CN118066021A - Aircraft fuel thermal management system, control method and aircraft - Google Patents

Abstract

The invention relates to the technical field of aircrafts, in particular to an aircraft fuel thermal management system, a control method and an aircraft. The aircraft fuel heat management system comprises a fuel heat exchange flow path, a lubricating oil heat exchange flow path and a power generation flow path. The arrangement of the power generation flow path can recycle the lubricating oil heat load when the lubricating oil heat load is overlarge, a part of the lubricating oil heat load (namely, a part of heat) heats working media in the power generation flow path through the evaporator, and the heated working media enter the expander to perform work in a reference way, so that a generator connected with the expander is pushed to work, and the purpose of converting the heat energy of the lubricating oil into electric energy is achieved. In addition, the fuel oil flowing out from the fuel pump of the airplane exchanges heat with the working medium in the power generation flow path through the condenser so as to ensure that the temperature of the fuel oil entering the combustion chamber does not exceed a limit value.

Description

Aircraft fuel thermal management system, control method and aircraft

Technical Field

The present invention relates to the technical field of aircraft, and in particular to an aircraft fuel thermal management system, a control method and an aircraft.

Background technique

With the increase in the number of onboard equipment and the improvement in engine power, the heat load inside the aircraft is getting bigger and bigger. Using ram air to cool the system will cause the loss of stealth and drag of the fuselage. At the same time, the increase in the flight Mach number will cause the temperature of the ram air to be high, making it unusable for cooling. Using engine bypass air to cool the system will cause a decrease in engine thrust and increase engine fuel consumption. The use of composite materials with low thermal conductivity in the fuselage structure further weakens the ability of the aircraft to dissipate heat to the external environment, making fuel the main heat sink for system cooling. The development of high-performance aircraft requires limiting the use of air heat sinks. Therefore, it is very important to study aircraft fuel thermal management systems without air heat sinks.

The flow path of the existing aircraft fuel thermal management system without air heat sink is shown in Figure 1, which has a fuel flow path and a lubricating oil flow path. The working principle of the fuel flow path shown in Figure 1 is: the aircraft fuel pump 2 draws the fuel from the fuel tank 1, first enters the airborne heat exchanger 3 to cool the airborne equipment, and then enters the fuel and lubricating oil heat exchanger 5 to absorb the engine lubricating oil heat load after further pressurization by the engine fuel pump 4. The fuel required for engine combustion is metered by the fuel metering valve 17 and enters the combustion chamber 18; the system's limiting temperatures include the outlet temperature _Tc1 of the airborne heat exchanger, the outlet temperature _Tc2 of the first heat exchange channel of the fuel and lubricating oil heat exchanger 5, and the outlet temperature _Tc3 of the heat load generating structure. When a certain limiting temperature of the system is about to exceed the limiting value, the mass flow of the aircraft fuel pump path entering the two heat exchangers is increased by opening the second fuel return valve 16. Ensure that the outlet temperature _Tc2 of the first heat exchange channel of the fuel and lubricating oil heat exchanger 5 is as high as possible under the premise that the temperature of each limit point does not exceed the limit value, thereby increasing the heat load taken away by burning the fuel. Finally, the fuel flowing through the second fuel return valve 16 will return to the fuel tank 1, and this part of the fuel is called hot return oil. The working principle of the lubricating oil flow path shown in Figure 1 is: the engine lubricating oil pump 7 draws the lubricating oil from the lubricating oil tank 6, first absorbs the engine lubricating oil heat load generated by the heat load generating structure, then enters the fuel and lubricating oil heat exchanger 5 to be cooled by the fuel, and finally returns to the lubricating oil tank 6. However, the existing aircraft fuel thermal management system has the following problems: when the engine lubricating oil heat load is too large, a large amount of engine lubricating oil heat load is directly returned to the fuel tank through the hot return oil, causing the temperature of the fuel tank to rise rapidly.

Therefore, there is an urgent need for an aircraft fuel thermal management system to solve the above technical problems.

Summary of the invention

The purpose of the present invention is to provide an aircraft fuel thermal management system that can utilize the lubricating oil temperature to generate electricity and avoid a rapid increase in the temperature of the fuel tank.

To achieve this object, the present invention adopts the following technical solutions:

Aircraft fuel thermal management system, including:

A fuel heat exchange flow path, comprising a fuel tank, an aircraft fuel pump, an onboard heat exchanger and an engine fuel pump, wherein the fuel tank, the aircraft fuel pump, the onboard heat exchanger and the engine fuel pump are connected in sequence, and an outlet of the engine fuel pump is connected to a combustion chamber for providing fuel to the combustion chamber;

a lubricating oil heat exchange flow path, comprising a lubricating oil tank, an engine lubricating oil pump, a heat load generating structure, a first regulating valve and a fuel lubricating oil heat exchanger, wherein the lubricating oil tank, the engine lubricating oil pump, the heat load generating structure, the first regulating valve and the fuel lubricating oil heat exchanger are connected to form a first circulation loop, the fuel lubricating oil heat exchanger has a first heat exchange passage and a second heat exchange passage, the inlet of the first heat exchange passage is communicated with the outlet of the engine fuel pump, the outlet of the first heat exchange passage is communicated with the combustion chamber, the inlet of the second heat exchange passage is communicated with the first oil outlet of the first regulating valve, and the outlet of the second heat exchange passage is communicated with the inlet of the lubricating oil tank;

