Guard system for a hazardous fluid circuit of an aircraft, and associated installation and use methods

Abstract

A containment system (2) for a portion (1P) of a fluid circuit (1) circulating a dangerous fluid in an aircraft (A) comprises: an outer casing (3) configured to be mounted around the portion (1P) of the fluid circuit (1), the outer casing (3) defining a sealed outer cavity around the portion (1P) of the fluid circuit (1), the outer casing (3) having an inside casing pressure (Pc) strictly lower than the atmospheric pressure; at least one inner casing (4) configured to be mounted around the portion (1P) of the fluid circuit (1) within the outer casing (3), the inner casing (4) defining a sealed inner cavity around the portion (1P) of the fluid circuit (1), the inner casing (4) having an inside casing pressure (Pe), and a discharge pump (5) fluidically connected to the inner casing (4), the discharge pump (5) being configured to suck a fluid leak (F) inside the inner casing (4) and to discharge it outside the outer casing (3).

Description

Technical Field

[0001] This invention relates to the field of protective installations for the flow of hazardous fluids (such as flammable or explosive fluids). This invention is particularly applicable to the protection of fuel circuits in aircraft. Background Technology

[0002] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various countries have already implemented, are implementing, or will implement various carbon emission limits. In particular, an ambitious standard applies to both new and existing aircraft, requiring the implementation of technical solutions to comply with current regulations. The civil aviation industry has been actively mobilizing for years to contribute to addressing climate change.

[0003] Technological research has significantly improved the environmental performance of aircraft. The applicant has considered influencing factors at every stage of design and development to obtain aviation components and products that are more energy-efficient, environmentally friendly, and have a controllable environmental impact when integrated and used in civil aviation, thereby improving the energy efficiency of aircraft. Therefore, the applicant continuously strives to reduce its negative impact on the climate and its environmental footprint by adopting green methods and employing development and manufacturing methods and processes that minimize greenhouse gas emissions.

[0004] This ongoing research and development effort focuses on next-generation aircraft engines, equipment weight reduction (particularly through the use of lighter materials and airborne equipment), the application of electric technology in propulsion systems, and aviation biofuels as an important complement to technological advancements.

[0005] Therefore, this invention represents a technological research outcome aimed at significantly improving aircraft performance and, in this sense, contributing to reducing the environmental impact of aircraft. Specifically, this invention relates to a cryogenic fuel circuit for supplying fuel to an aircraft turbine.

[0006] The common practice is to store fuels (such as hydrogen or methane) in liquid form to minimize the overall size and weight of the aircraft's storage tanks. For this purpose, the fuel is stored in cryogenic tanks on the aircraft and supplied to the turbines via a fluid loop. For example, the fuel stream is stored in cryogenic tanks at temperatures of -253 to -251°C (20 to 22 Kelvin).

[0007] In order for fuel stream Q to flow through the aircraft structure and reach the combustion chamber of turbine M, fuel stream Q must be regulated, i.e., pressurized and heated, to convert it into a gaseous state. For this purpose, as follows... Figure 1As shown, fuel flow Q flows through fluid loop CQ, and then sequentially through mechanical pump PO and heat exchanger EC. Mechanical pump PO is configured to cause fuel flow Q to flow in fluid loop CQ. Heat exchanger EC is configured to supply heat to fuel flow Q, thereby warming the fuel flow Q so that it can be injected into turbine M. In practice, the fuel flow Q is heated in the heat exchanger EC by heat provided by a heat source on the aircraft. For example, as Figure 1 As shown, the common practice is to use the heat transferred from the exhaust flow of the turbine TU stage of turbine M to heat the fuel flow Q, which is generated by the combustion of the fuel flow Q and the compressed air flow in the combustion chamber CC. It is well known that heat transfer is achieved through a heat transfer fluid FC (such as an inert gas like nitrogen) to prevent the risk of contact between oxidizing and reducing fluids in the heat exchanger EC.

[0008] However, between the cryogenic storage tank R and the heat exchanger EC, the fuel flow Q flows at extremely low temperatures (close to cryogenic temperatures). At such temperatures, it is impossible to use flexible seals to achieve a sealed connection between the various devices in the fluid loop CQ (such as the mechanical pump PO, the heat exchanger EC, and even the shut-off valve V used to control the flow and velocity of fuel Q in the fluid loop CQ). Therefore, it is impossible to ensure that fuel Q will not leak in the fluid loop CQ, which can be a significant drawback.

[0009] In addition, at low temperatures, the fluid circuit CQ must be thermally insulated from the outside air to minimize the risk of icing or frosting on the pipes and equipment.

