Aircraft cooling system and method for protecting the cooling system

Abstract

A closed aircraft cooling circuit (100) comprises at least one primary segment (11) and at least two secondary segments (12a, 12b, 12c, 12d) through which a heat transfer fluid circulates. Each secondary segment (12a, 12b, 12c, 12d) comprises: a leak detection device (17a, 17b, 17c, 17d), a shut-off valve (15a, 15b, 15c, 15d), and a check valve (16a, 16b, 16c, 16d). The cooling circuit (100) further comprises electronic circuitry configured to close the shut-off valve (15a, 15b, 15c, 15d) of a secondary segment when a leak is detected by the leak detection device of that secondary segment. This makes it possible to isolate a secondary segment when a leak is detected in that segment and to protect functionalities provided by components cooled by the cooling circuit. Figure to be published with the abbreviation: Fig. 1

Description

Title of the invention: Cooling circuit for aircraft and method for protecting the cooling circuit technical field

[0001] The present invention relates to the field of cooling circuits in an aircraft and relates more particularly to the protection of aircraft components cooled by cooling circuits in the event of a leak. STATE OF PRIOR ART

[0002] Liquid hydrogen is a cryogenic fluid that can be used as an energy source for electricity generation. For example, a hydrogen fuel cell can be used to power an aircraft's flight control and communication systems, as well as an onboard lighting system and various accessory devices used on board the aircraft. Liquid hydrogen can also serve as an energy source for aircraft propulsion, either by powering a fuel cell or through direct combustion, which has the advantage of releasing only water into the atmosphere.

[0003] Such a fuel cell generates heat, which needs to be managed to maintain or increase the fuel cell's efficiency. Furthermore, it is necessary to manage heat generated by systems onboard the aircraft. A cooling circuit through which a heat transfer fluid circulates can then be used in the aircraft to cool fuel cells and / or onboard systems, via heat exchangers.

[0004] However, leaks may occur in such a cooling circuit, thereby degrading the cooling performance of the fuel cells and / or on-board systems. This may lead to the unavailability of all the components, namely the fuel cells or on-board systems.

[0005] There is therefore a need to improve this situation.

[0006] It is desirable to provide a solution that manages a leak occurring in a cooling circuit, while preserving the functionality implemented by aircraft components cooled by such a cooling circuit. In particular, it is desirable to guarantee the availability of an aircraft propulsion system in the event of a leak occurring in such a cooling circuit when said cooling circuit is used to cool fuel cells powering that propulsion system.

[0007] It is therefore desirable to provide a solution that is lightweight and easy to install. Description of the invention

[0008] A cooling circuit is proposed for an aircraft, the cooling circuit being intended to cool functional components of the aircraft, a heat transfer fluid circulating in the cooling circuit in a predefined flow direction, the cooling circuit being a closed circuit comprising at least one main segment, the flow of the heat transfer fluid circulating entirely within at least one main segment. The cooling circuit further comprises at least two secondary segments, the flow of the heat transfer fluid being distributed parallel to the different secondary segments, and each secondary segment is arranged to cool at least one of the functional components and includes: - a leak detection device, - a shut-off valve, the shut-off valve being located at the inlet of the secondary segment relative to the predefined flow direction. - a non-return valve intended to prevent a reflux of the heat transfer fluid through the secondary segment in a direction opposite to the predefined flow direction, the non-return valve being located at the outlet of the secondary segment, relative to the predefined flow direction.

[0009] The cooling circuit further comprises electronic circuitry configured to trigger the closure of the shut-off valve of said secondary segment when a leak is detected by the leak detection device of said secondary segment, so as to stop the circulation of the heat transfer fluid through the secondary segment.

[0010] Thus, it is possible to isolate a secondary segment when a leak is detected in said secondary segment, in order to maintain the operation and efficiency of the functional elements cooled by the cooling circuit and located on other segments of the cooling circuit than the secondary segment on which the leak is detected. It is then possible to protect the functionalities provided by said elements in the event of a leak, without significantly increasing the mass of the cooling circuit and therefore preserving the aircraft's performance.

[0011] According to a particular embodiment, at least two functional elements cooled by the cooling circuit are fuel cells and each fuel cell is located on a separate secondary segment.

[0012] According to a particular embodiment, the leak detection device includes a drainage pipe arranged to recover at least part of the heat transfer fluid flowing out of the secondary segment in the event of a leak, and further includes a humidity sensor located in the drainage pipe.

