An aviation power plant fueled by liquid ammonia

Abstract

An aviation power device using liquid ammonia as fuel provided by an embodiment of the present invention includes a compressor, a combustion chamber, a turbine, and an exhaust device, and further includes: a heat exchanger, a heater, a decomposition furnace, a catalyst, a PSA gas separator, a liquid ammonia fuel tank, a hydrogen system, and a nitrogen system; by using the heat generated by the engine itself during operation to vaporize liquid ammonia into ammonia gas, the ammonia gas is decomposed into a mixture of hydrogen and nitrogen under the action of a catalyst, and further, the PSA gas separator separates the mixture gas into hydrogen and nitrogen, and then inputs them into the hydrogen system and the nitrogen system respectively. The hydrogen entering the hydrogen system is used as the fuel of the combustion chamber, enabling the aeroengine to have the ability to use ammonia fuel; the nitrogen in the nitrogen system can be used to cool the turbine stator blades, achieve engine thrust augmentation, replace and purge the hydrogen in the hydrogen pipeline entering the combustion chamber, drive the engine turbine, and dilute the flow rate of the hydrogen entering the combustion chamber.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft power plants, and particularly to an aviation power plant using liquid ammonia as fuel. Background Art

[0002] With the in-depth implementation of the concept of green aviation, on the basis of traditional aviation gas turbine engines, hydrogen-fueled engines have been developed through appropriate improvements to the combustion chamber components and fuel control systems. Hydrogen energy has become a popular and ideal clean energy for research at home and abroad because it contains no carbon element and has a high calorific value per unit mass. However, due to the low density and easy leakage of hydrogen, whether it is gaseous hydrogen or liquid hydrogen, the storage and transportation costs are relatively high; therefore, there is still a long way to go for the commercial application of hydrogen energy in the aviation field.

[0003] The current existing technologies mainly have the following disadvantages: (1) Traditional aviation power is provided by turbine engines burning kerosene. The combustion of fuel produces carbon dioxide, which is not a clean energy source, and aviation kerosene is derived from the refining of petroleum and is a non-renewable energy source. (2) Traditional aviation engines pursue high efficiency, resulting in the temperature of turbine components exceeding the temperature resistance limit of materials, and it is necessary to introduce compressor air for cooling of turbine components, which is not conducive to further improving the performance of the engine. (3) Currently, major aviation powers around the world are intensively carrying out research on aviation turbine engines based on hydrogen fuel. Although there is certain technical accumulation, hydrogen backfire and thermal ablation are still problems to be solved. (4) Hydrogen engines need to be equipped with a dedicated nitrogen source to replace and purge the hydrogen in the hydrogen pipeline during the start-up and shutdown processes of the engine to prevent the explosion risk caused by hydrogen residue. (5) There is still no good solution to the problem of how to store and transport hydrogen energy on aircraft, which is a huge obstacle to the engineering application of aviation power plants using hydrogen energy as fuel.

[0004] Therefore, overcoming the above-mentioned defects of the existing technology is an urgent technical problem for those skilled in the art. Summary of the Invention

[0005] In view of the above problems, the present invention provides an aviation power plant using liquid ammonia as fuel.

[0006] The object of the present invention can be achieved through the following solutions:

[0007] An aviation power plant using liquid ammonia as fuel provided by the present invention includes a compressor, a combustion chamber, a turbine and an exhaust device, and further includes: a heat exchanger, a heater, a decomposition furnace, a catalyst, a PSA gas separator, a liquid ammonia fuel tank, a hydrogen system and a nitrogen system;

[0008] The heat exchanger is integrated with the casing of the compressor, the heater is integrated with the casing of the turbine, and the decomposition furnace is integrated with the casing of the exhaust device;

[0009] One way of the liquid ammonia in the liquid ammonia fuel tank flows to the heater, and the other way flows to the heat exchanger and then into the heater;

[0010] Under the action of the high-temperature gas of the turbine, the liquid ammonia flowing through the heater is heated and vaporized into ammonia gas;

[0011] The heater is connected to the decomposer, and under the action of the catalyst, the ammonia gas decomposes into a mixture of hydrogen and nitrogen;

[0012] The mixture gas is separated into hydrogen and nitrogen by the PSA gas separator. The hydrogen enters the hydrogen system, and the nitrogen enters the nitrogen system; the hydrogen in the hydrogen system is used as the fuel of the combustion chamber.