[0010] Therefore, the usual practice is to adopt, for example Figure 1 The enclosure-based protective system 100 shown encloses all cryogenic equipment within the fluid loop CQ and isolates it from air. A vacuum pump 101 evacuates the interior of the enclosure 100 and removes any fuel Q leakage that may occur at the connections between equipment components. This evacuation prevents fuel Q from accumulating within the enclosure 100. The vacuum generated by the vacuum pump 101 also eliminates heat transfer (whether cold or hot) via convection or conduction by removing air as a heat transfer medium.

[0011] In practice, the vacuum pump 101 must operate continuously to maintain the vacuum and expel any fuel Q leakage from the housing 100. Therefore, a high-performance vacuum pump is required, which presents several disadvantages. In fact, such vacuum pumps are generally bulky, making them particularly inconvenient in aviation environments. Furthermore, the significant weight of the vacuum pump increases the aircraft's fuel consumption, thereby increasing greenhouse gas emissions. Additionally, this type of pump is energy-intensive and acts as a heat source, which is undesirable in the presence of fuels such as hydrogen or methane. Moreover, fuel Q leakage into the sealed housing 100 can affect the maintenance of the vacuum, thereby impacting the thermal insulation performance of the fluid circuit CQ.

[0012] Therefore, the present invention aims to at least partially eliminate the aforementioned adverse factors by providing a reliable and effective protective system for protecting hazardous fluid circuits in aircraft. This protective system achieves both thermal insulation of the fluid circuit and optimal venting of fluid leaks. In particular, the present invention relates to a high-performance protective system that does not require a vacuum pump.

[0013] In addition, the following documents are known: US20140026597A1, US2023143288A1 and US2023027471A1, which disclose a cryogenic fuel storage tank comprising two walls enclosing an intermediate volume, the intermediate volume being either evacuated or filled with an inert gas. Summary of the Invention

[0014] This invention relates to a protective system for a portion of a fluid circuit in an aircraft through which a hazardous fluid flows, the protective system comprising: - An outer casing configured to be mounted around the portion of the fluid circuit, the outer casing defining a sealed outer cavity around the portion of the fluid circuit, the outer casing having an internal pressure strictly below atmospheric pressure. - At least one inner housing, configured to be mounted within the outer casing surrounding said portion of the fluid circuit, the inner housing defining a sealed cavity around said portion of the fluid circuit to form a double-sealed cavity, the inner housing having an internal pressure, and - A discharge pump, which is fluidly connected to the inner housing, is configured to draw in any fluid leakage within the inner housing and discharge it outside the outer housing.

[0015] This protective system forms a double-sealed wall, with the outer casing providing thermal insulation and the inner casing, along with the venting pump, ensuring that any leaked hazardous fluids are completely expelled. Therefore, this type of protective system allows for the separation of insulation and venting functions, eliminating the need for a high-performance vacuum pump to continuously operate and maintain a vacuum within the system. Consequently, the elimination of the need to install such a pump in the aircraft reduces its weight and facilitates easier integration of the protective system. By eliminating the need to install a high-performance vacuum pump on the aircraft, fuel consumption and greenhouse gas emissions can be reduced.

[0016] The internal pressure of the enclosure is lower than atmospheric pressure, creating a relative vacuum within the outer enclosure, thereby providing effective thermal insulation for the fluid circuit outside the enclosure. Thanks to the protective system according to the invention, if a leak occurs in the inner casing, the leaked material is discharged by a drain pump, and the vacuum level inside the outer casing remains unchanged. In other words, there is no need to create a vacuum inside the outer casing, and the insulation function is continuously provided.

[0017] Preferably, the discharge pump is configured to generate a power output between 1 kW and 5 kW. This power level allows the discharge pump to expel hazardous fluid leaks without creating a pressure differential within the cavity. In other words, unlike prior art vacuum pumps, this discharge pump is advantageously lightweight and compact because it is not configured to generate a pressure differential, but rather to generate a flow rate capable of facilitating the flow of a mixture of air and hazardous fluids in the event of a leak.

[0018] Preferably, the pressure inside the tank is strictly lower than the pressure inside the housing to prevent the inner housing from being pressed against the portion of the fluid circuit. Therefore, hazardous fluid leaks may occur inside the inner housing and can be easily discharged to the outside via a drain pump, without the risk of hazardous fluid remaining inside the inner housing.

[0019] Because the inner housing has a lower vacuum level than the outer casing, there is no need to add a separate internal leak recovery system to each component in the fluid circuit. This significantly reduces weight and minimizes the overall size of the portion within the protection system. Integration of the fluid circuit is also simplified.

[0020] Preferably, the pressure inside the casing is lower than atmospheric pressure to limit the mixing of fuel and air within the enclosed space. Ideally, the pressure inside the casing should be around 100 Pa, which ensures that the air concentration is low enough to eliminate the risk of fire in the event of a fuel leak.

[0021] This internal pressure ensures that the inner housing does not press against the equipment in the fluid circuit, thereby eliminating the risk of damage or wear to the inner housing due to contact with the equipment, while also ensuring that any possible fluid leaks can be drained.

