Heat exchanger for aircraft, power unit for aircraft, and aircraft

Abstract

The invention relates to a heat exchanger for an aircraft, a power unit for an aircraft and an aircraft. In particular, the invention is in the field of heat exchangers configured for installation at the combustion gas outlet of a power unit of an aircraft.

Description

Technical Field

[0001] The invention relates to a heat exchanger for an aircraft. In particular, the invention belongs to the field of heat exchangers configured for installation at the combustion gas outlet of a power unit of an aircraft. The invention also relates to a power unit and an aircraft thereof. Background Art

[0002] Auxiliary power units or APUs are well known in the field of aviation technology and are engines capable of supplying energy to functions of an aircraft that are not considered propulsion functions. APUs are typically found in large aircraft and are located at or near the tail cone portion of these aircraft.

[0003] A typical APU generally includes a power section which is the power generating section of the APU, a load compressor section which provides pneumatic power to the aircraft, and a gearbox section which is responsible for transferring power from the main shaft of the engine to the generator for electrical power. APUs are also known to allow aircraft to be independent of external electrical and pneumatic power sources both on the ground and in flight.

[0004] It is known that a common engine that is part of an auxiliary power unit of the prior art generates exhaust gases due to the combustion of the fuel supplied to said engine. These exhaust gases are output from the APU at high temperatures, which it would be advantageous to recirculate. Some solutions based on heat exchangers are known in the art for using said heat generated by the exhaust gases in order to provide said heat back to the APU circuit.

[0005] A heat exchanger is a device for the exchange of energy between two sources, which may be fluid sources, gas sources, or fluid and gas sources, primarily based on heat. Conventional heat exchangers present a design that is made for establishing thermodynamic communication between the two sources, which usually flow in countercurrent or transverse directions, and are usually separated to prevent mixing between the two sources.

[0006] However, known solutions in the art include materials that are heavy relative to the total weight of the aircraft, such as heat exchangers based on shell and tube technology, which, while in operation, present a tendency to generate deposits, which reduces the efficiency of the heat exchangers known in the art. Furthermore, some problems known in this technical field are that any element added to the aircraft suffers from its weight impact and volume occupation relative to the entire aircraft.

[0007] There is a need in the art for a heat exchanger that allows solving the complex problems caused by its installation on a power unit of an aircraft in a high temperature and high flow rate environment, such as the exhaust gas output from an auxiliary power unit. In addition, the present invention provides a higher overall heat exchange performance and reduced weight compared to previously known technologies. Summary of the invention

[0008] The invention provides a heat exchanger according to a first inventive aspect, a power unit according to a second inventive aspect and an aircraft according to a third inventive aspect. The additional aspects disclose specific embodiments of the invention.

[0009] In a first inventive aspect, the invention provides a heat exchanger for an aircraft, the heat exchanger being arranged along a longitudinal direction XX' and comprising:

[0010] at least one plate having a first end and a second end according to a longitudinal direction XX', the at least one plate comprising an internal hollow volume configured to accommodate a second fluid for transferring heat from the first fluid located outside the at least one plate to the second fluid located inside the at least one plate in an operating mode of the heat exchanger,

[0011] a first collector and a second collector, the first collector and the second collector being configured to output the second fluid from the at least one plate and input the second fluid into the at least one plate, respectively, wherein

[0012] a first collector is located at a first end of at least one plate and a second collector is located at a second end of at least one plate,

[0013] The first collector comprises at least one fluid outlet and the second collector comprises at least one fluid inlet, and

[0014] The first collector and the second collector are configured to be in fluid communication with the interior hollow volume of the at least one plate, the at least one fluid outlet and the at least one fluid inlet,

[0015] at least one first sub-collector configured to connect the first collector to the first end of the at least one plate;

[0016] at least one second sub-collector configured for connecting the second collector to the second end of the at least one plate,

[0017] The liner has a length L along the longitudinal direction XX' T The liner is configured to define an inner chamber that confines at least one plate, a first collector and a second collector, and a first sub-collector and a second sub-collector, and

[0018] in,

[0019] At least one panel comprises at least two sheets defining a watertight and airtight inner chamber, the sheets being coupled to each other by means of discrete spot welds joining respective portions of each sheet and by means of continuous welding on corresponding contours of the sheets.

[0020] The heat exchanger of the invention provides a solution based on at least one plate having a first end and a second end according to a longitudinal direction XX', the at least one plate comprising an internal hollow volume configured to accommodate a second fluid for transferring heat from a first fluid located outside the at least one plate and flowing outside the at least one plate to a second fluid located inside the at least one plate in an operating mode of the heat exchanger.

