Improved cryogenic fluid supply device for aeronautical turbojet engines

Abstract

Improved cryogenic fluid supply device for an aeronautical turbojet engine. Cryogenic fluid supply device (10) for an aeronautical turbojet engine (1), a tank (20) storing the fluid in liquid form, the device (10) comprising a first exchanger (30) providing initial heating of the fluid drawn via a sampling duct (11), a main duct (12) connected in a loop to the first exchanger (30), a bypass channel (14) comprising a first branch (141) branching from the main duct (12) at a bypass point (140), up to a phase separator (50), a second branch (142) connecting the liquid phase of the phase separator (50) to the sampling duct (11), and a third branch (143) connecting the gaseous phase of the phase separator (50) to the main duct (12) downstream of the bypass point (140), a bypass valve (60) disposed downstream of the bypass point. (140),and mobile between a first position diverting the fluid flow via the bypass channel (14), and a second position limiting this deviation. Fig. 3.

Description

Title of the invention: Improved cryogenic fluid supply device for aeronautical turbojet engines. Technical field

[0001] The present invention relates to the field of engines, particularly aircraft engines, powered by a cryogenic fluid such as hydrogen, and more particularly to a cryogenic fluid supply device for an aircraft turbojet engine, and a method of supplying cryogenic fluid using such a device. The present invention can notably be used for an aircraft turbojet engine. Previous technique

[0002] Some next-generation aircraft engines are powered by cryogenic fluid, in particular hydrogen, more precisely dihydrogen (H2). Dihydrogen can power fuel cells that generate electricity to power electric motors, or directly power the aircraft's engines. Such a hydrogen propulsion system is already known for turboprop-equipped aircraft or rockets, but is still little used in aircraft turbojets, such as turbofan engines.

[0003] Gaseous hydrogen (GH2) has the disadvantage of being difficult to store due to its large volume, as the available space in aircraft, particularly in their wings, is limited. Furthermore, it has a lower efficiency than a liquid during pressurization prior to injection. To overcome these drawbacks, it is planned that next-generation aircraft will store hydrogen in liquid form (LH2).

[0004] To achieve this, liquid hydrogen is stored in a pressurized tank. Before being injected into the aircraft's engines during start-up, the liquid hydrogen drawn from the tank is heated to vaporize and is then injected into the engines in gaseous form. A heat exchanger system enables this heating of the hydrogen. Typically, this system may include a two-phase heat exchanger (LH2 / GH2) comprising a cold line (or cold source) through which the hydrogen flows in its liquid state, and a hot line (or hot source) through which the same hydrogen flows in its gaseous state. This two-phase heat exchanger serves to preheat the hydrogen.

[0005] The system also includes a second heat exchanger downstream of the two-phase heat exchanger, serving as the main heat source to ensure the target temperature for injection into the engine. The heat source of this second heat exchanger is a heat transfer fluid, and can be for example nitrogen gas (GN2). The hydrogen heated by its passage through this second exchanger is then returned to the hot line of the two-phase exchanger, which further improves the heat transfers of the latter, and thus improves the vaporization of the liquid hydrogen flowing in the cold line.

[0006] However, during certain operating phases, particularly during reactor start-up or idle operation, the walls of the two-phase heat exchanger are not yet sufficiently hot to ensure complete vaporization of the hydrogen at the exchanger outlet. Conversely, the exchanger walls may be much too hot compared to the incoming liquid hydrogen, as the flow velocity in the tubes is insufficient to ensure complete hydrogen vaporization. Figure 1 schematically illustrates incomplete hydrogen vaporization.

[0007] In the event of partial vaporization, an outer gaseous layer G (shown in gray in [Fig. 1]) can form at the wall P of the hydrogen flow channel, where heat transfers take place (symbolized by arrows in [Fig. 1]). This outer gaseous layer G can envelop a liquid hydrogen core L, as illustrated in [Fig. 1], this liquid core being able to propagate over long distances. Indeed, the outer gaseous layer G forms a thermal insulator that separates the liquid core L from the wall P, thus delaying the vaporization of the liquid hydrogen.

