Ammonia-water cooling combined power cycle system and method for incoming air

Abstract

This invention discloses a combined power cycle system and method for cooling incoming air using ammonia-water, relating to the aerospace field. The system can switch between turbine-ramjet operating modes through an adjustable structure. Particularly during turbine-ramjet switching, ammonia-water is used to cool the high-temperature incoming air in the intake duct. The absorbed ammonia-water is then distilled to separate high-temperature ammonia gas and water. This invention combines heat exchanger precooling and jet precooling, effectively increasing the pressure ratio of the fan and compressor through multiple air cooling processes. This improves the compressor outlet gas temperature, thereby reducing compressor power consumption and providing greater thrust. Ammonia, as a supplementary fuel, has a higher specific impulse, addressing the thrust gap during engine mode transitions and effectively widening the operating speed range of the turbine engine.

Description

Technical Field

[0001] This invention relates to the aerospace field, and more particularly to a combined power cycle system and method for cooling incoming air with ammonia and water. Background Technology

[0002] With the development of near-space hypersonic vehicles, combined engines are increasingly being used in reusable aircraft. Turbine-based ramjet combined cycle (TBCC) engines can meet the wide range of operational needs of aircraft transitioning from subsonic to hypersonic speeds, thus enabling horizontal takeoff and landing and reusability. However, due to the high temperatures caused by the stagnation of high-speed airflow at high Mach numbers, the turbine engine cannot provide sufficient initial power to the ramjet engine, thus limiting the mode transition between the two. To address the requirements of turbine engines operating at high Mach numbers, inlet precooling technology has gained increasing attention. It can effectively reduce the stagnation of high-temperature air to an inlet temperature suitable for conventional engines, reducing compressor work, lowering compressor outlet temperature, and alleviating engine thermal load; increasing air density and thus airflow, thereby increasing thrust, extending the flight envelope, and improving overall engine performance. There are two main methods for achieving this: one is to inject cooling media before the compressor / fan, i.e., jet precooling technology; the other is to install a precooler at the inlet, with efficient cooling indirectly dominated by the precooling heat exchanger.

[0003] Due to its high specific heat capacity, low cost, and ease of preparation, water is the cooling medium in most jet precooling technologies. However, during high-altitude, high-Mach-number flight, excessive liquid water injection can affect the combustion stability and efficiency of the main combustion chamber and afterburner. In heat exchanger precooling, fuel is typically used as the cold source, cooling the incoming air stream before it is fed into the combustion chamber for combustion. However, applying this to hypersonic flight results in a fuel requirement far exceeding the fuel requirement for combustion, reducing combustion efficiency and wasting energy. Fuel precooling also presents challenges such as high fuel pyrolysis temperatures, difficulty in utilizing heat sinks, fuel waste, and lower specific impulse. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems in the prior art by proposing a combined power circulation system and method that utilizes ammonia-water cooling to cool airflow.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A combined power cycle system for cooling incoming air with ammonia and water includes an intake duct, a separator, a condenser, a reboiler, an ammonia turbine, a heat exchanger, a first mixer, a fan, a compressor, an aviation kerosene tank, an aviation kerosene pump, a main combustion chamber, a high-pressure turbine, a low-pressure turbine, a second mixer, an afterburner, a nozzle, a first valve, a second valve, and a third valve.

[0007] The main combustion chamber includes a fuel inlet, an air inlet, an ammonia inlet, and a gas outlet, which are used to perform preliminary combustion of fuel entering from the fuel inlet, air entering from the air inlet, and ammonia entering from the ammonia inlet, and then discharge the generated gas from its gas outlet.

[0008] The afterburner includes a fuel inlet, a gas inlet, and a gas outlet, for mixing and burning the fuel entering from its fuel inlet and the gas entering from its gas inlet, generating gas which is then discharged from its gas outlet.

[0009] The air intake inlet is connected to the outside air, and the outlet is connected to the inlet of the first valve and the inlet of the second valve;

[0010] The outlet of the first valve is connected to the hot end inlet of the reboiler, and the outlet of the second valve is connected to the air inlet of the second mixer.

[0011] The hot end outlet of the reboiler is connected to the hot end inlet of the heat exchanger, and the hot end outlet of the heat exchanger is connected to the air inlet of the first mixer.

[0012] The cold end inlet of the condenser is connected to ammonia water, and the cold end outlet is connected to the inlet of the separator.

[0013] The upper outlet of the separator is connected to the hot end inlet of the condenser, the lower outlet is connected to the cold end inlet of the reboiler, and the cold end outlet of the reboiler is connected to the water side inlet of the first mixer.

