Fuel tank inerting system, fuel tank inerting method and aircraft

Abstract

The invention relates to a fuel tank inerting system, a fuel tank inerting method and an aircraft. On one hand, the low-temperature rare gas generated by gasification of the liquid rare gas is directly used for replacing oxygen and fuel steam in the fuel tank and reducing the temperature in the fuel tank, and on the other hand, the low-temperature rare gas is used for cooling the fuel steam discharged out of the fuel tank; and then the cooled fuel steam or the fuel liquid drops formed by condensation are returned to the fuel tank to further reduce the temperature in the fuel tank and the concentration of the fuel steam, so that double inerting of the fuel tank is realized. The fuel tank inerting system and method according to the present disclosure may be applicable to various types of aircraft.

Description

Technical Field

[0001] The present disclosure relates to the field of aviation, and in particular, to a fuel tank inerting system, a fuel tank inerting method, and an associated aircraft. Background Art

[0002] The content of this section only provides background information related to the present disclosure, and it may not constitute prior art.

[0003] When designing an aircraft's on-board fuel system, it is generally desired to maintain the oxygen concentration in the fuel tank at a level lower than the oxygen concentration required to support fuel combustion throughout the flight to ensure flight safety, which is generally referred to as "inerting" the fuel tank. According to general safety regulations, when the flight altitude is less than or equal to 10,000 feet, the safe level of oxygen concentration in the fuel tank should be maintained at less than or equal to 12%. When the flight altitude rises from 10,000 feet to 40,000 feet, the safe level of oxygen concentration in the fuel tank approximately linearly increases from 12% to 14.5%. In addition, it is also desired that the concentration of fuel vapor in the fuel tank be as low as possible. To this end, an inert gas can be introduced into the fuel tank to at least partially displace the gas (including air and fuel vapor) above the fuel located in the fuel tank. Currently, there is an on-board inert gas generation system applicable to aircraft that introduces compressed air from the compressor of the engine or other suitable parts through an air extraction system, and separates nitrogen from the compressed air through an air separation device, and then uses the separated nitrogen to be introduced into the fuel tank to inert the fuel tank. However, this on-board inert gas generation system must be used together with an air extraction system, so it is not applicable to aircraft without or unable to install an air extraction system, such as helicopters and aircraft with piston engines. Therefore, it is desirable to develop an on-board fuel tank inerting system and method applicable to aircraft without an air extraction system. In addition, even for aircraft that can be equipped with an air extraction system, there is a need to develop an alternative on-board fuel tank inerting system and method that does not rely on the air extraction system. When the air extraction system does not draw or draws as little compressed air as possible from the compressor, the propulsion efficiency and fuel consumption rate of the engine can be improved. Summary of the Invention

[0004] An object of the present disclosure is to provide an alternative on-board fuel tank inerting system and method for an aircraft. Another object of the present invention is to provide an on-board fuel tank inerting system and method for doubly inerting a fuel tank to reduce the oxygen concentration and fuel vapor concentration in the fuel tank and improve the operation safety of the aircraft.

[0005] A first aspect of the present disclosure provides a fuel tank inerting system, which includes a fuel tank, a liquid rare gas storage tank storing liquid rare gas, and a heat exchanger. The fuel tank includes at least one fluid inlet and a fluid outlet. The liquid rare gas storage tank is connected to at least one fluid inlet of the fuel tank via a first pipeline, and the fluid outlet of the fuel tank is connected to a second pipeline. The first pipeline and the second pipeline are jointly connected to the heat exchanger, so that the fluid in the first pipeline and the fluid in the second pipeline can exchange heat at the heat exchanger. Downstream of the heat exchanger, the second pipeline is connected to at least one fluid inlet of the fuel tank via a third pipeline, thereby allowing the fluid discharged from the fuel tank through the second pipeline to at least partially return to the fuel tank via the third pipeline after being cooled by the heat exchanger.

[0006] In some embodiments, a first regulating valve for controlling the on / off of the first pipeline may be provided in the first pipeline.

[0007] In some embodiments, the fuel tank inerting system may further include a fourth pipeline leading to an exhaust port. The second pipeline, the third pipeline, and the fourth pipeline are connected via a second regulating valve, and the second regulating valve is configured to selectively connect the second pipeline to the third pipeline and / or the fourth pipeline.

