Fuel supply system for hydrogen aircraft

Abstract

This invention provides a fuel supply system for hydrogen-powered aircraft that can suppress the accumulation of liquid hydrogen within the fuel supply piping. [Solution] The system comprises a hydrogen fuel tank 2, a plurality of fuel supply pipes 30 connecting the hydrogen fuel tank 2 and a hydrogen gas turbine engine 14, a plurality of pumps 32 that supply liquid hydrogen to the hydrogen gas turbine engine 14, and a plurality of return pipes 38 that return a portion of the liquid hydrogen flowing through the fuel supply pipes 30 to the hydrogen fuel tank 14. The plurality of fuel supply pipes 30 merge at a confluence 36 located downstream of the plurality of pumps 32, and each of the plurality of return pipes 38 has a first end 40 connected to the hydrogen fuel tank 2 and a second end 42 connected to the fuel supply pipe 30 between the pumps 32 and the confluence 36.

Description

Technical Field

[0001] The present disclosure relates to a fuel supply system for a hydrogen aircraft using hydrogen as an energy source.

Background Art

[0002] Patent Document 1 discloses a fuel supply system for an aircraft. Specifically, the fuel supply system disclosed in Patent Document 1 includes a bypass flow path that returns the surplus fuel discharged from the pump and not supplied to the engine to the upstream side of the pump. The bypass flow path is also referred to as a return pipe.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, hydrogen aircraft using hydrogen as an energy source have been proposed. In this case, in order to ensure redundancy, it is conceivable that a plurality of fuel supply pipes are connected to a hydrogen fuel tank, and the liquid hydrogen flowing through each fuel supply pipe merges downstream and is then supplied to the fuel supply destination. In this case, a pump is provided in each fuel supply pipe, and the liquid hydrogen discharged from each pump is supplied to the fuel supply destination via the fuel supply pipe. When applying a return pipe corresponding to the bypass flow path disclosed in Patent Document 1 in the above configuration, depending on the connection position between the fuel supply pipe and the return flow path, there is a possibility that the liquid hydrogen may stop flowing and liquid hydrogen may stagnate in a specific fuel supply pipe.

[0005] An object of the present disclosure is to provide a fuel supply system for a hydrogen aircraft that can suppress the stagnation of liquid hydrogen in the fuel supply pipe.

Means for Solving the Problems

[0006] A fuel supply system for a hydrogen aircraft according to a first aspect of the present disclosure comprises a hydrogen fuel tank for storing liquid hydrogen, a plurality of fuel supply pipes connecting the hydrogen fuel tank to a predetermined fuel supply destination, a plurality of pumps disposed in each of the plurality of fuel supply pipes for sending the liquid hydrogen from the hydrogen fuel tank to the fuel supply destination, and a plurality of return pipes connected to each of the plurality of fuel supply pipes for returning a portion of the liquid hydrogen flowing through the fuel supply pipe back to the hydrogen fuel tank, wherein when upstream and downstream are defined with respect to the direction in which the liquid hydrogen is sent out from the hydrogen fuel tank, the plurality of fuel supply pipes merge at a confluence located downstream of the plurality of pumps, and each of the plurality of return pipes has a first end connected to the hydrogen fuel tank and a second end connected to the fuel supply pipe between the pump and the confluence. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a fuel supply system for a hydrogen aircraft that can suppress the accumulation of liquid hydrogen in the fuel supply piping. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of the hydrogen aircraft disclosed herein. [Figure 2] This is a schematic diagram of a fuel supply system that supplies liquid hydrogen stored in a hydrogen fuel tank to a hydrogen gas turbine engine. [Figure 3] Figure 2 is a schematic diagram of a comparative example of a fuel supply system. [Figure 4] Figure 2 is a schematic diagram of another comparative example of a fuel supply system. [Modes for carrying out the invention]

[0009] [Embodiment] Hereinafter, embodiments of the fuel supply system for the hydrogen aircraft according to this disclosure will be described in detail with reference to the drawings. The hydrogen aircraft according to this disclosure flies using liquid hydrogen, a cryogenic liquid fuel, as its energy source. The hydrogen aircraft may be for passenger or cargo use. The propulsion system of the hydrogen aircraft may be, for example, a hydrogen combustion gas turbine engine or a hybrid propulsion system of the hydrogen combustion gas turbine engine and the electric propulsion system.

