A high-temperature fuel heat sink semi-closed air cycle aircraft environmental control system and method

Abstract

The present application provides a high-temperature fuel heat sink semi-closed air cycle aircraft environmental control system and method, which belongs to the field of aerospace. The system provided in the present application includes at least a first-pressure compressor, a second-pressure compressor, a first-temperature fuel heat exchanger, and a second-temperature fuel heat exchanger; the outlet of the first-pressure compressor is connected to the first passage inlet of the first-temperature fuel heat exchanger, and the supplementary air enters the first-temperature fuel heat exchanger after being pressurized and heated for the first time by the first-pressure compressor; the first passage outlet of the first-temperature fuel heat exchanger is connected to the inlet of the second-pressure compressor, and the outlet of the second-pressure compressor is connected to the first passage inlet of the second-temperature fuel heat exchanger; the first passage outlet of the second-temperature fuel heat exchanger is connected to the inlet of the first-pressure compressor via the cabin fresh air device and the electronic equipment heat dissipation device respectively. The system and method provided in the present application can reduce the heat transfer temperature difference, heat transfer loss, and compressor pressure ratio in the initial stage of fuel heat exchange, thereby improving system performance.

Description

Technical Field

[0001] The present application relates to the field of aviation electromechanical technology, and in particular to an environmental control system and method for a high-temperature fuel heat sink semi-closed air cycle aircraft. Background Art

[0002] The primary method for achieving aircraft environmental control is to use air circulation to transfer heat from the cabin and electronic equipment to heat sinks such as fuel and ram air, and to provide fresh air to the cabin.

[0003] However, as aircraft speeds increase, the use of ram air heat sinks becomes limited. This increased speed has two primary impacts on heat sinks: first, the increased influence of ram air holes on the aircraft's aerodynamic shape, significantly increasing flight drag and fuel consumption, limiting the use of ram air. Second, the overall temperature of the airframe's surface increases, raising the initial temperature of the ram air and making heat dissipation to the ram air more difficult.

[0004] With increasingly stringent ram air operating conditions, the environmental control system dissipates significant amounts of heat into the fuel, deteriorating the temperature matching between the air cycle and the fuel. To increase the fuel system's thermal capacity, the temperature difference between the fuel entering and exiting the environmental control system needs to be increased, allowing the fuel to absorb more heat per unit mass. Conventional solutions require that the air temperature be higher than the fuel outlet temperature in order for the air cycle to release heat to the fuel. This results in a large temperature difference and high heat transfer losses when exchanging heat between the low-temperature air and fuel. Furthermore, using a single compression cycle to raise the air temperature above the high-temperature fuel temperature results in a high compressor pressure ratio and low efficiency, further deteriorating system performance. Summary of the Invention

[0005] In view of this, the present application provides a high-temperature fuel heat sink semi-closed air cycle aircraft environmental control system and method, which can reduce the heat transfer temperature difference, heat transfer loss and compressor pressure ratio in the initial stage of fuel heat exchange, and improve system performance.

[0006] Specifically, this application is implemented through the following technical solutions:

[0007] In a first aspect, the present application provides a semi-closed air cycle aircraft environmental control system with a high-temperature fuel heat sink, the system comprising at least a first-pressure compressor, a second-pressure compressor, a first-temperature fuel heat exchanger, and a second-temperature fuel heat exchanger, wherein the ambient pressure of the first-pressure compressor is lower than the ambient pressure of the second-pressure compressor;

[0008] The outlet of the first-pressure compressor is connected to the inlet of the first passage of the first-temperature fuel heat exchanger, and the supplementary air enters the first-temperature fuel heat exchanger after being pressurized and heated for the first time by the first-pressure compressor; wherein the input air undergoes a first heat exchange with the first-temperature fuel in the first-temperature heat exchanger, and the temperature difference between the first-temperature fuel and the input air is less than a preset threshold;

[0009] The outlet of the first passage of the fuel first temperature heat exchanger is connected to the inlet of the second pressure compressor, and the outlet of the second pressure compressor is connected to the inlet of the first passage of the fuel second temperature heat exchanger; the air after the first heat exchange is input into the second pressure compressor for a second pressure and temperature increase, and then enters the fuel second temperature heat exchanger for a second heat exchange, and the temperature difference between the second temperature fuel and the temperature of the input air for the second heat exchange is less than a preset threshold;

[0010] The outlet of the first passage of the fuel second temperature heat exchanger is connected to the inlet of the first pressure compressor through the cabin fresh air device and the electronic equipment heat dissipation device respectively.