[0013] Further, the hydrogen system includes: a high-pressure hydrogen storage tank and a first control system; the hydrogen separated from the PSA gas separator flows into the high-pressure hydrogen storage tank in one way, and in the other way, it enters the combustion chamber as fuel under the control of the first control system.

[0014] Further, the high-pressure hydrogen storage tank stores hydrogen. When the engine of the aviation power device is just starting, the stored hydrogen participates in the combustion of the combustion chamber in advance to ensure the starting and operation of the engine.

[0015] Further, the nitrogen system includes: a high-pressure nitrogen storage tank, a second control system and a three-way valve;

[0016] The nitrogen separated from the PSA gas separator enters the high-pressure nitrogen storage tank through the first valve and the first pipeline; it enters the turbine through the second valve and the second pipeline under the control of the second control system; it is discharged into the exhaust device through the third valve and the third pipeline under the control of the second control system to achieve thrust augmentation.

[0017] Further, the high-pressure nitrogen storage tank stores nitrogen. When the engine of the aviation power device starts or stops, the stored nitrogen is used to displace and purge the hydrogen in the hydrogen pipeline entering the combustion chamber;

[0018] When the engine of the aviation power device starts, the stored nitrogen is used to blow the turbine to drive the engine rotor to achieve engine starting.

[0019] Further, when the thrust augmentation of the aviation power device is large, the nitrogen in the high-pressure nitrogen storage tank is used to be discharged into the exhaust device to achieve thrust augmentation.

[0020] Further, under the action of the second control system, the nitrogen in the high-pressure nitrogen storage tank is used to be mixed into the hydrogen pipeline where the hydrogen enters the combustion chamber to dilute the flow rate of the hydrogen.

[0021] Further, the aviation power device further includes: a first pump body, a second pump body, and a third pump body;

[0022] The first pump body is communicated with the liquid outlet of the liquid ammonia fuel tank, and the first pump body is used to extract the liquid ammonia into the heat exchanger and the heater respectively;

[0023] The second pump body is located between the decomposer and the PSA gas separator, and the second pump body is used to input the mixed gas decomposed into hydrogen and nitrogen into the PSA gas separator;

[0024] The third pump body is arranged after the PSA gas separator and before the hydrogen system and the nitrogen system. The third pump body is used to pressurize the separated hydrogen and nitrogen and input them into the hydrogen system and the nitrogen system respectively.

[0025] Further, the PSA gas separator is installed outside the engine casing of the aviation power device as an accessory.

[0026] Further, the liquid ammonia fuel tank is located on the aircraft where the aviation power device is located, and the hydrogen system and the nitrogen system are installed outside the engine casing.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] In the embodiment of the present invention, on the basis of the existing aviation engine or hydrogen fuel engine, the use of liquid ammonia is increased. By using the heat generated by the engine itself during operation, the liquid ammonia is vaporized into ammonia gas, and the ammonia gas is decomposed into a mixed gas of hydrogen and nitrogen under the action of a catalyst. Further, the PSA gas separator separates the mixed gas into hydrogen and nitrogen, and then inputs them into the hydrogen system and the nitrogen system respectively. The hydrogen entering the hydrogen system is used as the fuel of the combustion chamber, enabling the aviation engine to have the ability to use ammonia fuel. Compared with the kerosene used by traditional engines, which is a non-renewable energy source and the engine generates carbon dioxide and is not clean, the ammonia used in the aviation power device of the present invention is a renewable energy source and realizes zero carbon emissions. Compared with the complex and difficult problems of storing and transporting liquid hydrogen on airplanes, the storage and transportation of liquid ammonia is more mature, safe and convenient.