[0022] In one respect, the internal pressure is approximately 10 Pa, thus ensuring the effective thermal insulation performance of the protection system. Thanks to this internal pressure, hazardous fluids can flow within the fluid circuit at cryogenic temperatures without posing a risk of damage to the external environment of the fluid circuit, especially the turbine.

[0023] In the first embodiment, the inner shell is made of material with an elastic modulus E between 0.5 × 10⁻⁶. 3 With 5×10 3 The material is made of a pressure between MPa. Ideally, the elastic modulus E of the inner shell should be between 1 × 10 MPa. 3 MPa and 1.6×10 3The pressure is between MPa. Therefore, the material is semi-rigid and can be formed into a largely flexible inner shell, which helps to minimize its overall size. Such materials enable the safety of the fluid circuitry in confined environments, specifically near the aircraft turbine. This also reduces the weight of the protective system, which is particularly beneficial in aviation environments designed to limit greenhouse gas emissions from aircraft. The semi-rigid inner shell is also easier for operators to install and reduces their physical burden.

[0024] In the second embodiment, the inner shell is made of material with an elastic modulus E between 5 × 10⁻⁶. 3 With 200×10 3 The material is made of a pressure between MPa. Ideally, the elastic modulus E of the inner shell should be between 5 × 10 MPa. 3 With 100×10 3 Between MPa. Therefore, the material is rigid, which helps to form a rigid double barrier that is more resistant to the effects of ambient temperature in the environment where the fluid circuit section is installed.

[0025] In one embodiment, the protection system includes at least one thermal insulation wall installed within the outer enclosure, the thermal insulation wall being configured to thermally insulate a first internal volume of the outer enclosure from a second internal volume of the outer enclosure. Such thermal insulation walls enable the installation of fluid loop devices operating at different temperatures without allowing the temperature of any one device to affect adjacent devices within the fluid loop portion. In other words, the thermal insulation wall helps reduce heat radiation to protect certain devices within the fluid loop portion. In one aspect, the protective system includes a plurality of inner housings, all of which are configured to be mounted around the portion of the fluid circuit, each inner housing being configured to be mounted around a single portion of the portion of the fluid circuit. It is generally advantageous to mount the inner housings independently of each other, as this makes them easier to install within the protective system. This is particularly advantageous when the portion of the fluid circuit to be encapsulated is large.

[0026] Preferably, when the protection system is used in an aircraft, it is not equipped with a vacuum pump, which helps to reduce the weight and overall size of the protection system, thereby helping to reduce the aircraft's fuel consumption. In one embodiment, the discharge pump is an active pump, preferably a hydraulic or electric pump, which enables efficient discharge of fuel leaks while minimizing the risk of hazardous fluid buildup in the inner housing in the event of a leak in the equipment components of the fluid circuit.

[0027] Optionally, the discharge pump is a passive pump and includes a device that operates based on the Venturi effect, which eliminates the need for specific equipment components and thus helps to reduce the mass and overall size of the protection system, which is particularly advantageous in aviation environments.

[0028] In one embodiment, the hazardous fluid flowing through the fluid circuit is cryogenic fuel.

[0029] The present invention also relates to an aircraft comprising at least one fluid circuit through which a hazardous fluid flows, and at least one protective system as described above for protecting a portion of the fluid circuit.

[0030] Furthermore, the present invention relates to an installation method for installing a protective system for protecting a portion of a fluid circuit as described above, the installation method comprising the following steps: - Use a vacuum pump to establish the first vacuum level in the inner housing. Connect the discharge pump to the inner housing. - Using the vacuum pump, a second vacuum level is established in the outer casing, which is lower than the first vacuum level in the inner casing, and - Remove the vacuum pump.

[0031] Thanks to this installation method, the high-performance vacuum pump is only used during the installation of the protective system and is subsequently removed, ideally without being mounted on the aircraft. This significantly reduces the mass of both the protective system and the aircraft. Advantageously, the protective system also consumes very little energy during flight because there is no need to continuously operate the high-performance vacuum pump.

[0032] Finally, the present invention relates to a method of using a protective system as described above, the method comprising the steps of pumping out a leak of hazardous fluid present in the inner housing by a discharge pump and discharging it to the outside of the outer housing. Thanks to the protective system according to the invention, a high-performance vacuum pump is not required when using the system, as the vacuum level inside the chamber remains constant in the event of a hazardous fluid leak. Thermal insulation is also ensured. Attached Figure Description

[0033] The invention will be better understood by reading the following description given by way of example and by referring to the accompanying drawings given by way of non-limiting example, wherein the same reference numerals denote similar objects. Figure 1 This is a schematic diagram of a system for protecting hazardous fluid circuits based on existing technology. Figure 2 This is a schematic diagram of an aircraft that includes a fuel circuit that supplies fuel to the turbines.