[0008] In some embodiments, at least one of the first pipeline, the second pipeline, the third pipeline, and the fourth pipeline may be provided with a check valve.

[0009] In some embodiments, in the first pipeline, a pressure reducing valve may be provided downstream of the liquid rare gas storage tank.

[0010] In some embodiments, a dryer may be provided in the second pipeline or the third pipeline to remove moisture in the fluid in the second pipeline or the third pipeline.

[0011] In some embodiments, a suction device for sucking gas from the fluid outlet of the fuel tank may be provided in the second pipeline.

[0012] In some embodiments, the liquid rare gas in the liquid rare gas storage tank includes liquid argon.

[0013] In some embodiments, the fuel tank inerting system may further include an oxygen concentration sensor, a pressure sensor, and a temperature sensor provided at the fuel tank.

[0014] In some embodiments, the fuel tank inerting system may further include a controller, which is electrically connected or wirelessly signal-connected to the oxygen concentration sensor, the pressure sensor, and the temperature sensor, and the controller is electrically connected or wirelessly signal-connected to the first regulating valve and the second regulating valve. The controller is configured to control the operations of the first regulating valve and the second regulating valve based on the oxygen concentration in the fuel tank detected by the oxygen concentration sensor, the pressure in the fuel tank detected by the pressure sensor, and / or the temperature in the fuel tank detected by the temperature sensor.

[0015] A second aspect of the present disclosure provides an aircraft including the fuel tank inerting system according to the first aspect above.

[0016] A third aspect of the present disclosure provides a fuel tank inerting method, which includes: providing a liquid rare gas storage tank storing liquid rare gas, wherein the liquid rare gas storage tank is connected to at least one fluid inlet of the fuel tank via a first pipeline, and a fluid outlet of the fuel tank is connected to a second pipeline; providing a heat exchanger, the first pipeline and the second pipeline are jointly connected to the heat exchanger such that the fluid in the first pipeline and the fluid in the second pipeline can perform heat exchange at the heat exchanger, wherein, downstream of the heat exchanger, the second pipeline is connected to at least one fluid inlet of the fuel tank via a third pipeline; detecting the oxygen concentration in the fuel tank, and when the oxygen concentration in the fuel tank is greater than a threshold concentration, allowing the rare gas generated by the vaporization of the liquid rare gas in the liquid rare gas storage tank to pass through the first pipeline and into the fuel tank to displace the gas above the fuel in the fuel tank, and allowing the fluid discharged from the fuel tank through the second pipeline to at least partially return to the fuel tank via the third pipeline after being cooled by the heat exchanger.

[0017] In some embodiments, the method may further include: when the oxygen concentration in the fuel tank is less than or equal to the threshold concentration, stopping introducing rare gas into the fuel tank.

[0018] In some embodiments, the method may further include: detecting the pressure in the fuel tank, and when the pressure in the fuel tank is greater than a threshold pressure, connecting the second pipeline to an exhaust port; when the pressure in the fuel tank is less than or equal to the threshold pressure, disconnecting the second pipeline from the exhaust port.

[0019] In some embodiments, the method may further include: setting a first regulating valve and a second regulating valve, where the first regulating valve is disposed in a first pipeline to control the on-off of the first pipeline, and the second regulating valve is connected to a second pipeline, a third pipeline, and a fourth pipeline leading to an exhaust port, and the second regulating valve is configured to selectively connect the second pipeline to the third pipeline and / or the fourth pipeline; when the oxygen concentration in the fuel tank is greater than a threshold concentration, controlling the first regulating valve to open and controlling the second regulating valve to connect the second pipeline to the third pipeline; and when the oxygen concentration in the fuel tank is less than or equal to the threshold concentration, controlling the first regulating valve to close and controlling the second regulating valve to disconnect the second pipeline from the third pipeline.

