and cools the fuel cell 101 by flowing through the fuel cell components. As a result, the fluid removes heat from the fuel cell by passing through an inlet 108 into a heat exchange medium between the fuel cell and its environment. The fluid exits this heat exchange medium through an outlet 109 and circulates in the thermal management circuit.

[0037] A means of heat exchange is, in particular, a channel present on the bipolar plates included in the fuel cell. These bipolar plates enable the electrical connection in the fuel cell between two elementary cells. Thus, the passage of the heat transfer fluid takes place through grooves or channels in these plates and in the core of the fuel cell, allowing heat exchange.

[0038] The fuel cell 101 consumes fuel and oxidizer to provide electrical energy and requires cooling through the thermal circuit.

[0039] The three-way valve 104 allows switching between several lines and thus isolating or connecting different lines. This valve 104 is similar to a fluid switch. A three-way valve includes any type of valve that allows distributing a fluid between a first line that supplies the fluid to the valve, and two other lines that receive the fluid. The valve can then switch the fluid outlet according to the first or second receiving line. The three-way valve also allows supplying fluid at the outlet, the fluid coming from the two receiving lines. The distribution of the quantity of fluid from a receiving line depends on the state of the three-way valve. The valve allows for mixing of the fluids.

[0040] Furthermore, the thermal circuit connecting the fuel cell 101, the three-way valve 104, the pump, and the heat exchanger includes an intermediate branch. This branch allows the fuel cell 101 to be isolated in a circuit excluding the heat exchanger 103, and thus to operate in isolation without benefiting from cooling by the exchanger 103. The valve 104 thus allows the heat exchanger 103 to be isolated from the fuel cell 101 or not.

[0041] In addition, the thermometer 107 measures the temperature of the heat transfer fluid, either before the fluid passes through the fuel cell 101 or after the fluid passes through the fuel cell 101. The measurement is then communicated to a control system of the fuel cell 101. This control system, depending on the temperature measurement, can modify the state of the valve 104 in order to isolate the fuel cell from the heat exchanger 103 according to the measured temperature.

[0042] The invention makes it possible to regulate the temperature of such systems 100 alone or of a set of systems 100 in a parallel configuration, for example. In a particular embodiment, the fuel cells 101 alone are included in such an architecture, without including a thermal circuit.

[0043] [Fig. 2A] Fig. 2A is a diagram of an embodiment of a thermal management system. The management system comprises a set of electrochemical systems 100a-100c, three-way valves 209a-209c associated with each of the systems, a heat transfer fluid source 201 at a predefined temperature referred to as low temperature, and a heat transfer fluid source 203 at a predefined temperature referred to as high temperature, associated with a heating unit 202. The low temperature is lower than the high temperature.

[0044] The electrochemical systems 100a-100c are subsequently considered to be fuel cells.

[0045] The electrochemical systems 100a-100c, three-way valves 209a-209c, and the sources 201, 203 are interconnected by a set of conduits forming a thermal circuit. This circuit is called the secondary circuit, as opposed to the internal thermal circuit that may be present in the electrochemical systems 100a-100c. The thermal management circuit of the electrochemical systems 100a-100c is then called the primary circuit. The system further includes actuators 205a-205c and three-way valves 209a-209c. These actuators 205a-205c electrically actuate the valves 209a-209c individually. Alternatively, a single central control unit can individually control one or more valves 209a-209c actuated by their individual actuators 205a-205c.

[0046] Alternatively, devices equivalent to the three-way valves 209a-209c can be used, allowing the flow of fluid to be stopped in one pipe and / or directed into another pipe.

[0047] Alternatively, the valves 209a-209c can be operated mechanically, for example using a pneumatic system or manually.

[0048] In the embodiment considered, the fluid sources 201 and 203 are reservoirs comprising a closed shell such as a storage tank. A fluid storage tank also allows for more precise control of the temperature of the source 203 or the source 201 by preventing potential heat dissipation or, conversely, heat gain from the external environment.

[0049] The storage tank volume is judiciously sized to provide the necessary amount of heat to the fuel cells during the start-up phase, without a significant drop in the so-called high temperature. The embodiment shown here further includes a first set of pumps 206a-206c connected to the systems and allowing the heat transfer fluid to circulate at high or low temperatures. temperature in the thermal circuit. The heat transfer fluid in the hot fluid storage tank 203 is maintained at a high temperature by the heating unit 202.