[0014] The hot end outlet of the heat exchanger is connected to the air inlet of the first mixer;

[0015] The hot end outlet of the condenser is connected to the inlet of the ammonia turbine, the outlet of the ammonia turbine is connected to the cold end inlet of the heat exchanger, and the cold end outlet of the heat exchanger is connected to the ammonia inlet of the main combustion chamber.

[0016] The outlet of the first mixer is connected to the fan inlet, and the fan outlet is connected to the compressor inlet and the air inlet of the second mixer, respectively.

[0017] The compressor outlet is connected to the air inlet of the main combustion chamber;

[0018] The outlet of the aviation kerosene tank is connected to the inlet of the aviation kerosene pump, and the outlet of the aviation kerosene pump is connected to the inlet of the third valve and the fuel inlet of the afterburner, respectively.

[0019] The outlet of the third valve is connected to the fuel inlet of the main combustion chamber;

[0020] The gas outlet of the main combustion chamber is connected to the inlet of the high-pressure turbine, and the outlet of the high-pressure turbine is connected to the inlet of the low-pressure turbine.

[0021] The outlet of the low-pressure turbine is connected to the gas inlet of the second mixer, and the outlet of the second mixer is connected to the gas inlet of the afterburner.

[0022] The gas outlet of the afterburner is connected to the nozzle inlet, and the nozzle outlet is connected to the outside.

[0023] This invention also discloses a method for operating a combined power cycle system for cooling incoming air with ammonia and water, comprising the following operating methods:

[0024] When the aircraft is in turbine-ramjet transition mode (Ma 2.5~Ma 3.5): the first and third valves are opened, and the second valve is closed. Incoming air enters the intake duct, is cooled by the reboiler, and then passes through the reboiler and condenser. The separator absorbs heat from the incoming air and the initial cooling energy of the ammonia-water mixture. Utilizing the different volatilities of the components in the ammonia-water mixture, water is separated at the bottom of the separator, and most of the ammonia is separated at the top. The ammonia then enters the condenser, where it is cooled by the ammonia-water mixture. Afterward, it enters the ammonia turbine, where the work done drives the fan for compression. The ammonia, having performed work, enters the heat exchanger for secondary air cooling and finally enters the main combustion chamber. The air in the combustion chamber is used as fuel for combustion. Air mixes with water separated from the bottom of the separator for a third cooling process, then enters the fan for compression. Afterward, it splits into two paths: one path enters the second mixer via the bypass duct to mix with the work-generated gas; the other path enters the compressor for compression. The compressed air then enters the main combustion chamber. Fuel stored in the aviation kerosene tank is pressurized by the aviation kerosene pump, with one path entering the main combustion chamber and the other entering the afterburner. The air entering the main combustion chamber mixes with fuel and ammonia for combustion, limiting the maximum exhaust temperature to 1437°C. The maximum outlet temperature of the main combustion chamber is maintained by adjusting the fuel flow rate. The high-temperature, high-pressure gas generated in the main combustion chamber is sequentially passed through the high-pressure turbine and low-pressure turbine for expansion and work, driving the compressor and fan to compress air. The work-generated gas enters the second mixer to mix with the bypass duct air, then enters the afterburner to mix with fuel for combustion, limiting the maximum exhaust temperature to 1877°C. The maximum outlet temperature of the afterburner is maintained by adjusting the fuel flow rate. The high-temperature, high-pressure gas generated in the afterburner is discharged through the nozzle, generating thrust. The engine employs a maximum speed and temperature control strategy to control the fuel quantity so that the engine's maximum physical speed reaches 100%; the adjustable nozzle adjusts the throat and outlet area to match the output flow rate, ensuring that the nozzle can output maximum thrust.

[0025] When the aircraft is in ram mode, i.e. Ma3.5~Ma5: the second valve is opened and the first and third valves are closed; the air coming from the engine directly enters the mixer, and then enters the afterburner to mix and burn with the fuel. The generated high-temperature gas is introduced into the nozzle to expand and accelerate, and is discharged at high speed to generate thrust.