[0034] Figure 3 This is a schematic diagram of a system for protecting a fuel circuit according to a first embodiment of the present invention.

[0035] Figure 4 yes Figure 3 A close-up view of the protection system shown.

[0036] Figure 5 This is a schematic diagram of a system for protecting a fuel circuit according to a second embodiment of the present invention.

[0037] Figure 6 This is a schematic diagram of a system for protecting a fuel circuit according to a third embodiment of the present invention.

[0038] Figure 7 It is used for installation Figure 3 The diagram shows the steps of the protection system method.

[0039] It should be noted that the accompanying drawings illustrate the invention in detail in order to implement the invention, and the drawings can certainly be used to better define the invention if needed. Detailed Implementation

[0040] refer to Figure 2 The diagram illustrates an aircraft A comprising multiple turbines M, each turbine being supplied with fuel Q from a storage tank R containing fuel Q. In this example, fuel Q is dihydrogen, but it is self-evident that the invention is applicable to any type of hazardous fuel, particularly methane. In general, the invention is applicable to any circuit used for transporting hazardous fluids. Fuel Q is stored in a cryogenic tank R. For example, fuel stream Q is stored in cryogenic tank R at a temperature between -253°C and -251°C (20 Kelvin to 22 Kelvin). At this temperature, fuel stream Q is liquid. In order to be supplied to the combustion chamber CC of turbine M, fuel Q must be heated.

[0041] Therefore, refer to Figure 3 The aircraft A includes a fuel circuit 1 that connects a cryogenic storage tank R to the combustion chamber CC of a turbine M. A fuel stream Q flows from upstream to downstream through the fuel circuit 1 via a mechanical pump PO and passes through a heat exchanger EC, in which the fuel stream exchanges heat with a heat transfer fluid FC. In this example, the heat exchanger EC is configured to heat the fuel stream Q to its vaporization temperature. It goes without saying that the fuel stream Q can pass through more than one heat exchanger EC to allow for, for example, gradual heating of the fuel stream Q. In this example, a control valve V1 located upstream of the heat exchanger EC controls the flow rate of fuel Q in the fuel circuit 1, while a shut-off valve V2 located downstream of the heat exchanger EC controls the flow rate of fuel stream Q to the combustion chamber CC of the turbine M. It goes without saying that the fuel circuit 1 can include a varying number of devices. In this example, fuel circuit 1 includes a section 1P capable of causing a fuel Q leak, which must be controlled to ensure the safety of aircraft A. In this example, a mechanical pump PO, control valve V1, heat exchanger EC, and shut-off valve V2 are installed in section 1P of fluid circuit 1. Needless to say, section 1P can include various devices.

[0042] Part 1P of the fuel circuit 1 is made safe by the protection system 2, which will now be described in detail.

[0043] refer to Figure 3 and Figure 4 The protection system 2 includes an outer casing 3 and an inner casing 4, which are installed around a portion 1P of the fuel circuit 1 that requires safety protection.

[0044] like Figure 3 As shown, the outer casing 3 is installed around part 1P of the fuel circuit 1 and forms a sealed outer cavity around part 1P of the fluid circuit 1.

[0045] The dimensions of the outer casing 3 are determined to correspond to part 1P of the fuel circuit 1 that requires safety protection.

[0046] The outer casing 3 is preferably made of a rigid material to effectively protect portion 1P of the fuel circuit 1. Ideally, the outer casing 3 is made of metal or a composite material. Such an outer casing 3 provides thermal insulation to portion 1P of the fuel circuit 1, thereby preventing frost formation on the equipment components of the turbine M due to the low temperature of the fuel Q.

[0047] Preferably, refer to Figure 4 The outer casing 3 includes a first sealing member 30A installed at a first upstream end 13A of a portion 1P of the fuel circuit 1, corresponding to the inlet of the portion 1P into the outer casing 3, and a second sealing member 30B installed at a first downstream end 13B of the portion 1P of the fuel circuit 1, corresponding to the outlet of the portion 1P out of the outer casing 3. The outer casing 3 also includes a third sealing member 30C and a fourth sealing member 30D. The third sealing member 30C is installed at the inlet of the heat transfer fluid FC circuit into the outer casing 3, as previously described, the heat transfer fluid being configured to heat the fuel flow Q in the heat exchanger EC. The fourth sealing member is installed at the outlet of the heat transfer fluid FC circuit out of the outer casing 3. It goes without saying that the outer casing 3 may include a different number of sealing members 30. Specifically, if the fuel circuit 1 and / or the heat transfer fluid FC circuit has more than one inlet and more than one outlet in the outer casing 3, then the outer casing 3 includes a corresponding number of sealing members 30.