[0020] Embodiments of the present disclosure utilize liquid rare gas in a liquid rare gas storage tank to achieve dual inerting of the fuel tank. That is, on the one hand, the low-temperature rare gas is directly used to displace oxygen and fuel vapor in the fuel tank and reduce the temperature inside the fuel tank. On the other hand, the low-temperature rare gas is used to cool the fuel vapor discharged from the fuel tank, and then the cooled fuel vapor or the liquid fuel formed by condensation is returned to the fuel tank to further reduce the temperature and fuel vapor concentration inside the fuel tank. In addition, the fuel tank inerting system and method according to the present disclosure do not rely on an air extraction system that extracts air from the compressor of an aircraft engine and an air separation device that separates nitrogen from the extracted air, so it can be applied to various types of aircraft, especially aircraft without an air extraction system, such as helicopters or aircraft using piston engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Embodiments of the present disclosure will be described hereinafter only by way of example with reference to the drawings. In the drawings, the same features or components are denoted by the same reference numerals, and the drawings are not necessarily drawn to scale. In the drawings:

[0022] Figure 1 shows a schematic diagram of a fuel tank inerting system according to an embodiment of the present disclosure;

[0023] Figure 2 shows an aircraft equipped with Figure 1 a fuel tank inerting system;

[0024] Figure 3 shows a flowchart of an example method for controlling the oxygen concentration in the fuel tank by a controller of the fuel tank inerting system; and

[0025] Figure 4 shows a flowchart of an example method for controlling the pressure in the fuel tank by a controller of the fuel tank inerting system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its applications, and uses. It should be understood that in all these figures, like reference numerals indicate the same or similar parts and features. Each figure schematically shows the concept and principle of the embodiments of the present disclosure, and does not necessarily show the specific dimensions and their ratios of the various embodiments of the present disclosure. In a specific part of a specific figure, the relevant details or structures of the embodiments of the present disclosure may be illustrated in an exaggerated manner.

[0027] In the description of the embodiments of the present disclosure, the orientation terms related to "upper", "lower", etc. are described based on the upper and lower positions of the views shown in the figures. In actual applications, the "upper", "lower", etc. position relationships used herein can be defined according to the actual situation, and these relationships can be reversed with each other and are not intended to limit the scope of the present disclosure.

[0028] Figure 1 A schematic diagram of a fuel tank inerting system 1 according to the present disclosure is shown. Figure 2 A schematic diagram of an aircraft 2 equipped with a fuel tank inerting system 1 is shown. Figure 1 The solid arrows in it schematically represent the physical connections (such as fluid delivery pipelines) between the components and the fluid flow directions. Figure 1 The dashed arrows in it schematically represent the signal connections and signal transmission directions between the components. In Figure 2 it, the aircraft 2 is schematically shown as a helicopter, but it should be understood that the fuel tank inerting system 1 according to the present disclosure can be applied to any other suitable type of aircraft, such as a fixed-wing aircraft with a jet engine or a piston engine. In addition, the fuel tank inerting system 1 according to the present disclosure can also be used for applications other than aircraft, such as inerting the fuel tank of a ground gas turbine.

[0029] As Figure 1 shown, the fuel tank inerting system 1 includes a fuel tank 110 and a liquid rare gas storage tank 120 storing liquid rare gas. In this embodiment, the liquid rare gas in the liquid rare gas storage tank 120 may include liquid argon (LAR). Liquid argon is colorless, odorless, non-corrosive, non-toxic, non-flammable, has a low boiling point, and argon has a wide source, rich reserves, and is easy to obtain. It is the cheapest and most commonly used rare gas. Therefore, liquid argon is an ideal rare gas for the fuel tank inerting system 1. However, the present disclosure is not limited thereto. In other embodiments, any other suitable liquid rare gas or inert gas may also be used.