[0026] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0027] Using ammonia-water as a precooling agent, combining heat exchanger precooling and jet precooling, the incoming air is precooled three times during the transition from turbine mode to ramjet mode. This significantly reduces the compressor temperature, increasing the compressor's equivalent speed at the same maximum physical speed, resulting in better aerodynamic performance. This achieves the dual effect of cooling the air and reducing aviation kerosene consumption, expanding the turbine engine's operating range and resolving the thrust gap during engine mode transitions. The high-temperature ammonia separated from the precooled working fluid after heat absorption is introduced into the turbine for expansion, driving the fan for compression, and then enters the main combustion chamber for combustion, improving combustion efficiency and stability. Aviation kerosene remains the primary fuel in both the main combustion chamber and afterburner. The total temperature in the main combustion chamber reaches 1437℃, ensuring stable ammonia co-combustion within the main combustion chamber. Furthermore, ammonia-water has an initial temperature that can reach -30°C, which is a significant advantage over water, whose initial temperature is limited by its freezing point. Ammonia-water also allows for flexible adjustment of the coolant dosage by changing its concentration, avoiding the problem that the amount of fuel required for pre-cooling is much greater than the amount required for combustion. Moreover, as a chemical produced in large quantities, ammonia-water has advantages such as low price, convenient storage, and clean combustion. Ammonia also has good vaporization and heat absorption capabilities as a coolant. Ammonia has a high density and a high calorific value per unit volume, allowing for smaller aircraft sizes and easier storage conditions.

[0028] This invention has two operating states. When Ma is 2.5~3.5, it is in turbo-ramjet switching mode, with the first and third valves open and the second valve closed. The ramjet bypass duct is not open, and the incoming air is cooled by ammonia-water. Ammonia and water are then separated by a separator. The ammonia further cools the air before it enters the main combustion chamber for combustion. The water further cools the air a third time before both entering the fan for compression. This lowers the engine inlet temperature and allows the gaseous ammonia, after heat exchange, to be injected into the main combustion chamber for combustion, achieving a better pre-cooling effect than other pre-cooling media. When Ma is 3.5~5, it is in ramjet mode, with the second valve open and the first and third valves closed. Air enters the engine intake, converting kinetic energy into pressure energy. The increased pressure and temperature allow it to enter the afterburner and mix with fuel for combustion, generating high-temperature combustion gas that expands and accelerates through the nozzle before being discharged at high speed to generate thrust. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the present invention;

[0030] In the diagram, 1-Intake, 2-Separator, 3-Condenser, 4-Reboiler, 5-Ammonia Turbine, 6-Heat Exchanger, 7-First Mixer, 8-Fan, 9-Compressor, 10-Aviation Kerosene Tank, 11-Aviation Kerosene Pump, 12-Main Combustion Chamber, 13-High Pressure Turbine, 14-Low Pressure Turbine, 15-Second Mixer, 16-Afterburner, 17-Nozzle, 18-First Valve, 19-Second Valve, 20-Third Valve. Detailed Implementation

[0031] like Figure 1 As shown, the present invention also discloses a combined power cycle system for cooling incoming air with ammonia and water, including an intake duct, a separator, a condenser, a reboiler, an ammonia turbine, a heat exchanger, a first mixer, a fan, a compressor, an aviation kerosene tank, an aviation kerosene pump, a main combustion chamber, a high-pressure turbine, a low-pressure turbine, a second mixer, an afterburner, a nozzle, a first valve, a second valve, and a third valve;

[0032] The main combustion chamber includes a fuel inlet, an air inlet, an ammonia inlet, and a gas outlet, which are used to perform preliminary combustion of fuel entering from the fuel inlet, air entering from the air inlet, and ammonia entering from the ammonia inlet, and then discharge the generated gas from its gas outlet.

[0033] The afterburner includes a fuel inlet, a gas inlet, and a gas outlet, for mixing and burning the fuel entering from its fuel inlet and the gas entering from its gas inlet, generating gas which is then discharged from its gas outlet.

[0034] The air intake inlet is connected to the outside air, and the outlet is connected to the inlet of the first valve and the inlet of the second valve;

[0035] The outlet of the first valve is connected to the hot end inlet of the reboiler, and the outlet of the second valve is connected to the air inlet of the second mixer.

[0036] The hot end outlet of the reboiler is connected to the hot end inlet of the heat exchanger, and the hot end outlet of the heat exchanger is connected to the air inlet of the first mixer.

[0037] The cold end inlet of the condenser is connected to ammonia water, and the cold end outlet is connected to the inlet of the separator.

[0038] The upper outlet of the separator is connected to the hot end inlet of the condenser, the lower outlet is connected to the cold end inlet of the reboiler, and the cold end outlet of the reboiler is connected to the water side inlet of the first mixer.

[0039] The hot end outlet of the heat exchanger is connected to the air inlet of the first mixer;

[0040] The hot end outlet of the condenser is connected to the inlet of the ammonia turbine, the outlet of the ammonia turbine is connected to the cold end inlet of the heat exchanger, and the cold end outlet of the heat exchanger is connected to the ammonia inlet of the main combustion chamber.