[0008] However, unlike other applications such as rocket or turboprop engines, most of the equipment in aircraft turbojets is not designed for very low temperatures and two-phase flows. In particular, the second heat exchanger is a single-phase gaseous heat exchanger (GH2 / GN2). A temperature below 70 K (Kelvin) of the cold source could cause the nitrogen used in the hot source to solidify, which would degrade this equipment. The liquid hydrogen cores could also reach other equipment that is not designed for the low temperatures generated by liquid hydrogen.

[0009] There is therefore a real need for a hydrogen supply device for aeronautical turbojet engines, which is free, at least in part, from the disadvantages inherent in the aforementioned configuration. Description of the invention

[0010] The present description relates to a cryogenic fluid supply device for an aeronautical turbojet engine, the device being capable of drawing cryogenic fluid stored in a reservoir in liquid form, the device comprising a first heat exchanger capable of first heating the fluid drawn from the reservoir via a sampling conduit suitable for connecting the reservoir to the first exchanger, and a main conduit connected in a loop to the first exchanger, the device comprising: - a bypass channel comprising a first branch branching from the main conduit at a bypass point, up to a phase separator suitable for separating a liquid phase and a gaseous phase of the fluid, a second branch connecting the liquid phase from the phase separator to the sampling conduit, and a third branch connecting the gaseous phase from the phase separator to the main conduit downstream of the bypass point, - a bypass valve located downstream of the bypass point, and movable between a first position allowing a diversion of the fluid flow via the bypass channel, and a second position limiting this diversion.

[0011] In the present exposition, the terms "upstream" and "downstream" are defined with respect to the direction of flow of the fluid in the different channels of the device.

[0012] It is understood that the main conduit is connected at both ends to the first heat exchanger, thus forming a loop from the first heat exchanger back to it. The cryogenic fluid therefore flows first in the cold line (or cold source) of the first heat exchanger, then in the hot line (or hot source) of the first heat exchanger.

[0013] Since the temperature of the fluid flowing in the hot line is higher than that of the same fluid flowing in the cold line, the hot line therefore makes it possible to heat the fluid present in the cold line, and thus to vaporize the cryogenic fluid.

[0014] When the bypass valve is in its first position, allowing the fluid to be diverted via the bypass channel, the fluid from the first heat exchanger flowing in the main duct is then diverted via the bypass channel towards the phase separator. The gaseous phase of the fluid in the separator, which necessarily has a higher temperature than the liquid phase, can then be returned to the main duct downstream of the bypass point via the third branch, and flow downstream of the device without risk of damaging the equipment of the device or the turbojet engine, which are not designed for excessively large temperature differences.

[0015] Conversely, the liquid phase of the fluid in the separator, which has a lower temperature, can be returned, via the second branch, upstream of the first heat exchanger to flow back into it, thus benefiting from its heating again. This second pass further reduces the liquid content of the flow. This diversion can therefore be carried out until complete vaporization of the cryogenic fluid is achieved.

[0016] The device described herein thus makes it possible, particularly during engine start-up phases, to limit or even eliminate the risk of liquid cores being present in the flow of cryogenic fluid intended to be injected into the aircraft's engines. Consequently, the device described herein makes it possible to limit or even eliminate the risk of degradation of equipment not designed to withstand very low temperatures, thereby improving the lifespan of this equipment and the reliability of the fuel supply system.

[0017] In some embodiments, the first exchanger is a two-phase exchanger comprising a cold inlet suitable for connection to the tank via the sampling duct, a cold outlet connected to an upstream end of the main duct, a hot inlet connected to a downstream end of the main duct, and a hot outlet connected to an outlet duct suitable for bringing the fluid to the turbojet.

[0018] In certain embodiments, the phase separator is capable of receiving a two-phase mixture of the fluid via the first branch of the bypass channel, of storing the fluid in liquid form falling into a lower portion of the phase separator, and of accumulating the fluid in gaseous form in an upper portion of the phase separator, the second branch of the bypass channel being connected to the lower portion of the separator and comprising a single-phase outlet valve capable of allowing or preventing a flow of the fluid in liquid form from the phase separator to the sampling conduit.

[0019] In some embodiments, the single-phase outlet valve is a first single-phase outlet valve, the device comprising a second single-phase outlet valve disposed on the third branch of the bypass channel capable of permitting or preventing a flow of the fluid in gaseous form from the separator to the main conduit.