[0010] [Overview of Hydrogen Aircraft] Figure 1 is a perspective view showing the hydrogen aircraft 1 of this disclosure. The hydrogen aircraft 1 of this disclosure comprises an airframe 10, two hydrogen gas turbine engines 14, and a hydrogen fuel tank 2 mounted at the rear of the airframe 10. The mounting position of the hydrogen fuel tank 2 is not limited to the rear of the airframe 10, but can be set at an appropriate location on the airframe 10. In addition, the number of hydrogen gas turbine engines 14 may be three or more, or it may be just one.

[0011] The aircraft 10 comprises a fuselage 11, a pair of wings 12, and a tail wing 13. The fuselage 11 includes structural members such as a circular frame and stringers, and cylindrical fuselage panels. The pair of wings 12, including spars and flaps, extend from the fuselage 11 to the left and right sides, respectively. The tail wing 13 is located at the end of the fuselage 11 and comprises a vertical stabilizer and a horizontal stabilizer. The hydrogen gas turbine engine 14, which is the fuel source, is an internal combustion engine that uses liquid hydrogen LH as fuel, for example. The two hydrogen gas turbine engines 14 are each fixed to the pair of wings 12.

[0012] The hydrogen fuel tank 2 is a tank that stores liquid hydrogen LH, which is used as fuel for the hydrogen gas turbine engine 14. The hydrogen fuel tank 2 is located in a storage compartment at the rear end of the fuselage 11. Although the hydrogen fuel tank 2 shown in Figure 1 is depicted as a single tank for convenience, the hydrogen fuel tank 2 may consist of multiple tanks. A supply line 15 is interposed between the hydrogen fuel tank 2 and the hydrogen gas turbine engine 14. The supply line 15 supplies the liquid hydrogen LH stored in the hydrogen fuel tank 2 to the left and right hydrogen gas turbine engines 14.

[0013] Generally, tanks for storing liquid hydrogen (LH) require a high degree of thermal insulation to maintain an extremely low temperature. One way to ensure such thermal insulation is to make the tank a vacuum double-shell structure. The hydrogen fuel tank 2 of this embodiment also has a vacuum double-shell structure. As shown in the schematic AA cross-section attached to Figure 1, the hydrogen fuel tank 2 includes an outer tank 21 and an inner tank 22 spaced apart inside the outer tank 21. The internal space of the inner tank 22 is the storage space 20 for containing liquid hydrogen (LH). The outer tank 21 is configured to generate thermal insulation. The space between the inner surface of the outer tank 21 and the outer surface of the inner tank 22 is the vacuum layer VA. The vacuum layer VA is evacuated when the hydrogen fuel tank 2 is in operation. Vacuum is a state in which a space is filled with gas at a pressure lower than normal atmospheric pressure.

[0014] [Structure of the fuel supply system] Figure 2 is a schematic diagram of the fuel supply system FS that supplies liquid hydrogen LH stored in the hydrogen fuel tank 2 to the hydrogen gas turbine engine 14. Note that in Figure 2, one of the pair of hydrogen gas turbine engines 14 shown in Figure 1 is omitted. In the following description, upstream and downstream are defined based on the direction in which the liquid hydrogen LH is discharged from the hydrogen fuel tank 2. That is, when viewed from a certain position in the fuel supply system FS, the direction in which the liquid hydrogen LH is discharged from the hydrogen fuel tank 2 is the downstream side, and the opposite side is the upstream side.

[0015] The fuel supply system FS comprises a hydrogen fuel tank 2 and a supply line 15 for supplying liquid hydrogen LH stored in the hydrogen fuel tank 2 to a hydrogen gas turbine engine 14.

