METHOD FOR ADJUSTING A FUEL CELL COOLING SYSTEM
The method optimizes airflow through a movable shut-off device using real-time core temperature feedback to minimize drag and maintain efficient fuel cell cooling, improving aircraft performance.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- SAFRAN SA
- Filing Date
- 2023-09-21
- Publication Date
- 2026-06-26
Smart Images
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Abstract
Description
Title of the invention: METHOD FOR ADJUSTING A COOLING SYSTEM FOR A FUEL CELL Technical field of the invention
[0001] The present invention relates to a method for regulating a fuel cell cooling system. The invention also relates to a propulsion unit comprising a fuel cell cooled by a cooling system that is regulated by such a method. Technical background
[0002] An aircraft may include a propulsion unit equipped with one or more electric thrusters, each comprising, for example, a propeller driven by an electric motor.
[0003] The propulsive electrical energy required to power the electric thruster(s) is supplied in part or in whole by one or more electric generators.
[0004] In the remainder of the application, we will focus on the particular case in which the electric generator is a fuel cell, better known by the acronym "FPC" or the English term "fuel cell".
[0005] A fuel cell has the advantage of producing few polluting and noise emissions.
[0006] Such a fuel cell converts the chemical energy contained in a fuel / oxidizer pair (for example, the hydrogen / oxygen pair) into electrical energy. The fuel cell includes, in particular, a core formed by a stack of electrochemical cells.
[0007] The electrochemical reaction of the fuel / oxidizer couple produces not only electricity but also heat which is important to remove in order to allow its operation.
[0008] To achieve this, it is known to cool the core of the fuel cell with a cooling system which includes, in particular, a cooling circuit in which a heat transfer fluid circulates. To dissipate the thermal energy of the heat transfer fluid into the external environment, the cooling circuit includes one or more heat exchangers placed in a shrouded section which is supplied with air by an air inlet (or an air intake).
[0009] The passage of air through the duct generates aerodynamic drag that significantly penalizes the overall performance of the propulsion system and the aircraft. This is especially true since the duct and the heat exchangers generally exhibit large dimensions to meet cooling requirements in the most penalizing case, namely when the aircraft is at low speed and low altitude (high temperature), and the fuel cell is operating at full power (for example, during takeoff).
[0010] To limit aerodynamic drag, it is known to implant a flap in the vein, the flap being open when the fuel cell is active and closed when the fuel cell is inactive.
[0011] Motor manufacturers note that such a shutter adjustment can be improved.
[0012] Indeed, it has been observed, for example, that the airflow entering the duct is too high when the aircraft is cruising, as only a portion of this air is needed to cool the fuel cell core. This is explained in particular by the fact that the air temperature at altitude is lower than the air temperature at ground level.
[0013] Engine manufacturers also note that the temperature of the fuel cell core depends on many parameters, including flight conditions (aircraft altitude, aircraft speed, weather, etc.) and its operating regime.
[0014] The objective of the present invention is therefore to provide a simple, effective and economical solution for properly cooling the core of the fuel cell while minimizing aerodynamic drag. Summary of the invention
[0015] The invention thus proposes a method for adjusting a cooling system for a fuel cell intended to power an electric thruster of an aircraft propulsion unit, the cooling system comprising at least one heat exchanger placed in a stream supplied with air by an inlet and a movable inlet shut-off device, the fuel cell having a core placed in the stream downstream of the heat exchanger, the core being formed by a stack of electrochemical cells, the method comprising chronologically the steps of: a) measure the temperature of the fuel cell core; c) determine the setting of the obturator device from the heart temperature measured in step a), so that the heart temperature remains below a predetermined threshold temperature; d) adjust the obturator device according to the setting determined in step c), so as to adjust the flow of air entering the vein.
[0016] Such an adjustment method takes into account the temperature of the fuel cell core in order to rapidly adapt the airflow entering the duct according to the core's cooling requirements, and to minimize aerodynamic drag. produced by the passage of air through the duct throughout a flight (from takeoff to landing), to the benefit of the overall performance of the propulsion unit and the aircraft (fuel consumption, flight range, etc.).
