Fuel conditioning system for supplying an aircraft propulsion system with fuel from a cryogenic tank, and associated method

Abstract

The invention relates to a fuel conditioning system (SC) configured to supply an aircraft propulsion system with fuel (Q) from a cryogenic tank (R), the conditioning system (SC) comprising a plurality of compression modules (2A-2C) configured to increase the temperature of the fuel (Q) in an elementary tank (3A-3C) in an isochoric manner, and a metering tank (5) having a fixed calibrated volume (VOLc); wherein each compression module (2A-2C) comprises an inlet valve (V1A-V1C) for supplying the elementary tank (3A-3C) with a volume of fuel (Q) corresponding to the calibrated volume (VOLc) of the metering tank (5), an outlet valve (V2A-V2C) and a degassing valve (V3A-V3C) connected to the elementary tank (3A-3C) and configured to circulate a gaseous fuel flow (G) through a return circuit (CR).

Description

Fuel conditioning system for supplying an aircraft propulsion system with fuel from a cryogenic tank and associated method

[0001] The present invention relates to the field of aircraft comprising propulsion systems powered by fuel stored in a cryogenic tank.

[0002] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various carbon emission restrictions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new aircraft types and those already in operation, requiring the implementation of technological solutions to ensure their compliance with current regulations. Civil aviation has been mobilizing for several years now to contribute to the fight against climate change.

[0003] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

[0004] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0005] This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, as an essential complement to technological progress, aeronautical biofuels.

[0006] To this end, the invention is the result of technological research aimed at significantly improving aircraft performance and, in this sense, contributes to reducing the environmental impact of aircraft. For this purpose, the invention relates to propulsion systems powered by fuel stored in a cryogenic tank.

[0007] It is known to store fuel, particularly hydrogen, in liquid form to limit the size and mass of aircraft tanks. For example, fuel is stored at a temperature of around -253 to -251°C (20 to 22 Kelvins) in a cryogenic tank on the aircraft.

[0008] In order to be injected into the combustion chamber of a turbomachine, for example, the fuel must be conditioned, i.e. pressurized and heated, to allow for optimal combustion. Conditioning is necessary, for example, to reduce the risk of icing / solidification of the water vapor contained in the air circulating in the turbomachine, in particular, at the fuel injectors.

[0009] With reference to the, there is shown an SCAA conditioning system according to the prior art comprising a fuel circuit 101 connected at the inlet to a cryogenic tank R and at the outlet to the combustion chamber CC of a turbine engine M. A fuel flow Q circulates from upstream to downstream in the fuel circuit 101 and successively passes through a mechanical pump 102 and a heating module 103. The mechanical pump 102 is configured to circulate the fuel flow Q in the fuel circuit 101. The heating module 103 is configured to provide calories to the fuel flow Q in order to heat it so that it can be injected into the turbine engine M.

[0010] In practice, to carry out the pumping, a mechanical pump 102 of the positive displacement or centrifugal type, also called a high pressure pump, is generally used. Such a mechanical pump 102 has many disadvantages in terms of sealing, lubrication and efficiency. A mechanical pump 102 requires in particular a significant amount of energy to be able to ensure compression. To date, mechanical pumps 102 that can be used with cryogenic tanks do not allow operation over a wide range of flow rate / pressure for high efficiency. Also, in practice, it is necessary to use a mechanical pump 102 whose operating point is not optimal and which requires moving away from the recommended operating range of said mechanical pump 102, which increases the stresses applied to the mechanical pump 102 and reduces its efficiency.Such a mechanical pump 102 cannot therefore adapt its flow rate optimally according to the needs of the turbine engine. In practice, each pump operates for a specific operating point and the conditions deteriorate as one moves away from it, which leads to a drop in efficiency.

[0011] To avoid the use of a mechanical pump, document WO2022263307 discloses a SCAA conditioning system, shown in the, which comprises a first tank R1 of cryogenic fuel Q and a second buffer tank R2 of fuel Q whose pressure and temperature are close to the injection conditions in the turbomachine M. The SCAA conditioning system also comprises a plurality of elementary tanks REA-RED, mounted between the cryogenic tank R1 and the buffer tank R2, in which the fuel Q is heated by means of different elementary heat sources, which are configured to increase the temperature of the fuel Q in the elementary tank REA-RED in an isochoric manner. Compression is thus carried out in an isochoric manner and not mechanically, which makes it possible to eliminate the drawbacks relating to a mechanical pump.