A power generation circuit includes a condenser, a circulation pump, an evaporator, a first fuel oil return valve and an expander, wherein the condenser, the circulation pump, the evaporator and the expander form a second circulation loop, the evaporator has a third heat exchange channel and a fourth heat exchange channel, the outlet of the third heat exchange channel is communicated with the inlet of the expander, the inlet of the third heat exchange channel is communicated with the outlet of the circulation pump, the inlet of the fourth heat exchange channel is communicated with the outlet of the second heat exchange channel of the fuel and lubricating oil heat exchanger and the second oil outlet of the first regulating valve respectively, the outlet of the fourth heat exchange channel is communicated with the inlet of the lubricating oil tank, the condenser has a fifth heat exchange channel and a sixth heat exchange channel, the inlet of the fifth heat exchange channel is communicated with the outlet of the expander, the outlet of the fifth heat exchange channel is communicated with the inlet of the circulation pump, the inlet of the sixth heat exchange channel is communicated with the outlet of the aircraft fuel pump, the outlet of the sixth heat exchange channel is communicated with the inlet of the first fuel oil return valve, the outlet of the first fuel oil return valve is communicated with the fuel tank, and the expander is connected to a generator for driving the generator to generate electricity.

As a preferred technical solution of the above-mentioned aircraft fuel thermal management system, the fuel heat exchange flow path also includes a second fuel return valve, the inlet of the second fuel return valve is connected to the onboard heat exchanger and the outlet of the first heat exchange channel, and the outlet of the second fuel return valve is connected to the fuel tank.

As a preferred technical solution of the above-mentioned aircraft fuel thermal management system, the fuel heat exchange flow path also includes a second regulating valve, the third oil inlet of the second regulating valve is connected to the oil outlet of the onboard heat exchanger through an intermediate oil return branch, the fourth oil inlet of the second regulating valve is connected to the outlet of the first heat exchange channel, and the outlet of the second regulating valve is connected to the inlet of the second fuel return valve.

As a preferred technical solution of the above-mentioned aircraft fuel thermal management system, the first regulating valve and the second regulating valve are both electric proportional three-way valves, and the first fuel return valve and the second fuel return valve are both electric proportional valves.

As a preferred technical solution of the above-mentioned aircraft fuel thermal management system, the aircraft fuel thermal management system also includes a fuel metering valve, the inlet of the fuel metering valve is connected to the outlet of the first heat exchange channel, and the outlet of the fuel metering valve is connected to the combustion chamber.

As a preferred technical solution of the above-mentioned aircraft fuel thermal management system, the thermal load generating structure includes a bearing cavity and/or a gear box.

The present invention also provides an aircraft fuel thermal management control method, which is applied to the aircraft fuel thermal management system described in any of the above schemes, and comprises the following steps:

obtaining an outlet temperature of an aircraft fuel pump and comparing the outlet temperature of the aircraft fuel pump with a critical condensing temperature of the working fluid in the second circulation loop;

When the outlet temperature of the aircraft fuel pump is less than or equal to the critical condensation temperature of the working medium in the second circulation loop, the first oil outlet and the second oil outlet of the first regulating valve are opened, and the mass flow of the first oil outlet and the second oil outlet of the first regulating valve is adjusted to increase the outlet temperature _Tc2 of the first heat exchange channel, and _Tc2 does not exceed the first critical temperature, and the working medium flow of the circulation pump is adjusted. The outlet temperature T _c3 of the heat load generating structure is increased, and T _c3 does not exceed the second critical temperature, wherein the first critical temperature and the second critical temperature are both known values.

As a preferred technical solution of the above-mentioned aircraft fuel thermal management control method, the fuel heat exchange flow path further includes a second fuel return valve, the inlet of the second fuel return valve is connected to the onboard heat exchanger and the outlet of the first heat exchange channel, and the outlet of the second fuel return valve is connected to the fuel tank;

The fuel heat exchange flow path also includes a second regulating valve, a third oil inlet of the second regulating valve is connected to the oil outlet of the onboard heat exchanger, a fourth oil inlet of the second regulating valve is connected to the outlet of the first heat exchange channel, and the outlet of the second regulating valve is connected to the inlet of the second fuel return valve;

When the outlet temperature of the aircraft fuel pump is less than or equal to the critical condensing temperature of the working medium in the second circulation loop, the third oil inlet of the second regulating valve is opened, the fourth oil inlet of the second regulating valve is closed, and the opening of the second fuel return valve is adjusted to increase the outlet temperature T _c1 of the onboard heat exchanger, and T _c1 does not exceed the third critical temperature, wherein the third critical temperature is a known value.

As a preferred technical solution of the above-mentioned aircraft fuel thermal management control method, the fuel heat exchange flow path further includes a second fuel return valve, the inlet of the second fuel return valve is connected to the onboard heat exchanger and the outlet of the first heat exchange channel, and the outlet of the second fuel return valve is connected to the fuel tank;

The fuel heat exchange flow path also includes a second regulating valve, a third oil inlet of the second regulating valve is connected to the oil outlet of the onboard heat exchanger, a fourth oil inlet of the second regulating valve is connected to the outlet of the first heat exchange channel, and the outlet of the second regulating valve is connected to the inlet of the second fuel return valve;

When the outlet temperature of the aircraft fuel pump is greater than the critical condensing temperature of the working medium in the second circulation loop, the second oil outlet of the first regulating valve is closed, the first oil outlet of the first regulating valve is opened, the third oil inlet and the fourth oil inlet of the second regulating valve are opened, and the second circulation loop is closed. By adjusting the opening of the second fuel return valve and the flow ratio of the third oil inlet and the fourth oil inlet of the second regulating valve, the outlet temperature _Tc2 of the first heat exchange channel is increased, and _Tc2 does not exceed the first critical temperature.

The present invention also provides an aircraft, comprising the aircraft fuel thermal management system described in any of the above schemes.