[0020] In some embodiments, the device includes a second exchanger disposed on the main conduit and capable of carrying out a second heating of the fluid, the point of derivation of the bypass channel and a junction between the third branch of the bypass channel and the main conduit being disposed upstream of the second exchanger.

[0021] In some embodiments, the device includes a phase meter capable of measuring a liquid content of the fluid flow, the phase meter being disposed on the main conduit, downstream of the first exchanger and upstream of the bypass point of the bypass channel.

[0022] In certain embodiments, the device is configured such that, when a liquid content of the fluid flow measured by the phase meter is greater than or equal to a predetermined value, the bypass valve is placed in its first position, and when the liquid content measured by the phase meter is less than the predetermined value, the bypass valve is placed in its second position.

[0023] In some embodiments, the bypass valve is arranged on the first branch of the bypass channel.

[0024] In some embodiments, the bypass valve is a first bypass valve, the device comprising a second bypass valve disposed on the main conduit downstream of the bypass point.

[0025] In some embodiments, the device includes a first check valve disposed on the second branch of the bypass channel, and a second check valve disposed on the third branch of the bypass channel.

[0026] In some embodiments, the cryogenic fluid is dihydrogen.

[0027] The present description also relates to an aeronautical turbojet engine comprising a cryogenic fluid supply device according to any one of the preceding embodiments. The aeronautical turbojet engine may be a turbofan engine.

[0028] The present exposition also relates to a method of supplying cryogenic fluid to an aeronautical turbojet using a device according to any of the preceding embodiments, the method comprising controlling the bypass valve, to switch it between its first position allowing the diversion of the fluid flow via the bypass channel, and its second position limiting this diversion.

[0029] In some embodiments, the process comprises: - the measurement of the liquid content of the fluid flow downstream of the first exchanger and upstream of the bypass channel's diversion point using a phase meter, - when the liquid content of the fluid flow is greater than or equal to a predetermined value, the bypass valve switches to its first position, and - when the liquid content measured by the phase meter is less than the predetermined value, the bypass valve switches to its second position.

[0030] In some embodiments, a single-phase outlet valve is disposed on the second branch of the bypass channel, the method comprising opening the single-phase outlet valve when a volume of two-phase mixture in the phase separator reaches a predetermined threshold value.

[0031] The aforementioned features and advantages, as well as others, will become apparent from the following detailed description, examples of embodiments of the device and the feeding method. This detailed description refers to the accompanying drawings. Brief description of the drawings

[0032] The accompanying drawings are schematic and are intended primarily to illustrate the principles of the exposition. On these drawings, from one figure to another, identical elements (or parts of elements) are identified by the same reference symbols.

[0033] [Fig-1] Fig. 1 schematically represents a cross-sectional view of a conduit in in which a layer of cryogenic fluid in gaseous form coats a liquid core of the fluid;

[0034] [Fig.2] Fig.2 represents an aircraft comprising a power supply system according to the invention;

[0035] [Fig.3] The [Fig.3] schematically represents a cryogenic fluid supply device for an aeronautical turbojet engine, according to an embodiment of the invention;

[0036] [Fig.4] The [Fig.4] schematically represents a phase separator of the power supply device of the [Fig.3];

[0037] [Fig.5] Fig.5 schematically represents the steps of a cryogenic fluid supply process for an aeronautical turbojet engine according to the invention. Description of the implementation methods

[0038] To make the explanation more concrete, an example of a cryogenic fluid supply device 10 and a cryogenic fluid supply method are described in detail below, with reference to the accompanying drawings. It should be noted that the invention is not limited to this example.

[0039] Fig. 2 represents an aircraft 100 comprising a first engine 1, in particular a turbofan engine, carried by a first wing 110, and a second engine 2 carried by a second wing 120. The rest of the description is based on the first engine 1, but the characteristics described also apply to the second engine 2.

[0040] The aircraft 100 is a cryogenic fluid-powered aircraft, in particular a hydrogen-powered aircraft, more precisely one operating on dihydrogen H2 (hereafter referred to simply as hydrogen). In this example, an internal enclosure in the first wing 110 includes at least one tank 20 storing hydrogen in liquid form. The engine 1 is supplied with hydrogen drawn from the main tank 20, via a cryogenic fluid supply system, comprising the cryogenic fluid supply device 10, represented by a simple dashed line interrupted on [Fig.2]. Although in the example illustrated on [Fig.2], the tank 20 is arranged in the first wing 110, the tank 20 could also be arranged in the fuselage of the aircraft 100, without going out of the scope of the invention.

