Adjustment system for aircraft, aircraft and method for adjusting fuel of adjustment system

Abstract

The invention relates to a regulating system for an aircraft, an aircraft and a method for regulating fuel of a regulating system. In particular, the present invention pertains to a conditioning system having a new configuration comprising a power unit and a heat exchanger located at the output of the power unit. The aircraft comprises the adjusting system.

Description

Technical Field

[0001] The present invention relates to a regulation system for an aircraft. In particular, the present invention pertains to a regulation system of a new construction comprising a power unit and a heat exchanger at the output of the power unit.

[0002] The invention also relates to an aircraft comprising such a regulating system and to a method for regulating fuel by means of the regulating system of the invention. Background Art

[0003] Auxiliary power unit or APU is known in the field of aviation technology as an engine capable of supplying energy to functions of the aircraft that are not considered propulsion functions. APUs are usually found in large aircraft and are located at or near the tail cone portion of these aircraft.

[0004] A typical APU generally includes a power section as the power generation section of the APU, a load compressor section that provides pneumatic power to the aircraft, and a gearbox section responsible for transferring power from the main shaft of the engine to the generator for electrical power. The APU is also known as an electrical power source and a pneumatic power source that allow the aircraft to be independent of external power sources on the ground and in flight.

[0005] In addition, when the aircraft is on the ground, the auxiliary power unit in the aircraft can be used to replace the main engine when the main engine is not running. The APU also maintains short-term power to start the main engine during normal operation. The APU can be used to replace the power generated by the main engine when a failure occurs due to a dispatch condition or continue to be implemented to supply emergency power until the aircraft lands.

[0006] The prior art discloses engines for realizing hydrogen combustion for use in the aviation and automobile fields.

[0007] Furthermore, in the field of gas turbines for aircraft, known techniques provide for exhaust gas heat recovery. However, these processes and techniques used today are suitable for fossil fuel engines.

[0008] The known problems of hydrogen engines are based on conditioning the hydrogen fuel to ambient temperature and the correct pressure in order to supply the engines of the APU under suitable conditions and also on ensuring safe combustion avoiding damage to the various components and ducts of the auxiliary power unit. Due to the storage conditions of hydrogen in the field of aviation technology of about 20K, hydrogen is a fuel that requires specific dimensions and specific operating conditions of the systems that consume this type of fuel.

[0009] Furthermore, other known problems with the use of hydrogen for engines in aircraft are due to phase changes, since the hydrogen is in a liquid phase when stored in the aircraft before being supplied to the engines. However, in order for the engines of the APU to work optimally, the liquid hydrogen must undergo a phase change from liquid to gas. These phase changes also require that the system be designed and dimensioned so that the hydrogen remains stable as its conditions (temperature, pressure, etc.) vary throughout the auxiliary power system.

[0010] Finally, in the prior art, some configurations for conditioning the fuel introduced inside the power unit of an aircraft may include an additional fluid capable of withdrawing, at the output of the power unit, the heat recovered from the exhaust gases. Said heat then passes through an evaporator and through an additional circuit to the fuel before injection into the engine. The known problems of the configurations of the prior art make the whole system complex to realize, heavy in terms of the weight of the whole aircraft and onerous in terms of equipment maintenance.

[0011] Therefore, there is a need in the art for a regulation system that allows regulating fuel, preferably hydrogen, while optimizing the overall weight and complexity of said regulation system. At the same time, the regulation system of the solution also meets the requirements of hydrogen regulation such as operational requirements, functional requirements and safety requirements, so as to keep the fuel, such as hydrogen, in its optimal condition during any flight or ground operation of the aircraft. Summary of the invention

[0012] The invention provides a regulating system according to a first inventive aspect, an aircraft according to a second inventive aspect, and a method for regulating fuel in a regulating system according to a third inventive aspect and a fourth inventive aspect. Other aspects of the invention disclose specific embodiments of the invention.

[0013] In a first inventive aspect, the present invention provides a regulation system for an aircraft, the regulation system comprising a power unit, wherein the power unit comprises:

[0014] a fuel inlet configured to supply liquid fuel to the fuel conduit,

[0015] An engine, the engine comprising:

[0016] an inlet connected to a fuel conduit, and

[0017] outlet, which is connected to the power unit outlet,

[0018] The power unit outlet is configured to discharge gases from the engine,

[0019] A first heat exchanger, the first heat exchanger being connected to the power unit outlet, the first heat exchanger comprising:

[0020] Exhaust gas inlet,

[0021] Exhaust gas outlet,

[0022] fuel inlet and fuel outlet,

[0023] a first portion of the fuel conduit connects a fuel inlet of the regulating system to a fuel inlet of the first heat exchanger, and a second portion of the fuel conduit connects a fuel outlet of the first heat exchanger to an inlet of the engine,

[0024] a heating device including a fuel inlet and a fuel outlet, the heating device being located between the first heat exchanger and the engine, and wherein the heating device is configured to supply heat to the fuel of the fuel conduit and further configured to transform the fuel of the fuel conduit from a liquid form or a supercritical fluid form (SCF) to a cryogenic gas form,

[0025] a bypass conduit configured to connect the first portion of the fuel conduit to the second portion of the fuel conduit,

[0026] in,

[0027] The first heat exchanger is configured to transfer heat from exhaust gas at the power unit outlet to fuel in the fuel conduit.

[0028] The regulation system of the present invention comprises a power unit. In some embodiments, the power unit is an auxiliary power unit also called APU or any propulsion system configured to deliver power to an aircraft. In a specific embodiment where the power unit is an APU, the auxiliary power unit is configured to provide standard APU functions, which will deliver electrical and pneumatic power for ground operations and flight operations. In addition, the regulation system is suitable for installation in an aircraft.

[0029] The power unit of the present invention includes a fuel inlet that provides liquid fuel to a fuel conduit.