[0050] The high-temperature heat transfer fluid source 203 makes it possible to quickly obtain a large volume of hot fluid to heat the electrochemical devices 100a-100c.

[0051] The heating unit 202 may be included within the source, or external to it but in contact with the heat transfer fluid it contains or the casing of the source 203. Furthermore, the heating unit 202 may be an electric resistance heater, an airflow heater, an immersion heater, a burner, or any other heating element capable of increasing the temperature of the heat transfer fluid. The heating unit 202 may, for example, be a coiled tubular heat exchanger in contact with an external heat source.

[0052] In an alternative embodiment, the low-temperature heat transfer fluid source 201 can be an open-walled source such as a basin or an external medium, with or without flow. The low-temperature heat transfer fluid source 201 can be maintained at the low temperature using a cooling system such as an air conditioner or by heat exchange with a third heat transfer fluid source at a temperature lower than the low temperature.

[0053] The high-temperature heat transfer fluid source 203 can also be a source comprising an open envelope such as a natural hot water source or an industrial hot water source.

[0054] The low-temperature fluid source 201, also called the cold fluid source, supplies the heat transfer fluid to the circuit for cooling devices 100a-100c, while the high-temperature fluid source 203 heats devices 100a-100c by supplying a hot fluid.

[0055] Heating devices 100a-100c can precede their ignition so that devices 100a-100c quickly reach their optimal operating temperature range; this is known as preheating. Furthermore, the high-temperature heat transfer fluid can heat the devices after ignition to accelerate the temperature rise of device 100a-100c and quickly reach the optimal operating temperature range.

[0056] Thus, the two sources 201 and 203 supply the devices 100a-100c with the heat transfer fluid at high or low temperature as required. The devices 100a-100c are therefore heated or cooled to operate within their optimal operating temperature range.

[0057] The low-temperature fluid is drawn from the source 201 by the various pumps 206a-206c which direct it, using the three-way valves 209a-209c, to the different devices 100a-100c needing to be cooled. Each device 100a-100c is supplied with heat transfer fluid by a respective pump 206a-206c.

[0058] The heat transfer fluid is then at a temperature lower than that of the device, for example 100a, from which the pump 206a draws the fluid. The device 100a is cooled by the passage of the heat transfer fluid through contact with the element to be temperature-regulated, either via the primary circuit, for example through an internal heat exchanger 103.

[0059] Similarly, the pumps 206a-206c draw the high-temperature heat transfer fluid from the source 203. The fluid is conveyed by the pump 206a-206c respectively associated with the lOOa-lOOc system requiring heating. Heat is supplied by the heat transfer fluid either through direct contact with the element to be heated or via a primary thermal circuit which may include an internal heat exchanger 103. The three-way valves 209a-209c allow, depending on their position, the fluid to be conveyed either at the high temperature or at the low temperature to the lOOa-lOOc devices to which they are associated.

[0060] The heat transfer fluid, after cooling or heating the devices lOOa-lOOc, is returned to the high-temperature fluid source 203 through pipes. Thus, when the low-temperature fluid has been heated by the devices lOOa-lOOc, it does not return to the low-temperature fluid source 201, and the source 201 is efficiently maintained at a low temperature. Furthermore, the fluid returning to the source 203 may be at a temperature lower than the high temperature. The sizing of the source 203, and the combined operation of other electrochemical devices, makes it possible to maintain the source temperature within an operating range.

[0061] The heating unit 202 is a supplementary heating element used in certain cases, such as, for example, starting up lOOa-lOOc fuel cells after a long shutdown or during a long period without heat input. The heating unit 202 can also provide temporary heating when the fluid source 203 reaches a predetermined low critical temperature; in this case, the heat input from the lOOa-lOOc fuel cells is insufficient to maintain the temperature of the fluid source 203, and the heating unit 202 provides the necessary heat to maintain the temperature.

[0062] The high-temperature heat transfer fluid source 203 can also be equipped with a thermometer to measure and control the temperature of the heat transfer fluid it supplies to the rest of the secondary circuit.