[0041] The cryogenic fluid, in this case hydrogen, taken in liquid form from the tank 20, is then vaporized to be injected in gaseous form into the engine 1. It is then brought into contact with the oxygen of the air, which causes, through the input of heat, a chemical reaction producing the energy to operate the engine 1.

[0042] In order to ensure that most, if not all, of the hydrogen drawn from the tank 20 is vaporized so as not to damage the various equipment of the aircraft 100, the device 10 according to the invention is formed as follows. Figure 3 schematically represents the cryogenic fluid supply device 10, here hydrogen, according to the invention.

[0043] In the following description, the terms "upstream" and "downstream" are defined with respect to the direction of fluid flow in the various channels of the device, in particular in the sampling conduit 11, the main conduit 12, the outlet conduit 13, and the bypass conduit 14, described below. This direction of flow is symbolized by arrows in Figures 3 and 4.

[0044] The device 10 comprises, from upstream to downstream, a sampling conduit 11 suitable for sampling the fluid in the pressurized reservoir 20 storing hydrogen in liquid form, a first exchanger 30 connected to the reservoir 20 via the sampling conduit 11, a main conduit 12 making a loop from and to the first exchanger 30, and an outlet conduit 13 connecting the first exchanger 30 to the engine 1.

[0045] A shut-off valve 80 is located on the sampling line 11. When the tank 20 is pressurized during startup, opening the shut-off valve 80 sets the fluid in motion and thus starts the device 10. In particular, the hydrogen stored in the tank 20 is drawn off and conveyed to the first heat exchanger 30. It should be noted that, although not shown, a pump to ensure the necessary flow rate by means of a pressure increase can be located in a so-called cryogenic zone near the tank 20. In this respect, the shut-off valve 80 thus serves to precisely control the flow rate and is preferably located near the heat exchanger 30, in a so-called gaseous zone. It should therefore be understood that the figures are schematic, have an illustrative purpose, and do not necessarily reflect the actual arrangements and distances between the various components.

[0046] The first heat exchanger 30 is a two-phase LH2 / GH2 heat exchanger, in other words, with liquid hydrogen as the cold source and gaseous hydrogen as the hot source. More specifically, the first heat exchanger 30 comprises a cold line, or cold source 30a which is hydrogen in liquid form, and a hot line, or hot source 30b which is hydrogen in gaseous form.

[0047] To achieve this, the main conduit 12 is connected to the first heat exchanger 30 by forming a loop. More specifically, the main conduit 12 comprises an upstream end 12a connected to the cold line 30a of the first heat exchanger 30, and a downstream end 12b connected to the hot line 30b of the first heat exchanger 30.

[0048] The first exchanger 30 therefore has, on its cold line 30a, a cold inlet 31 connected to the sampling conduit 11 and a cold outlet 32 ​​connected to the upstream end 12a of the main conduit 12 and, on its hot line 30b, a hot inlet 33 connected to the downstream end 12b of the main conduit 12, and a hot outlet 34 connected to the outlet conduit 13.

[0049] The device 10 may further include a second heat exchanger 40, disposed on the main conduit 12 downstream of the first heat exchanger 30. The second heat exchanger 40 is a single-phase GH2 / GN2 heat exchanger, the cold source 40a being gaseous hydrogen from the cold line 30a of the first heat exchanger 30, having been vaporized, and the hot source 40b being a heat transfer fluid, here gaseous nitrogen (N2). Unlike air, the nitrogen-hydrogen mixture is not flammable in the event of accidental contact (for example, in the event of a fault in the second heat exchanger 40). It is therefore preferable to use such a heat transfer fluid instead of air to improve safety.

[0050] Thus, the first heat exchanger 30 performs an initial heating, or preheating, of the hydrogen, and the second heat exchanger 40 further increases the temperature of the hydrogen. This hot hydrogen then flows to the downstream end 12b of the main conduit 12 and then passes into the hot line 30b of the first two-phase heat exchanger 30 to heat its cold line 30a, and thus reach the target injection temperature to the engine 1 via the outlet conduit 13.