[0029] Other features and advantages of the present invention will be described in the following specification, and, in part, will become apparent from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained by the structures pointed out in the specification, claims and drawings. Description of the Drawings

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 Shows a schematic structural diagram of a traditional aero gas turbine engine;

[0032] Figure 2 Is a schematic structural diagram of an aero power device using liquid ammonia as fuel provided by an embodiment of the present invention;

[0033] In the figure: 1 - heat exchanger; 2 - heater; 3 - decomposition furnace; 4 - PSA gas separator; 5 - high-pressure hydrogen storage tank; 6 - high-pressure nitrogen storage tank; 7 - liquid ammonia fuel tank. Detailed implementation manners

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0035] An aero power device using liquid ammonia as fuel provided by an embodiment of the present invention is based on an existing aero engine or a hydrogen fuel engine. The aero power device using liquid ammonia as fuel has structures such as an engine accessory drive system, a compressor, a combustion chamber, a turbine, and an exhaust device of a traditional aero engine.

[0036] An aero power device using liquid ammonia as fuel provided by an embodiment of the present invention includes a compressor, a combustion chamber, a turbine, and an exhaust device, and further includes: a heat exchanger, a heater, a decomposition furnace, a catalyst, a PSA gas separator, a liquid ammonia fuel tank, a hydrogen system, and a nitrogen system;

[0037] The heat exchanger is integrated with the casing of the compressor, the heater is integrated with the casing of the turbine, and the decomposition furnace is integrated with the casing of the exhaust device;

[0038] One path of the liquid ammonia in the liquid ammonia fuel tank flows to the heater, and the other path flows to the heat exchanger and then flows into the heater;

[0039] Under the action of the high-temperature gas of the turbine, the liquid ammonia flowing through the heater is heated and vaporized into ammonia gas;

[0040] The heater is connected to the decomposer. Under the action of the catalyst, ammonia is decomposed into a mixture of hydrogen and nitrogen.

[0041] The mixture gas passes through the PSA gas separator and is separated into hydrogen and nitrogen. The hydrogen enters the hydrogen system, and the nitrogen enters the nitrogen system. The hydrogen in the hydrogen system is used as the fuel for the combustion chamber.

[0042] Based on the existing aeroengine or hydrogen fuel engine, the embodiment of the present invention adds the use of liquid ammonia. By using the heat generated by the engine itself during operation, liquid ammonia is vaporized into ammonia, and ammonia is decomposed into a mixture of hydrogen and nitrogen under the action of a catalyst. Further, the PSA gas separator separates the mixture gas into hydrogen and nitrogen, which are then respectively input into the hydrogen system and the nitrogen system. The hydrogen entering the hydrogen system is used as the fuel for the combustion chamber, enabling the aeroengine to have the ability to use ammonia fuel.

[0043] Compared with kerosene used in traditional engines, which is a non-renewable energy source and the engine produces carbon dioxide and is not clean, the ammonia used in the aero power device of the present invention is a renewable energy source and achieves zero carbon emissions. Compared with the complex and difficult problems of storing and transporting liquid hydrogen on airplanes, the storage and transportation of liquid ammonia are more mature, safe and convenient.

[0044] The aero power device using liquid ammonia as fuel provided by the embodiment of the present invention is based on the existing traditional aeroengine. The schematic diagram of the composition of the traditional aero gas turbine engine is as Figure 1 shown. It consists of a compressor, a combustion chamber, a turbine, an exhaust device, etc. The functions of its various components are as follows: The compressor increases the pressure of the air flow entering the engine and provides bleed air for intake anti-icing, bearing chamber ventilation and heat insulation, and hot section casing cooling; The combustion chamber has the function of burning fuel in a high-pressure air flow to form a gas with work capacity; The turbine has the function of extracting energy from the gas to form shaft power to drive the compressor to compress the air flow; The exhaust device is used to guide the gas after the turbine out of the engine to generate thrust.

[0045] Refer to Figure 2 for a detailed description of the structure and working principle of the aero power device using liquid ammonia as fuel provided by the embodiment of the present invention.