The present invention has at least the following beneficial effects:

The setting of the power generation circuit can reuse the heat load of the lubricating oil when the heat load of the lubricating oil is too large. A part of the heat load of the lubricating oil (that is, a part of the heat) is passed through the evaporator to heat the working medium in the power generation circuit. The heated working medium enters the expander to participate in the work, and then drives the generator connected to the expander to work, so as to achieve the purpose of converting the heat energy of the lubricating oil into electrical energy. In addition, the fuel flowing out of the aircraft fuel pump exchanges heat with the working medium in the power generation circuit through the condenser to ensure that the temperature of the fuel entering the combustion chamber does not exceed the limit value.

In addition, in the present invention, the intermediate oil return branch can reduce the fuel flow entering the fuel and lubricating oil heat exchanger, increase the temperature of the burning fuel, and facilitate the heat dissipation of the system.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

FIG1 is a schematic diagram of a flow path of an aircraft fuel thermal management system provided in the background art;

FIG2 is a schematic diagram of a flow path of an aircraft fuel thermal management system provided by an embodiment of the present invention;

FIG3 is a schematic diagram of the flow path of the aircraft fuel thermal management system provided by an embodiment of the present invention in working mode 1. FIG.

FIG4 is a schematic diagram of a flow path of an aircraft fuel thermal management system in working mode 2 provided by an embodiment of the present invention;

FIG5 is a flow chart 1 of an aircraft fuel thermal management control method provided by an embodiment of the present invention;

FIG6 is a second flow chart of an aircraft fuel thermal management control method provided by an embodiment of the present invention;

FIG7 is a graph showing the calculation results of the temperature variation over time of each limiting point in an embodiment of a conventional aircraft fuel thermal management system;

FIG8 is a diagram showing the calculation results of the temperature variation over time of each limiting point in the aircraft fuel thermal management system proposed by the present invention.

In the figure:

1. Fuel tank; 2. Aircraft fuel pump; 3. Airborne heat exchanger; 4. Engine fuel pump; 5. Fuel and lubricating oil heat exchanger; 6. Lubricating oil tank; 7. Engine lubricating oil pump; 8. Heat load generating structure; 9. First regulating valve; 10. Evaporator; 11. Condenser; 12. Circulating pump; 13. Expander; 14. First fuel return valve; 15. Second regulating valve; 16. Second fuel return valve; 17. Fuel metering valve; 18. Combustion chamber; 19. Generator;

_Tf - temperature of the fuel in the fuel tank; -Mass flow rate of aircraft fuel pump circuit; /> -Mass flow rate of the first fuel return valve circuit; /> -Mass flow rate of the onboard heat exchanger circuit; /> - onboard heat load power of the onboard heat exchanger; T _c1 - outlet temperature of the onboard heat exchanger; /> -Mass flow of the intermediate oil return branch; /> - mass flow of the engine fuel pump circuit; T _c2 - outlet temperature of the first heat exchange channel; /> -The mass flow of the oil return branch at the fuel side outlet of the fuel and lubricating oil heat exchanger;/> -Mass flow rate of the second fuel return valve circuit; /> -mass flow rate of fuel metering valve circuit; T _o -temperature of lubricating oil in lubricating oil tank; /> -Mass flow rate of engine oil pump circuit;/> - engine oil heat load power; T _c3 - outlet temperature of the heat load generating structure; /> - the oil mass flow rate entering the fuel-oil heat exchanger controlled by the first regulating valve; /> - the mass flow of the lubricating oil bypassing the fuel-oil heat exchanger controlled by the first regulating valve;/> -The working fluid flow rate of the circulation pump.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

In order to solve the problem in the prior art that when the thermal load of the engine lubricating oil is too large, a large amount of the thermal load of the engine lubricating oil is directly returned to the fuel tank through the hot return oil, causing the temperature of the fuel tank to rise rapidly, the present invention provides an aircraft fuel thermal management system that can reuse the thermal load of the engine lubricating oil to ensure the temperature of the fuel tank.

As shown in Figures 2 to 4, the aircraft fuel thermal management system includes a fuel heat exchange flow path, a lubricating oil heat exchange flow path and a power generation circuit, wherein the fuel heat exchange flow path includes a fuel tank 1, an aircraft fuel pump 2, an airborne heat exchanger 3 and an engine fuel pump 4, the fuel tank 1, the aircraft fuel pump 2, the airborne heat exchanger 3 and the engine fuel pump 4 are connected in sequence, the outlet of the engine fuel pump 4 is connected to the combustion chamber 18 for providing fuel to the combustion chamber 18, and the fuel flows into the combustion chamber 18 to participate in combustion through the engine fuel pump 4 to provide power.

The lubricating oil heat exchange flow path includes a lubricating oil tank 6, an engine lubricating oil pump 7, a heat load generating structure 8, a first regulating valve 9 and a fuel-lubricating oil heat exchanger 5. The lubricating oil tank 6, the engine lubricating oil pump 7, the heat load generating structure 8, the first regulating valve 9 and the fuel-lubricating oil heat exchanger 5 are connected to form a first circulation loop. The fuel-lubricating oil heat exchanger 5 has a first heat exchange channel and a second heat exchange channel. The inlet of the first heat exchange channel is connected to the outlet of the engine fuel pump 4, the outlet of the first heat exchange channel is connected to the combustion chamber 18, the inlet of the second heat exchange channel is connected to the first oil outlet of the first regulating valve 9, and the outlet of the second heat exchange channel is connected to the inlet of the lubricating oil tank 6; the fuel-lubricating oil heat exchanger 5 in the lubricating oil heat exchange flow path can achieve the purpose of heat exchange between the fuel and the lubricating oil, and then can transfer the heat of the lubricating oil to the fuel.