[0013] According to a particular embodiment, the leak detection device is a

[0014]

[0015]

[0016]

[0017]

[0018]

[0019] acoustic sensor associated with electronic circuitry, said electronic circuitry comprising means for determining, by comparison of a signal captured by the acoustic sensor with stored acoustic leakage signatures, whether said signal is representative of a leakage. According to one embodiment, at least one secondary segment of the cooling circuit further comprises at least one heat exchanger, said heat exchanger being intended to cool one of the functional elements or a fluid used by one of the functional elements. An aircraft incorporating such a cooling circuit is also proposed, in any of its embodiments. A method for protecting an aircraft cooling circuit is also proposed, the cooling circuit being intended to cool functional components of the aircraft. A heat transfer fluid circulates in a predefined flow direction within the cooling circuit. The cooling circuit is a closed circuit comprising at least one primary segment, with the heat transfer fluid flowing entirely through this primary segment. The cooling circuit further comprises at least two secondary segments, with the heat transfer fluid flow distributed in parallel through the different secondary segments, each secondary segment being arranged to cool at least one of the functional components. The method comprises the following steps: - detect, for each secondary segment, if a heat transfer fluid leak is present, - to stop the circulation of the heat transfer fluid through said secondary segment when a leak of heat transfer fluid is detected in said secondary segment, - prevent a reflux of the heat transfer fluid through said secondary segment in a direction opposite to the predefined flow direction. According to a particular embodiment, the step of stopping the circulation of the heat transfer fluid through the secondary segment involves stopping the flow of the heat transfer fluid at a place located at the inlet of the secondary segment, relative to the predefined direction of flow. According to a particular embodiment, the step of preventing the reflux of the heat transfer fluid through the secondary segment involves stopping the flow of the heat transfer fluid in a direction opposite to the predefined flow direction, at a place located at the outlet of the secondary segment, relative to the predefined flow direction. According to a particular embodiment, at least two functional elements cooled by the cooling circuit are fuel cells and each fuel cell is located on a separate secondary segment.

[0020] A computer program product is also proposed, which can be stored on a medium and / or downloaded from a communication network, in order to be read by a processor. This computer program includes instructions for implementing the method mentioned above in any of its embodiments, when said computer program is executed by the processor. The invention also relates to an information storage medium storing such a computer program comprising instructions for implementing the method mentioned above in any of its embodiments when said computer program is read from said storage medium and executed by the processor. Brief description of the drawings

[0021] The features of the invention mentioned above, as well as others, will become clearer upon reading the following description of at least one exemplary embodiment, said description being made in relation to the accompanying drawings, among which:

[0022] [Fig.1] schematically illustrates an aircraft cooling circuit according to a first particular embodiment of the present invention;

[0023] [Fig.2] schematically illustrates the aircraft cooling circuit according to a second embodiment of the invention;

[0024] [Fig.3] schematically illustrates the aircraft including the cooling circuit;

[0025] [Fig.4] schematically illustrates an example of the hardware architecture of a cooling circuit control unit;

[0026] [Fig.5] schematically illustrates steps in a process for protecting the aircraft's cooling circuit;

[0027] [Fig.6] schematically illustrates the cooling circuit according to a third particular embodiment; and

[0028] [Fig.7] schematically illustrates the cooling circuit according to a fourth particular embodiment.

[0029] DETAILED DESCRIPTION OF IMPROVEMENTS

[0030] Fig. 1 thus schematically illustrates a cooling circuit 100 of an aircraft 1 according to a particular embodiment.

[0031] The cooling circuit 100 comprises a heat transfer fluid circulating, in a closed circuit, in a pipe, according to a predefined flow direction 101. The predefined flow direction 101 is defined by means for circulating said heat transfer fluid in the cooling circuit, such as a pump 102. According to one embodiment, the heat transfer fluid is glycol water.

[0032] The cooling circuit 100 comprises at least one main segment 11 and at least two secondary segments 12a, 12b, 12c, 12d. The entire flow Heat transfer fluid circulates through at least one main segment 11. In addition, the flow of heat transfer fluid circulating in the main segment 11 is distributed to the various secondary segments 12a, 12b, 12c, 12d. In other words, the main segment 11 allows the secondary segments 12a, 12b, 12c, 12d to be supplied with heat transfer fluid in parallel.

[0033] For example, according to the embodiment shown in [Fig. 1], the entire flow of the heat transfer fluid circulating in the main segment 11 is distributed, at a first junction 103, into a first fraction circulating through the secondary segment 12a and an initial intermediate fraction circulating in an intermediate segment 110a in order to be distributed in the secondary segments 12b, 12c and 12d. The initial intermediate fraction of the heat transfer fluid flow is then distributed, at a second junction 104, between a second fraction circulating in the secondary segment 12b and a secondary intermediate fraction circulating in an intermediate segment 110b. Finally, the secondary intermediate fraction of the heat transfer fluid flow is distributed, at a third junction 105, between a third fraction circulating in the secondary segment 12c and a fourth fraction circulating in the secondary segment 12d.The said first, second, third and fourth fractions of the heat transfer fluid flow join, at the outlet of the secondary segments 12a, 12b, 12c, 12d, at a junction 106 for the fourth and third fractions, themselves joining, via an intermediate segment 110c, the second fraction at a junction 107, and joining in turn, via an intermediate segment 110d, the first fraction at a junction 108. .