[0030] In this embodiment, the liquid rare gas storage tank 120 is connected to the first fluid inlet 111 of the fuel tank 110 through the first pipeline 131, and the fluid outlet 112 of the fuel tank 110 is connected to the second pipeline 132. The second pipeline 132 can be connected to the second fluid inlet 113 of the fuel tank 110 through the third pipeline 133 to form a loop. In other embodiments, the first fluid inlet 111 and the second fluid inlet 113 can also be combined into the same fluid inlet. A suction device, such as a fan 140, for sucking gas from the fluid outlet 112 of the fuel tank 110 can be provided in the second pipeline 132. The first pipeline 131 and the second pipeline 132 are jointly connected to the heat exchanger 151, so that the fluid in the first pipeline 131 and the fluid in the second pipeline 132 can exchange heat at the heat exchanger 151. More specifically, at the heat exchanger 151, the low-temperature argon gas from the liquid rare gas storage tank 120 in the first pipeline 131 can cool the relatively high-temperature fluid (such as including air and fuel vapor) discharged from the fuel tank 110 in the second pipeline 132. Downstream of the heat exchanger 151, the second pipeline 132 can be connected to the third pipeline 133 leading to the second fluid inlet 113 of the fuel tank 110 and the fourth pipeline 134 leading to the exhaust port 170 through a three-way regulating valve 161. Specifically, the second pipeline 132 is connected to the inlet port of the three-way regulating valve 161, and the third pipeline 133 and the fourth pipeline 134 are respectively connected to the two outlet ports of the three-way regulating valve 161, so that the three-way regulating valve 161 can selectively control the communication between the second pipeline 132 and the third pipeline 133 and / or the fourth pipeline 134. The third pipeline 133 leading to the second fluid inlet 113 of the fuel tank 110 can send the fuel vapor or the condensed liquid fuel cooled by the heat exchanger 151 in the second pipeline 132 back to the fuel tank 110. The fourth pipeline 134 leading to the exhaust port 170 can discharge part of the gas to the atmosphere to avoid excessive pressure in the fuel tank 110 due to continuously introducing gas into the fuel tank 110. Preferably, a dryer 152 can also be connected in the second pipeline 132 or the third pipeline 133 to remove moisture in the fluid that will be returned to the fuel tank 110 through the second fluid inlet 113 of the fuel tank 110. The dryer 152 can be provided, for example, between the heat exchanger 151 and the second fluid inlet 113 of the fuel tank 110.

[0031] One or more regulating valves can be arranged in each pipeline to control the on / off of the pipeline, and these regulating valves can be manually or automatically operated. As Figure 1As shown, in addition to the above three-way regulating valve 161 for selectively controlling the on / off between the second pipeline 132 and the third pipeline 133 and / or the fourth pipeline 133, a two-way regulating valve 162 can also be provided in the first pipeline 131 to control the on / off of the first pipeline 131. In this embodiment, the two-way regulating valve 162 and the three-way regulating valve 161 are set as electric control valves. One or more check valves can also be arranged in each pipeline to prevent fluid backflow. In this embodiment, in the first pipeline 131, for example, between the heat exchanger 151 and the first fluid inlet 111 of the fuel tank 110, a first check valve 163 is arranged; in the second pipeline 132, for example, between the fluid outlet 112 of the fuel tank 110 and the heat exchanger 151, a second check valve 164 is arranged; a third check valve 165 is arranged in the third pipeline 133; and a fourth check valve 166 is arranged in the fourth pipeline 134. In addition, in the first pipeline 131, preferably downstream of the liquid rare gas storage tank 120, a pressure reducing valve 167 can be arranged to maintain the stability of the fluid pressure output from the liquid rare gas storage tank 120 and avoid excessive pressure in the first pipeline 131 and the downstream fuel tank 110. In this embodiment, the pressure reducing valve 167 is set as an electric control valve. It should be understood that Figure 2 the quantity, type and arrangement positions of the various valves shown are all exemplary, and any other suitable arrangement can be adopted according to actual needs.

[0032] One or more sensors can be arranged at the fuel tank 110. For example, an oxygen concentration sensor 181 for detecting the oxygen concentration in the fuel tank 110 and a pressure sensor 182 for detecting the pressure in the fuel tank 110. In addition, a temperature sensor 183 for detecting the temperature in the fuel tank 110 can also be provided. The fuel tank inerting system 1 can also include a controller 190, which is electrically connected or wirelessly signal-connected to one or more sensors at the fuel tank 110 and components such as the heat exchanger 151, the two-way regulating valve 162, the three-way regulating valve 161, the pressure reducing valve 167, and the fan 140. The controller 190 can be configured to receive the data sensed by one or more sensors at the fuel tank 110 and control various components in the fuel tank inerting system 1 via these data, such as controlling the opening and closing of the two-way regulating valve 162, the three-way regulating valve 161, and the pressure reducing valve 167, controlling the opening and closing of the fan 140, and / or controlling the opening and closing of the heat exchanger 151.