[0017] The method according to the invention may comprise one or more of the following features and / or steps, taken individually or in combination with each other: - the process includes the step of: b) measure the aircraft's flight altitude and / or measure the aircraft's flight speed and / or measure the air temperature in the vein; the setting of the shutter device being determined in step c) from the core temperature measured in step a), the flight altitude measured in step b) and / or the flight speed measured in step b) and / or the air temperature measured in step b); - Step c) includes the sub-steps consisting of: cl) compare the core temperature measured in step a) with the predetermined threshold temperature; c2) modulate the result of the comparison carried out in sub-step cl) with the flight altitude measured in step b) and / or the flight speed measured in step b) and / or the air temperature measured in step b); - the core temperature is measured in step a) using a temperature sensor that is specific to the core of the fuel cell; - the different stages of the process are repeated in a loop via a Proportional Integral Derivative controller known as PID.
[0018] The present invention also relates to an aircraft propulsion unit comprising an electric propulsion unit powered by a fuel cell which is cooled by a cooling system, the cooling system comprising at least one heat exchanger placed in a duct supplied with air by an inlet and a movable inlet closure device, the fuel cell having a core placed in the duct downstream of the heat exchanger, the core being formed by a stack of electrochemical cells, the cooling system being configured to be regulated by the regulation method as described above.
[0019] The propulsion unit according to the invention may comprise one or more of the following features and / or stages, taken individually or in combination with each other: - the sealing device is configured to fit at least partially into an internal compartment in one of its positions, the compartment being defined at least by a conduit delimiting the vein and a fairing of a nacelle; - the shuttering device includes at least one movable flap in translation, the flap being guided by a guidance device which is attached to the entrance; - the shutter comprises several slats which are hinged and sealed against each other; - the shuttering device includes a column of rotating movable shutters; - the shutters are adjusted independently of each other, or in common, or in groups. Brief description of the figures
[0020] The invention will be better understood and other details, features and advantages of the invention will become more apparent upon reading the following description, given by way of non-limiting example and with reference to the accompanying drawings in which:
[0021] [Fig-1] [Fig.1] is a schematic view of a propulsion group according to a first embodiment in which a shuttering device is in a first position;
[0022] [Fig.2] [Fig.2] is a view similar to [Fig.1] in which the shutter device is in a second position;
[0023] [Fig.3] [Fig.3] is a schematic view of a propulsion group according to a second embodiment in which a closing device is in a first position;
[0024] [Fig.4] [Fig.4] is a view similar to [Fig.3] in which the shutter device is in a second position;
[0025] [Fig.5] [Fig.5] is a diagram of a method for adjusting a cooling system according to a first embodiment;
[0026] [Fig.6] [Fig.6] is a diagram of a method for adjusting a cooling system according to a second embodiment. Detailed description of the invention
[0027] Figures 1 to 4 schematically represent a propulsion group 1 of aircraft 2. Aircraft 2 can be, for example, an airplane or a drone.
[0028] The propulsion unit 1 here comprises an electric thruster 3 having a propeller 4 driven directly or indirectly by an electric motor 5. The propeller 4 is mobile in rotation about a longitudinal axis X of the propulsion unit 1. The propeller 4 can be driven in rotation by the electric motor 5 via a speed reducer (for example an epicyclic gear reducer).
[0029] The electric motor 5 is powered directly or indirectly (for example, via batteries) by a fuel cell 6. Batteries can be used to store the electrical energy produced by the fuel cell 6. The fuel cell 6 includes, in particular, a core 7 formed by one or more stacks of electrical cells. chemical. The core 7 of the fuel cell 6 is commonly called a "stack" in English. The fuel cell 6 can be a hydrogen / oxygen cell, and in other words, a cell whose fuel is hydrogen and whose oxidant is oxygen.
[0030] The embodiments illustrated in figures 1 to 4 are in no way limiting, the propulsion group 1 could for example include several electric thrusters powered directly or indirectly by a single fuel cell.
[0031] The fuel cell 6 is cooled by a cooling system 8 comprising one or more heat exchangers 9 placed in a channel 10 supplied with air by an inlet 11 (or air intake) and a movable inlet 11 shut-off device 12. A channel is defined as an air passage delimited by a duct. The core 7 of the fuel cell 6 is placed in the channel 10 downstream of the heat exchanger(s) 9.