[0030] The fuel provided to the fuel inlet is in liquid phase and is previously stored under specific temperature and pressure conditions before being injected into the regulation system. In a preferred embodiment, the fuel is stored at a temperature in the range between 20 K and 30 K. At the fuel inlet, the fuel is injected at a temperature comprised in said temperature range.

[0031] The conditioning system of the present invention further comprises a heating device, a first heat exchanger and an engine.

[0032] In a first inventive aspect of the present invention, a heating device is located between the first heat exchanger and the engine. The heating device is configured to supply heat to the fuel of the fuel conduit so that the fuel reaches a desired temperature before being injected into the interior of the engine. In a preferred embodiment, at the fuel outlet of the heating device, the fuel is at a temperature of about 290K.

[0033] In operating mode, when the first heat exchanger has not reached its optimal mode, the heating device supplies the necessary heat for providing a temperature increase to the fuel in gaseous form in order to reach the required temperature before injection into the engine. That is, for example, if the required temperature is 290K and the temperature at the fuel output of the first heat exchanger is below 290K, the heating device is configured to provide the necessary remaining heat until the fuel reaches a temperature of 290K.

[0034] At the same time, the heating device is configured to transform the fuel of the fuel conduit from a liquid form or a supercritical fluid form (SCF) into a low-temperature gas form, that is, the heating device also fulfills the function of an evaporation device. One of the main functions of the evaporation device is to adjust the fuel entering the heating device from an inlet temperature to an outlet temperature, wherein the outlet temperature is significantly higher than the inlet temperature, while the fuel is also transformed from a liquid form or a supercritical fluid form (SCF) into a low-temperature gas form. Therefore, the heating device is able to resist and adapt to the change of phase of the fuel, that is, the change from liquid to gas.

[0035] The heating device will be considered as a support to the conditioning system of the invention, which will be switched off in the operating mode and the first heat exchanger of the conditioning system provides all the required energy / heat to the fuel of the fuel duct.

[0036] In other words, the energy of the heating device of the fuel supplied to the fuel duct is reduced, while the energy supplied to the fuel duct by the first heat exchanger is increased. That is, the balance between the heating device and the first heat exchanger is to be considered as an active control performed by the regulating system, more specifically an active control of the condition of the fuel of the power unit, more specifically the temperature of the fuel.

[0037] Advantageously, heating the fuel by means of the heating device avoids the condition of a cold start of the engine, which is considered to be the worst starting condition for any embodiment of a power unit, such as an auxiliary power unit or a thruster. In particular, a cold start of the engine is the worst starting condition for a power unit, because more fuel is needed for the engine to start, and at the same time more heat is needed from the heating device.

[0038] The regulating system of the invention further comprises a bypass conduit connecting the first portion of the fuel conduit to the second portion of the fuel conduit, that is, the regulating system can be adjusted so that the fuel of the fuel conduit is not injected into the first heat exchanger but is directed directly towards the inlet of the heating device.

[0039] In particular, the bypass conduit helps avoid cold start conditions also for the first heat exchanger. In the absence of the bypass conduit, fuel would be forced to be injected inside the heat exchanger even when the engine is not running or has not been recently started, which does not ensure that the first heat exchanger can operate in its optimal conditions. Therefore, under these conditions, the present invention helps to avoid damage to the first heat exchanger by means of the bypass conduit, so that the engine is started and a certain amount of exhaust gas is generated so that it can be ensured that the first heat exchanger is in optimal conditions for receiving liquid fuel through the fuel inlet of the first heat exchanger.

[0040] In an embodiment, the heating device comprises a dedicated external battery which ensures that energy is supplied to the heating device so that heat is supplied to the fuel of the fuel duct by means of the heating device, independently of the power produced by the power unit. In addition, by having a dedicated external battery, the aircraft is considered autonomous.

[0041] In an embodiment, the first heat exchanger comprises a plurality of plates receiving liquid fuel from a fuel conduit, also known as a pillow plate heat exchanger (PPHE).The temperature of the liquid fuel increases due to heat transferred from the exhaust gases of the engine.

[0042] Preferably, at the fuel inlet of the first heat exchanger, the liquid fuel temperature is about 20 K. Also preferably, at the fuel outlet of the first heat exchanger, the liquid fuel temperature is about 290 K.

[0043] In an embodiment, the engine of the present invention is a gas turbine.

[0044] Advantageously, the regulation system of the invention provides the fuel to the engine of the power unit at the desired temperature and in gaseous form at any time when the power unit is in operation, that is to say wherein the fuel is at a temperature of about 290 K. The regulation system of the invention thus allows a constant and precise control of the fuel condition before injection inside the engine of the power unit.

[0045] Furthermore, the invention requires only one circuit, the fuel conduit, to perform the heat transfer, which reduces the overall weight of the conditioning system. The invention also helps facilitate maintenance of the components of the system. For example, if a second circuit comprising a working fluid is required to supply heat, maintenance and eventual damage to the second circuit may reduce the performance of the conditioning system. That is, the construction required by the first inventive aspect of the invention also provides a less complex system for conditioning fuel.

[0046] In an embodiment, the regulation system further comprises a valve configured to open or close a flow of fuel into the regulation system at the fuel inlet.

[0047] Advantageously, if any fault or damage is detected at any time or in any element of the regulation system of the present invention, the fuel flow may be shut off.

[0048] In an embodiment, the regulation system further comprises a pumping device configured to supply fuel to the power unit.

[0049] Advantageously, the pumping device increases the pressure of the fuel in liquid form before the fuel is injected into the power unit. In addition, the pumping device requires much less power when it is placed close to the fuel inlet of the regulating system and when it is actuated on the fuel in liquid form relative to the power required when the fuel is in gaseous form.