[0063] The lOOa-lOOc devices are shown here in a parallel configuration; each is thus independently connected to the two heat transfer fluid sources. via the three-way valves 209a-209c. One device, for example 100a, can be cooled while another, for example 100b, can be heated.

[0064] In the embodiment presented, the system further comprises a set of thermometers 204a-204c, each associated with an electrochemical system 100a-100c, and a heat exchanger 208. The heat exchanger 208 is also connected to the two heat transfer fluid sources 201 and 203 and to a pump 207 in order to circulate the heat transfer fluid in an independent thermal circuit. In one embodiment, the heat exchanger 208 is included in the secondary thermal circuit without being isolated from the other components.

[0065] The heat exchanger 208 is positioned between the heat sources 203 and 201. The high-temperature heat transfer fluid can thus be conveyed to the heat exchanger 208 to dissipate the heat it carries. The heat is then transferred to the external environment with which the heat exchanger 208 communicates. The cooled heat transfer fluid then returns to the low-temperature heat source 201. Thus, maintaining the high temperature in the storage tank 203 is ensured both by the electrochemical systems in operation and by the auxiliary heating unit 202, which provides heat as needed.

[0066] In addition, a pump 207 recirculates the heat transfer fluid from the low-temperature source 201 to the heat exchanger 208 to remove excess heat. As a result, the source 201 is maintained at a low temperature.

[0067] Thermometers 204a-204c are positioned at the outlet of the heat transfer fluid relative to devices 100a-100c. They measure the temperature of the heat transfer fluid after the cooling or heating of a device 100a-100c and transmit the temperature measurement to the centralized control unit, which operates the actuators 205a-205c. The actuators actuate the three-way valves 209a-209c to supply devices 100a-100c with heat transfer fluid at either the high or low temperature, depending on the temperature measured by the thermometer 204a-204c associated with each device 100a-100c.

[0068] The system can then thermoregulate each device 100a-100c by drawing heat transfer fluid at the high or low temperature depending on the temperature measured by the thermometers 204a-204c for each device 100a-100c individually.

[0069] Furthermore, thanks to the three-way valves 209a-209c, the system is responsive and allows for rapid switching between hot and cold heat transfer fluid supply as needed. This responsiveness ensures the safety of the system, including the electrochemical devices, and prevents, in particular, a sudden and uncontrolled temperature increase in a malfunctioning device.

[0070] Preheating an electrochemical system 100a-100c before commissioning allows rapid access to this temperature range and ensures optimal operation. It also reduces component degradation related to the use of the device 100a-100c during commissioning, thereby lowering associated costs.

[0071] In addition, the high-temperature heat transfer fluid source 203 can be heated, in addition to the heating unit 202, by one or more operating heat-generating devices 100a-100c. The heat transfer fluid exiting the devices 100a-100c is at a temperature higher than the low temperature and is conveyed to the source 203.

[0072] The heat transfer fluid in the primary circuit may be the same as, or different from, the heat transfer fluid in the secondary circuit. In particular, the heat transfer fluid in the secondary circuit may be water, which is heated in the hot fluid source.

[0073] In one embodiment, the electrochemical systems 100a-100c may be, for example, proton exchange membrane fuel cells (PEMFCs) or alkaline exchange membrane fuel cells (AEMFCs) whose optimal operation is between 80°C and 100°C. In one embodiment, the temperature-controlled systems 100a-100c may be appropriately supplemented or entirely replaced by exothermic systems such as combustion engines or industrial processes requiring cooling.

[0074] [Fig.2B] [Fig.2B] is a diagram of an embodiment of a thermal management system according to the invention. This embodiment is an alternative to the embodiment shown in [Fig.2A].

[0075] The management system includes a set of electrochemical systems 100a-100c, three-way valves 209a-209c associated with each of the systems, a heat transfer fluid source 201 at a predefined temperature called low temperature and a heat transfer fluid source 203 at a predefined temperature called high temperature associated with a heating unit 202. The low temperature is lower than the high temperature.

[0076] The lOOa-lOOc electrochemical systems considered hereafter are fuel cells, however the invention is not limited to this type of electrochemical systems.

[0077] Alternatively, devices equivalent to the three-way valves 209a-209c can be used, allowing the flow of fluid to be stopped in one pipe and / or directed into another pipe.