[0033] Figure 3The flowchart of an example method 300 for a fuel tank inerting system 1 according to the present invention to control the oxygen concentration in a fuel tank 110 by a controller 190 is shown. First, in step 301, an oxygen concentration sensor 181 continuously detects the oxygen concentration in the fuel tank 110. In step 302, the controller 190 receives the oxygen concentration signal detected by the oxygen concentration sensor 181 and determines whether the detected oxygen concentration is less than or equal to a threshold concentration. If the detected oxygen concentration is less than or equal to the threshold concentration, no adjustment is required and the oxygen concentration in the fuel tank 110 continues to be monitored by the oxygen concentration sensor 181. If the detected oxygen concentration is greater than the threshold concentration, then in subsequent step 303, the controller 190 causes the fuel tank inerting system 1 to supply cryogenic argon gas to the fuel tank 110. Specifically, the controller 190 can control the two-way regulating valve 162 and the pressure reducing valve 167 (if any) in the first pipeline 131 to open, and control the three-way regulating valve 161 such that the second pipeline 132 communicates with the third pipeline 133. At this time, depending on whether the pressure in the fuel tank 110 exceeds a threshold pressure, the second pipeline 132 may or may not communicate with the fourth pipeline 134, which will be described below with reference to Figure 4Further introduction. Preferably, however, the controller 190 may first control the three-way regulating valve 161 to connect the second pipeline 132 and the fourth pipeline 134 and maintain this state for a period of time, so that a part of the oxygen-containing fuel vapor flushed out of the fuel tank 110 by the cryogenic argon gas is discharged through the exhaust port 170. Subsequently, the controller 190 controls the three-way regulating valve 161 to connect the second pipeline 132 and the third pipeline 133. Optionally, in step 303, the controller 190 may also control the heat exchanger 151 to open. In addition, when a fan 140 is provided in the second pipeline 132, the controller 190 may also simultaneously control the fan 140 to start to suck gas from the fluid outlet 112 of the fuel tank 110. Thus, the cryogenic argon gas generated by the vaporization of the liquid argon in the liquid rare gas storage tank 120 continuously enters the fuel tank 110 through the first pipeline 131 to displace the gas above the fuel, thereby reducing the oxygen concentration and fuel vapor concentration in the fuel tank 110, and at the same time reducing the temperature in the fuel tank 110. The displaced gas containing fuel vapor is discharged from the fuel tank 110 through the second pipeline 132 and is cooled by the cryogenic argon gas in the first pipeline 131 at the heat exchanger 151. Part of the fuel vapor may be cooled and liquefied into liquid fuel at the heat exchanger 151. The cooled gas and liquid fuel may at least partially return to the fuel tank 110 through the third pipeline 133 and the second fluid inlet 113 of the fuel tank 110. On the one hand, this is beneficial to reducing the fuel temperature and fuel vapor temperature in the fuel tank 110, enabling the fuel vapor in the fuel tank 110 to be liquefied to reduce the fuel vapor concentration. On the other hand, the fuel consumption rate is reduced by recovering the fuel. Subsequently, in step 304, the controller 190 determines again whether the oxygen concentration detected by the oxygen concentration sensor 181 is less than or equal to the threshold concentration. If the detected oxygen concentration is still greater than the threshold concentration, return to continue executing step 303. If the detected oxygen concentration is less than or equal to the threshold concentration, then in the subsequent step 305, the controller 190 stops supplying cryogenic argon gas to the fuel tank 110 by the fuel tank inerting system 1. Specifically, the controller 190 may control the two-way regulating valve 162 and the pressure reducing valve 167 (if any) in the first pipeline 131 to close, and optionally also control the three-way regulating valve 161 to disconnect the second pipeline 132 and the third pipeline 133. Optionally, the controller 190 may also control the heat exchanger 151 to close. When a fan 140 is provided in the second pipeline 132, the controller 190 may also simultaneously control the fan 140 to close.

[0034] According to general safety specifications, the oxygen threshold concentration in the fuel tank can be set as follows: when the flight altitude is less than or equal to 10,000 feet, the oxygen threshold concentration is 12% or lower; when the flight altitude rises from 10,000 feet to 40,000 feet, the oxygen threshold concentration linearly increases from 12% to 14.5%.