[0050] In an embodiment, the regulation system further comprises a second heat exchanger comprising a first inlet, a first outlet, a second inlet and a second outlet, wherein the first inlet and the first outlet of the second heat exchanger are connected to the first portion of the fuel conduit and the second inlet and the second outlet are connected to the second portion of the fuel conduit, the second heat exchanger being configured:

[0051] supplying heat from the fuel in the second portion of the fuel conduit to the fuel in the first portion of the fuel conduit, and

[0052] The fuel in the fuel conduit is converted from a liquid form or a supercritical fluid form to a cryogenic gas form.

[0053] Due to the second heat exchanger, the conditioning system provides enhanced performance, since the second heat exchanger supplies heat from the fuel in the second portion of the fuel conduit to the fuel in the first portion of the fuel conduit. That is, the second heat exchanger immediately transfers heat to the fuel in the fuel conduit after being introduced into the conditioning system through the fuel inlet, so that the fuel in the first portion of the fuel conduit reaches a higher temperature at the first outlet than its temperature at the first inlet.

[0054] When implemented in the conditioning system, the second heat exchanger is able to perform evaporation of the fuel, so that the fuel is transformed from liquid form into gaseous form before it is introduced inside the first heat exchanger.

[0055] The second heat exchanger relies on heat that can be transferred from the fuel once it is output from the first heat exchanger and enters the second portion of the fuel conduit. Preferably, the temperature of the fuel at the outlet of the first heat exchanger is higher than the temperature required for the engine to operate at its optimal conditions. By providing the fuel output from the first heat exchanger at a higher temperature than the temperature required for the engine to operate at its optimal conditions, the second heat exchanger is able to supply an amount of heat to the fuel in the first portion of the fuel conduit. The amount of heat is determined by the temperature delta between the temperature of the fuel at the fuel outlet of the first heat exchanger and the temperature required for the engine to be at its optimal condition, i.e. preferably 290K.

[0056] For example, the temperature at the fuel inlet of the conditioning system is 20K and reaches 110K after output from the second heat exchanger. At the same time, the fuel has been transformed into gaseous form before being injected into the first heat exchanger. At the fuel outlet of the first heat exchanger, the fuel of the second part of the fuel conduit reaches 380K, which provides additional heat to the fuel of the first part of the fuel conduit through the second heat exchanger. Ideally, the second heat exchanger is configured to output the gaseous fuel at a temperature of 290K at its second outlet, so that the heating device remains closed.

[0057] In an embodiment, the regulating system comprises a valve, preferably a mechanical valve, located between the first outlet of the second heat exchanger and the fuel inlet of the first heat exchanger.

[0058] Advantageously, the valve helps prevent fuel from entering the interior of the first heat exchanger in the event that damage or malfunction is detected within the interior of the first heat exchanger.

[0059] In an embodiment, the conditioning system further comprises a muffler, wherein the first heat exchanger is configured to be coupled inside the muffler.

[0060] In an embodiment, the conditioning system comprises a muffler located at the exhaust gas outlet of the first heat exchanger.

[0061] Advantageously, the muffler provides sound-damping properties at the output of the power unit.

[0062] In an embodiment, the first heat exchanger is configured to enclose the entire vertical cross-section of the power unit outlet.

[0063] Completely enclosing the area of ​​the power unit outlet with the heat exchanger ensures that a large portion of the heat of the fuel transferred to the fuel conduit is utilized based on the heat generated by the power unit outlet.

[0064] In an embodiment, the fuel inlet and the fuel outlet of the first heat exchanger are mounted in counter-flow relative to the exhaust gas inlet and the exhaust gas outlet of the first exchanger.

[0065] Mounting the fuel inlet and fuel outlet of the first heat exchanger in a counter-current manner relative to the exhaust gas inlet and exhaust gas outlet of the first exchanger helps to provide heat to the fuel in a gradually increasing gradient. At the exhaust gas inlet of the first heat exchanger, the temperature of the exhaust gas is higher than when the exhaust gas reaches the exhaust gas outlet. Therefore, by mounting the exhaust gas outlet at the same end of the first heat exchanger as the fuel inlet, the fuel inlet is able to gradually increase the temperature of the exhaust gas outlet inside the first heat exchanger. When the fuel reaches the fuel outlet, the fuel contacts the exhaust gas inlet, where the temperature of the exhaust gas is highest, and the temperature difference is low relative to the temperature difference between the fuel at the fuel inlet and the exhaust gas at the gas inlet.

[0066] Advantageously, this provides optimized heat transfer between the exhaust gases and the fuel.

[0067] In an embodiment, the first inlet and the first outlet of the second heat exchanger are arranged in counter-flow relative to the second inlet and the second outlet of the second heat exchanger.

[0068] As mentioned above, mounting the first inlet and the first outlet of the second heat exchanger in counter-flow relative to the second inlet and the second outlet of the second heat exchanger provides optimized heat transfer between the fuel output from the first heat exchanger and the fuel in the first portion of the fuel conduit. This helps to gradually increase the temperature gradient of the fuel when it is inside the second heat exchanger.

[0069] In an embodiment, the regulation system further comprises at least one temperature sensor.

[0070] In an embodiment, the regulation system comprises temperature sensors located at the inlet and outlet of the first heat exchanger, the second heat exchanger and the heating device, respectively.

[0071] In an embodiment, the regulating system further comprises at least two pressure sensors, which are respectively located at a fuel inlet of the first heat exchanger and a fuel outlet of the first heat exchanger.

[0072] In an embodiment, the regulation system further comprises at least four additional pressure sensors, which are located at the first inlet, the first outlet, the second inlet and the second outlet of the second heat exchanger.