[0016] The supply line 15 has two supply lines, namely a first supply line 15A and a second supply line 15B. The first supply line 15A and the second supply line 15B are arranged in parallel. By having the supply line 15 composed of the two parallel - arranged first supply line 15A and second supply line 15B, redundancy is ensured. As a result, even if one supply line fails, for example, liquid hydrogen LH can be supplied to the hydrogen gas turbine engine 14 via the other supply line, thereby improving safety and reliability.

[0017] The first supply line 15A includes a first fuel supply pipe 30A, a first pump 32A disposed on the first fuel supply pipe 30A, a first check valve 34A disposed on the first fuel supply pipe 30A, and a first return pipe 38A.

[0018] The first fuel supply pipe 30A is a pipe connecting between the hydrogen fuel tank 2 and the hydrogen gas turbine engine 14.

[0019] The first pump 32A sucks up liquid hydrogen LH from the hydrogen fuel tank 2 and sends out the liquid hydrogen LH towards the hydrogen gas turbine engine 14. Therefore, when the first pump 32A is driven, in the first fuel supply pipe 30A, the liquid hydrogen LH flows from the hydrogen fuel tank 2 towards the hydrogen gas turbine engine 14. The first pump 32A may use, for example, a turbo pump, a gear pump, a vane pump, or a piston pump, etc. Also, the first pump 32A may be a fixed - displacement pump or a variable - displacement pump.

[0020] The first check valve 34A is a check valve that prevents the backflow of liquid hydrogen LH in the first fuel supply pipe 30A. That is, the first check valve 34A allows liquid hydrogen LH to flow in from the upstream side of the first check valve 34A and flow out to the downstream side of the first check valve 34A, but prevents liquid hydrogen LH from flowing in from the downstream side of the first check valve 34A and flowing out to the upstream side of the first check valve 34A. The first check valve 34A is disposed on the first fuel supply pipe 30A. Specifically, the first check valve 34A is disposed between the first pump 32A and the confluence portion 36 in the first fuel supply pipe 30A. The confluence portion 36 is a portion where the first fuel supply pipe 30A and the second fuel supply pipe 30B, which will be described later, of the second supply line 15B merge.

[0021] The first return pipe 38A is provided to return a part of the liquid hydrogen LH supplied to the hydrogen gas turbine engine 14 through the first fuel supply pipe 30A, specifically, the surplus that is not burned in the hydrogen gas turbine engine 14, to the hydrogen fuel tank 2. The first return pipe 38A is disposed substantially in parallel with the first fuel supply pipe 30A. The first return pipe 38A has a first end portion 40A connected to the hydrogen fuel tank 2 and a second end portion 42A connected to the first fuel supply pipe 30A. The second end portion 42A is connected between the first pump 32A and the first check valve 34A in the first fuel supply pipe 30A.

[0022] The second supply line 15B includes the second fuel supply pipe 30B, a second pump 32B disposed on the second fuel supply pipe 30B, a second check valve 34B disposed on the second fuel supply pipe 30B, and a second return pipe 38B. Note that the first fuel supply pipe 30A and the second fuel supply pipe 30B are an example of a plurality of fuel supply pipes of the present disclosure. The first pump 32A and the second pump 32 are an example of a plurality of pumps of the present disclosure. The first check valve 34A and the second check valve 34B are an example of a plurality of check valves of the present disclosure. The first return pipe 38A and the second return pipe 38B are an example of a plurality of return pipes of the present disclosure.

[0023] The second fuel supply pipe 30B is a pipe that connects the hydrogen fuel tank 2 and the hydrogen gas turbine engine 14.

[0024] The second pump 32B draws up liquid hydrogen LH from the hydrogen fuel tank 2 and sends the liquid hydrogen LH to the hydrogen gas turbine engine 14. Therefore, when the second pump 32B is driven, liquid hydrogen LH flows from the hydrogen fuel tank 2 to the hydrogen gas turbine engine 14 in the second fuel supply piping 30B. The second pump 32B may be a gear pump, vane pump, or piston pump, similar to the first pump 32A. The second pump 32B may also be a fixed-displacement pump or a variable-displacement pump. In this embodiment, the first pump 32A and the second pump 32B are pumps with the same performance. That is, the discharge pressure of the first pump 32A and the discharge pressure of the second pump 32B are basically the same.