[0041] The outlet of the first mixer is connected to the fan inlet, and the fan outlet is connected to the compressor inlet and the air inlet of the second mixer, respectively.

[0042] The compressor outlet is connected to the air inlet of the main combustion chamber;

[0043] The outlet of the aviation kerosene tank is connected to the inlet of the aviation kerosene pump, and the outlet of the aviation kerosene pump is connected to the inlet of the third valve and the fuel inlet of the afterburner, respectively.

[0044] The outlet of the third valve is connected to the fuel inlet of the main combustion chamber;

[0045] The gas outlet of the main combustion chamber is connected to the inlet of the high-pressure turbine, and the outlet of the high-pressure turbine is connected to the inlet of the low-pressure turbine.

[0046] The outlet of the low-pressure turbine is connected to the gas inlet of the second mixer, and the outlet of the second mixer is connected to the gas inlet of the afterburner.

[0047] The gas outlet of the afterburner is connected to the nozzle inlet, and the nozzle outlet is connected to the outside.

[0048] This invention also discloses a method for operating a turbine-based combined power cycle system with ammonia-water cooling of incoming airflow, comprising the following operating steps:

[0049] When the aircraft is in turbine-ramjet conversion mode, i.e., Ma2.5~Ma3.5: the first and third valves are opened, and the second valve is closed; the incoming air from the engine enters the intake duct, is cooled by the reboiler, and the separator absorbs the heat of the incoming air and the initial cooling energy of the ammonia-water mixture through the reboiler and condenser. Utilizing the different volatility of the components in the ammonia-water mixture, water is precipitated at the bottom of the separator, and most of the ammonia is separated at the top; then the ammonia is passed into the condenser, cooled by the ammonia-water mixture, and then passed into the ammonia turbine. The work done is used to drive the fan for compression. The ammonia after work enters the heat exchanger for secondary cooling of the air, and finally enters the main combustion chamber as fuel for combustion; the air mixes with the water precipitated at the bottom of the separator for a third cooling, and then enters the fan for compression. Afterward, it is divided into two paths: one path enters the second mixer through the bypass duct to mix with the work-generated gas; the other path enters the compressor for compression. The compressed air enters the main combustion chamber to mix with the fuel and ammonia for combustion, limiting the maximum exhaust temperature to 1437℃. The maximum outlet temperature of the main combustion chamber is maintained by changing the fuel flow rate. The high-temperature, high-pressure gas generated in the main combustion chamber is sequentially fed into the high-pressure turbine and low-pressure turbine for expansion and work, driving the compressor and fan to compress air. The gas, after work, enters the second mixer to mix with the bypass air, and then enters the afterburner to mix with fuel for combustion. The maximum exhaust temperature is limited to 1877℃. The afterburner outlet temperature is maintained at its maximum value by adjusting the fuel flow rate. The high-temperature, high-pressure gas generated in the afterburner is discharged through the nozzle, generating thrust. The engine employs a maximum speed and temperature control strategy, controlling the fuel quantity to achieve 100% of the engine's maximum physical speed. The adjustable nozzle adjusts the throat and outlet area to match the output flow rate, ensuring the nozzle can output maximum thrust.

[0050] When the aircraft is in ram mode, i.e. Ma3.5~Ma5: the second valve is opened and the first and third valves are closed; the air coming from the engine directly enters the mixer, and then enters the afterburner to mix and burn with the fuel. The generated high-temperature gas is introduced into the nozzle to expand and accelerate, and is discharged at high speed to generate thrust.

