Aero-engine closed circulation system based on low-temperature fuel cold energy utilization

Abstract

The invention provides an aero-engine closed circulation system based on low-temperature fuel cold energy utilization, and belongs to the technical field of low-temperature fuel aero-engines. The low-temperature fuel storage tank conveys low-temperature fuel to a combustion chamber of the aero-engine through the first channel. The compression and expansion circulation assembly comprises a compressor, a first turbine, a first power generator and a wake flow heat exchanger; the compressor pressurizes a cycle working medium, the pressurized cycle working medium absorbs waste heat of high-temperature fuel gas through the wake flow heat exchanger and then enters the first turbine to expand and do work to drive the first turbine to rotate, the first turbine drives the compressor and the first power generator to operate, and the cycle working medium obtained after expansion and do work enters the second channel to exchange heat with low-temperature fuel. And the circulating working medium passing through the fuel preheating heat exchanger returns to the compressor. The cold energy utilization rate of low-temperature fuel of the aero-engine is increased, and the output work of the engine is increased.

Description

Technical Field

[0001] This application relates to the field of cryogenic fuel aviation engines, and in particular, to a closed-cycle system for an aviation engine based on the utilization of the cold energy of cryogenic fuels. Background Art

[0002] Due to the advantages of cryogenic fuels such as liquid hydrogen and liquefied natural gas, including environmental friendliness, low carbon emissions, non-toxicity, pollution-free, and high energy density, they have attracted the attention of researchers and are considered the most promising "decarbonization" path.

[0003] Taking hydrogen as an example, since the density of gaseous hydrogen is small, if gaseous hydrogen is used as the engine fuel, the storage tank volume is too large and the weight is too high to be integrated with the aircraft, and it will also occupy the effective volume of the aircraft. Moreover, the solid-state hydrogen storage technology is not yet mature. Therefore, the most promising airborne hydrogen storage method at present is liquid hydrogen, that is, the temperature is reduced to about 20K and stored at normal pressure or slightly positive pressure. If liquid hydrogen is directly burned, the atomization and evaporation of liquid hydrogen will absorb a large amount of heat. The liquid hydrogen of existing liquid hydrogen engines needs to be gasified by a vaporizer before entering the combustion chamber for combustion, and then enters the combustion chamber for combustion. Generally, the vaporizer is placed in the hot gas, and the high-temperature gas provides the heat required for the gasification of cryogenic fuel. However, this will reduce the heat of the gas and cause a decrease in thrust and cycle efficiency, and the huge cold energy of liquid hydrogen is not fully utilized. Summary of the Invention

[0004] In view of this, this application provides a closed-cycle system for an aviation engine based on the utilization of the cold energy of cryogenic fuels, which solves the problems in the prior art and improves the utilization rate of the cold energy of cryogenic fuels for aviation engines while increasing the output work of the engine.

[0005] The closed-cycle system for an aviation engine based on the utilization of the cold energy of cryogenic fuels provided by this application adopts the following technical solutions: A closed-cycle system for an aviation engine based on the utilization of the cold energy of cryogenic fuels, the aviation engine is a gas turbine engine, and the closed-cycle system of the aviation engine includes: A cryogenic fuel storage tank for storing liquid cryogenic fuel; A fuel preheating heat exchanger with a first channel and a second channel arranged at intervals inside. The cryogenic fuel storage tank is connected to the first channel, and the cryogenic fuel storage tank transports fuel to the combustion chamber of the aviation engine through the first channel; The compression-expansion cycle assembly includes a compressor, a first turbine, a first generator, and a wake heat exchanger. The wake heat exchanger is located inside the tail pipe. The outlet of the compressor is communicated with the inlet of the wake heat exchanger. The outlet of the wake heat exchanger is communicated with the inlet of the first turbine. The outlet of the first turbine is communicated with the inlet of the second channel. The outlet of the second channel is communicated with the inlet of the compressor to form a circulation loop. The output shaft of the first turbine is connected to the input shaft of the compressor, and the output shaft of the first turbine is connected to the input shaft of the first generator; The compressor pressurizes the circulating working fluid. After being pressurized, the circulating working fluid absorbs the waste heat of the high-temperature gas through the wake heat exchanger and then enters the first turbine to expand and do work to drive the first turbine to rotate. The first turbine drives the compressor and the first generator to operate. After expanding and doing work in the first turbine, the circulating working fluid enters the second channel to exchange heat with the low-temperature fuel. The low-temperature fuel is heated up and the circulating working fluid is cooled down. The circulating working fluid passing through the fuel preheating heat exchanger returns to the compressor and is compressed.