[0011] A second aspect of the present application provides an environmental control method for a semi-closed air cycle aircraft with a high-temperature fuel heat sink, the method comprising:

[0012] The supplementary air is input into the first pressure compressor for compression, and the pressure and temperature are increased for the first time. The obtained first pressure air is input into the first temperature heat exchanger for fuel oil for heat exchange, and the first heat absorption is performed.

[0013] The first pressure air after heat exchange is input into the second pressure compressor for compression, and the pressure and temperature are increased for the second time. The second pressure air is input into the second temperature heat exchanger for fuel oil for heat exchange, and the second heat absorption is performed.

[0014] The second pressure air after heat exchange is used to provide fresh air to the cabin and cooling for electronic equipment.

[0015] The environmental control system and method for a semi-closed air cycle aircraft with a high-temperature fuel heat sink provided by this application, firstly, achieves optimal matching of air and fuel at different temperature stages by providing two compressors with different ambient pressures and two heat exchangers with different temperatures. During the first heat exchange, the make-up air, after being pressurized and heated by the first-pressure compressor, exchanges heat with the first-temperature fuel in the first-temperature fuel heat exchanger, where the temperature difference is less than a preset threshold. This minimizes heat transfer temperature differences and reduces losses. Similarly, during the second heat exchange, the air exchanges heat with the second-temperature fuel in the second-temperature fuel heat exchanger, where the temperature difference is less than a preset threshold. This also ensures efficient heat transfer. By providing two high- and low-temperature fuel heat exchange processes, the initial heat transfer temperature difference is reduced, minimizing heat transfer losses and effectively utilizing the fuel heat sink. Secondly, the use of two compressors with different pressures—a first- and a second-pressure compressor—divides the compression process into two stages. The first-pressure compressor, with its lower ambient pressure, initially pressurizes and heats the air, avoiding the high compressor pressure ratio problem associated with traditional single-stage compression, which results from the need to release heat to the high-temperature fuel. This splitting of the compression process into two stages, coupled with intercooling, not only reduces the single-stage pressure ratio but also lowers the high-pressure stage inlet temperature, improving compressor and system performance. Thirdly, after leaving the fuel secondary temperature heat exchanger, the circulating air first provides fresh air to the cabin and then cools the electronic equipment. This tiered cooling design ensures a comfortable cabin temperature while preventing overheating of the electronic equipment, thereby improving equipment reliability and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural diagram of the first embodiment of the high-temperature fuel heat sink semi-closed air cycle aircraft environmental control system provided by this application;

[0017] Figure 2 This is a flow chart of Example 1 of the environmental control method for a semi-closed air cycle aircraft with a high-temperature fuel heat sink provided in this application;

[0018] Description of reference numerals:

[0019] 1-Shaft power input device; 2-Low-pressure compressor; 3-High-pressure compressor; 4-Expander; 5-Water separator; 6-Fuel low-temperature heat exchanger; 7-Fuel high-temperature heat exchanger; 8-Regenerator; 9-Electronic equipment cooling device; 10-Cabin fresh air device. DETAILED DESCRIPTION

[0020] Exemplary embodiments are described in detail herein, with examples illustrated in the accompanying drawings. When the following description refers to the drawings, identical numerals in different drawings represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with this application.

[0021] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms "a," "the," and "the" used in this application are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0022] It should be understood that although the terms first, second, third, etc. may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0023] Specific embodiments are given below to introduce the technical solutions of the present application in detail.

[0024] Figure 1 This is a structural diagram of the first embodiment of the high-temperature fuel heat sink semi-closed air cycle aircraft environmental control system provided by this application. Figure 1 The system provided in this embodiment includes at least a first-pressure compressor 2, a second-pressure compressor 3, a first-temperature fuel oil heat exchanger 6, and a second-temperature fuel oil heat exchanger 7. The ambient pressure of the first-pressure compressor 2 is lower than the ambient pressure of the second-pressure compressor 3.