[0012] However, to achieve isochoric compression, it is necessary that the quantity of fuel injected into an elementary tank be precise to ensure that an expected pressure / temperature torque is achieved at the outlet of the elementary tank. Indeed, too small a volume of liquid fuel, i.e. an insufficient quantity of fuel injected, can lead, for a target temperature, to compression at a pressure lower than the expected pressure value. Similarly, too small a volume of liquid fuel can lead, for a target pressure, to compression at a temperature higher than the expected temperature value. Similarly, too large a volume of fuel can lead, for a target temperature, to compression at a pressure higher than the expected pressure value, or, for a target pressure, to compression at a temperature lower than the expected temperature value.This can present a significant disadvantage in an aircraft conditioning system where fuel pressure and temperature must be precisely calibrated to achieve expected power levels in the turbomachine to enable optimal operation.

[0013] Furthermore, in such a conditioning system, the injection of cold liquid hydrogen into a hot elementary tank can cause instantaneous vaporization of the fuel, which can lead to the formation of a vapor lock at the inlet of the tank. Such a phenomenon is known to those skilled in the art as “vapor lock.” The formation of a vapor lock blocks the flow of fuel in the fuel system, which can lead to a malfunction.

[0014] The invention thus aims to eliminate at least some of these drawbacks by proposing a new fuel conditioning system allowing compression and heating with better efficiency and greater reliability. PRESENTATION OF THE INVENTION

[0015] The invention relates to a fuel conditioning system configured to supply a propulsion system of an aircraft from fuel from a cryogenic tank, the conditioning system comprising a fuel circuit connected at the inlet to the cryogenic tank and at the outlet to the propulsion system, a fuel flow circulating from upstream to downstream in the fuel circuit, a plurality of compression modules, mounted on the fuel circuit, configured to supply the propulsion system, each compression module comprising an elementary tank having a fixed volume and an elementary heat source configured to increase the temperature of the fuel in the elementary tank in an isochoric manner, and a metering tank mounted on the fuel circuit between the cryogenic tank and the plurality of compression modules, the metering tank having a fixed calibrated volume,each compression module comprising:an inlet valve connecting the metering tank to the elementary tank, so as to supply the elementary tank with a volume of fuel corresponding to the fixed calibrated volume of the metering tank,an outlet valve connecting the elementary tank to the propulsion system to supply it, anda degassing valve connected to the elementary tank and configured to circulate a flow of gaseous fuel in a return circuit.,

[0016] According to one aspect, optionally, each degassing valve of each compression module respectively connects the elementary tank of said compression module to the metering tank via the return circuit, so as to increase the fuel pressure in the metering tank and thus supply the elementary tank with a fuel flow having an increased distribution pressure.

[0017] The invention relates to a fuel conditioning system configured to supply a propulsion system of an aircraft from fuel from a cryogenic tank, the conditioning system comprising: a fuel circuit connected at the inlet to the cryogenic tank and at the outlet to the propulsion system, a fuel flow circulating from upstream to downstream in the fuel circuit, a plurality of compression modules, mounted on the fuel circuit, configured to supply the propulsion system, each compression module comprising an elementary tank having a fixed volume and an elementary heat source configured to increase the temperature of the fuel in the elementary tank in an isochoric manner, and a metering tank mounted on the fuel circuit between the cryogenic tank and the plurality of compression modules, the metering tank having a fixed calibrated volume,each compression module comprising:an inlet valve connecting the metering tank to the elementary tank, so as to supply the elementary tank with a volume of fuel corresponding to the fixed calibrated volume of the metering tank,an outlet valve connecting the elementary tank to the propulsion system to supply it, anda degassing valve connecting the elementary tank to the metering tank by a return circuit in which a gas flow circulates, so as to increase the fuel pressure in the metering tank and thus supply the elementary tank with a fuel flow having an increased distribution pressure.,

[0018] The conditioning system according to the invention allows, thanks to the metering tank, to supply each elementary tank with a predetermined quantity of fuel, which makes it possible to ensure that the fuel reaches a predetermined and optimal pressure and temperature pair at the outlet of each compression module to allow its injection into the propulsion system.

[0019] The return circuit also allows the gas flow to be injected into the metering tank, the internal pressure of which is increased, which makes it possible to slightly raise the pressure of the fuel flow that will be introduced into each elementary tank. The liquid fuel flow is advantageously pushed by the gas flow, which eliminates the need for a mechanical pump to convey the fuel flow from the metering tank to the compression modules. Due to the increase in the pressure of the fuel flow, the flow rate in the fuel circuit is also increased, which prevents the risk of rapid vaporization forming a plug that could block the inlet of the elementary tank.