[0006] Optionally, the closed-cycle system of the aero-engine further includes a second turbine and a second generator. The output shaft of the second turbine is connected to the input shaft of the second generator. The first channel is communicated with the combustion chamber of the aero-engine through the second turbine. After being heated up and gasified, the low-temperature fuel passing through the fuel preheating heat exchanger enters the second turbine to expand and do work to drive the output shaft of the second turbine to rotate. The second turbine drives the second generator to operate.

[0007] Optionally, the closed-cycle system of the aero-engine further includes an intercooler. The intercooler is located between the low-pressure compressor and the high-pressure compressor of the aero-engine. A channel for the low-temperature fuel to flow through is provided inside the intercooler. The low-temperature fuel in the intercooler exchanges heat with the compressed air discharged from the low-pressure compressor. The internal channel of the intercooler is communicated with the combustion chamber of the aero-engine. The low-temperature fuel passing through the fuel preheating heat exchanger enters the intercooler to exchange heat with the compressed air passing through the intercooler, is heated up, and then enters the combustion chamber of the aero-engine.

[0008] Optionally, a temperature sensor and a flow regulating valve are provided between the outlet of the low-temperature fuel channel of the intercooler and the combustion chamber. Optionally, the circulating working fluid is helium or supercritical carbon dioxide.

[0009] Optionally, the low-temperature fuel is liquid hydrogen or liquefied natural gas.

[0010] In summary, the present application includes the following beneficial technical effects: This application utilizes the cold energy of cryogenic fuel. Compared with directly using a vaporizer, it no longer requires additional heat supply, and the cold energy of the cryogenic fuel is fully utilized, improving the overall cycle efficiency. Moreover, the electricity generated by the first generator and the second generator can be used by the aircraft, increasing the output work of the engine.

[0011] This application adopts a coupled integrated design of a closed cycle, a cryogenic fuel vaporizer, and a wake heat exchanger, increasing the compactness of the entire system, reducing the weight of the closed cycle, and improving the power-to-weight ratio of the entire power system. Brief Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions of the embodiments of this application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0013] Figure 1 It is a schematic structural diagram of the first embodiment of the closed cycle system of an aeroengine based on the utilization of the cold energy of cryogenic fuel in this application; Figure 2 It is a schematic structural diagram of the second embodiment of the closed cycle system of an aeroengine based on the utilization of the cold energy of cryogenic fuel in this application.

[0014] Description of the reference numerals: 1. Fan; 2. Low-pressure compressor; 3. High-pressure compressor; 4. Combustion chamber; 5. High-pressure turbine; 6. Low-pressure turbine; 7. Tail nozzle; 8. Wake heat exchanger; 9. Compressor; 10. Fuel preheating heat exchanger; 11. Cryogenic fuel storage tank; 12. First generator; 13. First turbine; 14. Intercooler; 15. Second turbine; 16. Second generator. Detailed Embodiments

[0015] The embodiments of this application will be described in detail below with reference to the drawings.

[0016] The following describes the implementation manners of the present application through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all embodiments. The present application can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0017] It should be noted that the following describes various aspects of the embodiments within the scope of the appended claims. It should be obvious that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is illustrative only. Based on the present application, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, this device and / or practice this method can be implemented using other structures and / or functions in addition to one or more of the aspects described herein.

[0018] It should also be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present application in a schematic manner. The diagrams only show the components related to the present application rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in its actual implementation can be an arbitrary change, and the component layout type may also be more complex.

[0019] In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0020] An embodiment of the present application provides an aero - engine closed - cycle system based on the utilization of cold energy of low - temperature fuel.

