Low-pressure and high-temperature cold air preparation system and method adopting liquid nitrogen mixing

Abstract

The invention belongs to the technical field of thermal management of hypersonic aircrafts, and particularly relates to a low-pressure and high-temperature cold air preparation system and method adopting liquid nitrogen mixing, the system comprises a ramjet air inlet channel, the ramjet air inlet channel comprises a first section and a second section, the temperature and pressure of first section gas are larger than set values, and the temperature of second section gas is smaller than the set value; the cold air generating turbine is used for introducing a first section of gas of an air inlet channel of the ramjet and providing power for the cold air generating compressor through expansion work of the first section of gas; the cold air generating compressor introduces second-section gas, compresses and boosts the second-section gas through the power of a cold air generating turbine, and then discharges the compressed and boosted second-section gas into the high-pressure gas mixing chamber; the liquid nitrogen system is used for spraying atomized liquid nitrogen to the high-pressure gas machine mixing chamber; the high-pressure gas machine mixing chamber is used for carrying out mixing, heat exchange and phase change on the compressed and boosted second-section gas and atomized liquid nitrogen to form high-pressure and low-temperature mixed gas; and the vortex tube is used for leading out the high-pressure and low-temperature mixed gas and then enabling the high-pressure and low-temperature mixed gas to reach an airborne equipment cabin.

Description

Technical Field

[0001] The present application belongs to the field of hypersonic vehicle thermal management technology, and in particular relates to a system and method for producing low-pressure and high-temperature cold air using liquid nitrogen mixing. Background Art

[0002] A key challenge facing the development of hypersonic vehicles is the cooling of onboard equipment. With the advancement of aviation technology and the continuous increase in aircraft Mach numbers, the total temperature of the air surrounding the aircraft has increased, making direct bleed air cooling of onboard equipment impossible. Therefore, new methods for generating cooling air for onboard equipment are essential. Fuel regenerative cooling is currently a widely accepted form of aircraft cooling heat sink, but it has numerous drawbacks, including insufficient heat sink capacity within a limited volume; flammable and explosive fuel, resulting in a low safety factor; long-term contact between hydrocarbon fuel and piping structures, which can easily cause brittle breakage of metal materials; coking during the endothermic process of hydrocarbon fuel; and the complex catalytic cracking process of fuel, resulting in unstable cracking products. As hypersonic vehicles advance toward higher Mach numbers and altitudes, the development of efficient cooling air generation methods is essential. Summary of the Invention

[0003] In order to solve the above problems, the present application provides a low-pressure and high-temperature cold air production system using liquid nitrogen mixing, comprising:

[0004] The ramjet engine inlet comprises a first section and a second section, wherein the temperature and pressure of gas in the first section are greater than a set value, and the temperature of gas in the second section is less than the set value;

[0005] The cold air production turbine introduces the first section of gas from the ramjet inlet, and provides power to the cold air production compressor through the expansion of the first section of gas;

[0006] The cold air production compressor introduces the second stage gas, compresses and boosts the pressure of the second stage gas through the power of the cold air production turbine, and then discharges it into the mixing chamber of the high-pressure gas machine;

[0007] Liquid nitrogen system, used to spray atomized liquid nitrogen into the mixing chamber of the high-pressure gas machine;

[0008] The high-pressure gas mixing chamber mixes the compressed and pressurized second-stage gas with the atomized liquid nitrogen, exchanges heat and undergoes phase change to form a high-pressure and low-temperature mixed gas;

[0009] The vortex tube guides the high-pressure and low-temperature mixed gas out to the onboard equipment cabin for use as cooling air.

[0010] Preferably, the liquid nitrogen system includes a liquid nitrogen storage tank, a liquid nitrogen pump, a liquid nitrogen flow control valve, a flow meter and a nozzle; the liquid nitrogen storage tank sprays liquid nitrogen into the high-pressure gas mixing chamber through the nozzle via the liquid nitrogen pump, and the liquid nitrogen flow control valve and the flow meter are arranged between the nozzle and the liquid nitrogen pump.

[0011] Preferably, a temperature sensor is provided in the airborne equipment compartment, and the airborne control system controls the opening of the liquid nitrogen flow control valve according to the temperature sensor and the flow meter.

[0012] Preferably, a cold air flow valve is provided at the outlet of the cold air production compressor to control the outlet flow of the cold air production compressor.