[0025] The outlet of the first-pressure compressor 2 is connected to the inlet of the first passage of the first-temperature fuel heat exchanger 6. The supplementary air enters the first-temperature fuel heat exchanger 6 after being pressurized and heated for the first time by the first-pressure compressor 2. The input air undergoes a first heat exchange with the first-temperature fuel in the first-temperature heat exchanger 6. The temperature difference between the first-temperature fuel and the input air is less than a preset threshold.

[0026] The first passage outlet of the fuel first temperature heat exchanger 6 is connected to the inlet of the second pressure compressor 3, and the outlet of the second pressure compressor 3 is connected to the first passage inlet of the fuel second temperature heat exchanger 7; the air after the first heat exchange is input into the second pressure compressor 3 for a second pressure and temperature increase, and then enters the fuel second temperature heat exchanger 7 for a second heat exchange, and the temperature difference between the second temperature fuel and the second heat exchange input air is less than a preset threshold;

[0027] The first passage outlet of the fuel second temperature heat exchanger 7 is connected to the inlet of the first pressure compressor 2 through the cabin fresh air device 10 and the electronic equipment heat dissipation device 9 respectively.

[0028] It should be noted that in this system, the supplemental air flowing in from an air source such as the engine first enters the first pressure compressor 2 for compression, causing the air pressure and temperature to increase, i.e., the first pressure and temperature increase. The specific principle of the pressure and temperature increase is that the frequency of collisions between gas molecules increases during the compression process, thereby increasing the internal energy. The pressure- and temperature-boosted air then flows out of the outlet of the first pressure compressor 2 and enters the first-temperature fuel heat exchanger 6 for heat exchange with the first-temperature fuel therein. The heat exchange here is typically a partition-type heat exchange, i.e., the air and fuel transfer heat through the heat exchange wall surface rather than direct contact. This not only ensures effective heat transfer, but also avoids direct mixing between the air and fuel, ensuring safe operation of the system.

[0029] During the heat exchange process, incoming air exchanges heat with the first-temperature fuel. The air's heat is absorbed by the first-temperature fuel, causing the air temperature to drop while the first-temperature fuel's temperature to rise. To ensure system heat exchange efficiency and control heat exchanger load, the temperature difference between the first-temperature fuel and the incoming air should be kept below a preset threshold. This keeps the air and first-temperature fuel temperatures closer together, minimizing the heat transfer temperature difference and reducing heat losses during the transfer process, thereby improving heat exchange efficiency. The preset threshold is set based on actual needs.

[0030] It should be noted that after the air undergoes the first heat exchange with the first-temperature fuel in the first-temperature fuel heat exchanger 6, its temperature and pressure have already been partially reduced. At this point, the heat-exchanged air flows out of the first passage outlet of the first-temperature fuel heat exchanger 6 and is fed into the second-pressure compressor 3, which performs a second compression on the air that has undergone the first heat exchange. During this process, the air's pressure further increases, and with compression, the air's temperature also rises. Compared to the first compression, this second pressure and temperature increase brings the air to a higher pressure and temperature, facilitating further heat exchange. The air, after the second pressure and temperature increase, flows out of the outlet of the second-pressure compressor 3 and enters the second-temperature fuel heat exchanger 7. In the second-temperature heat exchanger 7, the air undergoes a second heat exchange with the even hotter second-temperature fuel. Heat is transferred from the air to the second-temperature fuel, causing the air temperature to decrease again while the second-temperature fuel temperature increases. Similar to the first heat exchange, the temperature difference between the second-temperature air and the second-temperature fuel in the second-temperature fuel heat exchanger 7 is also less than a preset threshold.

[0031] It should be noted that the ambient pressure of the first-pressure compressor 2 is lower than that of the second-pressure compressor 3, and the fuel temperature in the first-temperature fuel heat exchanger 6 is lower than that in the second-temperature fuel heat exchanger 7. Temperature matching is crucial throughout the heat transfer process. A smaller temperature difference between air and fuel can reduce the heat transfer temperature difference, minimize heat losses during heat transfer, and improve heat exchange efficiency. The make-up air first enters the first-pressure compressor 2, where the ambient pressure is lower, for a first pressurization and temperature increase. At this point, the air temperature is relatively low. It then enters the first-temperature fuel heat exchanger 6, where the temperature difference between the two is less than a preset threshold, achieving good temperature matching between the air and the low-temperature fuel. After the first heat exchange and the second pressurization and temperature increase, the air enters the second-temperature fuel heat exchanger 7 for a second heat exchange with the high-temperature fuel. Similarly, the temperature difference is maintained below a preset threshold, ensuring efficient heat exchange between the air and the high-temperature fuel. This arrangement allows the air temperature to gradually increase during circulation, gradually matching the temperature of the fuel. The heat exchange from relatively low-temperature air and low-temperature fuel to relatively high-temperature air and high-temperature fuel complies with the natural law of heat transfer and is conducive to the system efficiently transferring heat from air to fuel.