[0078] The three-way valves 209a-209c are operated automatically using actuators 205a-205c controlled by a central control unit not shown in [Fig.2B].

[0079] The management system further includes a pump 210 that draws the low-temperature heat transfer fluid from the source 201 to the fuel cells lOOa-lOOc. This pump 210 then delivers the low-temperature fluid to the three-way valves 209a-209c operated by the actuators 205a-205c.

[0080] A second pump 211 draws the high-temperature fluid from the source 203 to the fuel cells lOOa-lOOc. This pump 211 then allows the high-temperature fluid to be conveyed to the three-way valves 209a-209c operated by the actuators 205a-205c.

[0081] Thus, the high or low temperature fluid can be routed to each of the lOOa-lOOc fuel cells individually.

[0082] The heat transfer fluid is then heated by the fuel cells lOOa-lOOc and then conveyed to the high-temperature fluid source 203. The source 203 is maintained at the high temperature by the heat from the fuel cells, the heat being conveyed by the heat transfer fluid, or by an auxiliary heater of the heating unit 202.

[0083] The heating unit 202 may be included within the source, or external to it but in contact with the heat transfer fluid it contains or the casing of the source 203. Furthermore, the heating unit 202 may be an electric resistance heater, an airflow heater, an immersion heater, a burner, or any other heating element capable of increasing the temperature of the heat transfer fluid. The heating unit 202 may, for example, be a coiled tubular heat exchanger in contact with an external heat source.

[0084] The heating unit 202 is then used to maintain the temperature of the heat transfer fluid within the source 203 at the high temperature. The heating unit 202 prevents the source 203 from reaching a predetermined low critical temperature when the lOOa-lOOc fuel cells do not provide enough heat during their operation, during a prolonged shutdown, or during a start-up phase.

[0085] The fluid source 201 is maintained at a low temperature by the heat exchanger 208 which returns to the source 201 the heat transfer fluid whose heat has been removed by the exchanger 208. In an alternative embodiment, the fluid source 201 is cooled by a third fluid source to a temperature lower than the low temperature, or by a cooling system such as an air conditioner.

[0086] In an alternative embodiment, the thermal management system comprises a different pump configuration. The system includes pump 207 between the fluid source 201 and fluid source 203 and another pump located between the heat transfer fluid outlet of fuel cells 100a-100c and the heat transfer fluid inlet of fluid source 203.

[0087] The arrangement and number of pumps enabling the circulation of the heat transfer fluid in the thermal management system can then vary from one embodiment to another, depending on the needs of the system.

[0088] [Fig-3] Fig. 3 is a flowchart representing a thermal management process according to one embodiment of the invention. More specifically, [Fig.3] represents the thermal management for a start-up phase of a fuel cell system 100.

[0089] The method comprises steps represented by rectangles, states represented by ovals, and tests on conditions represented by diamonds. The result of the tests is represented by a solid line when it is positive, and by dashes when it is negative.

[0090] Figure 3 illustrates the thermal management of a device, for example 100a, comprising a primary circuit with a heat transfer fluid. The primary circuit communicates with the thermal management system circuit, called the secondary circuit, via an internal heat exchanger and the system's heat transfer fluid. Such a device 100a is shown in Figure 1 and includes, in particular, a three-way valve 104 for isolating or not isolating the heat exchanger 103 from the element to be heated or cooled.

[0091] The method comprises an initial state 300, followed by a standby step 301 of the complete thermal control system and device 100a. Device 100a is then stopped and awaiting instructions. The primary circuit is stopped, as is the individual supply of heat transfer fluid to the secondary circuit.

[0092] The next step, 302, is the commissioning step of the primary circuit of device 100a. The heat transfer fluid in the primary circuit circulates, and a temperature measurement of device 101 is available, either by means of a thermometer 107 present in the primary circuit or by measuring the temperature at the outlet of device 100a in the secondary circuit. The heat transfer fluid does not yet circulate in the secondary circuit specifically for device 100a. Furthermore, the primary circuit operates independently of the secondary circuit; the heat transfer fluid does not circulate in the internal heat exchanger 103; the fluid circulates in the primary circuit in a closed loop.