[0025] The second check valve 34B is a check valve that prevents backflow of liquid hydrogen LH in the second fuel supply pipe 30B. That is, the second check valve 34B allows liquid hydrogen LH to flow in from the upstream side of the second check valve 34B and to flow out to the downstream side of the second check valve 34B, but prevents liquid hydrogen LH from flowing in from the downstream side of the second check valve 34B and flowing out to the upstream side of the second check valve 34B. The second check valve 34B is installed on the second fuel supply pipe 30B. In detail, the second check valve 34B is installed on the second fuel supply pipe 30B between the second pump 32B and the junction 36.

[0026] The second return pipe 38B is provided to return a portion of the liquid hydrogen LH supplied to the hydrogen gas turbine engine 14 through the second fuel supply pipe 30B, specifically the excess that is not burned in the hydrogen gas turbine engine 14, back to the hydrogen fuel tank 2. The second return pipe 38B is arranged substantially in parallel with the second fuel supply pipe 30B. The second return pipe 38B has a first end 40B connected to the hydrogen fuel tank 2 and a second end 42B connected to the second fuel supply pipe 30B. The second end 42B is connected in the second fuel supply pipe 30B between the second pump 32B and the second check valve 34B.

[0027] The first fuel supply pipe 30A and the second fuel supply pipe 30B are arranged in parallel. Furthermore, the portion of the first fuel supply pipe 30A downstream of the first check valve 34A and the portion of the second fuel supply pipe 30B downstream of the second check valve 34B are connected to form a confluence section 36. The confluence section 36 is located upstream of the hydrogen gas turbine engine 14, which is the destination of the fuel supply. Downstream of the confluence section 36, the first fuel supply pipe 30A and the second fuel supply pipe 30B share a common pipe. The common pipe connecting the confluence section 36 and the hydrogen gas turbine engine 14 may be considered as a part of the first fuel supply pipe 30A and a part of the second fuel supply pipe 30B. The liquid hydrogen LH flowing in the first fuel supply pipe 30A and the liquid hydrogen LH flowing in the second fuel supply pipe 30B merge at the confluence section 36 and are then supplied to the hydrogen gas turbine engine 14.

[0028] Next, the operation of the fuel supply system FS will be described. In the fuel supply system FS, when the first pump 32A is driven, liquid hydrogen LH is supplied to the hydrogen gas turbine engine 14 through the first fuel supply pipe 30A. At this time, any excess liquid hydrogen LH flowing through the first fuel supply pipe 30A that is not burned in the hydrogen gas turbine engine 14 is returned to the hydrogen fuel tank 2 via the first return pipe 38A.

[0029] In addition, the second pump 32B is driven in parallel with the first pump 32A. When the second pump 32 is driven, liquid hydrogen LH is supplied to the hydrogen gas turbine engine 14 through the second fuel supply pipe 30B. At this time, any excess liquid hydrogen LH flowing through the second fuel supply pipe 30B that is not burned in the hydrogen gas turbine engine 14 is returned to the hydrogen fuel tank 2 via the second return pipe 38B.

[0030] In this way, by supplying liquid hydrogen (LH) from multiple fuel supply lines, even if the required amount of liquid hydrogen (LH) increases, a stable supply of liquid hydrogen (LH) can be provided to the hydrogen gas turbine engine 14. In addition, the supply of liquid hydrogen (LH) through multiple fuel supply lines ensures redundancy of the fuel supply system FS. Furthermore, by setting up a return line for each fuel supply line, any surplus liquid hydrogen (LH) is returned to the hydrogen fuel tank 2, thereby reducing the loss of liquid hydrogen (LH).