[0032] Specifically, by dividing the air compression process into two stages, initial compression (at a lower pressure) is performed in the first-pressure compressor 2, followed by further compression (at a higher pressure) in the second-pressure compressor 3. This avoids the need for high-pressure compression using only a single-stage compressor. This would require the system to compress the air to a higher pressure all at once, resulting in greater energy consumption and potentially excessively high air temperatures, impacting the efficiency of the heat exchanger. By providing two heat exchangers (a fuel-fired first-temperature heat exchanger and a fuel-fired second-temperature heat exchanger), with the first heat exchanger at a lower temperature than the second, the air temperature is gradually lowered during the staged heat exchange process, further improving the system's cooling efficiency.

[0033] Please continue to refer to Figure 1The second outlet of the first-temperature fuel heat exchanger 6 is connected to the second inlet of the second-temperature fuel heat exchanger 7. After undergoing inter-wall heat exchange in the first-temperature fuel heat exchanger 6, the fuel is heated and flows into the second-temperature fuel heat exchanger 7. By initially exchanging heat in the first-temperature fuel heat exchanger 6 before continuing to absorb heat in the second-temperature fuel heat exchanger 7, the fuel temperature is smoothly raised from a lower to a higher level, avoiding the sudden temperature increase that would occur in a single heat exchanger. After the initial heat absorption in the first-temperature fuel heat exchanger 6, the fuel temperature rises, but a certain temperature difference still exists compared to the air after the second pressurization and temperature increase. In the second-temperature fuel heat exchanger, the temperature difference between the fuel and the air remains within an appropriate range, allowing for continued efficient heat absorption. This staged heat exchange and gradual heat absorption optimizes system heat exchange efficiency, improves the heat sink efficiency of the fuel, reduces heat load pressure, and improves the overall energy efficiency of the system.

[0034] It should also be noted that the system also includes a regenerator 8, a water splitter 5 and an expander 4. The first passage outlet of the fuel second temperature heat exchanger 7 is connected to the first passage inlet of the regenerator 8, and the first passage outlet of the regenerator 8 is connected to the inlet of the expander 4 through the water splitter 5; the air flowing out of the fuel second temperature heat exchanger 7 is cooled and separated from water in turn and then flows into the expander 4; the outlet of the expander 4 is connected to the second passage inlet of the regenerator 8, and the air after expansion and cooling flows into the regenerator 8 to absorb heat.

[0035] Among them, the temperature of the air flowing out of the fuel oil second temperature heat exchanger 7 is relatively high and may contain moisture. After the cooling effect of the regenerator, the temperature of the air is reduced, and the moisture in the air may condense. Water separation is performed through the water divider 5 to remove the moisture in the air, preventing the air from being further cooled in the subsequent expander 4 due to excessive moisture content, which may cause adverse effects such as condensation and frost.

[0036] Expander 4 further reduces the air temperature through the expansion process. Expansion is an isentropic process, and the air temperature drops significantly after expansion. The expanded, cool air then enters regenerator 8, exchanging heat with the hot air in the system. This cooler air absorbs the excess heat from the hot air in regenerator 8, further improving the system's energy efficiency.

[0037] Please continue to refer to Figure 1The second outlet of the regenerator 8 is connected to the inlet of the cabin fresh air device 10. Part of the air output from the second outlet of the regenerator 8 provides fresh air for the cabin. The outlet of the cabin fresh air device 10 is connected to the inlet of the electronic equipment heat sink 9. The remaining air flowing through the cabin fresh air device 10 provides cooling for the electronic equipment. The outlet of the electronic equipment heat sink 9 is connected to the inlet of the first pressure compressor 2. The final portion of air flowing out of the electronic equipment heat sink 9 is combined with supplementary air from the air source and flows into the first pressure compressor 2. By properly distributing air between the cabin and the electronic equipment, effective control can be achieved based on different cooling requirements. The cabin requires relatively mild temperature control, while the electronic equipment requires cooler air for heat dissipation. Through segmented processing, the system can achieve different temperature adjustments in different areas, ensuring more precise and efficient thermal management of the overall system.