The power generation circuit includes a condenser 11, a circulating pump 12, an evaporator 10, a first fuel oil return valve 14 and an expander 13. The condenser 11, the circulating pump 12, the evaporator 10 and the expander 13 form a second circulation loop. The evaporator 10 has a third heat exchange channel and a fourth heat exchange channel. The outlet of the third heat exchange channel is connected to the inlet of the expander 13, the inlet of the third heat exchange channel is connected to the outlet of the circulating pump 12, and the inlet of the fourth heat exchange channel is connected to the outlet of the second heat exchange channel of the fuel oil heat exchanger 5 and the second oil outlet of the first regulating valve 9 respectively. The outlet of the fourth heat exchange passage is connected to the inlet of the lubricating oil tank 6. The condenser 11 has a fifth heat exchange passage and a sixth heat exchange passage. The inlet of the fifth heat exchange passage is connected to the outlet of the expander 13. The outlet of the fifth heat exchange passage is connected to the inlet of the circulating pump 12. The inlet of the sixth heat exchange passage is connected to the outlet of the aircraft fuel pump 2. The outlet of the sixth heat exchange passage is connected to the inlet of the first fuel return valve 14. The outlet of the first fuel return valve 14 is connected to the fuel tank 1. The expander 13 is connected to a generator 19 for driving the generator 19 to generate electricity. The setting of the power generation circuit can reuse the heat load of the lubricating oil when the heat load of the lubricating oil is too large. A part of the heat load (that is, a part of the heat) of the lubricating oil passes through the evaporator 10 to heat the working medium in the power generation circuit. The heated working medium enters the expander 13 to participate in work, thereby driving the generator connected to the expander 13 to work, thereby achieving the purpose of converting the heat energy of the lubricating oil into electrical energy. In addition, the fuel flowing out of the aircraft fuel pump 2 exchanges heat with the working medium in the power generation circuit through the condenser 11 to ensure that the temperature of the fuel entering the combustion chamber 18 does not exceed the limit value.

In some embodiments, in order to ensure that the outlet temperature of the onboard heat exchanger 3 is increased as much as possible without exceeding the third critical temperature, the fuel heat exchange flow path further includes a second fuel return valve 16, the inlet of the second fuel return valve 16 is connected to the outlet of the onboard heat exchanger 3 and the first heat exchange channel respectively, and the outlet of the second fuel return valve 16 is connected to the fuel tank 1. Adjusting the mass flow of the second fuel return valve The outlet temperature of the onboard heat exchanger 3 and the outlet temperature _Tc2 of the first heat exchange channel are increased as much as possible under the premise of ensuring that they do not exceed the third critical temperature and the first critical temperature.

When the power of the onboard equipment is too large, a large amount of fuel will enter the onboard heat exchanger 3 in order to cool the onboard equipment, so that the fuel flow entering the fuel and lubricating oil heat exchanger 5 is too large, which easily causes the outlet temperature _Tc2 of the first heat exchange channel of the fuel and lubricating oil heat exchanger 5 to be low, and weakens the ability of the system to remove the heat load by burning fuel. To this end, in some embodiments, the fuel heat exchange flow path also includes a second regulating valve 15, the third oil inlet of the second regulating valve 15 is connected to the oil outlet of the onboard heat exchanger 3 through the intermediate oil return branch, the fourth oil inlet of the second regulating valve 15 is connected to the outlet of the first heat exchange channel, and the outlet of the second regulating valve 15 is connected to the inlet of the second fuel return valve 16. The setting of the second regulating valve 15 can ensure that the fuel flow entering the fuel and lubricating oil heat exchanger 5 is reduced, and ensure that the outlet temperature _Tc2 of the first heat exchange channel of the fuel and lubricating oil heat exchanger 5 is as high as possible without exceeding the first critical temperature.

This ensures that the fuel flow rate entering the combustion chamber 18 is maintained while ensuring that the temperature of the fuel flowing out of the first heat exchange channel of the lubricating oil heat exchanger 5 is not higher than the critical temperature. When part of the fuel returns to the fuel tank 1, it ensures that the temperature of the returned fuel will not overheat and cause the overall rapid heating of the fuel tank 1.

It should be noted that the first regulating valve 9 and the second regulating valve 15 are both electric proportional three-way valves, and the first fuel return valve 14 and the second fuel return valve 16 are both electric proportional valves.

When the power generation circuit is working, the mass flow rates of the lubricating oil flowing out of the first oil outlet and the second oil outlet of the first regulating valve 9 are different. In order to ensure that most of the heat of the lubricating oil can be taken away by the burning fuel, the mass flow rate of the lubricating oil at the second oil outlet is usually smaller than the mass flow rate of the lubricating oil at the first oil outlet. At the same time, it is necessary to prevent the outlet temperature _Tc2 of the first heat exchange channel of the fuel-lubricating oil heat exchanger 5 from exceeding the first critical temperature.

In order to measure the mass flow rate of fuel entering the combustion chamber 18, in some embodiments, the aircraft fuel thermal management system also includes a fuel metering valve 17, the inlet of the fuel metering valve 17 is connected to the outlet of the first heat exchange channel, and the outlet of the fuel metering valve 17 is connected to the combustion chamber 18.

The heat load generating structure 8 includes a bearing cavity and/or a gear box, that is, the lubricating oil cools the bearing and/or the gear.

It is understood that in some embodiments, the lubricating oil flows into the bearing cavity to cool the bearing. In other embodiments, the lubricating oil flows into the gearbox to cool the gear. In other embodiments, the lubricating oil flows into the bearing cavity and the gearbox to cool the bearing and the gear.