[0073] The at least two pressure sensors and / or the at least four additional pressure sensors help to monitor the pressure inside the first heat exchanger and / or the second heat exchanger, respectively, during the operating mode. For example, under normal conditions, the inlet pressure at the fuel inlet of the first heat exchanger is higher than the pressure at the fuel outlet due to pressure losses inside the heat exchanger. When the pressure difference exceeds a certain threshold value, which is a pre-set value, then the monitoring provided by the at least two pressure sensors helps to detect if there is a fuel leak and thus shut down the regulation system. The same reasoning applies to the at least four additional pressure sensors of the second heat exchanger.

[0074] In an embodiment, the fuel of the fuel conduit is hydrogen (H2).

[0075] In an embodiment, the fuel of the fuel conduit is pure hydrogen.

[0076] In an embodiment, the fuel of the fuel conduit is a mixture of hydrogen and a fuel such as methane, propane, butane, etc. In the particular case where the fuel of the fuel conduit is a mixture, the hydrogen comprises a majority of the mixture.

[0077] In a second inventive aspect, the invention provides an aircraft comprising a regulating system according to any embodiment of the first inventive aspect.

[0078] In a third inventive step, the invention provides a method for conditioning the fuel of a conditioning system according to any embodiment comprising only a first heat exchanger, while the aircraft is on the ground or in flight, the method comprising the following steps:

[0079] a) supplying fuel to the fuel conduit through the fuel inlet,

[0080] b) Connect the bypass duct,

[0081] c) supplying fuel from the first portion of the fuel conduit through the bypass conduit to the second portion of the fuel conduit,

[0082] d) activating a heating device configured to supply heat to the fuel in the second portion of the fuel conduit until a fuel temperature reference value T is reached. E ,

[0083] e) running the engine,

[0084] f) Disconnect the bypass duct,

[0085] g) actuating a first heat exchanger configured to supply heat from the exhaust gas to the fuel of the fuel conduit, wherein the temperature of the fuel increases from a first temperature T1 to a second temperature T2,

[0086] h) When the fuel temperature T2 is equal to the reference value T EWhen the heating device is turned off,

[0087] In an embodiment of the conditioning system of the invention in which the second heat exchanger is not included, the method for conditioning the fuel of the conditioning system comprises the steps mentioned above.

[0088] In this document, "connecting the bypass conduit" means that the first portion of the fuel conduit is directly connected to the second portion of the fuel conduit. That is, the fuel located inside the fuel conduit is not introduced into the first heat exchanger, but is directed towards the heating device. That is, the bypass conduit acts as a bridge. Conversely, "disconnecting the bypass conduit" means that the first portion of the fuel conduit and the second portion of the fuel conduit are not directly connected, and the entire volume of fuel injected through the fuel inlet of the regulating system is introduced inside the fuel inlet of the first heat exchanger.

[0089] Fuel temperature reference value T E It is the temperature of the fuel required for the engine of the regulation system to reach its optimal operating condition. Preferably, the fuel temperature reference value T E It is about 290K.

[0090] In the present method, the temperature of the fuel increases from the first temperature T1 to the second temperature T2 after heat has been supplied to the fuel through the first heat exchanger. Preferably, under operating conditions, the second temperature T2 is equal to the fuel temperature reference value T E Or close to the fuel temperature reference value T E In this case, the performance provided by the first heat exchanger is able to supply the entire amount of heat required by the fuel so that the fuel reaches the fuel temperature reference value T E .

[0091] In some embodiments, the temperature of the fuel at the fuel inlet is equal to a first temperature T1 , preferably about 20K.

[0092] In a fourth inventive step, the invention provides a method for conditioning fuel of a conditioning system 100 comprising a first heat exchanger and a second heat exchanger according to any embodiment while the aircraft is on the ground or in flight, the method comprising the following steps:

[0093] a) supplying fuel to the fuel conduit through the fuel inlet,

[0094] b) opening the bypass conduit to supply fuel from the first portion of the fuel conduit to the second portion of the fuel conduit,

[0095] c) activating a heating device configured to supply heat to the fuel in the second portion of the fuel conduit until a fuel temperature reference value T is reached E ,

[0096] d) running the engine,

[0097] e) Disconnect the bypass duct,

[0098] f) actuating a first heat exchanger configured to supply heat from the exhaust gas to the fuel of the fuel conduit, wherein the temperature of the fuel increases from a first temperature T1 to a second temperature T2,

[0099] g) actuating a second heat exchanger configured to supply heat from the liquid fuel in the second portion of the fuel conduit to the liquid fuel in the first portion of the fuel conduit and transform the fuel in the fuel conduit from a liquid form or a supercritical fluid form to a cryogenic gaseous form.

[0100] In an embodiment of the present invention in which the conditioning system comprises a second heat exchanger, the method for conditioning a fuel of a conditioning system comprises the steps mentioned above.

[0101] Fuel temperature reference value T E It is the temperature of the fuel required for the engine of the regulation system to reach its optimal operating condition. Preferably, the fuel temperature reference value T E It is about 290K.

[0102] In the present method, the temperature of the fuel increases from the first temperature T1 to the second temperature T2 after heat has been supplied to the fuel by the first heat exchanger. In this case, the performance provided by the first heat exchanger is able to supply the entire amount of heat required by the fuel so that the fuel reaches the fuel temperature reference value T E .

[0103] In some embodiments, the temperature of the fuel at the fuel inlet is equal to a first temperature T1 , preferably about 20K.

[0104] In step g), and due to the second heat exchanger, and when the temperature T2 is greater than the temperature T1, the temperature of the fuel at the fuel outlet of the first heat exchanger generates heat so as to supply said heat to the fuel of the first portion of the fuel conduit and provide preheating of the fuel before the fuel is injected into the interior of the first heat exchanger. In addition, when the second heat exchanger is activated, the fuel introduced into the second heat exchanger through the first inlet is output through the first outlet and has been transformed from a liquid form or a supercritical fluid form into a low-temperature gas form. In this case, the second heat exchanger also assists as an evaporation device when the fuel is transformed from a liquid phase to a gas phase.