[0038] The air that has passed through the cabin and electronic equipment is returned to the system to merge with the make-up air and enter the first pressure compressor for re-compression. This semi-closed cycle design uses the return air for cooling, achieving air recycling. The system reduces the load demand on the compressor and reduces the power consumption of the compressor.

[0039] It should also be noted that the system also includes a shaft power input device 1, which is connected to the first pressure compressor 2 and arranged coaxially with the first pressure compressor 2, the second pressure compressor 3, and the expander 4. The shaft power input device 1 is provided to replenish energy for the entire system. During the air circulation process, the first pressure compressor 2, the second pressure compressor 3, and the expander 4 all consume energy to complete processes such as air compression and expansion. The shaft power input device 1 provides additional energy to ensure the proper functioning of these components. By coaxially arranging the first pressure compressor 2, the second pressure compressor 3, and the expander 4, and providing power to the system through the shaft power input device 1, direct power transmission is achieved, reducing energy losses in mechanical transmission. Compared to systems with separate arrangements, energy transfer is more efficient and power losses caused by multi-stage transmission are avoided. Furthermore, by designing multiple devices coaxially, the system can reduce independent transmission devices and components, reducing system complexity, helping to reduce the overall size and weight of the aircraft environmental control system and improving the power-to-weight ratio of the aircraft environmental control system.

[0040] The semi-closed air cycle aircraft environmental control system with a high-temperature fuel heat sink provided in this embodiment, firstly, achieves optimal matching of air and fuel at different temperature stages by providing two compressors with different ambient pressures and two heat exchangers with different temperatures. During the first heat exchange, the supplemental air, after being pressurized and heated by the first-pressure compressor, exchanges heat with the first-temperature fuel in the first-temperature fuel heat exchanger, where the temperature difference is less than a preset threshold. This minimizes heat transfer temperature differences and reduces losses. Similarly, during the second heat exchange, the air exchanges heat with the second-temperature fuel in the second-temperature fuel heat exchanger, where the temperature difference is less than a preset threshold. This also ensures efficient heat transfer. By providing two high- and low-temperature fuel heat exchange processes, the initial heat transfer temperature difference is reduced, minimizing heat transfer losses and effectively utilizing the fuel heat sink. Secondly, the use of two compressors with different pressures—a first- and a second-pressure compressor—divides the compression process into two stages. The first-pressure compressor, with its lower ambient pressure, initially pressurizes and heats the air, avoiding the problem of excessively high compressor pressure ratios caused by traditional single-stage compression to meet the heat release requirement for the high-temperature fuel. This splits the compression process into two stages, coupled with intercooling, not only reduces the single-stage pressure ratio but also lowers the high-pressure stage inlet temperature, improving compressor and system performance. Thirdly, after leaving the fuel secondary temperature heat exchanger, the circulating air first provides fresh air to the cabin and then cools the electronic equipment. This staged cooling design ensures a comfortable cabin temperature while preventing overheating of the electronic equipment, improving equipment reliability and stability. Furthermore, through two-stage compression, two heat exchanges, and a semi-closed air circulation system, the air output from the fuel secondary temperature heat exchanger is recycled, passing through the cabin fresh air supply and electronic equipment cooling system before returning to the primary pressure compressor inlet to merge with the make-up air. This reduces the amount of external air input required for the system, lowering energy consumption and improving system efficiency.

[0041] Figure 2 This is a flow chart of the first embodiment of the environmental control method for a semi-closed air cycle aircraft with a high-temperature fuel heat sink provided by this application. Figure 2 , based on the above system embodiment, the method includes:

[0042] S201, inputting the supplementary air into the first pressure compressor for compression, performing the first pressure and temperature increase, and inputting the first pressure air into the first temperature heat exchanger for fuel oil for heat exchange, performing the first heat absorption.