In an embodiment of the present invention, an aircraft fuel thermal management control method is also provided. The method is applied to the aircraft fuel thermal management system provided in the above embodiment, and can determine the opening of the first regulating valve 9, the second regulating valve 15 and the second fuel return valve 16 according to the size between the outlet temperature of the aircraft fuel pump and the critical condensing temperature of the working medium in the second circulation loop, and simultaneously adjust the working medium flow rate of the second circulation loop.

As shown in FIG5 , the aircraft fuel thermal management control method includes the following steps:

S101, obtaining the outlet temperature of the aircraft fuel pump 2 and comparing the outlet temperature of the aircraft fuel pump 2 with the critical condensation temperature of the working medium in the second circulation loop;

S102, when the outlet temperature of the aircraft fuel pump 2 is less than or equal to the critical condensation temperature of the working medium in the second circulation loop, the first oil outlet and the second oil outlet of the first regulating valve 9 are opened, the third oil inlet of the second regulating valve 15 is opened, and the fourth oil inlet of the second regulating valve 15 is closed, and the mass flow of the first oil outlet and the second oil outlet of the first regulating valve 9 is adjusted, and the mass flow of the second fuel return valve 16 is adjusted, so that the outlet temperature _Tc1 of the onboard heat exchanger and the outlet temperature _Tc2 of the first heat exchange channel are increased, and _Tc1 does not exceed the third critical temperature, and _Tc2 does not exceed the first critical temperature, and the working medium flow of the circulating pump 12 is adjusted The outlet temperature T _c3 of the heat load generating structure is increased, and T _c3 does not exceed the second critical temperature, wherein the third critical temperature, the first critical temperature and the second critical temperature are all known values.

Specifically, the first oil outlet and the second oil outlet of the first regulating valve are opened, the third oil inlet of the second regulating valve is opened, the fourth oil inlet of the second regulating valve is closed, the second circulation loop is opened, the mass flow rates of the first oil outlet and the second oil outlet of the first regulating valve are adjusted so that the outlet temperature _Tc2 of the first heat exchange channel is as high as possible without exceeding the first critical temperature, the mass flow rate of the second fuel return valve is adjusted so that the outlet temperature _Tc1 of the onboard heat exchanger is as high as possible without exceeding the third critical temperature, and the mass flow rate of the second circulation loop is adjusted so that the outlet temperature _Tc3 of the heat load generating structure is as high as possible without exceeding the second critical temperature, wherein the first critical temperature, the second critical temperature and the third critical temperature are all known values.

By adjusting the mass flow of the first oil outlet and the second oil outlet of the first regulating valve 9, the first heat exchange passage outlet temperature _Tc2 is ensured not to exceed the first critical temperature to dissipate the lubricating oil heat load generated by the engine, thereby preventing a large amount of engine lubricating oil heat load from being directly returned to the fuel tank through hot oil return when the lubricating oil heat load is too large, thereby preventing the temperature of the fuel tank 1 from rising rapidly, so that the engine lubricating oil heat load is preferentially transferred to the combustion fuel through the fuel and lubricating oil heat exchanger 5.

When the outlet temperature of the aircraft fuel pump is less than or equal to the critical condensation temperature of the working medium in the second circulation loop, the system executes working mode 1. Working mode 1 is: the third oil inlet of the second regulating valve 15 is opened, the fourth oil inlet of the second regulating valve is closed, and the mass flow of the second fuel return valve circuit is adjusted through the second fuel return valve 16. Ensure that the outlet temperature _Tc1 of the onboard heat exchanger is as high as possible without exceeding the limit value, reducing the heat load of the onboard equipment returning to the fuel tank. The mass flow of lubricating oil entering the fuel and lubricating oil heat exchanger controlled by the first regulating valve/> The outlet temperature _Tc2 of the first heat exchange passage of the fuel oil heat exchanger 5 is as high as possible without exceeding the limit value, thereby increasing the heat load removed by the system through the combustion of fuel. When the outlet temperature _Tc3 of the heat load generating structure is about to exceed the limit value, the first fuel return valve 14 and the power generation circuit are opened, the heat load of the engine lubricating oil is absorbed by the evaporator 10, and the working medium flow rate of the circulating pump is adjusted. The outlet temperature T _c3 of the heat load generating structure is made as high as possible without exceeding the limit value, so that the engine lubricating oil heat load 8 is preferentially transferred to the combustion fuel through the fuel lubricating oil heat exchanger 5 .

When the power of the onboard equipment is too large, the amount of fuel passing through the onboard heat exchanger 3 increases, which will cause the fuel flow entering the fuel and lubricating oil heat exchanger 5 to be too large, thereby causing the outlet temperature _Tc2 of the first heat exchange channel to be low. Therefore, in some embodiments, when the outlet temperature of the aircraft fuel pump 2 is less than or equal to the critical condensation temperature of the working medium in the second circulation loop, the opening of the second fuel return valve 16 is adjusted to increase _Tc1 , and _Tc1 does not exceed the third critical temperature, which is a known value. In this way, the fuel flow entering the fuel and lubricating oil heat exchanger 5 can be adjusted.

In some embodiments, when the outlet temperature of the aircraft fuel pump 2 is greater than the critical condensing temperature of the working medium in the second circulation loop, the system executes working mode 2, which is: the second oil outlet of the first regulating valve 9 is closed, the first oil outlet of the first regulating valve 9 is opened, the third oil inlet and the fourth oil inlet of the second regulating valve 15 are opened, and the second circulation loop is closed, so that the outlet temperature _Tc2 of the first heat exchange channel increases, and _Tc2 does not exceed the first critical temperature.