[0020] In addition, the injection of fuel into a first elementary tank is carried out using the residual pressure at the end of the cycle of a second elementary tank, which jointly makes it possible to raise the pressure in the metering tank and lower the pressure in the second metering tank, also making it possible to lower its temperature, with a view to a subsequent filling.

[0021] The return circuit coupled to the dosing tank makes it possible to increase the pressure of the fuel flow only in the dosing tank and not in the main cryogenic tank, which has larger dimensions, which is simpler and less restrictive.

[0022] The compression modules allow the fuel in each elementary tank to be heated isochorically, which allows the fuel pressure to be raised. The conditioning system is thus advantageously free of a high-pressure mechanical pump, unsuitable for the circulation of cryogenic fuel, to circulate the fuel flow in the fuel circuit.

[0023] Preferably, each elementary heat source provides calories from the turbine engine and / or the aircraft. Thus, the energy supplied comes from available heat sources and is not generated solely for isochoric compression, which improves the energy balance.

[0024] In a first embodiment, the propulsion system is an aircraft turbomachine.

[0025] In a second embodiment, the propulsion system is a fuel cell.

[0026] In a preferred embodiment, the conditioning system comprises at least a first heat exchanger configured to take calories from the gas flow circulating in the return circuit and transmit them to the fuel flow, so as to preheat it. The liquid fuel flow is thus advantageously heated before entering the elementary tank, which makes it possible to limit isochoric heating in the compression modules. The temperature of the gas flow is also advantageously lowered before being injected into the metering tank, in which the fuel is in the cryogenic state.

[0027] Preferably, the plurality of compression modules comprises at least three compression modules mounted in parallel and configured to operate out of phase. Each compression module can thus independently use various elementary heat sources. In addition, out-of-phase operation makes it possible to continuously supply the turbomachine with successive fuel flows from the different elementary tanks.

[0028] Preferably, all compression modules are identical, allowing identical compression and heating in each compression module. The fuel flow is thus in similar conditions at the outlet of each elementary tank.

[0029] In one embodiment, the conditioning system comprises a buffer tank mounted between the plurality of compression modules and the turbomachine, the buffer tank being configured to provide a homogeneous fuel flow to the turbomachine. The use of a buffer tank provides flexibility for the turbomachine, which constantly has fuel at a temperature and pressure close to the optimal injection conditions. The buffer tank also allows it to be filled gradually over time following isochoric compression.

[0030] In one embodiment, the conditioning system comprises a second heat exchanger mounted between the plurality of compression modules and the turbomachine, the second heat exchanger being configured to take calories from a heat source and transmit them to the fuel flow before powering the turbomachine. The second exchanger thus makes it possible to provide additional thermal energy which makes it possible to precisely adjust the temperature of the fuel flow before its injection into the turbomachine.

[0031] Preferably, the conditioning system comprises at least one mechanical booster pump mounted on the fuel circuit upstream of the metering tank. Such a pump makes it possible to adapt the thermodynamic state of the fuel flow at the inlet of the metering tank.

[0032] The invention also relates to an aircraft comprising a cryogenic tank, a turbomachine and a conditioning system as described previously, fluidically connecting the cryogenic tank and the turbomachine so as to supply it.

[0033] The invention finally relates to a method for conditioning a fuel configured to supply an aircraft turbomachine, the fuel coming from a cryogenic tank, the method being implemented by means of a conditioning system as described previously and comprising the steps of: filling the metering tank with a calibrated volume of fuel coming from the cryogenic tank, supplying one of the elementary tanks with the calibrated volume of fuel, and compressing the calibrated volume of fuel in the elementary tank in an isochoric manner, so as to reach a predetermined pressure.

[0034] Preferably, the conditioning method comprises a step of conveying a gas flow from one of the elementary tanks to the metering tank, so as to increase the pressure in the metering tank and to allow the supply of another elementary tank with a fuel flow having an increased distribution pressure. PRESENTATION OF FIGURES

[0035] The invention will be better understood upon reading the following description, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0036] This is a schematic representation of a first packaging system according to the prior art.

[0037] This is a schematic representation of a second packaging system according to the prior art.

[0038] This is a schematic representation of a packaging system according to a first embodiment of the invention.

[0039] This is a schematic representation of a packaging system according to a second embodiment of the invention.

[0040] This is a schematic representation of a first step of the packaging process according to an embodiment of the invention.

[0041] This is a schematic representation of a second step of the packaging method according to an embodiment of the invention.

[0042] This is a schematic representation of a third step of the packaging method according to an embodiment of the invention.

[0043] This is a schematic representation of a fourth step of the packaging method according to an embodiment of the invention.