[0013] A method for cooling low-pressure, high-temperature cold air using liquid nitrogen mixing, using the low-pressure, high-temperature cold air production system using liquid nitrogen mixing according to claim 4, comprising:

[0014] When the temperature of the airborne equipment compartment is lower than the first temperature, the liquid nitrogen system is shut down, and the airborne control system adjusts the opening of the cold air flow valve according to the temperature of the airborne equipment compartment;

[0015] When the temperature of the airborne equipment compartment is greater than or equal to the first temperature, the liquid nitrogen system is turned on, and the airborne control system adjusts the opening of the cold air flow valve and the opening of the liquid nitrogen flow control valve according to the temperature of the airborne equipment compartment.

[0016] When the temperature of the onboard equipment compartment is greater than or equal to the first temperature and less than the second temperature, the liquid nitrogen system is turned on, and the onboard control system adjusts the opening of the cold air flow valve and the opening of the liquid nitrogen flow control valve according to the temperature of the onboard equipment compartment, thereby reducing the temperature of the high-pressure gas mixing chamber to the rated operating temperature. Preferably, the rated operating temperature is 400K.

[0017] The advantages of this application include: 1. The liquid nitrogen cooling method has a fast cooling speed and good cooling effect, which can effectively solve the cooling problem of the onboard equipment compartment of a hypersonic aircraft. Liquid nitrogen cooling as a cold source has higher efficiency and a simpler structure than traditional fuel heat sinks and fuel cracking. In addition, nitrogen has stable chemical properties and is a typical inert gas. It has good safety and high reliability during the cooling and heat absorption process, is pollution-free to the environment, and does not damage onboard equipment.

[0018] 2. Liquid nitrogen has a low liquefaction temperature, and its endothermic gasification process involves chemical phase change. In addition, it is fully mixed with the high-temperature gas from the compressor in the high-pressure gas mixing chamber for heat exchange, which can effectively exert its cooling potential. Therefore, it is an efficient cooling heat sink.

[0019] 3. Considering the limited payload weight and space of the aircraft, it is difficult to load a large amount of liquid nitrogen for cooling. By mixing high-pressure gas with liquid nitrogen, the cooling effect of liquid nitrogen is amplified, the cooling capacity is increased, and the cooling advantages of liquid nitrogen are fully utilized.

[0020] 4. Since the amount of cooling air required by the onboard equipment under different operating conditions of the aircraft is different, the pressure and temperature parameters of the inlet gas also change at different flight altitudes and flight Mach numbers. The actual cooling air flow and cooling capacity requirements are constantly changing. The device takes into account the adjustment of the liquid nitrogen flow supply and can dynamically control the supply of liquid nitrogen cooling source according to the needs of the onboard equipment compartment. If necessary, the liquid nitrogen flow control valve can even be closed, and the required cooling air can be produced only by the cooling air production device, thereby saving liquid nitrogen consumption, extending the cooling endurance time, and further reducing the weight of the liquid nitrogen cooling source carried by the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A preferred embodiment of the present application is a low-pressure, high-temperature cold air production system using liquid nitrogen. DETAILED DESCRIPTION

[0022] To make the technical solution and its advantages of the present application clearer, the technical solution of the present application will be described in further detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of the present application and are only used to explain the present application, not to limit the present application. It should be noted that, for ease of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0023] like Figure 1 As shown, the present application provides a low-pressure and high-temperature cold air production system using liquid nitrogen mixing, comprising:

[0024] The ramjet engine inlet 9 includes a first section and a second section, wherein the temperature and pressure of the gas in the first section are greater than a set value, and the temperature of the gas in the second section is less than the set value;

[0025] The cold air production turbine 7 introduces the first stage gas of the ramjet inlet 9, and provides power for the cold air production compressor 8 through the expansion of the first stage gas;

[0026] The cold air production compressor 8 introduces the second stage gas, which is compressed and pressurized by the power of the cold air production turbine 7 and then discharged into the high-pressure gas mixing chamber 6;

[0027] Liquid nitrogen system, used for spraying atomized liquid nitrogen into the high-pressure gas mixing chamber 6;

[0028] The high-pressure gas mixing chamber 6 mixes the compressed and pressurized second-stage gas with the atomized liquid nitrogen, exchanges heat and undergoes phase change to form a high-pressure and low-temperature mixed gas;

[0029] The vortex tube 10 guides the high-pressure and low-temperature mixed gas out to the onboard equipment compartment 11 for use as cooling air.

[0030] Preferably, the liquid nitrogen system includes a liquid nitrogen storage tank 1, a liquid nitrogen pump 2, a liquid nitrogen flow control valve 3, a flow meter 4 and a nozzle 5; the liquid nitrogen storage tank 1 sprays liquid nitrogen into the high-pressure gas mixing chamber 6 through the nozzle 5 via the liquid nitrogen pump 2, and the liquid nitrogen flow control valve 3 and the flow meter 4 are arranged between the nozzle 5 and the liquid nitrogen pump 2.