[0105] In both of the above methods, the regulation system aims to regulate the fuel in the fuel duct without supplying heat through the heating device. That is, both regulation methods provide a step h) in which, once the temperature T2 of the fuel before injection into the engine is equal to the reference value T E , the heating device stops.

[0106] When the fuel temperature T2 is greater than the reference value T E When the fuel temperature is too high, the second heat exchanger transfers heat to the fuel in the first portion of the fuel conduit. At the same time, the second heat exchanger helps to reduce the fuel temperature T2, so that at the second outlet of the second heat exchanger, the fuel temperature is equal to the reference value T E .

[0107] In an embodiment, the bypass duct may be partially open so as to direct a portion of the fuel towards the first heat exchanger and the remainder of the fuel towards the second heat exchanger. Advantageously, this allows the conditioning system of the invention to always adapt to the conditions of the fuel located inside the conditioning system when in operating mode.

[0108] In an embodiment of the third aspect or the fourth aspect of the invention, i.e., a method for regulating the fuel of a regulating system, when the regulating system includes at least two pressure sensors and a valve located at the fuel inlet of the first heat exchanger, the method also includes the following step: if the increase between the pressure measured at the fuel inlet of the first heat exchanger and the pressure measured at the fuel outlet of the first heat exchanger exceeds a first predetermined threshold, the valve is closed.

[0109] In an embodiment, i.e. a method for regulating the fuel of a regulating system according to the invention, when the regulating system comprises at least four additional pressure sensors and a valve at the fuel inlet of the first heat exchanger, the method further comprises the following step of closing the valve:

[0110] closing the valve if the delta between the pressure measured at the first fuel inlet of the second heat exchanger and the pressure measured at the first fuel outlet of the second heat exchanger exceeds a second predetermined threshold, or

[0111] If a delta between a pressure measured at a second fuel inlet of the second heat exchanger and a pressure measured at a second fuel outlet of the second heat exchanger exceeds a third predetermined threshold, the valve is closed.

[0112] The first predetermined threshold, the second predetermined threshold and the third predetermined threshold are values ​​that can be modified at any time when in operating mode so that the regulating system of the present invention can adapt to real-time conditions.

[0113] In an embodiment, at least two of the pressure sensors detect a failure mode when a pressure measured by a pressure sensor at a fuel outlet of the first heat exchanger is not equal to a pressure measured by a pressure sensor at a fuel inlet of the first heat exchanger.

[0114] All features described in this application document (including claims, description and drawings) and / or all steps of the described methods may be combined in any combination, except combinations of these mutually exclusive features and / or steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0115] These and other features and advantages of the present invention will become clearly understood in light of the detailed description of the present invention which will become apparent from the preferred embodiments thereof, given by way of example only and not limited thereto, with reference to the accompanying drawings.

[0116] Figure 1 : The figure shows an embodiment of a regulating system according to an embodiment of the present invention.

[0117] Figure 2 : The figure shows an embodiment of a regulating system according to an embodiment of the present invention.

[0118] Figure 3 : The figure shows an embodiment of an aircraft comprising a regulating system according to any embodiment of the invention. DETAILED DESCRIPTION

[0119] Figure 1 A schematic diagram of a regulation system 100 for an aircraft according to an embodiment of the present invention is shown.

[0120] Figure 1 The regulation system 100 has a power unit 1, which includes a fuel inlet 2, a fuel conduit 3, an engine 4, a power unit outlet 5, a first heat exchanger 6, a heating device 7 and a bypass conduit 8. Figure 1 , the arrows shown along the fuel conduit 3 and inside the engine 4 indicate the direction of fuel flow.

[0121] In an embodiment, the power unit 1 is an auxiliary power unit or APU. In other embodiments, the power unit 1 is a propeller.

[0122] exist Figure 1 In the embodiment of the present invention, the regulating system 100 comprises a pumping device 10 and a valve 9 configured to supply fuel to the power unit 1 and located at the fuel inlet 2. In particular, the pumping device 10 helps to maintain the pressure required for the fuel to be injected into the power unit (1) at the fuel inlet (2). In addition, the valve 9 allows the regulating system 100 to be opened and closed in the case of performing maintenance or in any case where it is necessary to close the fuel access in the power unit 1, such as in the case of damage or failure of any component of the power unit 1.

[0123] In some embodiments, the fuel is hydrogen. In a preferred embodiment, the hydrogen is stored at 20K before injection into the power unit 1, and the conditioning system 100 of the present invention is able to provide heat to the hydrogen through the first heat exchanger 6 so that the temperature of the hydrogen before entering the engine 4 is about 290K.

[0124] The fuel inlet 2 is configured to supply fuel to a fuel conduit 3. A first portion 3.1 of the fuel conduit 3 connects the fuel inlet 2 of the conditioning system 100 to a fuel inlet 6.3 of the first heat exchanger 6, and a second portion 3.2 of the fuel conduit 3 connects the fuel outlet 6.4 of the first heat exchanger 6 to an inlet 4.1 of the engine 4.

[0125] The power unit outlet 5 is configured to exhaust gas from the engine 4. The power unit outlet is connected to the exhaust gas inlet 6.1 of the first heat exchanger 6 so that the exhaust gas is provided to the first heat exchanger 6 at its highest temperature. The exhaust gas is output from the first heat exchanger 6 through the gas outlet 6.2.

[0126] In a particular embodiment, engine 4 is a gas turbine.

[0127] exist Figure 1 In the embodiment, the exhaust gas outlet 6 . 2 of the first heat exchanger 6 is connected to a muffler 12 .

[0128] In an embodiment not shown in this set of figures, the first heat exchanger 6 is configured to be coupled inside the muffler 12 .