[0031] [Reasons for liquid hydrogen accumulation] In this embodiment, the first pump 32A and the second pump 32B are assumed to have the same performance and the same discharge pressure. However, due to manufacturing tolerances of the actual parts, for example, there may be a difference in the discharge pressure of the first pump 32A and the second pump 32B. In this case, depending on the connection position of the first return pipe 38A and the connection position of the second return pipe 38B, the flow of liquid hydrogen LH in the first fuel supply pipe 30A or the second fuel supply pipe 30B may be obstructed, and liquid hydrogen LH may accumulate in the first fuel supply pipe 30A or the second fuel supply pipe 30B. For example, if liquid hydrogen LH accumulates in the first fuel supply pipe 30A, the temperature of the first fuel supply pipe 30A may rise and the liquid hydrogen LH may vaporize. If the liquid hydrogen LH in the first fuel supply pipe 30A vaporizes, the vaporized hydrogen may enter the first pump 32A, causing it to run dry, or the vaporized hydrogen gas may cause the first fuel supply pipe 30A to become blocked. A similar phenomenon can occur even if liquid hydrogen LH accumulates in the second fuel supply pipe 30B.

[0032] The following describes structures in which liquid hydrogen (LH) accumulation may occur. Figure 3 is a schematic diagram of a fuel supply system (FSA), which is an example of a structure in which liquid hydrogen (LH) accumulation may occur. This fuel supply system (FSA) will be described as the first comparative example to the fuel supply system (FS) of this disclosure. In Figure 3, parts common to the fuel supply system (FS) shown in Figure 2 are denoted by the same reference numerals, and their descriptions are omitted.

[0033] The fuel supply system FSA in Figure 3 includes a supply line 50 between the hydrogen fuel tank 2 and the hydrogen gas turbine engine 14. The supply line 50 has a first supply line 50A and a second supply line 50B arranged in parallel.

[0034] The first supply line 50A includes a first fuel supply pipe 30A, a first pump 32A, a first check valve 34A, and a first return pipe 52A. The first return pipe 52A has a first end 54A connected to the hydrogen fuel tank 2 and a second end 56A connected to the first fuel supply pipe 30A. The second end 56A is connected upstream of the first pump 32A.

[0035] The second supply line 50B includes a second fuel supply pipe 30B, a second pump 32B, a second check valve 34B, and a second return pipe 52B. The second return pipe 52B has a first end 54B connected to the hydrogen fuel tank 2 and a second end 56B connected to the second fuel supply pipe 30B. The second end 56B is connected upstream of the second pump 32B.

[0036] As described above, in the fuel supply system FSA, the second end 56A of the first return pipe 52A is connected upstream of the first pump 32A, and the second end 56B of the second return pipe 52B is connected upstream of the second pump 32B. Here, if, for example, the discharge pressure of the first pump 32A becomes higher than the discharge pressure of the second pump 32B due to manufacturing errors of the actual parts, then liquid hydrogen LH may accumulate in the area R1 enclosed by the dashed line in Figure 3, i.e., upstream of the second pump 32B in the second fuel supply pipe 30B and in the second return pipe 52B.

[0037] The arrows in Figure 3 indicate the flow of liquid hydrogen LH when the discharge pressure of the first pump 32A becomes higher than the discharge pressure of the second pump 32B. When the discharge pressure of the first pump 32A becomes higher than the discharge pressure of the second pump 32B, the liquid hydrogen LH discharged from the first pump 32A flows into the second fuel supply pipe 30B via the confluence section 36. At this time, the pressure of the liquid hydrogen LH flowing downstream of the second check valve 34B becomes higher than the pressure of the liquid hydrogen LH flowing upstream of the second check valve 34B, causing the second check valve 34B to close. Consequently, liquid hydrogen LH accumulates in section R1 of the second fuel supply pipe 30B, which is enclosed by a dashed line. Furthermore, when the pressure of the liquid hydrogen LH stored in the hydrogen fuel tank 2 becomes higher than the pressure of the liquid hydrogen LH in the second return pipe 52B, the liquid hydrogen LH in the second return pipe 52B cannot return to the hydrogen fuel tank 2. As a result, liquid hydrogen LH remains in the second return pipe 52B.