[0048] In this example, each sealing member 30 takes the form of a flexible element, such as an elastic ring, which is configured to provide both mechanical connection to the outer housing 3 and a seal for the outer housing 3 against fluid and fire. Preferably, the outer casing 3 includes an opening (not shown), such as a hatch, to allow access to portion 1P of the fuel circuit 1, for example, for maintenance purposes. This opening can be resealed to ensure it is waterproof. The size of this opening should preferably be set to allow for the removal of equipment from portion 1P or to allow for complete removal of portion 1P from the fuel circuit 1. According to one aspect of the invention, during use, the outer casing 3 has a pressure strictly below atmospheric pressure (i.e., 10). 5 The internal pressure Pc of the tank is approximately 1 Pa. In other words, the internal volume enclosed by the outer casing 3 is under vacuum to minimize the risk of fuel Q mixing with air in the event of a leak in part 1P of the fuel circuit 1. Ideally, the internal pressure Pc should be between 1 Pa and 10 Pa. In this example, the internal pressure Pc is approximately 10 Pa.

[0049] Therefore, in one embodiment, the outer casing 3 has a connection opening 31, such as Figure 4 As shown, the connection port 31 is configured to connect to a vacuum pump at a specific point so that the internal volume of the outer casing 3 reaches the internal pressure Pc, as will be described in more detail below. The connection port 31 can be resealed to prevent leakage.

[0050] As described above and as Figure 3 and Figure 4 As shown, the inner housing 4 is mounted around portion 1P of the fuel circuit 1. More specifically, the inner housing 4 is mounted inside the outer housing 3 around portion 1P and forms a sealed inner cavity around portion 1P of the fluid circuit 1. Thus, the outer housing 3 and the inner housing 4 provide double protection for portion 1P of the fuel circuit 1. The dimensions of the inner casing 4 are configured to correspond to the portion 1P of the fuel circuit 1 that requires safety protection.

[0051] In the first embodiment, the inner shell 4 is made of a flexible material. Therefore, the inner shell 4 is deformable to minimize the overall size of the protective system 2. Specifically, in this embodiment, the inner shell 4 is made of a material with an elastic modulus between 500 and 5000 MPa. Ideally, the elastic modulus should be between 1000 and 1600 MPa. Such an elastic modulus allows for the formation of a semi-rigid inner shell 4 that is deformable while being strong enough to minimize the risk of damage to the inner shell 4. In this example, the inner shell 4 is made of a polymer-based material (single-layer, multi-layer, composite, or others), such as TFE (or Teflon®), natural or synthetic rubber, silicone, etc. To increase its mechanical strength, the inner shell 4 may include reinforcements (composite mesh, straps, or other reinforcing structures) made of, for example, polyester, nylon, aramid, or steel.

[0052] exist Figure 5 In the second embodiment shown, the inner housing 4 is made of a substantially rigid material, thereby ensuring effective thermal insulation between the portion 1P of the fuel circuit 1 and the low temperature of the fuel Q flowing within the fuel circuit 1. Furthermore, the inner housing 4 is therefore non-deformable, thereby minimizing the risk of damage to the protection system 3, for example by preventing the risk of the inner housing 4 cracking at corners or sharp edges when in contact with any equipment component of the fuel circuit 1. Specifically, in this embodiment, the inner housing 4 is made of a material with an elastic modulus E between 5 × 10⁻⁶ and 10⁻⁶. 3 With 200×10 3 The material is made of a strength between 5 and 10 MPa. Ideally, the modulus of elasticity should be between 5 and 10 MPa. 3 MPa and 100×10 3 Between MPa. In this example, the inner casing 4 is made of a metallic material, a composite material, or any material unaffected by fuel Q and capable of withstanding negative pressure. Specifically, in this embodiment, the inner casing 4 is made of, for example, the same material as the outer casing 3 to form a robust double-wall structure and enhance the thermal insulation of part 1P of the fluid circuit 1.

[0053] Preferably, refer to Figure 4The inner housing 4 includes a first sealing member 40A installed at a second upstream end 14A of a portion 1P of the fuel circuit 1, corresponding to the inlet of portion 1P into the inner housing 4, and a second sealing member 40B installed at a second downstream end 14B of the portion 1P of the fuel circuit 1, corresponding to the outlet of portion 1P out of the inner housing 4. The inner housing 4 also includes a third sealing member 40C installed at the inlet of the circuit of the heat transfer fluid FC into the inner housing 4, and a fourth sealing member 40D installed at the outlet of the circuit of the heat transfer fluid FC out of the inner housing 4. It goes without saying that the inner housing 4 may include a different number of sealing members 40. Specifically, if the fuel circuit 1 and / or the heat transfer fluid FC circuit has more than one inlet and more than one outlet in the inner housing 4, then the inner housing 4 includes a corresponding number of sealing members 40.