[0129] In some embodiments, the heat exchanger 6 is of the pillow plate heat exchanger type. The pillow plate heat exchanger provides high performance with a more compact structure and lower weight and lower pressure drop compared to ordinary heat exchangers, while providing good structural stability.

[0130] In an embodiment, the first heat exchanger 6 is configured to enclose the entire vertical cross-section of the power unit outlet 5 .

[0131] exist Figure 1 In the embodiment shown in FIG, the fuel inlet 6.3 and the fuel outlet 6.4 of the first heat exchanger 6 are mounted in counter-flow relative to the exhaust gas inlet 6.1 and the exhaust gas outlet 6.2 of the first exchanger 6. In the figure, the fuel flow and the exhaust gas flow inside the fuel conduit 3 are depicted by solid arrows.

[0132] exist Figure 1, the heating device 7 of the power unit 1 has a fuel inlet 7.1 and a fuel outlet 7.2. The heating device 7 is located between the first heat exchanger 6 and the engine 4. These heating devices 7 are configured to transform the fuel of the fuel conduit 3 from a liquid form or a supercritical fluid form (SCF) into a low-temperature gas form, and are also configured to supply heat to the fuel of the fuel conduit 3 located in the second portion 3.2 of the fuel conduit 3.

[0133] In some embodiments, the heating device 7 is provided with a dedicated battery, so that the function of the heating device 7 is independent of the remaining elements of the regulating system 100 .

[0134] Furthermore, in some embodiments, the heating device 7 is encapsulated in order to avoid leakage outside the encapsulation of the heating device 7 , which could damage the rest of the conditioning system 100 .

[0135] The regulating system 100 has a bypass conduit 8 configured to connect the first portion 3.1 of the fuel conduit 3 to the second portion 3.2 of the fuel conduit 3. When the bypass conduit 8 is switched on, the fuel located in the first portion 3.1 of the fuel conduit 3 is directed directly toward the second portion 3.2 of the fuel conduit 3 without entering the first heat exchanger 6. When the bypass conduit 8 is switched off, the fuel located in the first portion 3.1 of the fuel conduit 3 flows and is introduced into the interior of the first heat exchanger 6 through the fuel inlet 6.3. Then, the fuel output from the first heat exchanger 6 through the fuel outlet 6.4 is injected into the second portion 3.2 of the fuel conduit 3.

[0136] When in operating mode, the first heat exchanger 6 is configured to supply heat from the exhaust gas to the fuel of the fuel conduit 3. Due to the first heat exchanger 6, in particular due to the heat transferred from the exhaust gas to the fuel, the temperature of the fuel in the first portion 3.1 of the fuel conduit 3 increases from the first temperature T1 to the second temperature T2 when entering the second portion 3.2 of the fuel conduit 3. The fuel is then introduced into the heating device 7 at the second temperature T2, which provides the additional heat required by the fuel so that the fuel is heated to a temperature of the fuel reference value T2. E The fuel temperature reference value T E It is the optimal temperature for the engine 4 to reach its full performance. Preferably, the fuel temperature reference value T E It is about 290K.

[0137] When the fuel is introduced into the first heat exchanger 6 at the first temperature T1 and the fuel is heated to a temperature equal to the fuel temperature reference value T E When the fuel is output from the first heat exchanger 6 at the second temperature T2, the heating device 7 stops. In this embodiment, the first heat exchanger 6 can provide a fuel temperature reference value T EThe total amount of heat required. Preferably, the first temperature T1 is about 20K and the second temperature T2 is about 290K.

[0138] Figure 2 Another embodiment of the regulating system 100 is shown, which includes the above Figure 1 All components and technical effects mentioned in.

[0139] Figure 2 The regulating system 100 further comprises a second heat exchanger 11 and two pressure sensors 13.1, 13.2 located at the fuel inlet 6.3 of the first heat exchanger 6 and at the fuel outlet 6.4 of the first heat exchanger, respectively.

[0140] Figure 2 The second heat exchanger 11 of the embodiment depicted in FIG. 1 has a first inlet 11.1, a first outlet 11.2, a second inlet 11.3 and a second outlet 11.4. The first inlet 11.1 and the first outlet 11.2 of the second heat exchanger 11 are connected to the first portion 3.1 of the fuel conduit 3 and the second inlet 11.3 and the second outlet 11.4 are connected to the second portion 3.2 of the fuel conduit 3.

[0141] The second heat exchanger 11 is configured to supply heat from the fuel in the second portion 3.2 of the fuel conduit 3 to the fuel in the first portion 3.1 of the fuel conduit 3 and to transform the fuel in the fuel conduit 3 from a liquid form or a supercritical fluid form to a cryogenic gaseous form.

[0142] exist Figure 2 In the embodiment shown in , the first inlet 11.1 and the first outlet 11.2 of the second heat exchanger 11 are arranged in counter-flow relative to the second inlet 11.3 and the second outlet 11.4 of the second heat exchanger 11. In the figure, the fuel flow of the first part 3.1 of the fuel conduit 3 and the fuel flow of the second part 3.2 of the fuel conduit 3 are depicted by solid arrows.

[0143] When in operating mode and the second temperature T2 at the fuel outlet 6.4 of the first heat exchanger 6 is greater than T1, the second heat exchanger 11 is able to supply heat from the liquid fuel of the second portion 3.2 of the fuel conduit 3 to the liquid fuel of the first portion 3.1 of the fuel conduit 3. Due to the second heat exchanger 11, the temperature of the second portion 3.2 of the fuel conduit 3 at the fuel outlet 6.4 of the first heat exchanger 6 is reduced until the fuel temperature T2 is equal to the reference value T E .

[0144] The second heat exchanger 11 is also configured to convert the fuel of the fuel conduit 3 from a liquid form or a supercritical fluid form into a low temperature gas form.