[0044] This is a schematic representation of a fifth step of the packaging method according to an embodiment of the invention.

[0045] It should be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0046] With reference to the, there is shown a fuel conditioning system SC Q configured to supply an aircraft propulsion system with fuel Q from a cryogenic tank R. In this example, the propulsion system is an aircraft turbomachine M. The turbomachine M is configured to provide propulsion for the aircraft, in particular, by driving at least one propulsion member (not shown). It goes without saying that the invention also applies to other aircraft propulsion systems, for example a fuel cell. In this example, the fuel Q is liquid hydrogen but the invention applies to other types of fuel, for example, liquid methane or liquefied natural gas.

[0047] In this example, the fuel Q in the cryogenic tank R is stored at a temperature of the order of -253 to -251°C (20 to 22 Kelvins). At this temperature, the fuel Q is liquid. The fuel Q also has an initial pressure Pinit in the cryogenic tank R, preferably between 2.5 and 4 x 10 5 Pa.

[0048] The conditioning system SC according to the invention comprises a fuel circuit 1 (in solid lines in the figures) connected at the inlet to the cryogenic tank R and at the outlet to the propulsion system, in this example the turbomachine M. A fuel flow Q circulates from upstream to downstream in the fuel circuit 1 in order to increase in pressure and temperature so that it can be injected into the combustion chamber of the turbomachine M without the risk of icing the fuel injectors. Subsequently, the terms "upstream" and "downstream" are defined in relation to the direction of circulation of the fuel flow Q from upstream to downstream.

[0049] In order to allow the pressure and temperature to increase, the conditioning system SC according to the invention comprises a plurality of compression modules 2A-2C mounted on the fuel circuit 1 and configured to supply the turbomachine M with a compressed fuel flow Q.

[0050] In practice, the fuel flow Q is configured to be, at the outlet of the compression modules 2A-2C, at a pressure corresponding to a maximum compression pressure Pmax in the compression modules 2A-2C, the maximum pressure Pmax being greater than the initial pressure Pinit. The maximum pressure Pmax allows the turbomachine M to be supplied. More precisely, at the outlet of the compression modules 2A-2C, the pressure of the fuel flow Q is configured to be between an end-of-cycle pressure Pfc, defined according to the supply cycle of the turbomachine M from each compression module 2A-2C, as will be described in more detail later, and the maximum pressure Pmax. The end-of-cycle pressure Pfc thus corresponds to a supply limit of the turbomachine M. Such pressures correspond to limits set according to the needs of the turbomachine M and the aircraft.In this example, the maximum pressure Pmax is between 300 and 700 x 10. 5 Pa. Similarly, the end-of-cycle pressure Pfc is, in this example, between 20 and 100 x 10 5 Pa.

[0051] In this example, the different compression modules 2A-2C of the plurality of compression modules 2A-2C are mounted in parallel and are configured to each achieve an independent pressure increase. The different compression modules 2A-2C are configured to operate out of phase in order to ensure a continuous supply of the turbomachine M, as will be described in more detail later. In this example, the plurality of compression modules 2A-2C comprises three compression modules 2A-2C mounted in parallel. It goes without saying that the conditioning system SC could comprise a different number of compression modules 2A-2C, in particular to allow redundancy in the event of a breakdown for example or to improve the cycle of the conditioning system SC.

[0052] Still with reference to the, each compression module 2A-2C comprises an elementary tank 3A-3C having a fixed volume and an elementary heat source 4A-4C configured to increase the temperature of the fuel Q in the elementary tank 3A-3C in an isochoric manner.

[0053] To increase the temperature of the fuel Q in the elementary tank 3A-3C, the elementary heat sources 4A-4C come from the aircraft and / or the turbomachine M and can be of different natures. The calories can come for example from the lubricating oil, the turbine of the turbomachine M, the cabin air, the electrical and electronic systems and / or an independent heating system integrated into the aircraft. It goes without saying that the calories can come from a heat source other than the aircraft. Similarly, it goes without saying that the calories could also come from an intermediate heat transfer fluid which would circulate between a heat source and the elementary tank 3A-3C.

[0054] Each compression module 2A-2C advantageously makes it possible to increase the temperature of the fuel Q in an isochoric manner, thus making it possible to raise the pressure and temperature of the fuel flow Q, before supplying the turbomachine M. Thanks to the conditioning system SC according to the invention, it is not necessary to use a high-pressure mechanical pump, which is not very efficient in a cryogenic context.