[0054] In this example, each sealing member 40 takes the form of an elastic ring, within which the ends 1A, 1B of the fuel circuit 1 portion 1P or the circuit of the heat transfer fluid FC can extend. It goes without saying that each seal 40 can take different forms; for example, it can take the form of a clamping collar, specifically forming an integral part of the flange between two elements of the fuel circuit 1. Preferably, the inner housing 4 includes an opening (not shown) to allow access to a portion 1P of the fuel circuit 1, for example, for maintenance purposes. This opening can be resealed to ensure it is waterproof. In this example, the opening takes the form of a zipper fastener. Needless to say, the opening can take different forms, such as repositionable tape. The size of the opening should preferably be set to allow removal of the device from portion 1P or complete removal of said portion 1P from the fuel circuit 1. Alternatively, needless to say, the inner housing 4 may not have an opening and can be configured to be removed for maintenance and replaced with a new inner housing 4. According to one aspect of the invention, the inner housing 4 has an internal pressure Pe that is strictly greater than the internal pressure Pc, thereby preventing the inner housing 4 from being pressed against the portion 1P of the fluid circuit 1 due to the internal pressure Pc being lower than atmospheric pressure. Ideally, the internal pressure Pe should also be lower than atmospheric pressure, i.e., 105 Pa, so as to minimize the risk of fuel Q mixing with air in the event of a leak in the portion 1P of the fuel circuit 1. Ideally, the internal pressure Pe should be between 10 Pa and 100 Pa. In this example, the internal pressure Pe is approximately 100 Pa.

[0055] Therefore, in one embodiment, the inner housing 4 has a connection port 41 configured to temporarily connect a vacuum pump to bring the internal volume of the inner housing 4 to an internal pressure Pe, as will be described in more detail below. The connection port 41 can be resealed to prevent leakage.

[0056] In one embodiment, such as Figure 6 As shown, the protection system 2 includes multiple inner housings 4A, 4B, all of which are configured to be mounted around a portion 1P of the fluid circuit 1. Preferably, each inner housing 4A, 4B is configured to be mounted around a separate portion 11P, 12P of the portion 1P of the fluid circuit 1. In other words, the inner housings 4A, 4B are all mounted within the outer housing 3, surrounding different equipment within the portion 1P requiring safety protection. In this example, the protection system 2 includes two inner housings 4A and 4B; needless to say, the number of inner housings 4A and 4B may be more than two. Using multiple inner housings 4A, 4B effectively minimizes its overall size, thereby facilitating the mounting of the protection system 2 around the portion 1P of the fluid circuit 1. This embodiment also allows for independent maintenance of each component. In this embodiment, needless to say, the protection system 2 includes a sealing member 40 at each inlet and each outlet of the fuel circuit 1 of each inner housing 4A, 4B.

[0057] Because the outer casing 3 and the inner casing 4 are associated with different pressure levels, the protection system 2 does not require a high-performance vacuum pump when used on an aircraft. This has the advantage of reducing the mass and overall size of the protection system 2, and thus reducing the mass and overall size of the aircraft. This also helps to reduce the production cost and energy consumption of the aircraft.

[0058] refer to Figures 3 to 6 To discharge any potential fuel leak F within the inner housing 4, the protection system 2 includes a discharge pump 5 fluidly connected to the inner housing 4, and the discharge pump 5 is configured to discharge the fuel leak F to the outside of the outer housing 3. More specifically, the discharge pump 5 is configured to generate a flow rate sufficient to cause a mixture of air and hazardous fluid to flow upon leakage F. In other words, the discharge pump 5 has dimensions and characteristics configured to discharge the leak without generating sufficient power to create a pressure differential. Therefore, the discharge pump 5 is lightweight and compact.

[0059] Preferably, the exhaust pump 5 is configured to generate a power output between 1 kW and 5 kW. This power enables the exhaust pump 5 to discharge fuel leakage Q without creating a pressure difference between the internal cavity and the external cavity. Therefore, such an exhaust pump 5 is lightweight and compact.

[0060] To drain the leaked fuel Q, in this example, the protection system 2 includes a drain circuit 50 that connects the inner housing 4 to the outside of the protection system 2. When multiple inner housings 4A, 4B are present, a drain pump 5 is fluidly connected to each inner housing. In the first embodiment, the discharge pump 5 is an active pump and takes the form of, for example, a hydraulic pump or an electric pump.

[0061] In the second embodiment, the discharge pump 5 is a passive pump and operates according to the Venturi effect. In one example, the discharge circuit 50 includes a channel portion with a narrowed cross-section at its connection with the inner housing 4. Due to the pressure difference between the inner housing 4 and the outside of the outer casing 3, and the narrowing of the channel cross-section, the channel portion is able to draw in leaked fuel Q and transport it to the outside of the outer casing 3.