[0051] The preheating of the hydrogen carried out by the first exchanger 30 makes it possible to make the flow compatible with the heat transfer fluid of the second exchanger 40, namely dinitrogen N2, in particular to prevent the latter from solidifying.

[0052] However, as previously indicated with reference to [Fig.1], the temperature of the walls of the first heat exchanger 30 may not be sufficiently high in certain phases of operation, particularly at start-up, which leads to the formation of liquid cores (or plugs) L trapped in a gaseous layer G. Due to this incomplete vaporization, the liquid cores L thus isolated from the wall of the conduit by the gaseous phase G can propagate to the second heat exchanger 40, or even other equipment, resulting in the aforementioned disadvantages and degradations.

[0053] To overcome these drawbacks, the device 10 according to the invention also includes a bypass channel 14, branching off from the main conduit 12. More specifically, the channel branch 14 comprises a first branch 141, a second branch 142, and a third branch 143.

[0054] The first branch 141 derives from the main conduit 12 at a branch point 140, which is located between the first exchanger 30 and the second exchanger 40, i.e. downstream of the first exchanger 30 and upstream of the second exchanger 40. The device 10 further includes a phase separator 50. The first branch 141 connects the main conduit 12 to the phase separator 50.

[0055] The second branch 142 connects a lower portion 51 of the phase separator 50 to the sampling conduit 11, upstream of the cold inlet 31 of the first exchanger 30. The third branch 143 connects an upper portion 52 of the phase separator 50 to the main conduit 12, at a junction point 144 located downstream of the branch point 140, and upstream of the second exchanger 40.

[0056] The bypass channel 14 includes a bypass valve 60 disposed downstream of the bypass point 140. The bypass valve 60 is movable between a first position allowing a diversion of the fluid flow via the bypass channel 14, and a second position limiting this diversion.

[0057] By allowing "allowing a deviation of the fluid flow via the bypass channel 14", it is understood that the major part (for example 90% or more) of the hydrogen flow is diverted via the bypass channel 14. By "limiting this deviation", it is understood that a small proportion, for example less than 10%, or even 0%, of the flow is diverted to the bypass channel 14.

[0058] Preferably, the bypass valve 60 is arranged on the first branch 141 of the bypass channel 14. In this case, the first position is an open position of the valve 60, and the second position is a closed position of the valve 60.

[0059] It is thus understood that when the bypass valve 60 is in the open position, most of the flow can be diverted via the first branch 141 of the bypass channel 14. This diversion is made possible by the sizing of the equipment and conduits, and the pressure differences for example between the bypass point 140 and the phase separator 50.

[0060] Conversely, in its closed position, the bypass valve 60 prevents any flow via the first branch 141, all of this flow being therefore directed towards the second exchanger 40 via the main conduit 12.

[0061] The placement of the bypass valve 60 on the first branch 141 limits pressure losses when the bypass channel 14 is not active, and therefore prevents degradation of the system's performance during nominal operation. Indeed, according to an alternative configuration not shown, the bypass valve 60 can be placed downstream of the bypass point 140 on the main conduit 12.

[0062] In this case, the first position of the bypass valve 60 is a closed position, in which all of the hydrogen flow is diverted via the bypass channel 14, and the second position of the bypass valve 60 is an open position, in which most of the hydrogen flow continues its path to the second exchanger 40 via the main conduit 12, which limits the flow via the bypass channel 14. However, in this open position of the valve 60, the small proportion of the flow diverted in the first branch 141 nevertheless causes pressure losses on the main flow.

[0063] Thus, the arrangement of the bypass valve 60 on the first branch 141 as illustrated makes it possible to limit the pressure losses when the bypass channel 14 is inactive, the bypass valve 60 being closed and the entire flow being directed towards the second exchanger 40. The efficiency and performance of the device 10 are therefore improved.

[0064] It will be noted that in the open position of the bypass valve 60, although a small proportion of the flow may not be diverted and may continue its path in the main conduit 12 towards the second exchanger 40, these small quantities of fluid and therefore of liquid hydrogen, if any, will have little impact on the second exchanger 40 and on the other equipment.