[0055] Still with reference to the, each compression module 2A-2C comprises an inlet valve V1A-V1C mounted on the fuel circuit 1 upstream of the elementary tank 3A-3C to supply it with fuel Q, an outlet valve V2A-V2C mounted on the fuel circuit 1 downstream of the elementary tank 3A-3C to supply the turbomachine M, and a degassing valve V3A-V3C mounted on a return circuit CR (in dotted lines in the figures) and configured to circulate a gaseous fuel flow G in the return circuit CR. For the sake of brevity, the gaseous fuel flow G will hereinafter be referred to as gaseous flow G.

[0056] In order to increase the pressure of the fuel flow Q in each elementary tank 3A-3C, in an isochoric manner, up to the maximum pressure Pmax, it is necessary to supply each elementary tank 3A-3C with a predetermined quantity of fuel Q.

[0057] In this respect, the conditioning system SC according to the invention comprises a metering tank 5 mounted on the fuel circuit 1 between the cryogenic tank R and the plurality of compression modules 2A-2C. The metering tank 5 is configured to initially have a tank pressure Pmin, preferably between 0.5 and 2 x 10 5 Pa. In practice, the metering tank 5 is configured to receive a flow of liquid fuel Q from the cryogenic tank R, i.e. at the initial pressure Pinit, and to supply each compression module 2A-2C with a flow of fuel Q having a distribution pressure Pdist.

[0058] According to one aspect of the invention, the dosing reservoir 5 has a fixed calibrated volume VOLc. The calibrated volume VOLc is predetermined so as to allow compression in each elementary reservoir 3A-3C from the distribution pressure Pdist to the maximum pressure Pmax for a given target temperature.

[0059] In practice, the inlet valve V1A-V1C of each compression module 2A-2C connects the metering tank 5 to the elementary tank 3A-3C, so as to supply the latter with a volume of fuel Q corresponding to the calibrated volume VOLc of the metering tank 5. Each inlet valve V1A-V1C makes it possible to control the flow rate of the fuel flow Q entering the elementary tank 3A-3C to which it is connected.

[0060] According to a preferred aspect of the invention, the return circuit CR in which a gas flow G originating from the compression of the fuel flow Q in the elementary tank 3A-3C circulates, connects each elementary tank 3A-3C to the metering tank 5 so as to introduce the gas flow G therein. The gas flow G is configured to increase the pressure of the fuel Q in the metering tank 5 and thus supply the elementary tank 3A-3C with a fuel flow Q having an increased distribution pressure Pdist. In other words, each degassing valve V3A-V3C ensures the degassing of the elementary tank 3A-3C to the metering tank 5. Indeed, once the fuel flow Q has been heated and compressed isochorically, the elementary tank 3A-3C must be degassed to reduce its pressure so that it can be refilled.The return circuit CR thus makes it possible to both degas the elementary tank 3A-3C while increasing the fuel pressure Q in the metering tank 5, to allow the fuel flow Q to reach the increased distribution pressure Pdist at the outlet of the metering tank 5. The flow rate of the fuel flow Q in the fuel circuit 1 and therefore at the inlet of another elementary tank 3A-3C is thus increased and makes it possible to limit the risk of formation of an air bubble which could block the inlet of the elementary tank 3A-3C, as was the case in the prior art. Preferably, in order to control the degassing, the valves are controllable and connected to a control module (not shown) which makes it possible to control their degree of opening and their activation, in particular in a sequenced manner.

[0061] In this example, the conditioning system SC comprises a first valve V0 mounted on the fuel circuit 1 between the cryogenic tank R and the metering tank 5. The first valve V0 is configured to control the flow rate passage of fuel Q supplied to the metering tank 5.

[0062] According to a preferred aspect of the invention, the conditioning system SC comprises a second valve V4 mounted on the return circuit CR between the compression modules 2A-2C and the dosing tank 5. The second valve V4 is configured to control the passage of gas flow rate G injected into the dosing tank 5.

[0063] In this example, still with reference to the, the conditioning system SC also comprises a first discharge circuit CD1 mounted between the metering tank 5 and the exterior EXT of the conditioning system SC and configured to evacuate the gas flow G from the metering tank 5, when the elementary tank 3A-3C has been supplied, as will be described in more detail later. Preferably, the conditioning system SC comprises a third valve V5 mounted on the first discharge circuit CD1 and configured to control the evacuation of the gas flow G from the metering tank 5.

[0064] The conditioning system SC also comprises, in this example, a second discharge circuit CD2 mounted between the compression modules 2A-2C and the exterior EXT of the conditioning system SC and configured to evacuate a surplus of gas flow G from the elementary tanks 3A-3C when it is no longer necessary to supply the metering tank 5 with the gas flow G for example. Preferably, the conditioning system SC comprises a fourth valve V6 mounted on the second discharge circuit CD2 and configured to control the evacuation of the gas flow G from the conditioning system SC.