[0021] As Figure 1 shown, the aero - engine is a gas turbine engine. The gas turbine engine sequentially includes a fan 1, a low - pressure compressor 2, a high - pressure compressor 3, a combustion chamber 4, a high - pressure turbine 5, a low - pressure turbine 6, and a tail nozzle 7 from the intake end to the exhaust end.

[0022] As Figure 1As shown, in the first embodiment, a closed-cycle system for an aeroengine based on the utilization of the cold energy of cryogenic fuel includes: A cryogenic fuel storage tank 11 for storing liquid cryogenic fuel, where the cryogenic fuel is liquid hydrogen or liquefied natural gas.

[0023] A fuel preheating heat exchanger 10 with a first channel and a second channel arranged at intervals inside. The cryogenic fuel storage tank 11 is connected to the first channel, and the cryogenic fuel storage tank 11 supplies fuel to the combustion chamber 4 of the aeroengine through the first channel.

[0024] A compression-expansion cycle assembly includes a compressor 9, a first turbine 13, a first generator 12, and a wake heat exchanger 8. The wake heat exchanger 8 is located inside the tailpipe 7. There is a channel inside the wake heat exchanger 8, and the wake heat exchanger 8 is heated by the waste heat of the high-temperature gas in the tailpipe 7. The outlet of the compressor 9 is connected to the inlet of the internal channel of the wake heat exchanger 8. The outlet of the internal channel of the wake heat exchanger 8 is connected to the inlet of the first turbine 13. The outlet of the first turbine 13 is connected to the inlet of the second channel. The outlet of the second channel is connected to the inlet of the compressor 9 to form a circulation loop. The output shaft of the first turbine 13 is connected to the input shaft of the compressor 9, and the output shaft of the first turbine 13 is connected to the input shaft of the first generator 12. There is a circulating working fluid flowing in the circulation loop. The circulating working fluid is helium or supercritical carbon dioxide.

[0025] The compressor 9 pressurizes the circulating working fluid. After being pressurized, the circulating working fluid enters the first turbine 13 through the wake heat exchanger 8 to absorb the waste heat of the tailpipe 7 and expand to do work to drive the first turbine 13 to rotate. The first turbine 13 drives the compressor 9 and the first generator 12 to operate. After expanding and doing work in the first turbine 13, the circulating working fluid enters the second channel to exchange heat with the cryogenic fuel. The cryogenic fuel is heated up and the circulating working fluid is cooled down. The circulating working fluid passing through the fuel preheating heat exchanger 10 returns to the compressor 9 to be compressed and enters the next cycle. During the circulation process, the cold energy of the cryogenic fuel is used to reduce the temperature of the circulating working fluid, which is convenient for the compressor 9 to pressurize the circulating working fluid. At the same time, the high-temperature circulating working fluid discharged from the first turbine 13 heats the cryogenic fuel to gasify it, which is convenient for the combustion chamber 4 of the aeroengine to utilize. In this application, the cold energy of the cryogenic fuel is utilized. Compared with directly using a vaporizer, no additional heat needs to be provided, and the cold energy of the cryogenic fuel is also fully utilized, improving the overall cycle efficiency. Moreover, the electricity generated by the first generator 12 can be used by the aircraft, increasing the output work of the engine.

[0026] In this embodiment, an energy storage battery is set to supply power to the first generator 12 to drive the start of the compressor 9. After the compressor 9 starts and the circulating working fluid begins to circulate, the power supply is stopped, and the subsequent power of the compressor 9 comes from the first turbine 13.

[0027] In the cycle of this embodiment, the net work of the Brayton cycle is the difference between the work done by the turbine of the aero-engine and the work consumed by the compressor: ; The work done by the turbine of the aero-engine ; wherein, is the mass flow rate, is the specific heat at constant pressure, is the temperature before the turbine of the aero-engine, is the temperature at the outlet of the turbine of the aero-engine.

[0028] The work consumed by the compressor ; wherein, is the temperature at the inlet of the compressor, is the temperature at the outlet of the compressor; is the mass flow rate.

[0029] Therefore, the net work is: ; In addition, due to the addition of the compression-expansion cycle component of the closed cycle, there is an additional work output, which will be further increased.