[0065] However, in an alternative embodiment, the bypass valve 60 located on the first branch 141 downstream of the bypass point 140 may be a first bypass valve, the device 10 possibly comprising a second bypass valve (not shown), located downstream of the bypass point 140 on the main conduit 12. Thus, in the first position, the first bypass valve 60 is open, and the second bypass valve is closed. Conversely, in the second position, the first bypass valve 60 is closed, and the second control valve is open.

[0066] In a modified example, the bypass valve 60 can be a three-way valve, allowing selection of the opening or closing of either of the bypass conduit 14 and the main conduit 12. More specifically, in a first position, the three-way valve allows the diversion of the entire hydrogen flow, and in a second position, it prevents any diversion of the flow, the entire flow then being directed towards the second exchanger 40.

[0067] The bypass valve 60 can be controlled, for example by a calculation unit (not shown) which can be of the FADEC type (for "Full Authority Digital Engine Control" in English), so as to be switched between its first open position or its second closed position as required, in particular according to the liquid content of the hydrogen flow measured upstream of the bypass point 140, and at the outlet of the first exchanger 30.

[0068] To this end, the device 10 includes a phase meter 70, located between the first heat exchanger 30 and the bypass point 140, i.e., downstream of the cold outlet 32 ​​of the first heat exchanger 30 and upstream of the bypass point 140. The phase meter 70 can be, for example, an ultrasonic sensor, allowing the measurement of the liquid (and therefore gas) content of a two-phase flow, in this case, the hydrogen flow. Document FR 2 978 828 describes another example of a phase meter having a plurality of electrodes and which can be used in this example.

[0069] When hydrogen vaporization is incomplete at the outlet of the first heat exchanger 30, a two-phase flow is created downstream of it. This two-phase flow is represented by dashed lines in [Fig. 3]. It is therefore understood that a two-phase mixture flows in the portion of the main conduit 12 located between the cold outlet 32 ​​of the first heat exchanger 30 and the bypass point 140, and in the first branch 141 of the bypass conduit 14.

[0070] Thus, when the phase meter 70 detects the presence of liquid in the flow, the bypass valve 60 is placed in its first position, allowing the flow to be diverted via the first branch 141 of the bypass channel 14. The flow is then brought to the phase separator 50 via the first branch 141.

[0071] Figure 4 schematically represents a detailed view of the phase separator 50, explaining its operation. The phase separator 50 defines a volume, or capacity, within which the mixture can accumulate. The first branch 141 is connected to the upper portion 52 of the phase separator 50's capacity. A two-phase mixture of hydrogen in liquid L and gaseous G forms (symbolized by gray gas bubbles G in Figure 4) is therefore injected from the top of the capacity.

[0072] Due to the effects of gravity, the liquid phase L of the flow will then fall and accumulate in the lower portion 51 of the phase separator capacity 50, while the lighter gaseous phase G will accumulate in the upper portion 52.

[0073] The second branch 142 is intended to receive a single-phase flow of hydrogen in liquid form. For this purpose, the second branch 142 is connected to the lower portion 51 of the vessel, typically to the bottom of the phase separator vessel 50.

[0074] In an initial phase, before the engine is started, the liquid phase L stagnating in the lower portion 51 of the capacity cannot flow into the second branch 142. To do this, a single-phase outlet valve 53 is arranged on the second branch 142, at the outlet of the phase separator 50.

[0075] The third branch 143 is intended to receive a single-phase flow of hydrogen in gaseous form. For this purpose, the third branch 143 is connected to the upper portion 52 of the vessel, typically near or on the upper end of the phase separator 50. A single-phase outlet valve (not shown) may also be arranged on the third branch 143, at the outlet of the phase separator 50.

[0076] In order to control two-phase flow separation sequences, the phase separator 50 may also include sensors (not shown), allowing the volume and / or pressure of the mixture accumulated in the capacity of the phase separator 50 to be measured. These sensors, as well as the single-phase outlet valve 53, are preferably connected and controlled by the computing unit.

[0077] It should be noted that the device 10 may include a first check valve 15 disposed on the second branch 142 near the junction between the second branch 142 and the sampling conduit 11, and a second check valve 16 disposed on the third branch 143 near the junction point 144. These check valves 15, 16 limit the risk of backflow from the primary circuit, comprising the sampling conduit 11 and the main conduit 12, to the secondary circuit, i.e. to the bypass channel 14.