[0032] The heat exchanger(s) 9 allows the thermal energy from the core 7 of the fuel cell 6 to be evacuated into the air which passes through the vein 10.
[0033] As illustrated in Figures 1 to 4, the cooling system 8 here comprises several heat exchangers 9 arranged one behind the other, for example, three exchangers. The heat exchangers 9 are part of a cooling circuit in which a heat transfer fluid circulates by means of a pump. Each heat exchanger 9 comprises two independent paths, namely a first path in which the heat transfer fluid circulates and a second path in which air from the stream 10 circulates.
[0034] The heat exchangers 9 are for example tube exchangers and / or plate exchangers and / or finned exchangers, a succession of exchangers of the same type or of different types being possible.
[0035] As illustrated in figures 1 to 4, the vein 10 extends here along an axis which is substantially parallel to the longitudinal axis X. The vein 10 is delimited by a conduit 13 which is placed in a lower housing 14 of a nacelle 15, the electric motor 5 being placed in an upper housing 16 of the nacelle 15.
[0036] By convention in the present application, the terms "upstream" and "downstream" are defined with respect to the direction of airflow around the fairings of the nacelle 15 and in the channel 10, when the propulsion unit 1 is operating in "propulsor" mode.
[0037] Advantageously, the sealing device 12 is configured to fit at least partially into an internal compartment 17 in one of its positions, the compartment 17 being defined at least by the conduit 13 delimiting the vein 10 and a fairing 18 of the nacelle 15.
[0038] Such a configuration makes it possible to limit aerodynamic disturbances, and thus to reduce aerodynamic drag.
[0039] The shutter device 12 may include at least one movable flap 19 in translation, hereinafter referred to as sliding shutter 19.
[0040] By way of example, the shutter device 12 may include a single sliding flap 19, or an upper sliding flap 19 and a lower sliding flap 19.
[0041] Advantageously, each sliding flap 19 is aerodynamically profiled, and in other words each sliding flap 19 is profiled to minimize its drag regardless of its position.
[0042] A sliding shutter 19 can be formed from a single element.
[0043] A sliding shutter 19 may comprise several slats 20 which are hinged and The blades 20 are sealed against each other. This sealing of the blades 20 helps to limit air leakage when the flap 19 is in the closed position, thereby reducing aerodynamic drag.
[0044] Advantageously, each sliding shutter 19 is guided by a guide device which is fixed to the entrance 11. The guide device may include two guides or rails opposite each other in which the lateral ends of the shutter 19 or of the different slats 20 are placed.
[0045] Each sliding shutter 19 can be actuated directly or indirectly by one or more actuators 21. The actuator(s) 21 may be, for example, electrical and / or hydraulic and / or mechanical. The actuator(s) 21 may be connected to a sliding shutter 19 via a transmission mechanism. The mechanism may include one or more connecting rods, one or more reduction gears, or a specific kinematic system depending on the installation requirements.
[0046] A sliding shutter 19 can be wound onto a tube (spool or reel) controlled by one or more actuators 21.
[0047] Each sliding flap 19 is movable in translation between an open position and a closed position.
[0048] The shutter device 12 may include at least one rotating movable flap 22, hereinafter referred to as a pivoting flap 22.
[0049] Advantageously, a pivoting flap 22 is movable in rotation about a fixed axis in the frame of the propulsion group 1.
[0050] Advantageously, each pivoting flap 22 is aerodynamically profiled, and in other words each pivoting flap 22 is profiled to minimize its drag regardless of its position.
[0051] The shutter device 12 may include a column of pivoting shutters 22, so as to form a louver.
[0052] The pivoting flaps 22 can be actuated independently of each other by one or more actuators. Each pivoting flap 22 can be actuated di- directly or indirectly through the actuator(s).
[0053] Advantageously, each pivoting flap 22 is operated by an electric motor 23.
[0054] Conversely, the pivoting shutters 22 can be operated in a common manner by a or several actuators. The pivoting flaps 22 can be actuated directly or indirectly by the actuator(s).
[0055] The actuator(s) may be, for example, electric and / or hydraulic and / or mechanical. The actuator(s) may be linked to one or more pivoting flaps 22 via a transmission mechanism. The mechanism may include one or more connecting rods, one or more reduction gears, or a specific kinematic system depending on the installation requirements.