[0030] The Brayton cycle efficiency , and the cycle efficiency is the ratio of the net work to the input heat: ; wherein, is the input heat.

[0031] The compression-expansion cycle component of this application heats the low-temperature fuel, increasing the temperature of the fuel entering the combustion chamber. Without changing the temperature at the outlet of the turbine of the aero-engine, the heat provided by combustion can be reduced, that is, the input heat is reduced, the fuel consumption is decreased, and the closed cycle increases , so the efficiency of the Brayton cycle increases.

[0032] In the second embodiment: Such as Figure 2As shown, compared with the first embodiment, a closed-cycle system of an aero-engine based on the cold energy utilization of low-temperature fuel further includes a second turbine 15 and a second generator 16. The output shaft of the second turbine 15 is connected to the input shaft of the second generator 16. The first channel communicates with the combustion chamber 4 of the aero-engine through the second turbine 15. After the low-temperature fuel passing through the fuel preheating heat exchanger 10 is heated and vaporized, it enters the second turbine 15 to expand and do work to drive the output shaft of the second turbine 15 to rotate, and the second turbine 15 drives the second generator 16 to operate. By utilizing the expansion of the low-temperature fuel by the second turbine 15 and the second generator 16, the output work of the engine is further increased. At the same time, after passing through the fuel preheating heat exchanger 10, the temperature of the low-temperature fuel increases, which is not likely to cause air icing and endanger the safety of the engine.

[0033] The closed-cycle system of the aero-engine in this embodiment further includes an intercooler 14. The intercooler 14 is located between the low-pressure compressor 2 and the high-pressure compressor 3 of the aero-engine. A channel for the low-temperature fuel to flow through is provided inside the intercooler 14. The low-temperature fuel in the intercooler 14 exchanges heat with the compressed air discharged from the low-pressure compressor 2. The internal channel of the intercooler 14 communicates with the combustion chamber 4 of the aero-engine. The low-temperature fuel passing through the fuel preheating heat exchanger 10 enters the intercooler 14 to exchange heat with the compressed air passing through the intercooler 14 and is heated up and then enters the combustion chamber 4 of the aero-engine. Utilizing the low temperature of the low-temperature fuel to cool the compressed air can reduce the compression work of the compressor and improve the cycle efficiency.

[0034] In the cycle of this embodiment, the net work of the Brayton cycle is the difference between the work done by the aero-engine turbine and the work consumed by the compressor: ; The work done by the aero-engine turbine ; wherein, is the mass flow rate, is the specific heat at constant pressure, is the temperature before the aero-engine turbine, is the temperature at the outlet of the aero-engine turbine.

[0035] The intercooled Brayton cycle is usually divided into two-stage compressors, and an intercooler is added in the middle. The total compressor work is the sum of the work of the two-stage compressors: The work of the low-pressure compressor ; The work of the high-pressure compressor ; wherein, is the temperature at the inlet of the compressor, is the temperature at the inlet of the intercooler, is the temperature at the outlet of the intercooler, is the temperature at the outlet of the compressor, is the mass flow rate.

[0036] Therefore, the net output work is: .

[0037] Due to the addition of the intercooler, the temperature of the air entering the high-pressure compressor decreases, and the compression work of the high-pressure compressor decreases, while remains unchanged, but the output work of the turbine remains unchanged, so the net output work will increase. In addition, due to the addition of the closed cycle, there is an additional work output, which will further increase.

[0038] The Brayton cycle efficiency , and the cycle efficiency is the ratio of the net work to the input heat: ; wherein, is the input heat.

[0039] The intercooler reduces the temperature of the compression process and reduces the compression power consumption. Due to the addition of the closed cycle, there is an additional work output, which will further increase. The compression-expansion cycle component of the present application heats the low-temperature fuel, increases the temperature of the fuel entering the combustion chamber. Without changing the turbine outlet temperature of the aeroengine, the heat provided by combustion can be reduced, that is, the input heat is reduced, and the fuel consumption is decreased. Therefore, the cycle efficiency of the engine is significantly increased.