Claims

1. A combined power cycle system for ammonia-water cooling of an incoming air stream, characterized by, Includes an intake duct (1), a separator (2), a condenser (3), a reboiler (4), an ammonia turbine (5), a heat exchanger (6), a first mixer (7), a fan (8), a compressor (9), an aviation kerosene tank (10), an aviation kerosene pump (11), a main combustion chamber (12), a high-pressure turbine (13), a low-pressure turbine (14), a second mixer (15), an afterburner (16), a nozzle (17), a first valve (18), a second valve (19), and a third valve (20); The main combustion chamber (12) includes a fuel inlet, an air inlet, an ammonia inlet, and a gas outlet, which are used to perform preliminary combustion of fuel entering from the fuel inlet, air entering from the air inlet, and ammonia entering from the ammonia inlet, and to generate gas that is discharged from its gas outlet. The afterburner (16) includes a fuel inlet, a gas inlet and a gas outlet, for mixing and burning the fuel entering from its fuel inlet and the gas entering from its gas inlet, generating gas which is then discharged from its gas outlet; The air intake (1) is connected to the outside air at its inlet and to the inlet of the first valve (18) and the inlet of the second valve (19) at its outlet. The outlet of the first valve (18) is connected to the hot end inlet of the reboiler (4), and the outlet of the second valve (19) is connected to the air inlet of the second mixer (15). The hot end outlet of the reboiler (4) is connected to the hot end inlet of the heat exchanger (6), and the hot end outlet of the heat exchanger (6) is connected to the air inlet of the first mixer (7). The cold end inlet of the condenser (3) is connected to ammonia water, and the cold end outlet is connected to the inlet of the separator (2); The upper outlet of the separator (2) is connected to the hot end inlet of the condenser (3), and the lower outlet is connected to the cold end inlet of the reboiler (4). The cold end outlet of the reboiler (4) is connected to the water side inlet of the first mixer (7). The hot end outlet of the condenser (3) is connected to the inlet of the ammonia turbine (5), the outlet of the ammonia turbine (5) is connected to the cold end inlet of the heat exchanger (6), and the cold end outlet of the heat exchanger (6) is connected to the ammonia inlet of the main combustion chamber (12). The outlet of the first mixer (7) is connected to the inlet of the fan (8), and the outlet of the fan (8) is connected to the inlet of the compressor (9) and the air inlet of the second mixer (15). The outlet of the compressor (9) is connected to the air inlet of the main combustion chamber (12); The outlet of the aviation kerosene tank (10) is connected to the inlet of the aviation kerosene pump (11), and the outlet of the aviation kerosene pump (11) is connected to the inlet of the third valve (20) and the fuel inlet of the afterburner (16), respectively. The outlet of the third valve (20) is connected to the fuel inlet of the main combustion chamber (12); The gas outlet of the main combustion chamber (12) is connected to the inlet of the high-pressure turbine (13), and the outlet of the high-pressure turbine (13) is connected to the inlet of the low-pressure turbine (14). The outlet of the low-pressure turbine (14) is connected to the gas inlet of the second mixer (15), and the outlet of the second mixer (15) is connected to the gas inlet of the afterburner (16). The gas outlet of the afterburner (16) is connected to the inlet of the nozzle (17), and the outlet of the nozzle (17) is connected to the outside.

2. The method of operating an ammonia-water combined power cycle system for cooling a stream of air according to claim 1, wherein, This includes the following working methods: When the aircraft is in the turbine-ramjet conversion state, i.e., Ma2.5~Ma3.5: open the first valve (18) and the third valve (20), and close the second valve (19); the incoming air from the engine enters the intake duct (1), is cooled by the reboiler (4), and the separator (2) absorbs the heat of the incoming air and the initial cold energy of the ammonia-water through the reboiler (4) and the condenser (3). Taking advantage of the different volatility of the components in the ammonia-water, water is separated at the bottom of the separator (2), and most of the ammonia is separated at the top; then the ammonia is passed into the condenser (3), cooled by the ammonia-water, and then passed into the ammonia turbine (5). The work done is used to drive the fan (8) for compression. The ammonia after the work is done enters the heat exchanger (6) for secondary cooling of the air, and finally enters the main combustion chamber (12) as supplementary fuel for combustion; the air is mixed with the water separated at the bottom of the separator (2) for a third cooling, and then enters the main combustion chamber (12) together. The air is compressed by the fan (8) and then split into two paths: one path enters the second mixer (15) through the bypass duct and mixes with the gas after it has done work; the other path enters the compressor (9) and is compressed. The compressed air then enters the main combustion chamber (12). The fuel stored in the aviation kerosene tank (10) is pressurized by the aviation kerosene pump (11) and enters the main combustion chamber (12) in one path and the other path enters the afterburner (16). The air entering the main combustion chamber (12) mixes with the fuel and ammonia and burns. The resulting high-temperature and high-pressure gas is then passed through the high-pressure turbine (13) and the low-pressure turbine (14) to expand and do work, driving the compressor (9) and the fan (8) to compress the air. The gas after it has done work enters the second mixer (15) and mixes with the air in the bypass duct. Then it enters the afterburner (16) and mixes with the fuel and burns. The high-temperature and high-pressure gas generated in the afterburner is discharged through the nozzle (17) to generate thrust. When the aircraft is in ram mode, i.e. Ma3.5~Ma5: open the second valve (19), close the first valve (18) and the third valve (20); the air from the engine directly enters the second mixer (15), and then enters the afterburner (16) to mix and burn with the fuel. The generated high-temperature gas is introduced into the nozzle (17) to expand and accelerate, and is discharged at high speed to generate thrust.

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