[0065] In this example, still with reference to the, the conditioning system SC further comprises a fifth valve V7 mounted on the fuel circuit 1 between the metering tank 5 and the plurality of compression modules 2A-2C. The fifth valve V7 is configured to control the supply of fuel Q to the elementary tanks 3A-3C.

[0066] With reference to the, the conditioning system SC comprises in this example a heat exchanger 6, mounted on the fuel circuit 1 between the metering tank 5 and the plurality of compression modules 2A-2C. The first exchanger 6 is configured to take calories from the gas flow G circulating in the return circuit CR and transmit them to the fuel flow Q at the outlet of the metering tank 5. The gas flow G is thus cooled before being injected into the metering tank 5 while the fuel flow Q is reheated before being injected into the elementary tanks 3A-3C, allowing it to be preheated before isochoric compression.

[0067] In this example, the conditioning system SC comprises a buffer tank 7 mounted downstream of the plurality of compression modules 2A-2C. The buffer tank 7 is configured to receive the fuel flows Q from each elementary tank 3A-3C and to provide the turbomachine M with a homogeneous fuel flow Q. Preferably, the conditioning system SC comprises a sixth valve V8 mounted on the fuel circuit 1 between the buffer tank 7 and the turbomachine M and configured to control the flow rate of the fuel flow Q injected into the turbomachine M.

[0068] In a preferred embodiment, the conditioning system SC comprises a second heat exchanger 8 mounted on the fuel circuit 1 between the plurality of compression modules 2A-2C and the turbomachine M. In particular, in this example, the second heat exchanger 8 is preferably mounted between the buffer tank 7 and the turbomachine M. The second heat exchanger 8 is configured to heat the fuel flow Q from a heat source CH before its injection into the combustion chamber of the turbomachine M. This additional thermal energy makes it possible to precisely adjust the temperature of the fuel flow Q, thus allowing it to be injected at an optimal temperature.

[0069] In this example, the conditioning system SC also comprises a mechanical booster pump 9 mounted on the fuel circuit 1 between the cryogenic tank R and the dosing tank 5. The mechanical booster pump 9 helps to fill the dosing tank 5 with the fuel flow Q from the cryogenic tank R.

[0070] A method for conditioning fuel Q using the conditioning system SC as previously described will now be described with reference to Figures 5 to 9. In this example, a valve in the open position is shown in white in the figures and a closed valve is shown in black. In this example, all the valves of the conditioning system SC are initially in the closed position. In this example, the metering tank 5 is initially at the minimum pressure Pmin of between 0.5 and 2 x10 5Pa. In this example again, the plurality of compression modules 2A-2C comprises three compression modules 2A, 2B, 2C.

[0071] In a first step E1 shown in the, the first valve V0 is opened so as to fill the metering tank 5 with a flow of liquid fuel Q from the cryogenic tank R. In this same step, fuel Q has previously been injected into the elementary tank 3A of a first compression module 2A, hereinafter first elementary tank 3A, and has already been heated isochorically. The fuel Q in the first elementary tank 3A is then at the maximum pressure Pmax, in this example between 300 and 700 x10 5Pa, and at a target temperature Tc, in this example between -73 and 127°C (200 and 400K). In parallel with the filling of the metering tank 5, the outlet valve V2A of the first compression module 2A is opened, so as to supply the turbomachine M with the pressurized and heated fuel flow Q. As the fuel Q is conveyed to the turbomachine M, the pressure in the first elementary tank 3A drops.

[0072] In this first step, the elementary tank 3B of the second compression module 2B, hereinafter second elementary tank 3B, has a pressure between the minimum pressure Pmin of the metering tank 5 and the end-of-cycle pressure Pfc of the compression modules 2A-2C. The elementary tank 3C of the third compression module 2C, hereinafter third elementary tank 3C, has a pressure substantially equal to the minimum pressure Pmin of the metering tank 5.

[0073] In a second step E2, shown in the, the metering tank 5 is filled with a calibrated volume VOLc of fuel Q and the first valve V0 is closed. The outlet valve V2A of the first compression module 2A is still open and the latter supplies the turbomachine M.