[0093] In one embodiment, the electrochemical system 100a does not include a primary circuit and only comprises an electrochemical device 101, so this step of putting the primary circuit into service is absent from the process.

[0094] A first test 303 is carried out on the measured temperature of the device 100a, if this is lower than the nominal operating temperature of the device 100a then the process proceeds to the next test 304.

[0095] If the measured temperature is greater than or equal to the nominal operating temperature of the device 100a, the process proceeds to step 311 described below.

[0096] Test 304 compares the measured temperature to the so-called high temperature, corresponding to the temperature of the heat transfer fluid supplied by the heated fluid source 203.

[0097] If the device 100a is at a temperature lower than the high temperature, the process begins the preheating 320 of the device according to steps 305 and 306. During step 305, the primary circuit no longer operates in isolation and can exchange heat through the heat exchanger 103. During this step 305, the internal three-way valve 104 remains unchanged or is switched to the internal exchanger 103 of the electrochemical device 100a.

[0098] The process then proceeds to step 306, which involves circulating the heat transfer fluid from the secondary circuit individually to device 100a. The pump 206a associated with the device, or in an alternative embodiment, the pump 211, is activated and delivers the high-temperature heat transfer fluid to device 100a. During this step, the position of valve 209a is checked and switched from the hot source 203. The internal heat exchanger 103 recovers the heat supplied by the secondary circuit, and the primary circuit heats device 101.

[0099] The cycle 320 is repeated as long as the temperature measured at the electrochemical device is not greater than or equal to the high temperature and the operating temperature.

[0100] In one embodiment, the electrochemical system 100a does not have a primary circuit and comprises only an electrochemical device 101. Thus, preheating is carried out directly through the secondary circuit in contact with the electrochemical device 101.

[0101] If the result of test 304 indicates that device 101 is at a temperature greater than or equal to the high temperature, the prior art start-up process 321 is initiated and forms an isolated and individual heating sequence of device 101.

[0102] During step 307 the heat transfer fluid of the secondary circuit remains or becomes unused to heat device 101.

[0103] The following step 308 is a step for maintaining the circulation of the heat transfer fluid in the primary closed loop circuit and is derived with respect to the exchanger 103.

[0104] Device 101 is then put into service in step 309, and is supplied with reagents.

[0105] In step 310, the device is operating but at a low temperature, since the measured temperature is lower than the operating temperature. The operation of the device generates heat, and the primary circuit, being insulated from the heat exchanger and the secondary circuit, accelerates the heating of the device until it reaches the operating temperature. Steps 307 to 310 form the heating sequence 321 with the device in operation. However, the device 100a operates at a temperature lower than the optimal operating temperature; therefore, it is considered to be operating at a low temperature.

[0106] During test 303, if the device is at a measured temperature greater than or equal to the operating temperature, the process switches to thermoregulation mode in nominal phase 322. At step 311, the device is considered to be at least at its operating temperature and will therefore be thermoregulated by all of the steps 311 to 314.

[0107] During step 312, the circulation of the heat transfer fluid in the secondary circuit is activated, supplying the system 100a with a "cold" fluid. Heat is then removed from the device through the primary circuit and the heat exchanger 103, and the secondary circuit. The temperature of the device is regulated in the primary circuit by controlling the pump 102 and the internal three-way valve 104. This allows the device to be temporarily isolated from the secondary circuit for temperature regulation. The primary and secondary circuits can be quickly reconnected by activating the three-way valve 104, as shown in [Fig. 1] for a device with a primary circuit.

[0108] During step 313 of the process, system 100a is in nominal operating mode. System 100a generates heat, which is removed by the heat transfer fluid and conveyed to the source 203. This heat maintains the source 203 at its high temperature. Fluid at a lower temperature is drawn by pump 206a or 210 from the source 201 and conveyed to system 100a to maintain it within its nominal operating temperature range. Fluid can also be drawn from the high-temperature source 203 to maintain system 100a within its nominal operating temperature range. Thus, heat is supplied to and removed from system 100a, allowing the system to be maintained within its nominal operating temperature range.