[0062] In one respect, the discharge pump 5 is connected to the aircraft's computer so that it is activated only when necessary, such as when a leak F is detected.

[0063] refer to Figure 5 and Figure 6 In one embodiment, the protection system 2 includes a thermal insulation wall 6 installed within an outer housing 3, the thermal insulation wall being configured to divide the internal volume of the outer housing 3 into a first basic volume 3A and a second basic volume 3B. Each basic volume 3A, 3B includes segments 11P, 12P of a portion 1P of the fluid circuit 1. Only a single thermal insulation wall 6 has been described; however, it is self-evident that the protection system 2 may alternatively include more than one thermal insulation wall 6 to provide thermal insulation for more than two basic volumes 3A, 3B within the outer housing 3. Alternatively, the thermal insulation wall 6 is installed within an inner housing 4 to provide thermal insulation for two basic volumes 4C, 4D of a single inner housing 4, such as... Figure 5 As shown.

[0064] The thermal insulation wall 6 is configured to provide thermal insulation to the first basic volume 3A and the second basic volume 3B, thereby thermally insulating one or more components of the fuel circuit 1 from other components of the fuel circuit 1 present in the outer casing 3. For this purpose, the thermal insulation wall 6 is preferably made of a rigid material to provide effective thermal protection. In this example, the thermal insulation wall 6 comprises a stack of reflective material layers (referred to by those skilled in the art as a "multilayer insulation"), which helps to minimize heat radiation loss. Alternatively, the thermal insulation wall 6 may be made of a material that reduces heat loss.

[0065] In one embodiment, the protection system 2 includes a first pressure sensor (not shown) configured to measure the internal pressure Pc within the outer housing 3 to ensure optimal operation of the protection system 2. The protection system 2 also includes a second pressure sensor (not shown) configured to measure the internal pressure Pe within the inner housing 4.

[0066] In one aspect, the protection system 2 may include a fuel sensor, specifically a hydrogen sensor, to detect leaks F in the inner housing 4.

[0067] Now refer to Figure 7 A method for installing the protection system 2 as described above is described.

[0068] In the first step E1, part 1P of the fuel circuit 1 is positioned inside the inner housing 4. In practice, part 1P is inserted through the access port. Then, part 1P of the fuel circuit 1 and the inner housing 4 are positioned inside the outer housing 3. In practice, part 1P and the inner housing 4 are inserted through the access port.

[0069] Then, in step E2, the operator fluidly connects the discharge pump 5 to the inner housing 4.

[0070] like Figure 4 As shown, each sealing member 40A, 40B, 40C, and 40D is then installed at the upstream end 14A and downstream end 14B of the portion 1P of the fuel circuit 1, and at the inlet and outlet of the circuit of the heat transfer fluid FC within the inner casing 4, respectively. Similarly, each sealing member 30A, 30B, 30C, and 30D is installed at the ends 13A and 13B of the portion 1P of the fuel circuit 1, and at the inlet and outlet of the circuit of the heat transfer fluid FC within the outer casing 3, respectively.

[0071] The opening in the inner housing 4 is then sealed to form a sealed inner cavity around the portion 1P of the fluid circuit 1.

[0072] In the third step E3, the operator connects the vacuum pump PV (different from the exhaust pump 5) to the connection port 41 of the inner housing 4 to create a vacuum in the inner housing 4 by evacuating the air present in it. Evacuation continues until the pressure inside the inner housing 4 reaches a predetermined internal pressure Pe. In this example, the internal pressure Pe is approximately 100 Pa. In other words, this step establishes an initial vacuum level in the inner housing 4. When the internal pressure of the inner housing 4 reaches the internal pressure Pe, the vacuum pump PV is turned off and the connection port 41 is sealed closed.

[0073] Then the opening in the outer casing 3 is closed to form a sealed outer cavity around part 1P of the fluid circuit 1. In step E4, the operator connects the vacuum pump PV to the connection port 31 of the outer housing 3 to create a vacuum in the outer housing 3 by evacuating air from the outer housing. Evacuation continues until the pressure inside the outer housing 3 reaches a predetermined internal pressure Pc, which is lower than the internal pressure Pe. In this example, the internal pressure Pc is approximately 10 Pa. In other words, in this step, a second vacuum level lower than the first vacuum level is created in the outer housing 3. In this example, the second vacuum level is 10% of the first vacuum level. When the pressure inside the outer housing 3 reaches the internal pressure Pc, the vacuum pump is turned off and the connection port 31 is sealed closed. The inner housing 4 is not subjected to forces that tend to press it against the equipment in part 1P. Therefore, the inner housing 4 is configured to accommodate potential leaks while having a smaller volume than the outer housing 3, which makes it easier to control the internal pressure Pe. The internal pressure Pc of the housing is preferably kept constant, and the outer housing 3 provides thermal insulation.