[0034] According to an alternative embodiment (not shown), the entire flow of the heat transfer fluid circulating in the main segment 11 is distributed at a single inlet junction between a first fraction circulating in a first secondary segment, a second fraction circulating in a second secondary segment, a third fraction circulating in a third secondary segment, and a fourth fraction circulating in a fourth secondary segment. At the outlet of the secondary segments, these heat transfer fluid flow fractions can also rejoin in the main pipe 11 at a single outlet junction.

[0035] The cooling circuit 100 is intended to cool functional elements EF of the aircraft 1. To this end, each secondary segment 12a, 12b, 12c, 12d is arranged to cool at least one functional element EF of the aircraft 1. Cooling can be achieved by thermal conduction, through the wall of the pipe of the secondary segment 12a, 12b, 12c, 12d, between the heat transfer fluid and the functional element EF. Alternatively, the secondary segment (for example 12a) includes a heat exchanger 13a enabling heat exchange between the heat transfer fluid and the functional element EF. According to another alternative, the secondary segment 12d includes a heat exchanger 13d allowing heat exchange between the heat transfer fluid and another fluid circulating in a pipe 14d. The other fluid can thus be itself cooled (for example, oil used in an engine) and transported to cool a functional element EF of the aircraft 1.

[0036] Each secondary segment 12a, 12b, 12c, 12d further comprises a shut-off valve 15a, 15b, 15c, 15d located at the inlet of the secondary segment 12a, 12b, 12c, 12d relative to the predefined flow direction 101, in other words between the inlet of said secondary segment 12a, 12b, 12c, 12d and at least one functional element EF or the heat exchanger 13a, 13d located on said secondary segment.

[0037] The inlet of the secondary segment is located at the junction between the main segment 11 and said secondary segment 12a, 12b, 12c, 12d, on the side of the inlet of the heat transfer fluid into the secondary segment with respect to the predefined flow direction 101. Alternatively, when the heat transfer fluid flows through an intermediate segment 110a, 110b before entering the secondary segment 12a, 12b, 12c, 12d, the inlet of the secondary segment in question is located at the junction between the last intermediate segment 110a 110b through which the heat transfer fluid flows before entering the secondary segment 12a, 12b 12c, 12d and said secondary segment 12a, 12b, 12c, 12d. For example, the inlet of secondary segment 12a is located at junction 103, the inlet of secondary segment 12b is located at junction 104, the inlets of secondary segments 12c and 12d are located at junction 105.

[0038] In other words, the inlet of the secondary segment 12a, 12b, 12c, 12d is located, on the side of the inlet of the heat transfer fluid in the secondary segment with respect to the predefined flow direction 101, at the junction between said secondary segment and an earlier segment of the cooling circuit closest to said secondary segment and through which passes a fraction of the heat transfer fluid flow greater than the fraction of heat transfer fluid circulating in said secondary segment and comprising said fraction of heat transfer fluid circulating in said secondary segment, said earlier segment of the cooling circuit being the main segment 11 or an intermediate segment 110a, 110b.

[0039] Each shut-off valve 15a, 15b, 15c, 15d thus allows the circulation of the heat transfer fluid through the secondary segment in question 12a, 12b, 12c, 12d to be stopped when said shut-off valve 15a, 15b, 15c, 15d is triggered, while maintaining the circulation of the heat transfer fluid in the other secondary segments 12a, 12b, 12c, 12d. When the shut-off valve 15a, 15b, 15c, 15d is not triggered, in other words when the shut-off valve is in an inactive state, the heat transfer fluid circulates normally badly through said stop valve 15a, 15b, 15c, 15d and therefore through the respective secondary segment 12a, 12b, 12c, 12d.

[0040] Each secondary segment 12a, 12b, 12c, 12d further comprises a non-return valve 16a, 16b, 16c, 16d. Each non-return valve 16a, 16b, 16c, 16d is intended to prevent a reflux of the heat transfer fluid through the secondary segment in question 12a, 12b, 12c, 12d, in other words intended to prevent the circulation of the heat transfer fluid in a direction opposite to the predefined flow direction 101 in said secondary segment 12a, 12b, 12c, 12d.