[0043] It should be noted that the first-temperature fuel is input into the first-temperature fuel heat exchanger, where it undergoes inter-wall heat exchange with the air that has been pressurized and heated for the first time. The temperature difference between the air that has been pressurized and heated for the first time and the first-temperature fuel is less than a preset threshold. In a specific implementation, external supplemental air is first input into the first-pressure compressor. Due to the lower ambient pressure of the first-pressure compressor, it compresses the incoming air, increasing its pressure and temperature, completing the first pressurization and temperature increase. At this point, the state of the supplemental air changes, and it can be recorded as first-pressure air. The first-pressure air is then fed into the first-temperature fuel heat exchanger for inter-wall heat exchange, exchanging heat with the first-temperature fuel. During the heat exchange process, the air releases some heat, lowering its temperature, while the fuel absorbs heat, raising its temperature. Furthermore, during this process, the temperature difference between the first-pressure air and the first-temperature fuel is designed to be less than a preset threshold, thereby achieving efficient heat exchange.

[0044] S202: The first-pressure air after heat exchange is input into the second-pressure compressor for compression, and the pressure and temperature are increased for the second time. The obtained second-pressure air is input into the second-temperature heat exchanger for fuel oil for heat exchange, and the second heat absorption is performed.

[0045] Specifically, the purpose of the first and second pressure and temperature increases is to reduce the heat transfer difference between the fuel and the air and improve heat sink utilization. Therefore, the temperature required for the first pressure and temperature increase is determined by the temperature of the incoming supplemental air. A heat transfer difference for optimal heat sink utilization is determined, a temperature difference is calculated based on this heat transfer difference, a first air target temperature is calculated based on this temperature difference and the fuel temperature of the first-temperature fuel heat exchanger, and the first pressure and temperature increase of the supplemental air is performed based on the first air target temperature. Similarly, a heat transfer difference for optimal heat sink utilization is determined for the second-temperature fuel heat exchanger, a temperature difference is calculated based on this heat transfer difference, a second air target temperature is calculated based on this temperature difference and the fuel temperature of the second-temperature fuel heat exchanger, and the second pressure and temperature increase is performed based on the second air target temperature.

[0046] It should be noted that the fuel at the second temperature is output from the first-temperature fuel heat exchanger and enters the second-temperature fuel heat exchanger, where it undergoes inter-wall heat exchange with the air that has been pressurized and heated for the second time, producing fuel at a third temperature. The third-temperature fuel is higher than the second-temperature fuel. In practice, after the initial heat exchange in the first-temperature fuel heat exchanger, the air temperature has already dropped. This cooled first-pressure air is then fed into the second-pressure compressor for further compression. In the second-pressure compressor, the air is compressed again, further increasing both its pressure and temperature, completing the second pressurization and heating. At this point, the state of the first-pressure air output after the first heat exchange has changed and can be recorded as second-pressure air. The second-pressure air enters the second-temperature fuel heat exchanger, where it undergoes a second heat exchange with the higher-temperature fuel. The air releases some heat, while the fuel absorbs this heat, further increasing its temperature. Similarly, the temperature difference between the second-pressure air and the second-temperature fuel remains within a preset threshold, ensuring heat exchange stability and efficiency. The purpose of this second heat exchange is to further reduce the air temperature.

[0047] It should be noted that the temperature difference between the air after the first pressurization and heating and the fuel at the first temperature is smaller than the temperature difference between the supplemental air and the fuel at the first temperature; and the temperature difference between the air after the second pressurization and heating and the fuel at the second temperature is smaller than the temperature difference between the air after the first pressurization and heating and the fuel at the second temperature. This ensures a small heat transfer temperature difference between the air and the fuel during the heat exchange process, allowing heat to be transferred more efficiently from the air to the fuel, improving the efficiency of the entire heat exchange process. Furthermore, due to the more efficient heat transfer, the need for over-compression of the air to meet heat exchange requirements can be reduced to a certain extent, thereby reducing compressor power consumption and improving the overall energy efficiency of the system.

[0048] It should also be noted that the second-pressure air after heat exchange is sequentially fed into a regenerator, a water separator, and an expander. After cooling, water separation, and expansion and cooling, it flows through the expander into the regenerator to absorb heat. The temperature of the air after expansion and cooling is lower than the temperature of the make-up air entering from the inlet of the first-pressure compressor. Specifically, after the second heat exchange, the air temperature is still relatively high. In this case, the second-pressure air after heat exchange is fed into the regenerator. The regenerator cools the high-temperature air by exchanging heat with the low-temperature air and recovers some of the heat. After initial cooling in the regenerator, the air enters the water separator, where moisture is separated. During the cooling process, water vapor condenses into liquid water. The water separator effectively removes this liquid water, preventing it from affecting equipment efficiency or damaging the system. The air is then fed into the expander. In the expander, the air rapidly cools due to volume expansion. Finally, the cooled air flows into the regenerator again, exchanging heat with the high-temperature air. At this point, the expanded cold air absorbs the heat released by the hot air, further cooling it while also slightly increasing its own temperature. The expanded air is significantly cooler, typically lower than the temperature of the make-up air entering from the first compressor inlet. This temperature difference can be used for a new round of heat exchange, helping to improve the energy efficiency of the entire system.