[0038] Figure 4 is a schematic diagram of a fuel supply system FSB, which is another example of a structure in which liquid hydrogen (LH) accumulation may occur. In the fuel supply system FSB, the second end of the first return pipe is connected downstream of the first check valve 34A, and the second end of the second return pipe is connected downstream of the second check valve 34B. This fuel supply system FSB will be described as a second comparative example to the fuel supply system FS of this disclosure. The structure of the fuel supply system FSB will be described below.

[0039] The fuel supply system FSB includes a supply line 60 between the hydrogen fuel tank 2 and the hydrogen gas turbine engine 14. The supply line 60 has a first supply line 60A and a second supply line 60B arranged in parallel.

[0040] The first supply line 60A includes a first fuel supply pipe 30A, a first pump 32A, a first check valve 34A, and a first return pipe 62A. The first return pipe 62A has a first end 64A connected to the hydrogen fuel tank 2 and a second end 66A connected to the first fuel supply pipe 30A. The second end 66A is connected downstream of the first check valve 34A.

[0041] The second supply line 60B includes a second fuel supply pipe 30B, a second pump 32B, a second check valve 34B, and a second return pipe 62B. The second return pipe 62B has a first end 64B connected to the hydrogen fuel tank 2 and a second end 66B connected to the second fuel supply pipe 30B. The second end 66B is connected downstream of the second check valve 34B.

[0042] As described above, in the fuel supply system FSB, the second end 66A of the first return pipe 62A is connected downstream of the first check valve 34A, and the second end 66B of the second return pipe 62B is connected downstream of the second check valve 34B. Here, for example, if the discharge pressure of the first pump 32A becomes higher than the discharge pressure of the second pump 32B, liquid hydrogen LH may accumulate in the area R2 enclosed by the dashed line in Figure 4, that is, upstream of the second check valve 34B of the second fuel supply pipe 30B.

[0043] The arrows in Figure 4 indicate the flow of liquid hydrogen LH when the discharge pressure of the first pump 32A is higher than the discharge pressure of the second pump 32B. When the discharge pressure of the first pump 32A becomes higher than the discharge pressure of the second pump 32B, a portion of the liquid hydrogen LH discharged from the first pump 32A flows into the second fuel supply pipe 30B via the confluence section 36. The liquid hydrogen LH that flows into the second fuel supply pipe 30B is returned to the hydrogen fuel tank 2 via the second return pipe 62B. At this time, the pressure of the liquid hydrogen LH flowing downstream of the second check valve 34B becomes higher than the pressure of the liquid hydrogen LH flowing upstream of the second check valve 34B, causing the second check valve 34B to close. As a result, the flow of liquid hydrogen LH is obstructed in the portion R2 enclosed by the dashed line located upstream of the second check valve 34B in the second fuel supply pipe 30B, causing a stagnation of liquid hydrogen LH.

[0044] [Structure that suppresses the accumulation of liquid hydrogen] To suppress the accumulation of the liquid hydrogen LH mentioned above, in the fuel supply system FS, as shown in Figure 2, the second end 42A of the first return pipe 38A is connected between the first pump 32A and the first check valve 34A in the first fuel supply pipe 30A. In addition, the second end 42B of the second return pipe 38B is connected between the second pump 32B and the second check valve 34B in the second fuel supply pipe 30B.

[0045] The operation of the fuel supply system FS when the discharge pressure of the first pump 32A becomes higher than the discharge pressure of the second pump 32B will be explained below with reference to Figure 2. The arrows in Figure 2 indicate the flow of liquid hydrogen LH when the discharge pressure of the first pump 32A becomes higher than the discharge pressure of the second pump 32B. When the first pump 32A is driven, as shown by the solid arrows, the liquid hydrogen LH discharged from the first pump 32A is supplied to the hydrogen gas turbine engine 14 from the first fuel supply pipe 30A via the first check valve 34A and the confluence section 36. At this time, a portion of the liquid hydrogen LH flowing through the first fuel supply pipe 30A flows into the second fuel supply pipe 30B via the confluence section 36. As a result, the pressure of the liquid hydrogen LH flowing downstream of the second check valve 34B becomes higher than the pressure of the liquid hydrogen LH flowing upstream of the second check valve 34B, causing the second check valve 34B to close.