[0056] The pivoting shutters can be adjusted independently of each other or in common or in groups.
[0057] Each pivoting flap 22 is movable in rotation between an open position and a closed position.
[0058] Advantageously, the adjacent edges of two successive flaps 22 can be provided with sealing elements, in order to limit in particular air leaks between the flaps 22 when they are in the closed position.
[0059] Advantageously, the cooling system 8 is controlled by a computer 24. The computer 24 thus controls the actuator(s) 21, 23 of the shutter device 12 based in particular on information reported by various sensors 25 and a program pre-recorded in the computer 24.
[0060] The computer 24 may be specific to the cooling system 8. The computer may then be informed about the state of various parameters (core temperature, flight altitude, flight speed, etc.) via different sensors specific to this computer, in order to improve the safety of the cooling system.
[0061] The computer 24 can also be the computer controlling the fuel cell 6 or be integrated into the general computer of the propulsion group 1.
[0062] Advantageously, the calculator 24 is configured to carry out the various adjustment processes of the cooling system 8, as described in the rest of the description.
[0063] According to the first embodiment illustrated in Figures 1 and 2, the shutter device 12 comprises a single sliding flap 19 which is movable in translation between an open position ([Fig.1]) and a position at least partially closed ([Fig.2]).
[0064] The sliding shutter 19 here comprises several blades 20 which are articulated and sealed against each other.
[0065] In the open position ([Fig. 1]), the sliding flap 19 is entirely housed in an internal compartment 17 which is radially defined between the conduit 13 and a fairing 18 of gondola 15.
[0066] By way of example, the open position ([Fig. 1 ]) is used when aircraft 2 is taking off while the closed position ([Fig.2]) is used when aircraft 2 is in cruise.
[0067] According to the second embodiment illustrated in Figures 3 and 4, the shutter device 12 comprises a column of pivoting flaps 22, so as to form a louver. Each pivoting flap 22 is movable in rotation about a fixed axis in the frame of the propulsion unit 1.
[0068] In [Fig. 3], the shutter device 12 is in an open position in which all the pivoting flaps 22 are in the open position. In [Fig. 4], the shutter device 12 is in an intermediate position in which two central flaps 22 are in the open position and four peripheral flaps 22 are in the closed position. The shutter device 12 could also be in a closed position in which all the pivoting flaps 22 are in the closed position.
[0069] Each pivoting flap 22 is here operated by an electric motor 23.
[0070] By way of example, the open position ([Fig.3]) is used when aircraft 2 is taking off while the intermediate position ([Fig.4]) is used when aircraft 2 is in cruise.
[0071] According to the invention, the cooling system 8 is configured to be adjusted by an adjustment method.
[0072] More specifically, the adjustment process chronologically comprises the steps of: a) measure the temperature of the core 7 of the fuel cell 6; c) determine the setting of the obturator device 12 from the temperature of the heart 7 measured in step a), so that the temperature of the heart 7 remains below a predetermined threshold temperature; d) adjust the obturator device 12 according to the setting determined in step c), so as to adjust the flow of air entering the vein 10.
[0073] Such an adjustment method takes into account the temperature of the fuel cell core so as to quickly adapt the airflow entering the duct according to the core's cooling requirements, and to minimize the aerodynamic drag produced by the passage of air through the duct throughout a flight (from takeoff to landing), to the benefit of the overall performance of the propulsion group and the aircraft (consumption, flight range, etc.).
[0074] The process may include a step consisting of: b) measure the flight altitude of aircraft 2 and / or measure the flight speed of aircraft 2 and / or measure the air temperature in the vein 10; the setting of the shutter device 12 being determined in step c) from the core temperature 7 measured in step a), the flight altitude measured in step b) and / or the flight speed measured in step b) and / or the air temperature measured in step b).
[0075] Advantageously, when the process includes step b), step b) is carried out before step c).
[0076] When the process includes step b), step c) may include the substeps of: cl) compare the core temperature 7 measured in step a) with the predetermined threshold temperature; c2) modulate the result of the comparison carried out in sub-step cl) with the flight altitude measured in step b) and / or the flight speed measured in step b) and / or the air temperature measured in step b).