[0031] Preferably, a temperature sensor is provided in the airborne equipment compartment 11 , and the airborne control system controls the opening of the liquid nitrogen flow control valve 3 according to the temperature sensor and the flow meter 4 .

[0032] Preferably, a cold air flow valve is provided at the outlet of the cold air production compressor 8 to control the outlet flow of the cold air production compressor 8 .

[0033] A method for cooling low-pressure, high-temperature cold air using liquid nitrogen mixing, using the low-pressure, high-temperature cold air production system using liquid nitrogen mixing according to claim 4, comprising:

[0034] When the temperature of the airborne equipment compartment 11 is lower than the first temperature, the liquid nitrogen system is turned off, and the airborne control system adjusts the opening of the cold air flow valve according to the temperature of the airborne equipment compartment 11;

[0035] When the temperature of the onboard equipment compartment 11 is greater than or equal to the first temperature, the liquid nitrogen system is turned on, and the onboard control system adjusts the opening of the cold air flow valve and the opening of the liquid nitrogen flow control valve 3 according to the temperature of the onboard equipment compartment 11.

[0036] When the temperature of the onboard equipment compartment 11 is greater than or equal to the first temperature and less than the second temperature, the liquid nitrogen system is turned on, and the onboard control system adjusts the opening of the cold air flow valve and the opening of the liquid nitrogen flow control valve 3 according to the temperature of the onboard equipment compartment 11, thereby reducing the temperature of the high-pressure gas mixing chamber 6 to the rated operating temperature. Preferably, the rated operating temperature is 400K.

[0037] One implementation method is: when the hypersonic aircraft reaches a certain operating state, the onboard equipment compartment cooling control system issues a command and the cold air production device proposed in the present invention is turned on. Figure 1 As shown, liquid nitrogen flow control valve 3 is open, liquid nitrogen pump 2 is operating, and liquid nitrogen coolant, under pressure, flows from liquid nitrogen storage tank 1 into the pipeline. The flow rate is measured by flow meter 4 and fed back to the onboard control system. When the cooling demand of the equipment cabin changes, the liquid nitrogen coolant flow rate can be controlled by liquid nitrogen flow control valve 3.

[0038] In the other branch, the cold air production turbine 7 takes gas with higher parameters from the ramjet engine intake 9. The gas expands and performs work in the turbine 7, driving the shaft to rotate. The cold air production compressor 8 obtains power and takes gas with lower temperature from the middle position of the ramjet engine intake 9. The gas is compressed and pressurized and then discharged into the high-pressure gas mixing chamber 6.

[0039] Liquid nitrogen flowing from the liquid nitrogen storage tank 1 enters the nozzle 5 in the high-pressure gas mixing chamber 6 along the pipeline, where it is atomized and sprayed out. In the high-pressure gas mixing chamber 6, it is fully mixed, heat-exchanged, and phase-changed with the high-temperature, high-pressure gas from the cold air production compressor 8, reducing the temperature of the high-pressure gas to approximately 400K. Finally, the mixed gas flows out of the outlet of the high-pressure gas mixing chamber 6 and enters the vortex tube 10. The high-pressure gas rotates at high speed in the vortex tube 10 to exchange heat, and the lower-temperature gas gathers at the center axis of the tube. After being drawn out of the vortex tube, it reaches the onboard equipment compartment for use as cold air.

[0040] When the cooling amount required for the onboard equipment decreases, the liquid nitrogen flow rate is reduced or even closed by adjusting the liquid nitrogen flow control valve 3, and only the cold air production turbine 7, the cold air production compressor 8 and the vortex tube 10 are in operation to save the consumption of liquid nitrogen coolant.

[0041] The advantages of this application include: 1. The liquid nitrogen cooling method has a fast cooling speed and good cooling effect, which can effectively solve the cooling problem of the onboard equipment compartment of a hypersonic aircraft. Liquid nitrogen cooling as a cold source has higher efficiency and a simpler structure than traditional fuel heat sinks and fuel cracking. In addition, nitrogen has stable chemical properties and is a typical inert gas. It has good safety and high reliability during the cooling and heat absorption process, is pollution-free to the environment, and does not damage onboard equipment.

[0042] 2. Liquid nitrogen has a low liquefaction temperature, and its endothermic gasification process involves chemical phase change. In addition, it is fully mixed with the high-temperature gas from the compressor in the high-pressure gas mixing chamber for heat exchange, which can effectively exert its cooling potential. Therefore, it is an efficient cooling heat sink.