[0074] Still in this step E2, the degassing valve V3B of the second compression module 2B (whose pressure is always between the minimum pressure Pmin of the metering tank 5 and the end-of-cycle pressure Pfc) is opened so as to evacuate the remaining gas flow G from the third elementary tank 3C. The second valve V4 mounted on the return circuit CR between the compression modules 2A-2C and the metering tank 5 is also open. A gas flow G is then conveyed in the return circuit CR from the second elementary tank 3B to the metering tank 5, so as to increase the pressure of the liquid fuel Q in the metering tank 5 and to push it out of the metering tank 5. The second valve V4 authorizes the flow of gas flow G injected into the metering tank 5.The liquid fuel flow Q at the distribution pressure Pdist is routed to the third compression module 2C, whose elementary tank 3C is at the minimum pressure Pmin.

[0075] The inlet valve V1C of the third compression module 2C is then opened and the third elementary tank 3C is filled with fuel Q from the metering tank 5. Thanks to the calibrated volume VOLc of the metering tank 5, the third elementary tank 3C is filled with a precise quantity of fuel Q. The flow of fuel Q at the distribution pressure Pdist then has a sufficient flow rate to avoid the formation of a vapor lock at the inlet of the third elementary tank 3C.

[0076] In this example, the gas flow G passes, in this second step E2, through a first heat exchanger 6 in which it transfers calories to the fuel flow Q leaving the dosing tank 5 so as to preheat it.

[0077] With reference to the, in a third step E3, when the third elementary tank 3C is filled with the calibrated volume VOLc of fuel Q, the inlet valve V1C of the third compression module 2C is closed. An elementary heat source 4C heats the third elementary tank 3C and the temperature T of the fuel Q increases isochorically. Thus the pressure P of the fuel Q in the third elementary tank 3C also increases.

[0078] The second valve V4 is closed to stop the delivery of gas flow G to the dosing tank 5. The third valve V5 mounted on the first discharge circuit CD1 is opened and the gas flow G is discharged from the dosing tank 5 to the outside of the conditioning system SC. In other words, the dosing tank 5 is purged and the internal pressure drops to the minimum pressure Pmin.

[0079] Still in this third step E3, the fourth valve V6 mounted on the second discharge circuit CD2 is opened and the gas flow G remaining in the second elementary tank 3B is evacuated from the conditioning system SC. In other words, the second elementary tank 3B is emptied and the internal pressure P drops to the minimum pressure Pmin.

[0080] The outlet valve V2A of the first compression module 2A is still open. The pressure P in the first elementary tank 3A continues to drop while remaining higher than the end-of-cycle pressure Pfc and the latter still supplies the turbomachine M.

[0081] In a fourth step E4, with reference to the, when the dosing tank 5 has been emptied of the gas flow G, the third valve V5 mounted on the first discharge circuit CD1 is closed. The pressure in the dosing tank 5 has dropped back to the minimum pressure Pmin.

[0082] Similarly, in the second elementary tank 3B, the remaining gas flow G has been completely evacuated, the pressure has dropped back to the minimum pressure Pmin and the second degassing valve V3B is closed, as is the fourth valve V6. The second elementary tank 3B is ready for a new filling of fuel Q in liquid state.

[0083] In this fourth step E4, the elementary heat source 4C still transfers calories to the fuel Q in the third elementary tank 3C, its temperature T still increases isochorically. The pressure of the fuel Q in the third elementary tank 3C increases up to the maximum pressure Pmax.

[0084] Furthermore, the outlet valve V2A of the first compression module 2A is always open. The pressure in the first elementary tank 3A continues to decrease and the latter supplies the turbomachine M until the pressure reaches the end-of-cycle pressure Pfc. In this example, the outlet valve V2A of the first compression module 2A is open until the pressure in the first elementary tank 3A reaches a pressure between 20 and 100 x 10 5 Pa.

[0085] When the pressure in the first elementary tank 3A is substantially equal to the end-of-cycle pressure Pfc, the outlet valve V2A of the first compression module 2A is closed, in a fifth step E5, shown in the.

[0086] The pressure in the third elementary tank 3C has reached the maximum pressure Pmax and the heat input by the elementary heat source 4C is stopped. Thanks to the calibrated volume VOLc of fuel Q injected into the third elementary tank 3C, the pressure and temperature reached by the heat input are precise to allow the turbomachine M to be supplied under optimal conditions. The outlet valve V2C of the third compression module 2C is then opened and the latter supplies the turbomachine M with a gas flow G as soon as the supply by the first compression module 2A is stopped. The turbomachine M is advantageously supplied continuously.

[0087] In this fifth step E5, the dosing tank 5 at the minimum pressure Pmin is ready to be supplied with liquid fuel Q from the cryogenic tank R.