[0078] A method for supplying cryogenic fluid to the engine 1 using the device 10 will be described in the remainder of the description with reference to figures 3 to 5.

[0079] Initially, before starting the engine 1, the stop valve 80 and the single-phase outlet valve 53 are closed, and the exchangers 30, 40 and the phase separator 50 are filled with gaseous hydrogen, in order to be able to receive liquid hydrogen without mixing with air (step S0).

[0080] Moreover, this initial sweep of the entire device 10 with gaseous hydrogen allows the first exchanger 30 to be preheated, the hot line 30b of the latter not having yet been able to benefit from a reheating by a first passage of hydrogen in the second exchanger 40.

[0081] When the engine 1 is started, the shut-off valve 80 is opened, allowing the hydrogen to be circulated from the tank 20 to the first exchanger 30. The phase meter 70 then continuously measures the liquid content of the flow at the outlet of the first exchanger 30 (step SI).

[0082] A comparison between the value measured by the phase meter 70 and a predetermined threshold value strictly greater than zero is then performed by the calculation unit (step S2). When the liquid content is greater than or equal to the predetermined threshold value ("O" in step S2), the calculation unit controls the bypass valve 60 to switch it to its first position (step S3), allowing the diversion of the fluid flow via the bypass channel 14.

[0083] The phase separator 50, initially containing only hydrogen in gaseous form, is then filled, from its upper end, with the two-phase mixture. The volume of liquid L accumulating in the lower portion 51 of the phase separator 50 then pushes out the gaseous phase G present in the upper portion 52. Furthermore, the increase in temperature and pressure within the capacity causes the hydrogen bubbles G present in the liquid L to degas.

[0084] The gaseous phase G is then evacuated via the third branch 143 towards the main conduit 12 which it joins at the junction point 144. Only hydrogen in gaseous form can then flow via the main conduit 12 downstream, in particular towards the second exchanger 40.

[0085] A volume of the two-phase mixture, in particular of liquid hydrogen L present in the capacity of the phase separator 50, can be determined by the computing unit, via sensors present in the phase separator 50, and compared to a predetermined threshold value (step S4).

[0086] As long as the volume of liquid hydrogen L in the phase separator 50 remains below the predetermined threshold value (“N” in step S4), the single-phase outlet valve 53 remains closed while the bypass valve 60 remains open, and the capacity of the phase separator 50 therefore continues to fill (step S3).

[0087] Conversely, when this volume reaches the predetermined threshold value (“O” in step S4), the single-phase outlet valve 53 can then be opened, allowing the liquid hydrogen to be evacuated via the second branch 142 (step S5).

[0088] This liquid hydrogen is then conveyed to the sampling line 11, upstream of the first heat exchanger 30, and passes again through the cold line 30a of the first heat exchanger 30, allowing the hydrogen to be heated again. The liquid content of the two-phase hydrogen is then measured again by the phase meter 70 and compared to the threshold value predetermined by the calculation unit (step SI). This cycle is repeated until the liquid hydrogen is completely vaporized.

[0089] It is understood that, as this cycle repeats and the liquid hydrogen separated by the phase separator 50 passes back through the first exchanger 30, the concentration of liquid hydrogen in the flow decreases. When the phase meter 70 detects a liquid concentration in the flow below the predetermined value (“N” in step S2), for example, zero, the processing unit can then switch the bypass valve 60 to its second closed position (step S6). In other words, the bypass channel 14 remains active until the hydrogen has completely vaporized.

[0090] The flow of hydrogen, then entirely gaseous, can thus be totally directed towards the second exchanger 40 without risking freezing the heat transfer fluid of the latter, and therefore without risking degrading the second exchanger 40 or the other equipment.

[0091] Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

[0092] It is also evident that all the characteristics described with reference to a process are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a process.