[0049] S203: Utilize the second pressure air after heat exchange to sequentially provide fresh air to the cabin and provide cooling for electronic equipment.

[0050] It should be noted that the second-pressure air after heat exchange is used to sequentially provide fresh air to the cabin and cooling for electronic equipment. Specifically, the air output from the regenerator after absorbing heat is divided into a first portion and a second portion according to its intended destination. These destinations include the cabin and electronic equipment. The first portion is used to provide fresh air to the cabin, while the second portion is used to cool the electronic equipment. The second portion of air, after providing cooling for the electronic equipment, is combined with supplemental air from the air source and fed into the first-pressure compressor, completing a semi-closed air cycle. By distributing the regenerator's output air on demand, the different target areas (the cabin and electronic equipment) receive the appropriate temperature and flow rate, ensuring both passenger comfort and safe equipment operation. Furthermore, the air is distributed to the cabin and electronic equipment on demand, and the system can adjust the air distribution ratio based on actual needs, ensuring precise and reliable temperature control across different functional areas to accommodate varying flight conditions or mission requirements. In addition, the air cooled by the electronic equipment is not discharged directly, but merges with the supplementary air and enters the first pressure compressor, completing a semi-closed cycle. This not only avoids energy waste, but also ensures the recycling of air and improves the overall energy efficiency of the system.

[0051] The environmental control method for a semi-closed air cycle aircraft with a high-temperature fuel heat sink provided in this embodiment sets up a two-stage fuel heat exchange and a two-stage compression process, thereby improving the temperature matching of the entire fuel heat exchange process and the efficiency of the air compression process.

[0052] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A high-temperature fuel heat sink semi-closed air cycle aircraft environmental control system, characterized in that: The system comprises at least a first-pressure compressor, a second-pressure compressor, a first-temperature fuel oil heat exchanger, and a second-temperature fuel oil heat exchanger, wherein the ambient pressure of the first-pressure compressor is lower than the ambient pressure of the second-pressure compressor; The outlet of the first-pressure compressor is connected to the inlet of the first passage of the first-temperature fuel heat exchanger, and the supplementary air enters the first-temperature fuel heat exchanger after being pressurized and heated for the first time by the first-pressure compressor; wherein the input air undergoes a first heat exchange with the first-temperature fuel in the first-temperature heat exchanger, and the temperature difference between the first-temperature fuel and the input air is less than a preset threshold; The outlet of the first passage of the fuel first temperature heat exchanger is connected to the inlet of the second pressure compressor, and the outlet of the second pressure compressor is connected to the inlet of the first passage of the fuel second temperature heat exchanger; the air after the first heat exchange is input into the second pressure compressor for a second pressure and temperature increase, and then enters the fuel second temperature heat exchanger for a second heat exchange, and the temperature difference between the second temperature fuel and the temperature of the input air for the second heat exchange is less than the preset threshold; The outlet of the first passage of the fuel second temperature heat exchanger is connected to the inlet of the first pressure compressor via the cabin fresh air device and the electronic equipment heat dissipation device in sequence; The temperature required for the first pressure and temperature increase is determined by the temperature of the input supplemental air. A heat transfer difference for optimal heat sink utilization is determined, a temperature difference is calculated based on the heat transfer difference, a first air target temperature is calculated based on the temperature difference and the fuel temperature of the first fuel temperature heat exchanger, and the pressure and temperature of the supplemental air are first increased and increased based on the first air target temperature. A heat transfer difference for optimal heat sink utilization is determined in the second fuel temperature heat exchanger, a temperature difference is calculated based on the heat transfer difference, a second air target temperature is calculated based on the temperature difference and the fuel temperature of the second fuel temperature heat exchanger, and the pressure and temperature are second increased and increased based on the second air target temperature. The temperature difference between the air after the first pressurization and temperature increase and the fuel at the first temperature is smaller than the temperature difference between the supplementary air and the fuel at the first temperature; the temperature difference between the air after the second pressurization and temperature increase and the fuel at the second temperature is smaller than the temperature difference between the air after the first pressurization and temperature increase and the fuel at the second temperature; The system further comprises a regenerator, a water separator and an expander; the expander is coaxially arranged with the first pressure compressor and the second pressure compressor; The outlet of the first passage of the second temperature fuel heat exchanger is connected to the inlet of the first passage of the regenerator, and the outlet of the first passage of the regenerator is connected to the inlet of the expander through the water separator; the air flowing out of the second temperature fuel heat exchanger is cooled and separated from the water in sequence before flowing into the expander; The expander outlet is connected to the inlet of the second passage of the regenerator, and the air after expansion and cooling flows into the regenerator to absorb heat; The second passage outlet of the regenerator is connected to the first pressure compressor inlet via the cabin fresh air device and the electronic equipment heat dissipation device in sequence.