[0074] The description will now be as previously referenced. Figure 3 The method of using the aforementioned protective system 2. The inner shell 4 and the outer casing 3 are sealed and waterproof. An internal pressure Pe and a casing pressure Pc lower than the internal pressure Pe are applied inside the inner shell 4 and the outer casing 3, respectively.

[0075] In this example, in step EA, a leak F is detected at one of the components in section 1P of the fuel circuit 1. The leak F occurs in the inner housing 4. In this example, the leak F is detected by a fuel sensor installed inside the inner housing 4.

[0076] Then, in step EB, the discharge pump 5 is activated to draw in the fuel leak F and discharge it to the outside of the outer casing 3. Since the discharge pump 5 is connected to the inner casing 4, the pressure Pc inside the casing remains unaffected by the discharge of the leak F, and thermal insulation is ensured by the outer casing 3 over a long period of time, thereby effectively protecting part 1P of the fuel circuit 1.

Claims

1. A protective system (2) for a portion (1P) of a fluid circuit (1) through which a hazardous fluid flows in an aircraft (A), characterized in that, include: - Outer housing (3), which is configured to be mounted around the portion (1P) of the fluid circuit (1), the outer housing (3) defining a sealed outer cavity around the portion (1P) of the fluid circuit (1), the outer housing (3) having an internal pressure (Pc) strictly below atmospheric pressure. - At least one inner housing (4) configured to be mounted within the outer casing (3) surrounding the portion (1P) of the fluid circuit (1), the inner housing (4) defining a sealed cavity around the portion (1P) of the fluid circuit (1) to form a double-sealed cavity, the inner housing (4) having an internal pressure (Pe), and - Discharge pump (5), which is fluidly connected to the inner housing (4), and is configured to draw out fluid leakage (F) within the inner housing (4) and discharge it outside the outer housing (3).

2. The protection system (2) as described in claim 1, characterized in that, The pressure inside the chamber (Pc) is strictly lower than the pressure inside the outer shell (Pe) to prevent the inner shell (4) from being pressed against the portion (1P) of the fluid circuit (1).

3. The protection system (2) as described in claim 1 or 2, characterized in that, The inner shell (4) is made of material with an elastic modulus E between 0.5 × 10⁻⁶. 3 With 5×10 3 Made of materials with pressures between MPa.

4. The protection system (2) as described in claim 1 or 2, characterized in that, The inner shell (4) is made of material with an elastic modulus E between 5 × 10⁻⁶. 3 With 200×10 3 Made of materials between Pa.

5. The protection system (2) as described in any one of claims 1 to 4, characterized in that, The protective system (2) includes at least one heat insulation wall (6) installed inside the outer casing (3), the heat insulation wall (6) being configured to provide thermal insulation to a first internal volume (3A) and a second internal volume (3B) of the outer casing (3).

6. The protection system (2) as described in any one of claims 1 to 5, characterized in that, The protection system (2) includes a plurality of inner housings (4A, 4B), all of which are configured to be mounted around the portion (1P) of the fluid circuit (1), and each inner housing (4A, 4B) is configured to be mounted around a corresponding individual portion (11P, 12P) of the portion (1P) of the fluid circuit (1).

7. The protection system (2) as described in any one of claims 1 to 6, characterized in that, The protective system (2) does not require a vacuum pump when used in the aircraft.

8. The protection system (2) as described in any one of claims 1 to 7, characterized in that, The discharge pump (5) is an active pump, preferably a hydraulic pump or an electric pump.

9. The protection system (2) as described in any one of claims 1 to 8, characterized in that, The discharge pump (5) is a passive pump and includes a device that operates based on the Venturi effect.

10. The protection system (2) as described in any one of claims 1 to 9, characterized in that, The hazardous fluid flowing through the fluid circuit (1) is cryogenic fuel.

11. An aircraft, characterized in that, The aircraft includes at least one fluid circuit (1) through which a hazardous fluid flows, and at least one protective system for a portion (1P) of the fluid circuit (1) as claimed in any one of claims 1 to 10.

12. A method for installing a protective system (2) as described in any one of claims 1 to 10 for protecting a portion (1P) of the fluid circuit (1), characterized in that, Includes the following steps: -A first vacuum level is established in the inner housing (4) by means of a vacuum pump (PV), - Connect the discharge pump (5) to the inner housing (4) in fluid. - A second vacuum level is established in the outer casing (3) by the vacuum pump (PV), the second vacuum level being lower than the first vacuum level in the inner casing (4), and - Remove the vacuum pump (PV).

13. A method of using the protection system (2) as described in any one of claims 1 to 9, characterized in that, The method of use includes the steps of pumping out the dangerous fluid leak (F) present in the inner housing (4) by a discharge pump (5) and discharging it to the outside of the outer housing (3).

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