Claims

Demands

1. Cryogenic fluid supply device (10) for an aeronautical turbojet engine (1), the device (10) being capable of drawing cryogenic fluid stored in a reservoir (20) in liquid form, the device (10) comprising a first heat exchanger (30) capable of first heating the fluid drawn from the reservoir (20) via a sampling conduit (11) capable of connecting the reservoir (20) to the first heat exchanger (30), and a main conduit (12) connected in a loop to the first heat exchanger (30), the device (10) comprising: - a bypass channel (14) comprising a first branch (141) branching from the main conduit (12) at a bypass point (140), to a phase separator (50) capable of separating a liquid phase and a gaseous phase of the fluid, a second branch (142) connecting the liquid phase of the phase separator (50) to the sampling conduit (11),and a third branch (143) connecting the gaseous phase of the phase separator (50) to the main conduit (12) downstream of the bypass point (140), - a bypass valve (60) disposed downstream of the bypass point (140), and movable between a first position allowing a diversion of the fluid flow via the bypass channel (14), and a second position limiting this diversion.

2. Device (10) according to claim 1, wherein the first exchanger (30) is a two-phase exchanger comprising a cold inlet (31) adapted to be connected to the tank (20) via the sampling conduit (11), a cold outlet (32) connected to an upstream end (12a) of the main conduit (12), a hot inlet (33) connected to a downstream end (12b) of the main conduit (12), and a hot outlet (34) connected to an outlet conduit (13) adapted to bring the fluid to the turbojet (1).

3. A device (10) according to claim 1 or 2, wherein the phase separator (50) is adapted to receive a two-phase mixture of the fluid via the first branch (141) of the bypass channel (14), to store the fluid in liquid form falling into a lower portion (51) of the phase separator (50), and to accumulate the fluid in gaseous form in an upper portion (52) of the phase separator (50), the second branch (142) of the bypass channel (14) being connected to the lower portion (51) of the phase separator (50) and comprising a single-phase outlet valve (53) suitable for permitting or preventing the flow of fluid in liquid form from the phase separator (50) to the sampling conduit (11).

4. Device (10) according to any one of claims 1 to 3, comprising a second exchanger (40) disposed on the main conduit (12) and being capable of carrying out a second heating of the fluid, the branch point (140) of the branch channel (14) and a junction (144) between the third branch (143) of the branch channel (14) and the main conduit (12) being disposed upstream of the second exchanger (40).

5. Device (10) according to any one of claims 1 to 4, comprising a phase meter (70) capable of measuring a liquid content of the fluid flow, the phase meter (70) being disposed on the main conduit (12), downstream of the first exchanger (30) and upstream of the bypass point (140) of the bypass channel (14).

6. Device (10) according to claim 5, configured such that, when a liquid content of the fluid flow measured by the phase meter (70) is greater than or equal to a predetermined value, the bypass valve (60) is placed in its first position, and when the liquid content measured by the phase meter (70) is less than the predetermined value, the bypass valve (60) is placed in its second position.

7. Device (10) according to any one of claims 1 to 6, wherein the bypass valve (60) is disposed on the first branch (141) of the bypass channel (14).

8. Device (10) according to any one of claims 1 to 7, comprising a first check valve (15) disposed on the second branch (142) of the bypass channel (14), and a second check valve (16) disposed on the third branch (143) of the bypass channel (14).

9. Device (10) according to any one of claims 1 to 8, wherein the cryogenic fluid is dihydrogen.

10. Aeronautical turbojet (1) comprising a cryogenic fluid supply device (10) according to any one of the preceding claims.

11. A method for supplying cryogenic fluid to an aeronautical turbojet engine (1) using a device (10) according to any one of the claims 1 to 9, the method comprising controlling the bypass valve (60), to switch it between its first position allowing the diversion of the fluid flow via the bypass channel (14), and its second position limiting this diversion.

12. A method according to claim 11, comprising: - the measurement (SI) of a liquid content of the fluid flow downstream of the first exchanger (30) and upstream of the bypass point (140) of the bypass channel (14) by means of a phase meter (70), - when the liquid content of the fluid flow is greater than or equal to a predetermined value, the switching (S3) of the bypass valve (60) to its first position, and - when the liquid content measured by the phase meter (70) is less than the predetermined value, the switching (S6) of the bypass valve (60) to its second position.

13. A method according to claim 12, wherein a single-phase outlet valve (53) is disposed on the second branch (142) of the bypass channel (14), the method comprising opening (S5) the single-phase outlet valve (53) when a two-phase mixing volume in the phase separator (50) reaches a predetermined threshold value.

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