[0046] When the second check valve 34B closes, the flow of liquid hydrogen LH in the second fuel supply pipe 30B is obstructed, potentially causing liquid hydrogen LH to accumulate in the second fuel supply pipe 30B. However, since the second end 42B of the second return pipe 38B is connected upstream of the second check valve 34B, the liquid hydrogen LH discharged from the second pump 32B is returned to the hydrogen fuel tank 2 via the second return pipe 38B, as shown by the dashed arrow in Figure 2. As a result, the flow of liquid hydrogen LH in the second fuel supply pipe 30B is no longer obstructed, and the accumulation of liquid hydrogen LH is suppressed.

[0047] [Differentiation] In the above embodiment, a first check valve 34A was installed on the first fuel supply pipe 30A and a second check valve 34B was installed on the second fuel supply pipe 30B. However, the system may be implemented with at least one of the first check valve 34A and the second check valve 34B omitted. In this case, the second end 42A of the first return pipe 38A is connected in the first fuel supply pipe 30A between the first pump 32A and the junction 36, and the second end 42B of the second return pipe 38B is connected in the second fuel supply pipe 30B between the second pump 32B and the junction 36. By connecting each second end 42A, 42B to the above-described positions, the accumulation of liquid hydrogen LH in the first fuel supply pipe 30A and the second fuel supply pipe 30B can be suppressed.

[0048] In the above embodiment, the first fuel supply pipe 30A and the second fuel supply pipe 30B merged at a junction 36 set upstream of the hydrogen gas turbine engine 14. However, the location of the junction 36 is not particularly limited as long as it is downstream of the first check valve 34A and the second check valve 34B.

[0049] In the above embodiment, the fuel supply destination to which liquid hydrogen LH is supplied was a hydrogen gas turbine engine 14, but this disclosure is not limited thereto. The fuel supply destination may be, for example, an APU (Auxiliary Power Unit) or a fuel cell. The APU is a small engine mounted separately from the hydrogen gas turbine engine used for propulsion. The APU supplies compressed air necessary to start the hydrogen gas turbine engine and generates electricity, among other things.

[0050] In the above embodiment, the fuel supply system FS had two fuel supply pipes, a first fuel supply pipe 30A and a second fuel supply pipe 30B, but the disclosure is not limited thereto. The fuel supply system may have, for example, three or more fuel supply pipes arranged in parallel, with a return pipe provided for each fuel supply pipe. In other words, the disclosure can be applied to any fuel supply system having multiple fuel supply pipes arranged in parallel.

[0051] [Summary of this disclosure] A fuel supply system for a hydrogen aircraft according to a first aspect of the present disclosure comprises a hydrogen fuel tank for storing liquid hydrogen, a plurality of fuel supply pipes connecting the hydrogen fuel tank to a predetermined fuel supply destination, a plurality of pumps disposed in each of the plurality of fuel supply pipes for sending the liquid hydrogen from the hydrogen fuel tank to the fuel supply destination, and a plurality of return pipes connected to each of the plurality of fuel supply pipes for returning a portion of the liquid hydrogen flowing through the fuel supply pipe back to the hydrogen fuel tank, wherein when upstream and downstream are defined with respect to the direction in which the liquid hydrogen is sent out from the hydrogen fuel tank, the plurality of fuel supply pipes merge at a confluence located downstream of the plurality of pumps, and each of the plurality of return pipes has a first end connected to the hydrogen fuel tank and a second end connected to the fuel supply pipe between the pump and the confluence.