[0043] 3. Considering the limited payload weight and space of the aircraft, it is difficult to load a large amount of liquid nitrogen for cooling. By mixing high-pressure gas with liquid nitrogen, the cooling effect of liquid nitrogen is amplified, the cooling capacity is increased, and the cooling advantages of liquid nitrogen are fully utilized.

[0044] 4. Since the amount of cooling air required by the onboard equipment under different operating conditions of the aircraft is different, the pressure and temperature parameters of the inlet gas also change at different flight altitudes and flight Mach numbers. The actual cooling air flow and cooling capacity requirements are constantly changing. The device takes into account the adjustment of the liquid nitrogen flow supply and can dynamically control the supply of liquid nitrogen cooling source according to the needs of the onboard equipment compartment. If necessary, the liquid nitrogen flow control valve can even be closed, and the required cooling air can be produced only by the cooling air production device, thereby saving liquid nitrogen consumption, extending the cooling endurance time, and further reducing the weight of the liquid nitrogen cooling source carried by the aircraft.

[0045] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A low-pressure, high-temperature cold air production system using liquid nitrogen mixing, characterized in that: include: The ramjet engine air inlet (9) comprises a first section and a second section, wherein the temperature and pressure of the gas in the first section are greater than a set value, and the temperature of the gas in the second section is less than the set value; The cold air production turbine (7) introduces the first section of gas from the ramjet engine inlet (9), and provides power for the cold air production compressor (8) through the expansion of the first section of gas; The cold air production compressor (8) introduces the second stage gas, compresses and increases the pressure of the second stage gas through the power of the cold air production turbine (7), and then discharges the second stage gas into the high-pressure gas mixing chamber (6); A liquid nitrogen system for spraying atomized liquid nitrogen into the high-pressure gas mixing chamber (6); The high-pressure gas mixing chamber (6) mixes the compressed and pressurized second-stage gas with the atomized liquid nitrogen, exchanges heat and undergoes phase change to form a high-pressure and low-temperature mixed gas; The vortex tube (10) leads the high-pressure and low-temperature mixed gas out to the onboard equipment cabin (11) for use as cooling air.

2. The low-pressure, high-temperature cold air production system using liquid nitrogen as claimed in claim 1, characterized in that: The liquid nitrogen system comprises a liquid nitrogen storage tank (1), a liquid nitrogen pump (2), a liquid nitrogen flow control valve (3), a flow meter (4) and a nozzle (5); the liquid nitrogen storage tank (1) sprays liquid nitrogen into a high-pressure gas mixing chamber (6) through a nozzle (5) via the liquid nitrogen pump (2); the liquid nitrogen flow control valve (3) and the flow meter (4) are arranged between the nozzle (5) and the liquid nitrogen pump (2).

3. The low-pressure, high-temperature cold air production system using liquid nitrogen as claimed in claim 2, characterized in that: A temperature sensor is provided in the onboard equipment compartment (11), and the onboard control system controls the opening of the liquid nitrogen flow control valve (3) according to the temperature sensor and the flow meter (4).

4. The low-pressure, high-temperature cold air production system using liquid nitrogen as claimed in claim 2, characterized in that: A cold air flow valve is provided at the outlet of the cold air production compressor (8) for controlling the outlet flow of the cold air production compressor (8).

5. A low-pressure, high-temperature cold air cooling method using liquid nitrogen admixture, characterized in that: The low-pressure, high-temperature cold air production system using liquid nitrogen admixture as claimed in claim 4 comprises: When the temperature of the onboard equipment compartment (11) is lower than a first temperature, the liquid nitrogen system is shut down, and the onboard control system adjusts the opening of the cold air flow valve according to the temperature of the onboard equipment compartment (11); When the temperature of the onboard equipment compartment (11) is greater than or equal to a first temperature, the liquid nitrogen system is turned on, and the onboard control system adjusts the opening of the cold air flow valve and the opening of the liquid nitrogen flow control valve (3) according to the temperature of the onboard equipment compartment (11).

6. The low-pressure, high-temperature cold air production system using liquid nitrogen as claimed in claim 5, characterized in that: When the temperature of the onboard equipment compartment (11) is greater than or equal to the first temperature and less than the second temperature, the liquid nitrogen system is turned on, and the onboard control system adjusts the opening of the cold air flow valve and the opening of the liquid nitrogen flow control valve (3) according to the temperature of the onboard equipment compartment (11), so that the temperature of the high-pressure gas mixing chamber (6) is reduced to the rated operating temperature.

7. The low-pressure, high-temperature cold air production system using liquid nitrogen as claimed in claim 5, characterized in that: The rated operating temperature is 400K.

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