[0145] In an embodiment, the bypass duct 8 may be partially open so as to direct a portion of the fuel towards the first heat exchanger 6 and the rest of the fuel towards the second heat exchanger 11. Advantageously, this allows the conditioning system 100 to always adapt to the conditions of the fuel located inside the conditioning system 100 when in operating mode.

[0146] exist Figure 1 or Figure 2 In an embodiment not shown, the regulating system 100 further comprises temperature sensors at the inlets 6.1, 6.3, 11.1, 11.3, 7.1 and outlets 6.2, 6.4, 11.2, 11.4, 7.2 of the first heat exchanger 6, the second heat exchanger 11 and the heating device 7, respectively.

[0147] exist Figure 1 or Figure 2 In an embodiment not shown in the figure, the regulating system further comprises at least four additional pressure sensors which are located at the first inlet 11.1, the first outlet 11.2, the second inlet 11.3 and the second outlet 11.4 of the second heat exchanger 11, respectively.

[0148] At least two pressure sensors 13.1, 13.2 and / or at least four additional pressure sensors help to monitor the pressure inside the first heat exchanger 6 and / or the second heat exchanger 11, respectively, during the operating mode.

[0149] For example, under normal conditions, due to pressure losses inside the heat exchanger, the inlet pressure at the fuel inlet 6.3 of the first heat exchanger 6 is higher than the pressure at the fuel outlet 6.4. When the pressure difference, also called pressure delta, exceeds a certain threshold value of a pre-set value, then the monitoring provided by the at least two pressure sensors 6.3, 6.4 helps detect if there is a fuel leak and thus shut down the regulation system. The same reasoning applies to the at least four additional pressure sensors of the second heat exchanger 11.

[0150] When in operation mode and the temperature at the second outlet 11.4 of the second heat exchanger 11 is lower than the fuel temperature reference value T E The heating device 7 is able to provide the additional heat required by the fuel in the second portion 3.2 of the fuel conduit 3. Due to the heating device 7, the fuel reaches the fuel temperature reference value T before being injected inside the engine 4. E .

[0151] When in operation mode and the temperature at the second outlet 11.4 of the second heat exchanger 11 is greater than or equal to the temperature reference value T E When , the heating device 7 stops.

[0152] For example, the temperature at the fuel inlet 2 of the conditioning system 100 is preferably about 20 K and can reach 110 K after being output from the second heat exchanger due to the heat transfer of the fuel of the second portion 3.2 of the fuel conduit 3. At the same time, the fuel has been transformed into a gaseous form before being injected into the first heat exchanger. At the fuel outlet 6.4 of the first heat exchanger 6, the fuel of the second portion 3.2 of the fuel conduit 3 reaches 380 K, which provides additional heat to the fuel of the first portion 3.1 of the fuel conduit 3 via the second heat exchanger 11. Ideally, the second heat exchanger 11 is capable of reducing the temperature of the fuel at 380 K and is configured to be at a temperature reference value T at the second outlet 11.4 of the second heat exchanger 11. E , preferably outputting gaseous fuel at 290K.

[0153] Also in the operating mode, if the delta between the pressure measured by the first pressure sensor 13.1 at the fuel inlet 6.3 of the first heat exchanger 6 and the pressure measured by the second pressure sensor 13.2 at the fuel outlet 6.4 of the first heat exchanger 6 exceeds a first predetermined threshold, the regulating system 100 is able to shut off the fuel injection in the first heat exchanger 6 by means of the valve 14, preferably a mechanical valve. Thus, the pressure sensors 13.1, 13.2 provide a fault detection mode, enabling the regulating system 100 of the invention to avoid further damage.

[0154] In an embodiment not shown in this group of figures, when the regulating system 100 comprises at least four additional pressure sensors and a valve 14 located at the fuel inlet 6 . 3 of the first heat exchanger 6 , the method further comprises the following step of closing the valve 14 :

[0155] If the increase between the pressure measured at the first fuel inlet 11.1 of the second heat exchanger 11 and the pressure measured at the first fuel outlet 11.2 of the second heat exchanger 11 exceeds a second predetermined threshold, the valve 14 is closed, or

[0156] If the increase between the pressure measured at the second fuel inlet 11 . 3 of the second heat exchanger 11 and the pressure measured at the second fuel outlet 11 . 4 of the second heat exchanger 11 exceeds a third predetermined threshold, the valve 14 is closed.

[0157] Figure 3 An aircraft 200 is shown comprising a regulation system 100 according to any embodiment of the invention.

Claims

1. A control system (100) for an aircraft, the control system (100) comprising a power unit (1), wherein: The power unit (1) comprises: a fuel inlet (2) configured to supply liquid fuel to a fuel conduit (3), An engine (4), the engine (4) comprising: an inlet (4.1) connected to the fuel conduit (3), and an outlet (4.2), said outlet (4.2) being connected to a power unit outlet (5), The power unit outlet (5) is configured to discharge gas from the engine (4), a first heat exchanger (6), the first heat exchanger (6) is connected to the power unit outlet (5), the first heat exchanger (6) comprises: Exhaust gas inlet (6.1), Exhaust gas outlet (6.2), The fuel inlet (6.3), and Fuel outlet (6.4), A first portion (3.1) of the fuel conduit (3) connects the fuel inlet (2) of the regulating system (100) to the fuel inlet (6.3) of the first heat exchanger (6), and a second portion (3.2) of the fuel conduit (3) connects the fuel outlet (6.4) of the first heat exchanger (6) to the inlet (4.1) of the engine (4), a heating device (7), the heating device (7) comprising a fuel inlet (7.1) and a fuel outlet (7.2), the heating device (7) being located between the first heat exchanger (6) and the engine (4), and wherein the heating device (7) is configured to supply heat to the fuel in the fuel conduit (3) and also to transform the fuel in the fuel conduit (3) from a liquid form or a supercritical fluid form into a low-temperature gas form, a bypass conduit (8) configured to connect the first portion (3.1) of the fuel conduit (3) to the second portion (3.2) of the fuel conduit (3), wherein: The first heat exchanger (6) is configured to transfer heat from exhaust gases at the power unit outlet (5) to fuel in the fuel conduit (3).