[0041] Each check valve 16a, 16b, 16c, 16d is located at the outlet of said secondary segment 12a, 12b, 12c, 12d, relative to the predefined flow direction 101. In other words, each check valve 16a, 16b, 16c, 16d is located between the functional element EF or the heat exchanger 13a, 13d located on the secondary segment and the outlet of said secondary segment 12a, 12b, 12c, 12d.

[0042] The outlet of the secondary segment is located at the junction between the main segment 11 and said secondary segment 12a, 12b, 12c, 12d, on the side of the heat transfer fluid outlet of the secondary segment with respect to the predefined flow direction 101. Alternatively, when the heat transfer fluid flows, exiting the secondary segment 12a, 12b, 12c, 12d, in an intermediate segment before joining the main segment 11 between the secondary segment 12a, 12b, 12c, 12d, the outlet of the secondary segment in question is located at the junction between said secondary segment 12a, 12b, 12c, 12d and the first intermediate segment through which the heat transfer fluid flows before joining the main segment 11.For example, the output of secondary segment 12a is located at junction 108, the output of secondary segment 12b is located at junction 107, the outputs of secondary segments 12c and 12d are located at junction 106.

[0043] In other words, the outlet of the secondary segment 12a, 12b, 12c, 12d is located, on the side of the outlet of the heat transfer fluid of the secondary segment with respect to the predefined flow direction 101, at the junction between said secondary segment and a posterior segment of the cooling circuit closest to said secondary segment and through which passes a fraction of the heat transfer fluid flow greater than the fraction of heat transfer fluid circulating in said secondary segment and including said fraction of heat transfer fluid circulating in said secondary segment, said posterior segment of the cooling circuit being the main segment 11 or an intermediate segment.

[0044] Thus, when the shut-off valve of a secondary segment (for example 12b) is triggered, the pressure of the heat transfer fluid in the other secondary segments (12a, 12c, 12d) places the corresponding check valve (16b) in the closed position, and thus prevents a backflow of the heat transfer fluid into the secondary segment in question (12b) in the opposite direction to the predefined flow direction 101.

[0045] Each secondary segment 12a, 12b, 12c, 12d further comprises a leak detector 17a, 17b, 17c, 17d enabling the detection of whether a leak is present on said secondary segment 12a, 12b, 12c, 12d, in other words whether part of the heat transfer fluid flow is flowing out of the pipe forming the secondary segment 12a, 12b, 12c, 12d, in an area located between the shut-off valve 15a, 15b, 15c, 15d and the non-return valve 16a, 16b, 16c, 16d. The leak detector 17a, 17b, 17c, 17d is arranged to detect a potential leak of the heat transfer fluid between the shut-off valve 15a, 15b, 15c, 15d and the check valve 16a, 16b, 16c, 16d in the corresponding secondary segment 12a, 12b, 12c, 12d. The leak detector 17a, 17b, 17c, 17d is, for example, an acoustic sensor, such as a Bragg grating in an optical fiber, enabling the detection of acoustic signatures of liquid leaks in a pipeline.An electronic circuit, associated with the acoustic sensor, contains a copy of said acoustic leakage signatures and also includes means for comparing a signal captured by the acoustic sensor with acoustic leakage signatures stored in memory. This electronic circuit, associated with the acoustic sensor, thus makes it possible to determine whether a signal captured by the acoustic sensor is representative of a leak. Alternatively, the electronic circuit implements a signal processing algorithm to detect, through mathematical analysis of a signal captured by the acoustic sensor, the presence of a signature representative of a leak.

[0046] According to another example, the leak detector 17a, 17b, 17c, 17d is a humidity sensor placed in a drainage pipe dedicated to leak detection and associated with the secondary segment 12a, 12b, 12c, 12d in question. The drainage pipe is, for example, installed around the pipe of the secondary segment 12a, 12b, 12c, 12d so that in the event of a leak of the heat transfer fluid from the pipe of the secondary segment 12a, 12b, 12c, 12d, some of the heat transfer fluid ends up in the drainage pipe. The humidity sensor then detects the presence of heat transfer fluid in the drainage pipe and transmits information indicating a leak in the secondary segment 12a, 12b, 12c, 12d in question. The humidity sensor can, for example, be a fiber optic sensor, a float valve, or a reflection sensor.

[0047] The cooling circuit further comprises a control unit 400 (not shown in [Fig. 1]), or alternatively a set of control units 400, capable of receiving information from each leak detector 17a, 17b, 17c, 17d indicating the presence of a leak on the respective secondary segments 12a, 12b, 12c, 12d. The control unit 400, or alternatively the set of control units 400, is further capable of transmitting instructions to each shut-off valve 15a, 15b, 15c, 15d in order to trigger said shut-off valve 15a, 15b, 15c, 15d. when information representative of the presence of a leak is detected on the secondary segment 12a, 12b, 12c, 12d on which is located said shut-off valve 15a, 15b, 15c, 15d.