The power generation circuit is closed, the first fuel return valve 14 is closed, and the second regulating valve 15 starts to work, and the mass flow of the second fuel return valve circuit is adjusted through the second fuel return valve 16. Under the premise of ensuring that the outlet temperature _Tc1 of the onboard heat exchanger does not exceed the third critical temperature, the outlet temperature _Tc2 of the first heat exchange channel does not exceed the first critical temperature, and the outlet temperature _Tc3 of the heat load generating structure does not exceed the second critical temperature, the outlet temperature _Tc2 of the first heat exchange channel is made as high as possible to increase the heat load removed by burning fuel. When the increase of the outlet temperature _Tc2 of the first heat exchange channel is constrained by the outlet temperature _Tc1 of the onboard heat exchanger, the mass flow rate of the outlet of the onboard heat exchanger 3 entering the intermediate oil return branch of the second regulating valve 15 is controlled by the second regulating valve 15. The outlet temperature _Tc2 of the first heat exchange channel is made as high as possible under the premise that both the outlet temperature _Tc2 of the first heat exchange channel and the outlet temperature _Tc3 of the heat load generating structure do not exceed the limit value, thereby further increasing the heat load removed by burning fuel.

By connecting the outlet of the onboard heat exchanger 3 to the fuel oil heat exchanger 5 and the second regulating valve 15 respectively, the flow rate of fuel entering the fuel oil heat exchanger 5 can be reduced, thereby increasing the temperature of the burning fuel and increasing the heat load of the system taken away by the burning fuel. At the same time, by providing a power generation circuit between the first circulation loop and the fuel heat exchange flow path, the heat load of the engine oil is converted into heat work in the process of being transferred to the fuel, reducing the heat load of the engine oil returned to the fuel tank 1, and also reducing the temperature of the fuel flowing back to the fuel tank 1. The aircraft fuel thermal management control method proposed in the present invention effectively improves the heat dissipation capacity of the thermal management system by increasing the system heat load taken away by the burning fuel and the heat-to-work conversion, and overcomes the shortcomings of the existing thermal management system that the temperature of the burning fuel is low and a large amount of the engine oil heat load is directly returned to the fuel tank through the hot return oil.

As shown in FIG6 , the method specifically includes the following steps:

S201, obtaining the outlet temperature of the aircraft fuel pump 2;

S202, comparing whether the outlet temperature of the aircraft fuel pump 2 is not greater than the critical condensation temperature of the working medium in the second circulation loop, if so, executing step S203, if not, executing step S204;

S203, the first oil outlet and the second oil outlet of the first regulating valve 9 are opened, the third oil inlet of the second regulating valve 15 is opened, the fourth oil inlet of the second regulating valve 15 is closed, the second circulation loop is opened, the mass flow of the first oil outlet and the second oil outlet of the first regulating valve 9 is adjusted so that the outlet temperature _Tc2 of the first heat exchange channel is as high as possible without exceeding the first critical temperature, the mass flow of the second fuel return valve 16 is adjusted so that the outlet temperature _Tc1 of the onboard heat exchanger is as high as possible without exceeding the third critical temperature, and the mass flow of the second circulation loop is adjusted so that the outlet temperature _Tc3 of the heat load generating structure is as high as possible without exceeding the second critical temperature, wherein the first critical temperature, the second critical temperature and the third critical temperature are all known values.

S204, the second oil outlet of the first regulating valve 9 is closed, the first oil outlet of the first regulating valve 9 is opened, the third oil inlet and the fourth oil inlet of the second regulating valve 15 are opened, and the second circulation loop is closed. By adjusting the second fuel return valve 16 and the second regulating valve 15, the outlet temperature _Tc2 of the first heat exchange channel is as high as possible without exceeding the first critical temperature, and the outlet temperature _Tc1 of the onboard heat exchanger does not exceed the third critical temperature, and the outlet temperature _Tc3 of the heat load generating structure does not exceed the second critical temperature.

In order to better illustrate the advantages of the embodiments of the present invention, the following will use a specific embodiment to compare the thermal flight time of the aircraft fuel thermal management system provided in the prior art and the aircraft fuel thermal management system provided in this application under a single working condition, wherein the thermal flight time refers to the longest time that the aircraft thermal management system can work normally under the condition of meeting the temperature limit, and the thermal flight time is an important indicator for evaluating the performance of the thermal management system. It should be noted that the working fluid (i.e., working medium), component parameters, and working parameters provided in this embodiment are only an example for comparative calculation, and the scope of application of the present invention is far more than this.

In this embodiment, the temperature rise _ΔTp of the fluid passing through the aircraft fuel pump 2, the engine fuel pump 4 and the engine lubricating oil pump 7 is calculated using the following formula:

Where _ηp is the total efficiency of the pump, _ΔPup is the total pressure rise of the pump, ρ is the density of the fluid, and _cp is the constant-pressure specific heat of the fluid.

In this embodiment, the temperature rise ΔT _h of the fluid passing through the onboard heat exchanger 3 and the heat load generating structure 8 is calculated using the following formula:

In the formula is the heat load power of the heat source, /> is the mass flow rate of the fluid.

In this embodiment, the heat transfer capacity of the fuel oil heat exchanger 5 is The corresponding temperature rise ΔT _u and temperature drop ΔT _d on the cold and hot fluid sides are calculated using the following formulas:

Where KA is the total thermal conductance of the heat exchanger, _ΔTm is the logarithmic mean temperature difference between the cold and hot fluids in the heat exchanger, and the subscripts 1 and 2 represent the cold and hot side fluids, respectively.

In this embodiment, the changes of the mass M and temperature T of the fuel tank 1 and the lubricating oil tank 6 over time are calculated using the following formula:

Where the subscripts in and out represent the flow into and out of the tank, respectively.