2. The regulating system (100) according to the preceding claim, further comprising a valve (9) configured to open or close the flow of fuel entering the regulating system (100) at the fuel inlet (2).

3. The regulation system (100) according to any one of the preceding claims, further comprising a pumping device (10) configured to supply fuel to the power unit (1).

4. The conditioning system (100) according to any one of the preceding claims, further comprising a second heat exchanger (11), the second heat exchanger (11) comprising: First entrance (11.1), First exit (11.2), The second entrance (11.3), and Second exit (11.4), The first inlet (11.1) and the first outlet (11.2) of the second heat exchanger (11) are connected to the first portion (3.1) of the fuel conduit (3), and the second inlet (11.3) and the second outlet (11.4) are connected to the second portion (3.2) of the fuel conduit (3), and the second heat exchanger (11) is configured as follows: supplying heat from the fuel in the second portion (3.2) of the fuel conduit (3) to the fuel in the first portion (3.1) of the fuel conduit (3), and The fuel in the fuel conduit (3) is converted from a liquid form or a supercritical fluid form into a low-temperature gas form.

5. The regulating system (100) according to any one of the preceding claims, further comprising a muffler (12), wherein: The first heat exchanger (6) is configured to be coupled inside the muffler (12).

6. The regulating system (100) according to any one of the preceding claims, wherein: The first heat exchanger (6) is configured to enclose the entire vertical cross-section of the power unit outlet (5).

7. The regulating system (100) according to any one of the preceding claims, wherein: The fuel inlet (6.3) and the fuel outlet (6.4) of the first heat exchanger (6) are mounted in counter-flow relative to the exhaust gas inlet (6.1) and the exhaust gas outlet (6.2) of the first heat exchanger (6).

8. The regulating system (100) according to any one of claims 4 to 7, wherein: The first inlet (11.1) and the first outlet (11.2) of the second heat exchanger (11) are arranged in counter-flow relative to the second inlet (11.3) and the second outlet (11.4) of the second heat exchanger (11).

9. The regulation system (100) according to any of the preceding claims, further comprising at least one temperature sensor.

10. The regulating system (100) according to any one of the preceding claims, further comprising at least two pressure sensors (13.1, 13.2), wherein the at least two pressure sensors (13.1, 13.2) are respectively located at the fuel inlet (6.3) of the first heat exchanger (6) and at the fuel outlet (6.4) of the first heat exchanger.

11. The regulating system (100) according to any one of the preceding claims, wherein: The fuel of the fuel pipe (3) is hydrogen (H2).

12. An aircraft (200) comprising a regulating system (100) according to any one of the preceding claims.

13. A method for regulating fuel of a regulating system (100), the regulating system (100) being a regulating system according to any one of claims 1 to 3, 5 to 7 or 9 to 11, the regulation being performed when the aircraft (200) is on the ground or in flight, the method comprising the following steps: a) supplying fuel through the fuel inlet (2) to the fuel conduit (3), b) Connect the bypass conduit (8), c) supplying fuel from the first portion (3.1) of the fuel conduit (3) through the bypass conduit (8) to the second portion (3.2) of the fuel conduit (3), d) activating a heating device (7) configured to supply heat to the fuel in the second portion (3.2) of the fuel duct (3) until a fuel temperature reference value T E , e) running the engine (4), f) disconnecting the bypass conduit (8), g) actuating a first heat exchanger (6) configured to supply heat from the exhaust gas to the fuel of the fuel conduit (3), wherein the temperature of the fuel increases from a first temperature T1 to a second temperature T2, h) When the fuel temperature T2 is equal to the reference value T E When the heating device (7) is stopped.

14. A method for regulating fuel of a regulating system (100), the regulating system (100) being a regulating system according to any one of claims 4 or 8 or any one of claims 5 to 7 or 9 to 11 when dependent on claim 4 or 8, the regulation being performed when the aircraft (200) is on the ground or in flight, the method comprising the following steps: a) supplying fuel through the fuel inlet (2) to the fuel conduit (3), b) opening a bypass conduit (8) to supply fuel from the first portion (3.1) of the fuel conduit (3) to the second portion (3.2) of the fuel conduit (3), c) activating a heating device (7) configured to supply heat to the fuel in the second portion (3.2) of the fuel duct (3) until a fuel temperature reference value T E , d) running the engine (4), e) disconnecting the bypass conduit (8), f) actuating a first heat exchanger (6) configured to supply heat from the exhaust gas to the fuel of the fuel conduit (3), wherein the temperature of the fuel increases from a first temperature T1 to a second temperature T2, g) actuating a second heat exchanger (11) configured to supply heat from the liquid fuel in the second portion (3.2) of the fuel conduit (3) to the liquid fuel in the first portion (3.1) of the fuel conduit (3) and to convert the fuel in the fuel conduit (3) from a liquid form or a supercritical fluid form into a cryogenic gaseous form.

15. The method for regulating the fuel of a regulating system (100) according to claim 13 or 14, when the regulating system (100) comprises at least two pressure sensors (13.1, 13.2) and a valve (14) at the fuel inlet (6.3) of the first heat exchanger (6), the method further comprising the following steps: The valve (14) is closed in case a delta between a pressure measured at the fuel inlet (6.3) of the first heat exchanger (6) and a pressure measured at the fuel outlet (6.4) of the first heat exchanger (6) exceeds a first predetermined threshold.

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