[0046] Combined with the embodiment of the present invention, the heat exchanger 1 is integrated with the casing of the compressor, the heater 2 is integrated with the casing of the turbine, the decomposer 3 is integrated with the casing of the exhaust device, the PSA gas separator 4 is installed outside the engine casing of the aero power device as an accessory, the liquid ammonia fuel tank 7 is located on the airplane where the aero power device is located, and the hydrogen system and the nitrogen system are installed outside the engine casing. Preferably, the aviation device is an airplane, and the engine of the aero power device is an airplane engine.

[0047] In a preferred embodiment, the hydrogen system includes a high-pressure hydrogen storage tank 5 and a first control system; the nitrogen system includes a high-pressure nitrogen storage tank 6, a second control system, and a three-way valve.

[0048] In a preferred embodiment, the aviation power device further includes a first pump body, a second pump body, and a third pump body.

[0049] The liquid ammonia fuel tank 7 is connected to the heat exchanger 1 and the heater 2 through pipelines respectively. The first pump body is connected to the liquid outlet of the liquid ammonia fuel tank 7. Under the pumping action of the first pump body, the liquid ammonia is divided into two paths. One path of the liquid ammonia flows to the heater 2; the other path of the liquid ammonia enters the heat exchanger 1 according to the cooling capacity requirement of the compressor to cool down the compressor, which can realize the improvement of the engine performance parameters. After the liquid ammonia comes out of the heat exchanger 1, it converges with the previous path and flows into the heater 2.

[0050] Under the action of the high-temperature gas of the turbine, the liquid ammonia flowing through the heater 2 is heated and vaporized into ammonia gas. The vaporized ammonia gas is controlled by a valve and enters the decomposition furnace 3. The heater 2 and the decomposition furnace 3 are connected through a pipeline, and a valve is arranged therebetween. The decomposition furnace 3 heats and keeps the ammonia gas warm through the high-temperature gas flowing through the exhaust device. Under the action of the catalyst, the ammonia gas is chemically decomposed into a mixture of hydrogen and nitrogen.

[0051] A second pump body is arranged between the decomposition furnace 3 and the PSA gas separator 4, and the two are connected through a pipeline. The second pump body is used to input the mixture of hydrogen and nitrogen into the PSA gas separator 4.

[0052] The PSA gas separator 4 separates the mixture gas into hydrogen and nitrogen. The hydrogen and nitrogen are respectively pressurized by the third pump body and then transported into the hydrogen system and the nitrogen system. The PSA gas separator 4 is connected to the hydrogen system and the nitrogen system through pipelines respectively. The third pump body is arranged on the pipelines between the PSA gas separator 4 and the hydrogen system and the nitrogen system. The third pump body is arranged behind the PSA gas separator 4 and in front of the hydrogen system and the nitrogen system.

[0053] Combined with the embodiments of the present invention, the hydrogen gas that enters the hydrogen system after being pressurized by the third pump body is divided into two paths by a valve. One path flows into the high-pressure hydrogen storage tank 5 until the high-pressure hydrogen storage tank 5 is full, and the other path enters the combustion chamber of the aircraft engine under the control of the first control system as the final fuel for combustion. The high-pressure hydrogen storage tank 5 stores hydrogen gas. When the aircraft engine is just started, the stored hydrogen gas participates in the combustion of the combustion chamber in advance to ensure the start and operation of the engine until the aviation power device using liquid ammonia as fuel generates enough hydrogen gas.

[0054] Combined with the embodiments of the present invention, the nitrogen gas that enters the nitrogen gas system after being pressurized by the third pump body is divided into three paths by a three-way valve. One path enters the high-pressure nitrogen gas storage tank 6 through the first pipeline via the first valve; another path enters the turbine through the second pipeline via the second valve and, under the control of the second control system, cools the turbine rotor and stator blades; and the last path is discharged into the exhaust device through the third pipeline via the third valve to achieve thrust augmentation under the control of the second control system.