[0077] Advantageously, the predetermined threshold temperature corresponds to the maximum permissible temperature of the core 7 of the fuel cell 6. A margin may optionally be applied.
[0078] Advantageously, the temperature of the core 7 is measured in step a) by means of a temperature sensor 25 which is specific to the core 7 of the fuel cell 6.
[0079] As illustrated in Figures 1 to 4, the core temperature 7, which is measured via the temperature sensor 25, is reported to the computer 24, which controls the cooling system 8.
[0080] The different steps of the process can be repeated in a loop via a Proportional-Integral-Derivative (PID) controller; this PID controller is also known as a PID controller. A PID controller is a universal controller that combines the capabilities of proportional, derivative, and integral control.
[0081] According to the first embodiment illustrated in [Fig.5], the adjustment process chronologically comprises steps a), c) and d).
[0082] According to the second embodiment illustrated in [Fig.6], the adjustment process chronologically comprises steps a), b), c) and d).
Claims
Demands
1. Method of adjusting a cooling system (8) of a fuel cell (6) intended to power an electric thruster (3) of an aircraft propulsion unit (1) (2), the cooling system (8) comprising at least one heat exchanger (9) placed in a channel (10) supplied with air by an inlet (11) and a movable inlet (12) shut-off device (11), the fuel cell (6) having a core (7) placed in the channel (10) downstream of the heat exchanger (9), the core (7) being formed by a stack of electrochemical cells, the method comprising chronologically the steps of: a) measuring the temperature of the core (7) of the fuel cell (6); c) determine the setting of the obturator device (12) from the temperature of the heart (7) measured in step a), so that the temperature of the heart (7) remains below a predetermined threshold temperature;d) adjust the obturator device (12) according to the setting determined in step c), so as to adjust the flow of air entering the vein (10).;
2. A method according to claim 1, characterized in that the method comprises the step of: b) measuring the flight altitude of the aircraft (2) and / or measuring the flight speed of the aircraft (2) and / or measuring the air temperature in the vein (10); the setting of the closure device (12) being determined in step c) from the core temperature (7) measured in step a), the flight altitude measured in step b) and / or the flight speed measured in step b) and / or the air temperature measured in step b).
3. Method according to claim 2, characterized in that step c) comprises the substeps of: c1) comparing the core temperature (7) measured in step a) with the predetermined threshold temperature; c2) modulating the result of the comparison made in substep c1) with the flight altitude measured in step b) and / or the flight speed measured in step b) and / or the air temperature measured in step b).
4. A method according to any one of the preceding claims, characterized in that the temperature of the core (7) is measured in step a) by means of a temperature sensor (25) which is specific to the core (7) of the battery. combustible (6).
5. A method according to any one of the preceding claims, characterized in that the different steps of the method are repeated in a loop via a Proportional Integral Derivative controller, also known as a PID controller.
6. Aircraft propulsion system (1) (2) comprising an electric propulsion unit (3) powered by a fuel cell (6) which is cooled by a cooling system (8), the cooling system (8) comprising at least one heat exchanger (9) placed in a channel (10) supplied with air by an inlet (11) and a movable inlet (12) shut-off device (11), the fuel cell (6) having a core (7) placed in the channel (10) downstream of the heat exchanger (9), the core (7) being formed by a stack of electrochemical cells, the cooling system (8) being configured to be tuned by the tuning method according to any one of claims 1 to 5.
7. Propulsion unit (1) according to the preceding claim, characterized in that the sealing device (12) is configured to fit at least partially into an internal compartment (17) in one of its positions, the compartment (17) being defined at least by a conduit (13) delimiting the vein (10) and a fairing (18) of a nacelle (15).
8. Propulsion unit (1) according to any one of claims 6 or 7, characterized in that the shutter device (12) comprises at least one flap (19) movable in translation, the flap (19) being guided by a guide device which is integral with the inlet (11).
9. Propulsion unit (1) according to the preceding claim, characterized in that the flap (19) comprises several blades (20) which are articulated and sealed against each other.
10. Propulsion unit (1) according to claim 6, characterized in that the shuttering device (12) comprises a column of rotating movable flaps (22).
11. Propulsion unit (1) according to the preceding claim, characterized in that the flaps (22) are adjusted independently of each other or in common or in groups.