[0035] Similar to the above-described method 300, the controller 190 may also be configured to control the opening and closing of the three-way regulating valve 161, the two-way regulating valve 162, the pressure reducing valve 167, the heat exchanger 151, and the fan 140 based on the temperature detected by the temperature sensor 183 in the fuel tank 110 to maintain the temperature in the fuel tank 110 within a preset threshold temperature range. For example, when the temperature detected by the temperature sensor 183 in the fuel tank 110 is greater than the threshold temperature, the controller 190 may control the two-way regulating valve 162 and the pressure reducing valve 167 (if any) in the first pipeline 131 to open, control the three-way regulating valve 161 to connect the second pipeline 132 with the third pipeline 133, and control the heat exchanger 151 and the fan 140 (if any) to open, thereby allowing the low-temperature argon gas and the fluid cooled by the heat exchanger 151 to be delivered to the fuel tank 110 to reduce the temperature in the fuel tank 110. When the temperature detected by the temperature sensor 183 in the fuel tank 110 is less than or equal to the threshold temperature, the controller 190 may stop supplying the low-temperature argon gas to the fuel tank 110 by the fuel tank inerting system 1. Specifically, the controller 190 may control the two-way regulating valve 162 and the pressure reducing valve 167 (if any) in the first pipeline 131 to close, and optionally, the controller may also control the three-way regulating valve 161 to disconnect the second pipeline 132 from the third pipeline 133, and control the heat exchanger 151 and the fan 140 (if any) to close.

[0036] Figure 4FIG. 0 shows a flowchart of an exemplary method 400 for a fuel tank inerting system 1 according to the present invention to control the pressure in a fuel tank 110 by a controller 190. First, in step 401, a pressure sensor 182 continuously detects the pressure in the fuel tank 110. In step 402, the controller 190 receives the pressure data detected by the pressure sensor 182 and determines whether the detected pressure is less than or equal to a threshold pressure. If the detected pressure is less than or equal to the threshold pressure, no adjustment is required and the pressure in the fuel tank 110 is continuously monitored by the pressure sensor 182. If the detected pressure is greater than the threshold pressure, then in a subsequent step 403, the controller 190 controls a three-way regulating valve 161 such that a second pipeline 132 communicates with a fourth pipeline 134, thereby allowing at least part of the fluid in the second pipeline 132 to be discharged to an exhaust port 170 via the fourth pipeline 134 and then discharged to the atmosphere through the exhaust port 170. At this time, as described above, depending on whether the oxygen concentration and / or temperature in the fuel tank 110 exceeds the corresponding threshold, the second pipeline 132 may or may not communicate with a third pipeline 133. That is to say, the second pipeline 132 may communicate with both the third pipeline 133 and the fourth pipeline 134 simultaneously, such that a part of the fluid in the second pipeline 132 returns to the fuel tank 110 via the third pipeline 133 to inert the fuel tank 110, while another part of the fluid in the second pipeline 132 is discharged to the atmosphere via the fourth pipeline 134 and the exhaust port 170 to avoid excessive pressure in the fuel tank 110. Subsequently, in step 404, the controller 190 determines again whether the pressure detected by the pressure sensor 182 is less than or equal to the threshold pressure. If the detected pressure is still greater than the threshold pressure, return to step 403 and continue to execute. If the detected pressure is less than or equal to the threshold pressure, then in a subsequent step 405, the controller controls the three-way regulating valve 161 to disconnect the second pipeline 132 from the fourth pipeline 134 and stop discharging gas to the atmosphere. The threshold pressure can be set according to safety specifications and the pressure-bearing level of the fuel tank 110.

[0037] The controller 190 can execute at least two of the above-mentioned method 300, method 400, and the method for controlling the temperature in the fuel tank simultaneously, so as to ensure that at least two of the oxygen concentration, pressure, and temperature in the fuel tank 110 are maintained within the corresponding threshold ranges simultaneously.

[0038] The controller 190 can be set, for example, as a controller that executes the above-mentioned methods through a computer program. In other embodiments, the controller 190 can also control each component through a hardware circuit that does not include computer software, such as an analog circuit or a digital circuit or any other suitable means.

[0039] Although in the above embodiments, the controller 190 reliably and automatically controls components such as the two-way regulating valve 162, the three-way regulating valve 161, the pressure reducing valve 167, the heat exchanger 151, and the fan 140 based on the signals of one or more sensors, the present disclosure is not limited thereto. In some embodiments, the controller 190 may be omitted, and the above methods 300, 400, and the method of controlling the temperature inside the fuel tank performed by the controller 190 may be manually executed by an operator. For example, the operator may manually control the opening and closing of components such as the two-way regulating valve 162, the three-way regulating valve 161, the pressure reducing valve 167, the heat exchanger 151, and the fan 140 based on whether the data detected by one or more sensors is higher than the corresponding threshold.