[0109] In one embodiment, the electrochemical device does not include a primary circuit and is directly included in the secondary circuit. Thermal regulation is performed by the secondary circuit through the supply of heat transfer fluid at high or low temperature. The three-way valve 209a is controlled by the control unit to supply a mixture of hot and cold heat transfer fluid and thus provide the electrochemical device 101 with a heat transfer fluid at the correct temperature to ensure its Thermoregulation. The three-way valve 209a can then be considered a mixing valve between the high-temperature fluid source 203 and the low-temperature fluid source 201. The quantity of heat transfer fluid at high or low temperature is determined by the state of the three-way valve 209a; thus, depending on the required temperature, the three-way valve 209a opens more or less to the high-temperature fluid source 203 or to the low-temperature fluid source 201.

[0110] A test 314 is performed regularly during this nominal operating cycle 322. The test 314 verifies that the system 100a is maintained in operation. If the system 100a is maintained in operation, the nominal operating cycle 322 is repeated; otherwise, the process initiates a cooling and shutdown cycle 323 of the system 100a.

[0111] The cooling and shutdown cycle 323 includes the steps 315 of shutting down system 100a and the step 316 of cooling system 100a using the primary and secondary loop.

[0112] Step 315 terminates the supply of reactive gas to system 100a and allows system 100a to be shut down.

[0113] Step 316 is the cooling of system 100a. The internal valve 104 is in position to allow heat to be removed from system 101 using the heat exchanger 103 and the secondary circuit. The hot heat transfer fluid in the secondary circuit is routed to the source 203, and low-temperature fluid is drawn from the source 201 by the pump 206a or 210 and routed to system 100a.

[0114] A test 317 verifies that the measured temperature of system 100a is lower than a predetermined temperature corresponding to system 100a at rest. If the measured temperature is higher than this predetermined temperature, cycle 323 is maintained until system 100a has cooled down.

[0115] If the temperature is lower than the predetermined temperature, the system 100a is stopped and cooled and the process begins step 318.

[0116] Step 318 terminates the circulation of heat transfer fluids in the primary circuit of system 100a and in the secondary circuit associated with system 100a using the three-way valve 209a.

[0117] The process terminates and is in state 319.

[0118] In an alternative embodiment where system 100a does not include a primary circuit, cycles 322 and 323 are carried out in a similar way, omitting the parts corresponding to the primary circuit.

[0119] In an alternative embodiment, the three-way valves 104 and 209a are equivalent devices for stopping the flow of a fluid in a pipe and / or directing it into another pipe.

[0120] Devices 100a can for example be fuel cells (PEM or AEM) when dealing with electrochemical systems 100a comprising a primary circuit.

[0121] [Fig.4] Fig.4 is a flowchart representing a thermal management process According to one embodiment of the invention, and more particularly, the localized heating of the fluid source to the high temperature 203 by activating one or more electrochemical devices 100a-100c when all the electrochemical devices are normally off and the source temperature 203 is less than or equal to the so-called low temperature. The steps of the process are represented by rectangles, while the tests under specific conditions are represented by diamonds. The test result is represented by a solid line when it is positive, and by dashes when it is negative.

[0122] This embodiment incorporates the steps of [Fig. 3] and introduces the heating 324 of the heat transfer fluid source to the high temperature. During test 303, if the measured temperature of the device is higher than the nominal operating temperature, a second test 315 is performed. This test 325 compares a temperature measurement of the hot heat transfer fluid source 203 to the so-called high temperature, i.e., the temperature at which the heat transfer fluid from this source 203 should be. The setpoint temperature is lower than the operating temperature of the electrochemical device.

[0123] If the measured temperature is lower than the high temperature, then the fluid source 203 must be heated. The process then proceeds to step 326, during which the heat transfer fluid of the secondary circuit is heated by the primary circuit of one or more operating electrochemical devices 100a-100c generating heat at the nominal temperature.

[0124] This set of steps 324 makes it possible to utilize the heat produced by the electrochemical devices 100a-100c to heat and maintain the source 203 at a high temperature. Thus, the complete system makes it possible to use and conserve a large part of the energy supplied by the electrochemical devices 100a-100c.

[0125] In one embodiment, the electrochemical devices lOOa-lOOc do not include a primary thermal circuit. In this case, the electrochemical devices lOOa-lOOc, when put into operation, directly heat the heat transfer fluid in the secondary circuit.