[0040] In other embodiments, a temperature sensor and a flow regulating valve are provided between the outlet of the low-temperature fuel passage of the intercooler 14 and the combustion chamber 4 for controlling the temperature and flow rate of the low-temperature fuel in real time to prevent the compression air passage from icing.

[0041] The above is only the specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An aircraft engine closed cycle system based on the utilization of cryogenic fuel cold energy, the aircraft engine is a gas turbine engine, characterized in that: The closed cycle system of an aircraft engine includes: A cryogenic fuel storage tank (11) for storing liquid cryogenic fuel; A fuel preheating heat exchanger (10) is provided with a first channel and a second channel arranged at intervals therein, the cryogenic fuel storage tank (11) is connected to the first channel, and the cryogenic fuel storage tank (11) transports fuel to a combustion chamber (4) of an aircraft engine through the first channel; A compression-expansion cycle assembly, comprising a compressor (9), a first turbine (13), a first generator (12) and a wake heat exchanger (8), wherein the wake heat exchanger (8) is located inside a tail nozzle (7), the outlet of the compressor (9) is connected to the inlet of the wake heat exchanger (8), the outlet of the wake heat exchanger (8) is connected to the inlet of the first turbine (13), the outlet of the first turbine (13) is connected to the inlet of the second channel, the outlet of the second channel is connected to the inlet of the compressor (9), forming a circulation loop, the output shaft of the first turbine (13) is connected to the input shaft of the compressor (9), and the output shaft of the first turbine (13) is connected to the input shaft of the first generator (12); The compressor (9) pressurizes the circulating working fluid, and the pressurized circulating working fluid absorbs the waste heat of the high-temperature combustion gas through the tail flow heat exchanger (8) and enters the first turbine (13) to expand and perform work, thereby driving the first turbine (13) to rotate. The first turbine (13) drives the compressor (9) and the first generator (12) to operate. The circulating working fluid that has expanded and performed work in the first turbine (13) enters the second channel to exchange heat with the low-temperature fuel, the low-temperature fuel is heated and the circulating working fluid is cooled. The circulating working fluid that has passed through the fuel preheating heat exchanger (10) returns to the compressor (9) to be compressed.

2. The closed cycle system of an aircraft engine based on utilization of cold energy of cryogenic fuel according to claim 1, characterized in that: The aircraft engine closed cycle system also includes a second turbine (15) and a second generator (16), wherein the output shaft of the second turbine (15) is connected to the input shaft of the second generator (16), the first channel is connected to the combustion chamber (4) of the aircraft engine through the second turbine (15), and the low-temperature fuel is heated and gasified after passing through the fuel preheating heat exchanger (10) and enters the second turbine (15) to expand and perform work to drive the output shaft of the second turbine (15) to rotate, and the second turbine (15) drives the second generator (16) to operate.

3. The closed cycle system of an aircraft engine based on utilization of cold energy of cryogenic fuel according to claim 1 or 2, characterized in that: The aircraft engine closed cycle system also includes an intercooler (14), which is located between the low-pressure compressor (2) and the high-pressure compressor (3) of the aircraft engine. The intercooler (14) is provided with a channel for circulating low-temperature fuel. The low-temperature fuel in the intercooler (14) exchanges heat with the compressed air discharged from the low-pressure compressor (2). The internal channel of the intercooler (14) is connected to the combustion chamber (4) of the aircraft engine. The low-temperature fuel passes through the fuel preheating heat exchanger (10) and enters the intercooler (14) to heat exchange with the compressed air passing through the intercooler (14) and heat up before entering the combustion chamber (4) of the aircraft engine.

4. The closed cycle system of an aircraft engine based on utilization of cold energy of cryogenic fuel according to claim 3, characterized in that: A temperature sensor and a flow regulating valve are provided between the low-temperature fuel channel outlet of the intercooler (14) and the combustion chamber (4).

5. The closed cycle system of an aircraft engine based on utilization of cold energy of cryogenic fuel according to claim 1, characterized in that: The circulating working fluid is helium or supercritical carbon dioxide.

6. The closed cycle system of an aircraft engine based on utilization of cold energy of cryogenic fuel according to claim 1, characterized in that: The cryogenic fuel is liquid hydrogen or liquefied natural gas.

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