[0040] The fuel tank inerting system and method according to various embodiments of the present disclosure utilize the liquid rare gas storage tank 120 to store and release rare gases to displace the air containing fuel vapor above the fuel in the fuel tank. Some existing fuel tank inerting systems need to draw compressed air from the compressor of the aircraft engine and separate nitrogen therefrom for inerting the fuel tank, which limits the application of such fuel tank inerting systems to aircraft with an air extraction system. In contrast, the fuel tank inerting system and method according to the present disclosure do not rely on the air extraction system of the aircraft, and thus can be applied to various types of aircraft. In addition, eliminating the air extraction system for drawing compressed air from the compressor or at least reducing the amount of air drawn from the compressor is also beneficial to improving the propulsion efficiency and fuel consumption rate of the aircraft engine. Preliminary test verification shows that the weight of the fuel tank inerting system according to the present disclosure is comparable to or even possibly lower than that of the existing fuel tank inerting system with an air extraction system. Therefore, replacing the existing fuel tank inerting system with the fuel tank inerting system according to the present disclosure will not cause additional weight gain to the aircraft.

[0041] On the other hand, while the fuel tank inerting system and method according to various embodiments of the present disclosure utilize rare gases to displace the gas above the fuel in the fuel tank, they also effectively reduce the temperature inside the fuel tank and the concentration of fuel vapor in the fuel tank by using cryogenic gases and cooled fuel vapor or fuel droplets, thereby achieving double inerting of the fuel tank. In addition, recycling the cooled fuel vapor or fuel droplets back to the fuel tank reduces fuel loss.

[0042] Preferably, liquid argon is used as the liquid rare gas for fuel tank inerting. Compared with nitrogen, argon has stronger chemical inertness. In addition, argon also has the advantages of being non-toxic and harmless, having a low boiling point, being widely sourced, having rich reserves, being easily obtainable, and having low costs.

[0043] Herein, exemplary embodiments of a fuel tank inerting system, a fuel tank inerting method, and an aircraft according to the present disclosure have been described in detail, but it should be understood that the present disclosure is not limited to the specific embodiments described and illustrated above. Without departing from the gist and scope of the present disclosure, those skilled in the art can make various modifications and variations to the present disclosure. All such modifications and variations fall within the scope of the present disclosure. Moreover, all components described herein can be replaced by other technically equivalent components.

Claims

1. A fuel tank inerting system (1), characterized in that, Comprising: A fuel tank (110), the fuel tank comprising at least one fluid inlet (111, 113) and a fluid outlet (112); A liquid rare gas storage tank (120) storing liquid rare gas, wherein the liquid rare gas storage tank is connected to the at least one fluid inlet of the fuel tank via a first pipeline (131), and the fluid outlet of the fuel tank is connected to a second pipeline (132); and A heat exchanger (151), the first pipeline and the second pipeline are jointly connected to the heat exchanger such that the fluid in the first pipeline and the fluid in the second pipeline can perform heat exchange at the heat exchanger, Wherein, downstream of the heat exchanger, the second pipeline is connected to the at least one fluid inlet of the fuel tank via a third pipeline (133), thereby allowing the fluid discharged from the fuel tank through the second pipeline to at least partially return to the fuel tank via the third pipeline after being cooled by the heat exchanger.

2. The fuel tank inerting system (1) according to claim 1, characterized in that, A first regulating valve (162) for controlling the on-off of the first pipeline is provided in the first pipeline.

3. The fuel tank inerting system (1) according to claim 2, characterized in that, The fuel tank inerting system further includes a fourth pipeline (134) leading to an exhaust port (170), the second pipeline, the third pipeline and the fourth pipeline are connected via a second regulating valve (161), and the second regulating valve (161) is configured to selectively communicate the second pipeline (132) with the third pipeline (133) and / or the fourth pipeline (134).

4. The fuel tank inerting system (1) according to claim 3, characterized in that, At least one of the first pipeline, the second pipeline, the third pipeline, and the fourth pipeline is provided with a check valve (163, 164, 165, 166).