[0048] Thus, when a heat transfer fluid leak is detected in a secondary segment 12a, 12b, 12c, 12d, the circulation of the heat transfer fluid through the secondary segment 12a, 12b, 12c, 12d is stopped by the triggering of the associated shut-off valve 15a, 15b, 15c, 15d.

[0049] The cooling circuit 100 further includes a second-type heat exchanger 111 designed to enable a second-type heat exchange between the heat transfer fluid and another fluid, referred to as the cooling fluid, circulating in a pipe 112. This second-type heat exchange results in a transfer of heat from the heat transfer fluid to the cooling fluid, thereby cooling the heat transfer fluid that has been heated by the various first-type heat exchanges. In a particular embodiment, the second-type heat exchanger 111 is a ram air exchanger, the cooling fluid then being ram air.The quantity of dynamic air sent into the second type heat exchanger 111 can be controlled in order to allow control of the temperature of the heat transfer fluid at the outlet of the heat exchanger 111 and thus control of the temperature of the functional elements EF of the aircraft 1.

[0050] The functional elements EF of the aircraft 1 cooled by the cooling circuit 100 can be fuel cells or on-board systems including: DC-DC type current converters, dihydrogen recirculation pumps, electrical power distribution boxes, a turbine engine air compressor, a propulsion engine control unit or a heat transfer fluid pump motor control unit.

[0051] According to a particular embodiment, the cooling circuit 100 is intended to cool at least two fuel cells 21a, 21b, 21c. Each fuel cell 21a, 21b, 21c is located on a separate secondary segment 12a, 12b, 12c.

[0052] For example, as illustrated in [Fig. 2], the secondary segment 12a is arranged to cool a first fuel cell 21a. According to one embodiment, the fuel cell 21a has integrated cooling channels through which the heat transfer fluid circulating in the secondary segment 12a flows. The cooling channels act as a heat exchanger, thus transferring heat from the fuel cell to the heat transfer fluid and thereby cooling the fuel cell 21a.

[0053] In parallel with the secondary segment 12a, the secondary segment 12b is arranged to cool a second fuel cell 21b.

[0054] In parallel with the secondary segments 12a and 12b, the secondary segment 12c is arranged to cool a third fuel cell 21c.

[0055] The secondary segment 12d can be used to cool another functional element EF of the aircraft 1 such as those mentioned in [Fig.1].

[0056] In other words, each of the separate secondary segments, respectively 12a, 12b and 12c, is intended to cool a separate fuel cell, respectively 21a, 21b and 21c.

[0057] When a leak occurs in one of the secondary segments 12a, 12b, or 12c, for example, in secondary segment 12a, the leak detection by the leak detector 17a triggers the shut-off valve 15a, thus stopping the circulation of the heat transfer fluid in said secondary segment 12a. The fuel cell 21a can therefore no longer be cooled, resulting in a decrease in efficiency and potentially requiring the shutdown of fuel cell 21a, but the other fuel cells 21b and 21c can continue to operate without loss of power. Therefore, it is possible to maintain a minimum thrust output of aircraft 1 even in the event of a heat transfer fluid leak in the cooling circuit 100. Furthermore, the operation of any other functional element EF of aircraft 1 cooled by secondary segment 12d is maintained.Furthermore, the preservation of minimum thrust power and the maintenance of the functionalities ensured by the on-board systems are achieved without significantly increasing the mass of the cooling circuit, which makes it possible to maintain the performance of aircraft 1 and limits the increase in the drag of aircraft 1.

[0058] Figure 3 schematically illustrates aircraft 1 comprising the cooling circuit 100. Aircraft 1 comprises electric motors 30 which are powered by hydrogen fuel cells 21a, 21b, 21c. According to a particular embodiment, aircraft 1 comprises self-contained propeller propulsion systems 31 ('pod'), each of said self-contained propeller propulsion systems 31 comprising at least two fuel cells 21a, 21b, 21c and comprising a motor 30 electrically connected to the fuel cells 21a, 21b, 21c.

[0059] Fig. 4 schematically illustrates an example of the hardware architecture of the control unit 400 of the cooling circuit 100. The control unit 400 then comprises, connected by a communication bus 410: a processor or CPU (Central Processing Unit) 401; a RAM (Random Access Memory) 402; a ROM (Read Only Memory) 403; a storage unit or a storage media reader, such as a HDD (Hard Disk Drive) 404; and an interface 405 allowing communication with the leak detectors 17a, 17b, 17c, 17d and with the shut-off valves 15a, 15b, 15c, 15d.