In this embodiment, the mass conservation equation and the energy conservation equation need to be satisfied at the hybrid node.

In this embodiment, the amount of heat absorbed by the working fluid in the second circulation loop in the evaporator 10 is Use the following formula to calculate:

In the formula, _heva,out and _heva,in represent the specific enthalpy of the working fluid flowing out of and into the evaporator respectively.

In this embodiment, the output power of the expander 13 in the second circulation loop is Use the following formula to calculate:

Where η _t,s is the isentropic expansion efficiency, h _t,in and h _t,s,out represent the specific enthalpy of the working fluid flowing into and out of the expander after ideal isentropic expansion, respectively.

In this embodiment, the heat released in the condenser 11 in the second circulation loop is Use the following formula to calculate:

Where hcon _,in and hcon _,out represent the specific enthalpy of the working fluid flowing into and out of the condenser, respectively.

In this embodiment, the input power of the circulation pump 12 in the second circulation loop is Use the following formula to calculate:

Where _hp,out and _hp,in represent the specific enthalpy of the working fluid flowing out of and into the circulating pump respectively.

In this embodiment, the power generation of the generator 19 is Use the following formula to calculate:

Wherein η _m is the mechanical efficiency of the expander 13, and η _e is the power generation efficiency of the generator 19.

In this embodiment, the working fluid of the fuel heat exchange flow path is RP-3 aviation kerosene, the working fluid of the first circulation loop is 4050 aviation lubricating oil, and the working fluid of the second circulation loop is R245fa.

In this embodiment, the components and operating parameters of the aircraft fuel thermal management system are shown in Table 1.

Table 1 Various components and working parameters of the system in this embodiment

In Table 1, ΔP _up,1 , ΔP _up,2 and ΔP _up,3 are the total pressure rises of aircraft fuel pump 2, engine fuel pump 2 and engine oil pump 7, respectively; η _p,1 , η _p,2 and η _p,3 are the total efficiencies of aircraft fuel pump 2, engine fuel pump 4 and engine oil pump 7, respectively; η _p,4 is the total efficiency of the circulation pump in the organic Rankine cycle; M _fuel and M _oil are the masses of the fluids in the fuel tank and the oil tank, respectively; is the hot return oil flow /> The upper limit of

T _cl,lim , T _c2,lim and T _c3,lim are limit values of T _c1 , T _c2 and T _c3 , respectively.

FIG7 shows the change of the temperature of each limiting point in the old system with time under the single working condition of this embodiment. From the calculation results, it can be seen that the outlet temperature _Tc1 of the onboard heat exchanger 3 is the main factor limiting the increase of the fuel side outlet temperature _Tc2 of the fuel oil heat exchanger 5. At 3187s, Reach/> At this time, the thermal management system fails. Figure 8 shows the temperature change of each limit point in the new system over time under the single working condition of this embodiment. From the calculation results, it can be seen that under the action of multiple temperature controllers, whether in working mode 1 or working mode 2, the outlet temperature _Tc2 of the first heat exchange channel of the fuel oil heat exchanger 5 can be effectively maintained near the limit value, increasing the heat load taken away by the system through the combustion of fuel. At this time, the thermal flight time of the thermal management system is increased to 3560s, which is 11.7% higher than that of the old system. At the same time, 6.47MJ of electricity is generated through the second circulation loop, which reduces the thermal load of the system to a certain extent.

An embodiment of the present invention further provides an aircraft, comprising the aircraft fuel thermal management system provided by the above embodiment.

Since the aircraft fuel thermal management system described above is included, the aircraft according to the embodiment of the present invention has all the advantages and beneficial effects of the above embodiments, which will not be described in detail herein.

In addition, the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims (10)

1. An aircraft fuel thermal management system, comprising:

The fuel oil heat exchange flow path comprises a fuel tank (1), an aircraft fuel pump (2), an onboard heat exchanger (3) and an engine fuel pump (4), wherein the fuel tank (1), the aircraft fuel pump (2), the onboard heat exchanger (3) and the engine fuel pump (4) are sequentially communicated, and an outlet of the engine fuel pump (4) is communicated with a combustion chamber (18) and is used for providing fuel oil for the combustion chamber (18);

The lubricating oil heat exchange flow path comprises a lubricating oil tank (6), an engine lubricating oil pump (7), a heat load generation structure (8), a first regulating valve (9) and a combustion lubricating oil heat exchanger (5), wherein the lubricating oil tank (6), the engine lubricating oil pump (7), the heat load generation structure (8), the first regulating valve (9) and the combustion lubricating oil heat exchanger (5) are connected to form a first circulation loop, the combustion lubricating oil heat exchanger (5) is provided with a first heat exchange channel and a second heat exchange channel, an inlet of the first heat exchange channel is communicated with an outlet of the engine fuel pump (4), an outlet of the first heat exchange channel is communicated with a combustion chamber (18), an inlet of the second heat exchange channel is communicated with a first oil outlet of the first regulating valve (9), and an outlet of the second heat exchange channel is communicated with an inlet of the lubricating oil tank (6);

a power generation flow path comprising a condenser (11), a circulating pump (12), an evaporator (10), a first fuel return valve (14) and an expander (13), wherein the condenser (11), the circulating pump (12), the evaporator (10) and the expander (13) form a second circulation loop, the evaporator (10) is provided with a third heat exchange channel and a fourth heat exchange channel, the outlet of the third heat exchange channel is communicated with the inlet of the expander (13), the inlet of the third heat exchange channel is communicated with the outlet of the circulating pump (12), the inlet of the fourth heat exchange channel is respectively communicated with the outlet of the second heat exchange channel of the fuel heat exchanger (5) and the second oil outlet of the first regulating valve (9), the outlet of the fourth heat exchange channel is communicated with the inlet of the fuel tank (6), the condenser (11) is provided with a fifth heat exchange channel and a sixth heat exchange channel, the inlet of the fifth heat exchange channel is communicated with the outlet of the expander (13), the inlet of the fifth heat exchange channel is communicated with the inlet of the fuel return valve (14), the inlet of the fuel return valve (1) is communicated with the inlet of the fuel return valve (14), the expander (13) is connected with a generator (19) for pushing the generator (19) to generate electricity.