[0052] According to the first embodiment described above, redundancy in the fuel supply system is ensured by providing multiple fuel supply pipes connecting the fuel supply tank and the fuel supply destination, and liquid hydrogen can be stably delivered to the fuel supply destination. Furthermore, since each of the multiple return pipes has a second end that is connected to the fuel supply pipe between the pump and the junction, the stagnation of liquid hydrogen that occurs when the return pipe is connected upstream of the pump can be suppressed.

[0053] A fuel supply system for a hydrogen aircraft according to a second embodiment further comprises a plurality of check valves disposed between the pump and the junction in each of the plurality of fuel supply pipes to prevent backflow of the liquid hydrogen, wherein the second end of each of the plurality of return pipes may be connected between the pump and the check valve.

[0054] According to the second embodiment, the second end of each of the multiple return pipes is connected between the pump and the check valve, thereby suppressing the accumulation of liquid hydrogen that occurs when the return pipe is connected downstream of the check valve.

[0055] The third embodiment of the hydrogen aircraft fuel supply system is the first or second embodiment of the hydrogen aircraft fuel supply system, wherein the confluence is located upstream of the fuel supply destination.

[0056] According to the third embodiment, since the confluence is located upstream of the fuel supply destination, if liquid hydrogen discharged from the fuel supply pipe flows into other fuel supply pipes via the confluence, there is a possibility of liquid hydrogen stagnation. In contrast, by connecting the second end of each of the multiple return pipes between the pump and the confluence in the fuel supply pipe, the stagnation of liquid hydrogen can be suppressed.

[0057] The fourth embodiment of the hydrogen aircraft fuel supply system is a hydrogen aircraft fuel supply system according to any of the first to third embodiments, wherein the fuel supply destination is a hydrogen gas turbine engine.

[0058] According to the fourth embodiment, liquid hydrogen is supplied to the hydrogen gas turbine engine from multiple fuel supply pipes, thereby ensuring a stable supply of liquid hydrogen to the hydrogen gas turbine engine. [Explanation of symbols]

[0059] 1: Hydrogen aircraft 2: Hydrogen fuel tank 14: Hydrogen gas turbine engine (fuel supply source) 30A: 1st fuel supply pipe (fuel supply pipe) 30B: 2nd fuel supply pipe (fuel supply pipe) 32A: Pump No. 1 (Pump) 32B: Second pump (pump) 34A: First check valve (check valve) 34B: Second check valve (check valve) 36: Confluence 38A: First return piping (return piping) 38B: Second return piping (return piping) 40A: 1st end 40B: 1st end 42A: 2nd end 42B: 2nd end FS: Fuel Supply System

Claims

1. A hydrogen fuel tank for storing liquid hydrogen, Multiple fuel supply pipes connecting the hydrogen fuel tank and a predetermined fuel supply destination, A plurality of pumps are provided in each of the plurality of fuel supply pipes to send the liquid hydrogen from the hydrogen fuel tank to the fuel supply destination, The system comprises a plurality of return pipes connected to each of the plurality of fuel supply pipes, which return a portion of the liquid hydrogen flowing through the fuel supply pipes back to the hydrogen fuel tank, When upstream and downstream are defined with respect to the direction in which the liquid hydrogen is discharged from the hydrogen fuel tank, the multiple fuel supply pipes merge at a confluence located downstream of the multiple pumps, Each of the plurality of return pipes has a first end connected to the hydrogen fuel tank and a second end connected to the fuel supply pipe between the pump and the confluence. Fuel supply system for hydrogen-powered aircraft.

2. The system further comprises a plurality of check valves disposed between the pump and the junction in each of the plurality of fuel supply pipes to prevent backflow of the liquid hydrogen, The fuel supply system for a hydrogen aircraft according to claim 1, wherein the second end of each of the plurality of return pipes is connected between the pump and the check valve.

3. The fuel supply system for a hydrogen aircraft according to claim 1 or 2, wherein the confluence is located upstream of the fuel supply destination.

4. The fuel supply system for a hydrogen aircraft according to claim 1 or 2, wherein the fuel supply destination is a hydrogen gas turbine engine.

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