[0060] The processor 401 is capable of executing instructions loaded into RAM 402 from ROM 403, external memory (not shown), a storage medium, or a communication network. When the control unit 400 is powered on, the processor 401 is capable of reading instructions from RAM 402 and executing them. These instructions form a computer program causing the processor 401 to implement all or part of the algorithms and steps described below in relation to the control unit 400.

[0061] Thus, all or part of the algorithms and steps described below in relation to the control unit 400 can be implemented in software form by executing a set of instructions by a programmable machine, such as a DSP (Digital Signal Processor) or a microcontroller, or in hardware form by a dedicated machine or component, such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit).

[0062] Fig. 5 schematically illustrates steps of a method for protecting the cooling circuit 100 of the aircraft 1. These steps form an algorithm implemented by the control unit 400 of the cooling circuit 100, and independently for each secondary segment 12a, 12b, 12c, 12d.

[0063] In a first step 501, the control unit 400 determines whether a leak is detected by the leak detector 17a, 17b, 17c, 17d of the secondary segment 12a, 12b, 12c, 12d in question. If so, a step 502 is carried out. Otherwise, the control unit 400 returns to step 501.

[0064] In step 502, the control unit 400 triggers the shut-off valve 15a, 15b, 15c, 15d of the secondary segment 12a, 12b, 12c, 12d on which the leak was detected in the previous step 501.

[0065] In a subsequent step 503, the control unit 400 detects whether a maintenance operation has been performed and whether the leak has been repaired. For example, a maintenance operator can, after performing a maintenance operation, send information to the control unit 400 indicating that the leak has been repaired by pressing a dedicated button. If the leak has been repaired, a step 504 is performed. Otherwise, the control unit 400 repeats step 503.

[0066] In step 504, the shut-off valve 15a, 15b, 15c, 15d, which was triggered in step 502, is opened, so as to allow the heat transfer fluid to flow again into the secondary segment 12a, 12b, 12c, 12d in question. Alternatively, the control unit 400 is reset or reconfigured, so as to deactivate the shut-off valve 15a, 15b, 15c, 15d and to wait for leak detection on the secondary segment 12a, 12b, 12c, 12d in question.

[0067] The control unit 400 then returns to the initial step 501.

[0068] Figure 6 schematically illustrates the cooling circuit 100 according to a third particular embodiment.

[0069] The cooling circuit 100 then comprises, connected together in a closed circuit, a main circuit 600 and a secondary circuit 601. The main circuit 600 comprises several portions of main segment 611a, 611b, 611c, three secondary segments 612a, 612b, 612c, and two tertiary segments 612e and 612f. Upon entering the main circuit 600, according to the predefined flow direction 101, the heat transfer fluid passes through a first portion of main segment 611a, is distributed in parallel into the secondary segments 612a, 612b and 612c, passes through a second portion of secondary segment 611b, is distributed in parallel into the tertiary segments 612e and 612f and returns to a third portion of main segment 611e. At the exit of the third portion of the main segment 611c, the heat transfer fluid is returned to the first portion of the main segment 611a and / or sent to the secondary circuit 601.

[0070] Each secondary segment 612a, 612b, 612c and tertiary segment 612e, 612f of the main circuit 600 comprises a shut-off valve 15, located at the inlet of said secondary segment 612a, 612b, 612c or tertiary segment 612e, 612f relative to the predefined flow direction 101, comprises a non-return valve 16, located at the outlet of said secondary segment 612a, 612b, 612c or tertiary segment 612e, 612f relative to the predefined flow direction 101 and further comprises a leak detection device 17, located between the shut-off valve 15 and the non-return valve 16 of said secondary segment 612a, 612b, 612c or tertiary segment 612e, 612f.

[0071] Each of the secondary segments 612a, 612b, 612c is arranged to cool a separate fuel cell 21 located on the aforementioned secondary segment 12a, 12b, 12c. Each of the tertiary segments 612e, 612f is arranged to allow heating of the heat transfer fluid. Thus, the tertiary segments 612e, 612f each include a heat exchanger 13 performing a second-type heat exchange with dynamic air (DA) from the aircraft 1 and thereby transferring heat from the dynamic air (DA) to the heat transfer fluid.

[0072] The cooling circuit 100 further comprises a control unit 400 (not shown in [Fig.6]), or alternatively a set of control units 400, in the form of electronic circuitry, capable, for each secondary segment 612a, 612b, 612c or tertiary segment 612e, 612f, of receiving from the leak detector 17 of said secondary segment 612a, 612b, 612c or tertiary segment 612e, 612f, information representative of the presence of a leak on said secondary segment 612a, 612b, 612c or tertiary segment 612e, 612f. The control unit 400, or alternatively the set of control units 400, is capable, for a said secondary segment 612a, 612b, 612c or tertiary segment 612e, 612f, of transmitting instructions to the shut-off valve 15 of said secondary segment 612a, 612b, 612c or tertiary segment 612e, 612f in order to trigger said valve stop 15 when information representative of the presence of a leak is detected on said secondary segment 612a, 612b, 612c or tertiary 612e, 612f.