[0088] All the steps of the process are then repeated so as to inject a determined quantity of fuel Q successively into each of the three elementary tanks 3A-3C to heat it successively in each in an isochoric manner and thus ensure a continuous supply of the turbomachine M with a fuel flow Q in the gaseous state whose pressure and temperature are optimal to guarantee optimal performance of the turbomachine M.

Claims

Fuel conditioning system (SC) configured to supply a propulsion system of an aircraft from fuel (Q) from a cryogenic tank (R), the conditioning system (SC) comprising: a fuel circuit (1) connected at the inlet to the cryogenic tank (R) and at the outlet to the propulsion system, a flow of fuel (Q) circulating from upstream to downstream in the fuel circuit (1), a plurality of compression modules (2A-2C), mounted on the fuel circuit (1), configured to supply the propulsion system, each compression module (2A-2C) comprising an elementary tank (3A-3C) having a fixed volume and an elementary heat source (4A-4C) configured to increase the temperature of the fuel in the elementary tank (3A-3C) in an isochoric manner, and a metering tank (5) mounted on the fuel circuit (1) between the cryogenic tank (R) and the plurality of compression modules (2A-2C),the dosing tank (5) having a calibrated volume (VOL, C ) fixed, each compression module (2A-2C) comprising: an inlet valve (V1A-V1C) connecting the metering tank (5) to the elementary tank (3A-3C), so as to supply the elementary tank (3A-3C) with a volume of fuel (Q) corresponding to the calibrated volume (VOL C ) fixed to the dosing tank (5), an outlet valve (V2A-V2C) connecting the elementary tank (3A-3C) to the propulsion system to supply it, and a degassing valve (V3A-V3C) connected to the elementary tank (3A-3C) and configured to circulate a flow of gaseous fuel (G) in a return circuit (CR). Conditioning system (SC) according to claim 1, in which the propulsion system is an aircraft turbomachine (M). The conditioning system (SC) of claim 1, wherein the propulsion system is a fuel cell. Conditioning system (SC) according to one of claims 1 to 3, in which each degassing valve (V3A-V3C) of each compression module (2A-2C) respectively connects the elementary tank (3A-3C) of said compression module (2A-2C) to the metering tank (5) by the return circuit (CR), so as to increase the fuel pressure (Q) in the metering tank (5) and thus supply the elementary tank (3A-3C) with a flow of fuel (Q) having an increased distribution pressure (Pdist). Conditioning system (SC) according to one of claims 1 to 4, comprising at least one first heat exchanger (6) configured to take calories from the gas flow (G) circulating in the return circuit (CR) and transmit them to the fuel flow (Q), so as to preheat it. Conditioning system (SC) according to one of claims 1 to 5, wherein the plurality of compression modules (2A-2C) comprises at least three compression modules (2A-2C) mounted in parallel and configured to operate out of phase. Packaging system (SC) according to claim 6, wherein the three compression modules (2A-2C) are identical. Conditioning system (SC) according to one of claims 1 to 7, comprising a buffer tank (7) mounted between the plurality of compression modules (2A-2C) and the propulsion system, the buffer tank (7) being configured to provide a homogeneous fuel flow to the propulsion system. Conditioning system (SC) according to one of claims 1 to 8, comprising a second heat exchanger (8) mounted between the plurality of compression modules (2A-2C) and the propulsion system, the second heat exchanger (8) being configured to take calories from a heat source (CH) and transmit them to the fuel flow (Q) before supplying the propulsion system. Conditioning system (SC) according to one of claims 1 to 9, comprising at least one mechanical booster pump (9) mounted on the fuel circuit (1) upstream of the dosing tank (5). Aircraft comprising a cryogenic tank (R), a propulsion system and a conditioning system (SC) according to one of claims 1 to 10 fluidly connecting the cryogenic tank (R) and the propulsion system so as to supply it. Method for conditioning a fuel (Q) configured to supply an aircraft propulsion system, the fuel (Q) coming from a cryogenic tank (R), the method being implemented by means of a conditioning system (SC) according to one of claims 1 to 10 and comprising the steps of: filling the metering tank (5) with a calibrated volume (VOLc) of fuel (Q) coming from the cryogenic tank (R), supplying one of the elementary tanks (3A-3C) with the calibrated volume (VOLc) of fuel (Q), and compressing the calibrated volume (VOLc) of fuel (Q) in the elementary tank (3A-3C) in an isochoric manner, so as to reach a predetermined pressure. Conditioning method according to claim 12, comprising a step of conveying a gas flow (G) from one of the elementary tanks (3A-3C) to the metering tank (5), so as to increase the pressure in the metering tank (5) and to allow the supply of another elementary tank (3A-3C) with a fuel flow (Q) having an increased distribution pressure (Pdist).

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