[0055] In a preferred embodiment, the high-pressure nitrogen gas storage tank 6 stores nitrogen gas. When the aircraft engine starts or stops, the stored nitrogen gas is used to displace and purge the hydrogen gas in the hydrogen pipeline entering the combustion chamber to prevent the explosion risk caused by hydrogen residue. When the aircraft engine starts, the stored nitrogen gas is also used to blow the turbine to drive the engine rotor to achieve engine startup. When the thrust augmentation of the aircraft engine is relatively large, the nitrogen gas in the high-pressure nitrogen gas storage tank 6 can be discharged into the exhaust device to achieve thrust augmentation. Preferably, under the action of the second control system, the nitrogen gas in the high-pressure nitrogen gas storage tank 6 is also used to be mixed into the hydrogen pipeline where hydrogen enters the combustion chamber to dilute the hydrogen gas flow rate and reduce the risks of hydrogen backfire and thermal ablation in the combustion chamber.

[0056] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0057] (1) Compared with traditional kerosene which is a non-renewable energy source and the engine produces carbon dioxide and is not clean, ammonia in the present invention is a renewable energy source and burns with zero carbon.

[0058] (2) Compared with the traditional aero-engine turbine components that need to introduce compressor air for cooling, the engine of the present invention is cooled by the by-product nitrogen gas of ammonia, which can further improve the performance parameters of the engine.

[0059] (3) Compared with the problems of hydrogen backfire and thermal ablation faced by the current direct hydrogen combustion engines, the engine of the present invention can dilute the hydrogen gas flow rate with nitrogen gas and reduce the risks of hydrogen backfire and thermal ablation in the combustion chamber.

[0060] (4) Compared with the hydrogen combustion engines that need to be equipped with a dedicated nitrogen gas source, the present invention can produce nitrogen gas by itself for displacing and purging the hydrogen gas in the hydrogen pipeline during the engine start-stop process to prevent the explosion risk caused by hydrogen residue.

[0061] (5) Compared with the complex and difficult problems of liquid hydrogen storage and transportation on aircraft, the storage and transportation of liquid ammonia are more mature, safe and convenient.

[0062] Combined with the embodiments of the present invention, the working process of the aviation power device using liquid ammonia as fuel provided by the embodiments of the present invention will be described next. The aircraft engine will be taken as an example for illustration.

[0063] During engine startup, the nitrogen in the high-pressure nitrogen storage tank 6 displaces and purges the hydrogen in the hydrogen pipeline entering the combustion chamber to prevent the explosion risk caused by hydrogen residue; the stored nitrogen is also used to drive the turbine to drive the engine rotor to achieve engine startup.

[0064] The hydrogen in the high-pressure hydrogen storage tank 5 participates in combustion in advance to ensure the startup and operation of the engine until the liquid ammonia in the liquid ammonia fuel tank 7 passes through the heat exchanger, heater, decomposer, and PSA gas separator to generate sufficient hydrogen and nitrogen. The generated hydrogen flows into the high-pressure hydrogen storage tank 5 all the way, and the other part enters the combustion chamber of the engine as the final fuel for combustion under the control of the first control system.

[0065] The generated nitrogen is divided into three paths by valves. It enters the high-pressure nitrogen storage tank 6 through the first pipeline via the first valve; it enters the turbine through the second pipeline via the second valve and cools the stator blades of the turbine under the control of the second control system; it is discharged into the exhaust device through the third pipeline via the third valve to achieve thrust augmentation. If the aircraft needs a large thrust augmentation of the engine, the nitrogen in the high-pressure nitrogen storage tank 6 can also be discharged into the exhaust device to achieve a short-term large thrust augmentation. Among them, the nitrogen in the high-pressure nitrogen storage tank 6 can be controlled by the second control system to be gas-mixed into the hydrogen pipeline entering the combustion chamber as needed to dilute the hydrogen flow rate and reduce the risks of hydrogen flashback and thermal ablation in the combustion chamber.

[0066] After the engine shuts down, the nitrogen in the high-pressure nitrogen storage tank 6 displaces and purges the hydrogen in the hydrogen pipeline entering the combustion chamber to prevent the explosion risk caused by hydrogen residue.