[0073] The secondary circuit 601 includes a main segment 61 on which are located a pump 102 driving the circulation of the heat transfer fluid in the predefined flow direction 101 and a heat transfer fluid reservoir R. The secondary circuit 601 further includes at least two secondary segments 62 in which the heat transfer fluid is distributed in parallel. Each of said secondary segments 62 is arranged to cool a functional element of the aircraft 1. For example, the first two secondary segments 62 are arranged to each cool a propulsion assembly EP comprising at least one engine control unit and an electric motor. The second two secondary segments 62 are arranged to each cool a DC-DC converter C. A third secondary segment 62 is arranged to cool an electrical power distribution box EPD.

[0074] The secondary circuit 601 includes, on the main segment 61, a heat exchanger 613 which performs a heat exchange between the heat transfer fluid and oil circulating in a pipe 64 so as to cool the oil. The oil is, for example, used as a lubricant in a gearbox B.

[0075] Figure 7 schematically illustrates the cooling circuit 100 according to a fourth specific embodiment. The cooling circuit 100 according to the fourth specific embodiment comprises the elements of the cooling circuit 100 according to the third specific embodiment and further comprises, on each secondary segment 62 of the secondary circuit 601, a shut-off valve 715, a check valve 716, and a leak detection device 717. For each secondary segment 62, the shut-off valve 715 is located at the inlet of the secondary segment 62, relative to the predefined flow direction 101, the check valve 716 is located at the outlet of the secondary segment 62, relative to the predefined flow direction 101, and the leak detection device 717 is located, on the secondary segment 62, between the shut-off valve 715 and the check valve 716.

[0076] The cooling circuit 100 further comprises a control unit 400 (not shown in [Fig.7]), or alternatively a set of control units 400, in the form of electronic circuitry, capable, for each secondary segment 62, of receiving from the leak detector 717 of said secondary segment 62, information representative of the presence of a leak on said secondary segment 62, and of transmitting instructions to the shut-off valve 715 of said secondary segment 62 in order to trigger said shut-off valve 715 when information representative of the presence of a leak is detected on said secondary segment 62.

Claims

Demands

1. Propulsion system (31) for an aircraft (1), the cooling circuit (100) being intended to cool functional elements (FE) of the aircraft (1), comprising: - at least two fuel cells (21a, 21b, 21c), - an electric motor (30) electrically connected to the fuel cells (21a, 21b, 21c), - functional elements (FE), - at least two heat exchangers (13) designed to perform heat exchange with dynamic air (RA), and - a cooling circuit (100) intended to cool the fuel cells and functional elements, such that in operation a heat transfer fluid circulates in the cooling circuit (100) in a predefined direction (101), the cooling circuit (100) being a closed circuit comprising at least one main segment (11), the flow of the heat transfer fluid circulating entirely in the at least one main segment (H), characterized in that the cooling circuit further comprises - at least one secondary segment (12a, 12b, 12c) corresponding to each fuel cell (21a, 21b, 21c), arranged to cool said fuel cell, - at least one secondary segment (12d) corresponding to the functional elements (EF), arranged to cool said functional elements, - at least one tertiary segment (612e, 612f) corresponding to each heat exchanger (13) with dynamic air (RA), and - a control unit in the form of electronic circuitry (400), in that each secondary segment and each tertiary segment comprises: - a leak detection device (17a, 17b, 17c, 17d), - a shut-off valve (15a, 15b, 15c, 15d), the shut-off valve being located at the inlet of the secondary or tertiary segment relative to the predefined flow direction (101), and - a non-return valve (16a, 16b, 16c, 16d) intended to prevent a reflux of the heat transfer fluid through the secondary (12a, 12b, 12c, 12d) or tertiary segment in a direction opposite to the predefined flow direction (101), the non-return valve being located at the outlet of the secondary or tertiary segment, relative to the predefined flow direction (101), and in that the control unit (400) is configured to trigger the closure of the shut-off valve (15a, 15b, 15c, 15d) of said secondary or tertiary segment when a leak is detected by the leak detection device (17a, 17b, 17c, 17d) of said secondary or tertiary segment, so as to stop the circulation of the heat transfer fluid through said secondary (12a, 12b, 12c, 12d) or tertiary segment in order to maintain the operation of the fuel cells or functional elements cooled by the cooling circuit and which are located on other segments of the cooling circuit than the secondary or tertiary segment on which the leak is detected.