[0126] The process then proceeds to steps 327 and 328, which, as before, allow the electrochemical devices lOOa-lOOc to be thermoregulated by enabling heat exchange between the primary and secondary circuits via the heat exchanger 103 and by circulating the heat transfer fluid in the circuit secondary. Thus, the electrochemical system(s) 100a-100c provide the heat to increase the temperature of source 203.

[0127] Finally, steps 326, 327 and 328 are carried out until the heat transfer fluid source 203 reaches the high temperature and test 325 is carried out regularly after step 313.

[0128] If, during test 325, the measured temperature of the source 203 is not lower than the high temperature, the fluid source 203 is considered hot and operational. The process repeats the steps of the nominal phase thermoregulation 322 of the electrochemical systems 100a-100c according to steps 311 to 314.

[0129] Thus, the hot heat transfer fluid source 203 is heated, for example up to 60°C or more, in order to be able to use the fluid at the high temperature to heat the electrochemical systems 100a-100c. This temperature then depends on the electrochemical devices 100a-100c concerned and the heat transfer fluid chosen.

Claims

Demands

1. A thermal control system for an assembly of at least two electrochemical devices (100a-100c), the thermal control system comprising a first source (201) of a heat transfer fluid, a heat exchanger (208), a heating unit (202) for said heat transfer fluid, a pump (206a-206c) for circulating the heat transfer fluid, and at least two valves (209a-209c), each connected to one of said electrochemical devices (100a-100c), the heat transfer fluid being supplied by the source (201) at a temperature below a first predetermined threshold temperature referred to as the low temperature, and the heating unit (202) supplying heat to the heat transfer fluid, said heat exchanger (208) cooling the heat transfer fluid by exchange with a medium external to the control system, said pump (206a-206c) allowing the fluid heat transfer fluid to reach each of the two electrochemical devices (100a-100c),and each of said valves (209a-209c) allowing an interruption of the circulation of heat transfer fluid to one of the electrochemical devices, said thermal control system being characterized in that the system further comprises a second source (203) of the heat transfer fluid, the fluid of the second source (203) being at a second temperature higher than a second predetermined threshold temperature called the high temperature, and said high temperature being higher than the low temperature, said fluid of the second source (203) being further heated by at least one of the electrochemical devices (100a-100c) by contact of the heat transfer fluid with at least one device (100a-100c), and at least one of the electrochemical devices being heated by the heat transfer fluid of the second fluid source (203).

2. Thermal control system according to claim 1 characterized in that said valves (209a-209c) are three-way valves connecting the respective electrochemical devices (100a-100c) and pumps (206a-206c) either to the first or second source (201, 203) and switching between the two sources (201, 203) of heat transfer fluid.

3. Thermal regulation system according to any one of claims 1 to 2, characterized in that the electrochemical devices (100a-100c) are fuel cells.

4. Thermal regulation system according to any one of claims 1 to 3, characterized in that the fluid from the first fluid source (201) is further cooled by a cooling system or by a third fluid source to a temperature lower than the low temperature.

5. Thermal regulation system according to any one of claims 1 to 4, characterized in that the heating unit is an electric resistance or a coiled tubular heater, or a heat exchanger, with a dedicated or captured heat source.

6. Thermal control system according to any one of claims 1 to 5, characterized in that the three-way valves (209a-209c) are automatically controlled electrically or by a mechanical system.

7. Thermal regulation system according to any one of claims 1 to 6, characterized in that at least one of the two sources (201,203) of heat transfer fluid is a storage tank.

8. Thermal regulation system according to any one of claims 1 to 7, characterized in that the system further or at least comprises a thermometer (204a-204) for measuring a temperature of said electrochemical devices (100a-100c), the measured temperature being transmitted to a central control unit for operating actuators (205a-205c) operating the three-way valves (209a-209c).

9. Thermal regulation system according to any one of claims 1 to 8, characterized in that the at least two electrochemical devices (100a-100c) are individually connected to the heat transfer fluid sources (201, 203) in a parallel configuration.

10. A thermal control method implementing the thermal control system according to any one of claims 1 to 9, characterized in that during circulation of the heat transfer fluid from the second source (203) to at least one of the electrochemical devices (100a-100c), said at least one electrochemical device (100a-100c) is at rest and at a temperature below a predetermined temperature known as the nominal operating temperature.

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