2. The system according to claim 1, wherein: The first pressure compressor and the second pressure compressor are coaxially arranged; The second passage outlet of the first temperature fuel heat exchanger is connected to the second passage inlet of the second temperature fuel heat exchanger. After the fuel undergoes wall-type heat exchange in the first temperature fuel heat exchanger, it is heated and flows into the second temperature fuel heat exchanger.

3. The system according to claim 1, wherein: The outlet of the second passage of the regenerator is connected to the inlet of the cabin fresh air device, and part of the air output from the outlet of the second passage of the regenerator provides fresh air for the cabin here; The cabin fresh air device outlet is connected to the electronic equipment heat dissipation device inlet, and the remaining air passing through the cabin fresh air device provides cooling for the electronic equipment; The outlet of the electronic equipment heat sink is connected to the inlet of the first pressure compressor, and the last part of the air flowing out of the electronic equipment heat sink and the supplementary air from the air source are merged into the first pressure compressor.

4. The system according to claim 3, characterized in that The system further includes a shaft work input device, which is connected to the first pressure compressor and is coaxially arranged with the first pressure compressor, the second pressure compressor and the expander.

5. A method for controlling the environmental conditions of a semi-closed air cycle aircraft with a high-temperature fuel heat sink, characterized in that: The environmental control method for a semi-closed air cycle aircraft with a high-temperature fuel heat sink is applied to the system according to any one of claims 1 to 4, and the method comprises: The supplementary air is input into the first pressure compressor for compression, and the pressure and temperature are increased for the first time. The first pressure air is then input into the first temperature heat exchanger for fuel oil for heat exchange, and the first heat absorption is performed. The first pressure air after heat exchange is input into the second pressure compressor for compression, and the pressure and temperature are increased for the second time. The second pressure air is input into the second temperature heat exchanger for fuel oil for heat exchange, and the second heat absorption is performed. The second pressure air after heat exchange is used to provide fresh air to the cabin and cooling for electronic equipment.

6. The method according to claim 5, characterized in that The method further comprises: The first temperature fuel is input into the first temperature fuel heat exchanger and exchanges heat with the air after the first pressurization and temperature increase. The temperature difference between the air after the first pressurization and temperature increase and the first temperature fuel is less than a preset threshold. The first-temperature fuel heat exchanger outputs the second-temperature fuel, which enters the second-temperature fuel heat exchanger, undergoes inter-wall heat exchange with the air that has been pressurized and heated for the second time, and outputs the third-temperature fuel; the temperature of the third-temperature fuel is higher than that of the second-temperature fuel.

7. The method according to claim 5, characterized in that The second pressure air after heat exchange is sequentially input into the regenerator, water separator and expander, and after cooling, water separation and expansion cooling, flows into the regenerator through the expander to absorb heat; wherein the temperature of the air after expansion and cooling is lower than the temperature of the supplementary air input from the inlet of the first pressure compressor.

8. The method according to claim 7, characterized in that The air outputted from the regenerator after absorbing heat is divided into a first part and a second part according to the target; the target includes the cabin and electronic equipment; The first part is used to provide fresh air to the cabin; The second part is used to provide cooling for electronic equipment; The second part of air after providing cooling for the electronic equipment is merged with the supplementary air from the air source and input into the first pressure compressor to complete the semi-closed air cycle.

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