2. Propulsion system according to claim 1, wherein the leak detection device (17a, 17b, 17c, 17d) is an acoustic sensor associated with electronic circuitry, said electronic circuitry comprising means for determining, by comparison of a signal captured by the acoustic sensor with stored acoustic leak signatures, whether said signal is representative of a leak.

3. Propulsion system according to any one of claims 1 and 2, wherein the leak detection device (17a, 17b, 17c, 17d) comprises a drain pipe arranged to recover at least a portion of the heat transfer fluid flowing out of the secondary segment (12a, 12b, 12c, 12d) in the event of a leak, and further comprises a moisture sensor located in the drain pipe.

4. Propulsion system according to any one of claims 1 to 3, wherein at least one secondary segment (12a, 12b, 12c, 12d) further comprises at least one heat exchanger (13a, 13d), said heat exchanger (13a, 13d) being intended to cool one of the functional elements (FE) or a fluid used by one of the functional elements (FE).

5. Aircraft comprising a propulsion system (31) according to any one of claims 1 to 4.

6. A method for protecting an aircraft (1) propulsion system (31), the propulsion system (31) comprising: - at least two fuel cells (21a, 21b, 21c), - an electric motor (30) electrically connected to the fuel cells (21a, 21b, 21c), - functional elements (FE), - at least two heat exchangers (13) designed to perform heat exchange with dynamic air (RA), and - a cooling circuit (100) intended to cool the fuel cells and functional elements, such that in operation, a heat transfer fluid circulates in the cooling circuit (100) in a predefined direction (101), the cooling circuit (100) being a closed circuit comprising at least one main segment (11), the flow of the heat transfer fluid circulating entirely in the at least one main segment (11), the process being characterized in that the cooling circuit (100) further comprises: - at least one secondary segment (12a, 12b, 12c) corresponding to each fuel cell (21a, 21b, 21c), arranged to cool said fuel cell, - at least one secondary segment (12d) corresponding to the functional elements (EF), arranged to cool said functional elements, and - at least one tertiary segment (612e, 612f) corresponding to each heat exchanger (13) with dynamic air (RA), and - a control unit in the form of electronic circuitry (400), and in that each secondary segment and each tertiary segment comprises: - a leak detection device (17a, 17b, 17c, 17d), - a shut-off valve (15a, 15b, 15c, 15d), the shut-off valve being located at the inlet of the secondary or tertiary segment relative to the predefined flow direction (101), and - a non-return valve (16a, 16b, 16c, 16d) intended to prevent backflow of the heat transfer fluid through the secondary or tertiary segment (12a, 12b, 12c, 12d) in the opposite direction to the predefined flow direction (101), the non-return valve being located at the outlet of the secondary or tertiary segment, relative to the predefined flow direction (101), the process comprises the following steps: - detect (501) for each secondary (12a, 12b, 12c, 12d) or tertiary segment if a heat transfer fluid leak is present, - stop (502) the circulation of the heat transfer fluid through said secondary (12a, 12b, 12c, 12d) or tertiary segment when a heat transfer fluid leak is detected in said secondary (12a, 12b, 12c, 12d) or tertiary segment, - prevent backflow of the heat transfer fluid through said secondary or tertiary segment (12a, 12b, 12c, 12d) into a reverse direction to the predefined flow direction (101) in order to maintain the operation of fuel cells or functional elements cooled by the cooling circuit and which are located on other segments of the cooling circuit than the secondary or tertiary segment on which the leak is detected.

7. A method according to claim 6, wherein the step of stopping the circulation of the heat transfer fluid through the secondary (12a, 12b, 12c, 12d) or tertiary segment comprises stopping the flow of the heat transfer fluid at a location at the inlet of the secondary (12a, 12b, 12c, 12d) or tertiary segment relative to the predefined flow direction (101)

8. A method according to any one of claims 6 and 7, wherein the step of preventing reflux of the heat transfer fluid through the secondary (12a, 12b, 12c, 12d) or tertiary segment comprises stopping the flow of the heat transfer fluid in a direction opposite to the predefined flow direction (101), at a location situated at the outlet of the secondary (12a, 12b, 12c, 12d) or tertiary segment relative to the predefined flow direction (101).

9. Product computer program that can be stored on a medium and / or downloaded from a communication network, in order to be read by a processor, and characterized in that it includes instructions to implement the method according to any one of claims 6 to 8, when said computer program is executed by the processor.

10. Information storage medium storing a computer program comprising instructions to implement the method according to any one of claims 7 to 8 when said computer program is read from said storage medium and executed by the processor.

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