2. The aircraft fuel thermal management system according to claim 1, wherein the fuel heat exchange flow path further comprises a second fuel return valve (16), an inlet of the second fuel return valve (16) being in communication with an outlet of the on-board heat exchanger (3) and an outlet of the first heat exchange channel, an outlet of the second fuel return valve (16) being in communication with the fuel tank (1).

3. The aircraft fuel thermal management system according to claim 2, characterized in that the fuel heat exchange flow path further comprises a second regulating valve (15), a third oil inlet of the second regulating valve (15) is communicated with an oil outlet of the on-board heat exchanger (3) through an intermediate oil return branch, a fourth oil inlet of the second regulating valve (15) is communicated with an outlet of the first heat exchange channel, and an outlet of the second regulating valve (15) is communicated with an inlet of the second fuel return valve (16).

4. An aircraft fuel thermal management system according to claim 3, wherein the first regulating valve (9) and the second regulating valve (15) are both electric proportional three-way valves, and the first fuel return valve (14) and the second fuel return valve (16) are both electric proportional valves.

5. The aircraft fuel thermal management system according to claim 1, further comprising a fuel metering valve (17), an inlet of the fuel metering valve (17) being in communication with an outlet of the first heat exchanging channel, an outlet of the fuel metering valve (17) being in communication with the combustion chamber (18).

6. Aircraft fuel thermal management system according to claim 1, characterized in that the thermal load generating structure (8) comprises a bearing cavity and/or a gearbox.

7. Method for controlling the thermal management of the fuel of an aircraft, characterized by being applied to a thermal management system of the fuel of an aircraft according to any one of claims 1 to 6, comprising the steps of:

obtaining the outlet temperature of the aircraft fuel pump (2) and comparing the outlet temperature of the aircraft fuel pump (2) with the critical condensation temperature of working medium in the second circulation loop;

When the outlet temperature of the aircraft fuel pump (2) is less than or equal to the critical condensation temperature of working medium in the second circulation loop, a first oil outlet and a second oil outlet of the first regulating valve (9) are opened, and the mass flow of the first oil outlet and the second oil outlet of the first regulating valve (9) is regulated so as to ensure that the outlet temperature T _c2 of the first heat exchange channel is increased, and T _c2 does not exceed the first critical temperature, and the flow of the working medium of the circulation pump is regulated To raise the outlet temperature T _c3 of the thermal load-generating structure, and T _c3 does not exceed a second critical temperature, wherein both the first critical temperature and the second critical temperature are known values.

8. The aircraft fuel thermal management control method according to claim 7, characterized in that the fuel heat exchange flow path further comprises a second fuel return valve (16), an inlet of the second fuel return valve (16) being in communication with the on-board heat exchanger (3) and an outlet of the first heat exchange channel, an outlet of the second fuel return valve (16) being in communication with the fuel tank (1);

The fuel oil heat exchange flow path further comprises a second regulating valve (15), a third oil inlet of the second regulating valve (15) is communicated with an oil outlet of the airborne heat exchanger (3), a fourth oil inlet of the second regulating valve (15) is communicated with an outlet of the first heat exchange channel, and an outlet of the second regulating valve (15) is communicated with an inlet of the second fuel oil return valve (16);

When the outlet temperature of the aircraft fuel pump (2) is smaller than or equal to the critical condensation temperature of working medium of the second circulation loop, a third oil inlet of the second regulating valve is opened, a fourth oil inlet of the second regulating valve is closed, the opening degree of the second fuel oil return valve (16) is regulated to improve the outlet temperature T _c1 of the on-board heat exchanger, and the T _c1 does not exceed a third critical temperature, wherein the third critical temperature is a known value.

9. The aircraft fuel thermal management control method according to claim 7, characterized in that the fuel heat exchange flow path further comprises a second fuel return valve (16), an inlet of the second fuel return valve (16) being in communication with the on-board heat exchanger (3) and an outlet of the first heat exchange channel, an outlet of the second fuel return valve (16) being in communication with the fuel tank (1);

The fuel oil heat exchange flow path further comprises a second regulating valve (15), a third oil inlet of the second regulating valve (15) is communicated with an oil outlet of the airborne heat exchanger (3), a fourth oil inlet of the second regulating valve (15) is communicated with an outlet of the first heat exchange channel, and an outlet of the second regulating valve (15) is communicated with an inlet of the second fuel oil return valve (16);

When the outlet temperature of the aircraft fuel pump (2) is higher than the critical condensation temperature of working media of the second circulation loop, the second oil outlet of the first regulating valve is closed, the first oil outlet of the first regulating valve (9) is opened, the third oil inlet and the fourth oil inlet of the second regulating valve (15) are opened, the second circulation loop is closed, and the outlet temperature T _c2 of the first heat exchange channel is increased and T _c2 does not exceed the first critical temperature by adjusting the opening of the second fuel return valve (16) and the flow ratio of the third oil inlet and the fourth oil inlet of the second regulating valve (15).

10. Aircraft, characterized in that it comprises an aircraft fuel thermal management system according to any one of claims 1-6.