[0067] Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An aviation power unit using liquid ammonia as fuel, comprising a compressor, a combustion chamber, a turbine and an exhaust device, characterized in that: It also includes: a heat exchanger (1), a heater (2), a decomposition furnace (3), a catalyst, a PSA gas separator (4), a liquid ammonia fuel tank (7), a hydrogen system and a nitrogen system; The heat exchanger (1) is integrated with the casing of the compressor, the heater (2) is integrated with the casing of the turbine, and the decomposition furnace (3) is integrated with the casing of the exhaust device; The liquid ammonia in the liquid ammonia fuel tank (7) flows to the heater (2) in one path and flows to the heat exchanger (1) in another path and then flows into the heater (2); Under the action of the high-temperature combustion gas of the turbine, the liquid ammonia flowing through the heater (2) is heated and gasified into ammonia gas; The heater (2) is connected to the decomposition furnace (3), and under the action of the catalyst, the ammonia is decomposed into a mixed gas of hydrogen and nitrogen; The mixed gas is separated into hydrogen and nitrogen by the PSA gas separator (4), the hydrogen enters the hydrogen system, and the nitrogen enters the nitrogen system; the hydrogen in the hydrogen system is used as fuel for the combustion chamber; The nitrogen system comprises: a high-pressure nitrogen storage tank (6), a second control system and a three-way valve; The nitrogen separated from the PSA gas separator (4) enters the high-pressure nitrogen storage tank (6) through a first valve and a first pipeline; enters the turbine through a second valve and a second pipeline under the control of the second control system; and enters the exhaust device through a third valve and a third pipeline under the control of the second control system to achieve thrust increase.

2. The aviation power plant according to claim 1, characterized in that: The hydrogen system comprises: a high-pressure hydrogen storage tank (5) and a first control system; the hydrogen separated from the PSA gas separator (4) flows into the high-pressure hydrogen storage tank (5) in one way and enters the combustion chamber as fuel under the control of the first control system in the other way.

3. The aviation power plant according to claim 2, characterized in that: The high-pressure hydrogen storage tank (5) stores hydrogen. When the engine of the aviation power unit is just started, the stored hydrogen participates in the combustion of the combustion chamber in advance to ensure the starting and operation of the engine.

4. The aviation power plant according to claim 1, characterized in that: The high-pressure nitrogen storage tank (6) stores nitrogen. When the engine of the aviation power unit is started or stopped, the stored nitrogen is used to replace and blow away the hydrogen in the hydrogen pipeline entering the combustion chamber. When the engine of the aviation power unit is started, the stored nitrogen is used to blow the turbine and drive the engine rotor to start the engine.

5. The aviation power plant according to claim 1, characterized in that: When the thrust increase of the aviation power device is large, the nitrogen in the high-pressure nitrogen storage tank (6) is used to be discharged into the exhaust device to achieve thrust increase.

6. The aviation power plant according to claim 1, characterized in that: Under the action of the second control system, the nitrogen in the high-pressure nitrogen storage tank (6) is used to be mixed into the hydrogen pipeline for the hydrogen to enter the combustion chamber, so as to dilute the flow rate of the hydrogen.

7. The aviation power plant according to claim 1, characterized in that: The aviation power device further includes: a first pump body, a second pump body and a third pump body; The first pump body is in communication with the liquid outlet of the liquid ammonia fuel tank (7), and the first pump body is used to draw the liquid ammonia into the heat exchanger (1) and the heater (2) respectively; The second pump body is located between the decomposition furnace (3) and the PSA gas separator (4), and the second pump body is used to input the mixed gas decomposed into hydrogen and nitrogen into the PSA gas separator (4); The third pump body is arranged after the PSA gas separator (4) and before the hydrogen system and the nitrogen system. The third pump body is used to pressurize the separated hydrogen and nitrogen and input them into the hydrogen system and the nitrogen system respectively.

8. The aviation power plant according to claim 1, characterized in that: The PSA gas separator (4) is installed as an accessory outside the engine casing of the aviation power unit.

9. The aviation power plant according to claim 1, characterized in that: The liquid ammonia fuel tank (7) is located on the aircraft where the aviation power unit is located, and the hydrogen system and the nitrogen system are installed outside the engine casing.

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