5. The fuel tank inerting system (1) according to claim 2, characterized in that, In the first pipeline, a pressure reducing valve (167) is provided downstream of the liquid rare gas storage tank.

6. The fuel tank inerting system (1) according to any one of claims 1 to 5, characterized in that, A dryer (152) is provided in the second pipeline or the third pipeline to remove moisture in the fluid in the second pipeline or the third pipeline.

7. The fuel tank inerting system (1) according to any one of claims 1 to 5, characterized in that, A suction device for sucking gas from the fluid outlet of the fuel tank is provided in the second pipeline.

8. The fuel tank inerting system (1) according to any one of claims 1 to 5, characterized in that, The liquid rare gas in the liquid rare gas storage tank includes liquid argon.

9. The fuel tank inerting system (1) according to claim 3, characterized in that, The fuel tank inerting system further includes an oxygen concentration sensor (181), a pressure sensor (182) and a temperature sensor (183) provided at the fuel tank.

10. The fuel tank inerting system (1) according to claim 9, characterized in that, The fuel tank inerting system further includes a controller (190), the controller is electrically connected or wirelessly signal-connected to the oxygen concentration sensor (181), the pressure sensor (182) and the temperature sensor (183), and the controller is electrically connected or wirelessly signal-connected to the first regulating valve and the second regulating valve, and the controller is configured to control the operation of the first regulating valve and the second regulating valve based on the oxygen concentration in the fuel tank detected by the oxygen concentration sensor (181), the pressure in the fuel tank detected by the pressure sensor (182) and / or the temperature in the fuel tank detected by the temperature sensor (183).

11. An aircraft (2), characterized in that, The aircraft includes a fuel tank inerting system (1) according to any one of claims 1 to 10.

12. A method for inerting a fuel tank, characterized in that, The fuel tank inerting method includes: providing a liquid rare gas storage tank (120) storing liquid rare gas, wherein the liquid rare gas storage tank is connected to at least one fluid inlet (111, 113) of a fuel tank (110) via a first pipeline (131), and a fluid outlet (112) of the fuel tank is connected to a second pipeline (132); providing a heat exchanger (151), the first pipeline and the second pipeline are jointly connected to the heat exchanger so that the fluid in the first pipeline and the fluid in the second pipeline can perform heat exchange at the heat exchanger, wherein, downstream of the heat exchanger, the second pipeline is connected to the at least one fluid inlet (111, 113) of the fuel tank via a third pipeline (133); and detecting the oxygen concentration in the fuel tank, when the oxygen concentration in the fuel tank is greater than a threshold concentration, allowing the rare gas generated by the gasification of the liquid rare gas in the liquid rare gas storage tank to pass through the first pipeline into the fuel tank to displace the gas above the fuel in the fuel tank, and allowing the fluid discharged from the fuel tank through the second pipeline to at least partially return to the fuel tank via the third pipeline after being cooled by the heat exchanger.

13. The fuel tank inerting method according to claim 12, wherein The fuel tank inerting method further includes: when the oxygen concentration in the fuel tank is less than or equal to the threshold concentration, stopping the introduction of the rare gas into the fuel tank.

14. The fuel tank inerting method according to claim 13, characterized in that, The fuel tank inerting method further includes: detecting the pressure in the fuel tank, when the pressure in the fuel tank is greater than a threshold pressure, communicating the second pipeline with an exhaust port (170); when the pressure in the fuel tank is less than or equal to the threshold pressure, disconnecting the second pipeline from the exhaust port.

15. The fuel tank inerting method according to claim 14, wherein, The fuel tank inerting method further includes: setting a first regulating valve (162) and a second regulating valve (161), the first regulating valve (162) is arranged in the first pipeline to control the on-off of the first pipeline, the second regulating valve (161) connects the second pipeline, the third pipeline and a fourth pipeline (134) leading to the exhaust port (170), and the second regulating valve (161) is configured to selectively communicate the second pipeline (132) with the third pipeline (133) and / or the fourth pipeline (134); when the oxygen concentration in the fuel tank is greater than the threshold concentration, controlling the first regulating valve to open and controlling the second regulating valve to communicate the second pipeline with the third pipeline; and when the oxygen concentration in the fuel tank is less than or equal to the threshold concentration, controlling the first regulating valve to close and controlling the second regulating valve to disconnect the second pipeline from the third pipeline.

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