[0021] The length L of the liner tube of the heat exchanger of the present invention along the longitudinal direction XX' T The liner defines a circumference of the inner chamber, which provides a watertight and airtight closed volume, thereby allowing optimal heat transfer between the first fluid and the second fluid, eliminating any external interference.

[0022] In an embodiment, the liner has a length L along the longitudinal direction XX' T An extended generally cylindrical shape.

[0023] The first end of at least one plate corresponds to the first end of the liner, and the second end of at least one plate corresponds to the second end of the liner.

[0024] In an operating mode, a second fluid contained within the interior hollow volume of at least one plate is introduced into the at least one plate through at least one fluid inlet, then through a second collector, and finally through at least one second sub-collector, the at least one fluid inlet, the second collector, and the at least one second sub-collector all being located at the second end of the liner. The at least one fluid inlet, the second collector, and the at least one second sub-collector are all in fluid communication with each other and with the at least one plate.

[0025] When in the operating mode, at the end of the at least one plate opposite to the first end of the liner, the second fluid is removed from the interior hollow volume of the at least one plate through the at least one first sub-collector, the first collector, and the at least one fluid outlet in sequence. The at least one first sub-collector, the first collector, and the at least one fluid outlet are all in fluid communication with the at least one plate.

[0026] A second fluid contained within the interior of at least one plate flows in a direction opposite to the longitudinal direction XX' and through channels defined by the interior chamber between discrete spot welds joining respective portions of at least two sheets. In an operating mode, when the second fluid flows from the second end to the first end of the at least one plate, the at least one plate facilitates heat transfer from the first fluid located outside the at least one plate to the second fluid contained within the interior of the at least one plate along its surface area.

[0027] Also in the operating mode, the first fluid flows to the outside of at least one plate and contacts with the surface area, the outer surface of the sheet defining the at least one plate, such that said contact enhances the heat transfer from one fluid to the other fluid. The first fluid flows along the longitudinal direction XX' so that the first fluid and the second fluid are arranged to flow in opposite directions, also called counter-flow.

[0028] In particular, the first fluid is introduced into the heat exchanger from the first end of at least one plate at a first temperature, and the first fluid leaves the heat exchanger from the second end of at least one plate at a second temperature lower than the second temperature. Thus, the introduction side of the first fluid corresponds to the second fluid outlet, and the outlet side of the first fluid corresponds to the second fluid inlet. This configuration provides a continuous temperature gradient of the first fluid contained inside the at least one plate so as to provide an efficient and progressive heat transfer from the first fluid to the second fluid. Due to this particular arrangement, the heat exchanger of the present invention provides a second fluid that can recollect heat from the first fluid in an optimal manner.

[0029] Furthermore, the specific configuration of the at least one plate provides a high turbulence between the at least two sheets of each of the at least one plate, so that it confers a high overall heat transfer performance to the heat exchanger of the invention. Additionally, due to the small volume defined between the at least two sheets, a smaller pump capacity is required for the input and output of the fluid inside the at least one plate. Overall, the at least one plate confers a reduced system weight to the heat exchanger of the invention for the heat transfer between two fluids realized in an aircraft.

[0030] In a particular embodiment, the liner includes at least two sections and an attachment device configured for securing the sections of the liner together.

[0031] In some embodiments, the attachment means are provided on the outer surface of the liner and at each end of the liner. In some preferred embodiments, the attachment means are located above and below the liner at both the first end and the second end of the liner, symmetrically arranged with respect to the longitudinal direction XX', and may be bolts, springs, a combination of the two, and optionally, may also include a seal.

[0032] Advantageously, the liner has at least two parts, which facilitates assembly / disassembly operations and maintenance, since the elements housed inside the liner of the heat exchanger are more easily accessible.

[0033] In an embodiment, the liner has two generally semi-cylindrical portions and an attachment arrangement configured for securing the two generally semi-cylindrical portions of the liner to each other.

[0034] Furthermore, when the liner has two generally semi-cylindrical sections, attachment means configured for securing said sections together provide a solution for counteracting thermal expansion of at least one plate located inside the liner.

[0035] In a specific embodiment, the first collector and the second collector are annular in shape or open ring in shape, preferably circular in shape.

[0036] The first collector and the second collector are annular or open-loop shaped, preferably circular shaped, so as to provide an optimal fit inside the liner of the heat exchanger of the present invention and high flow properties for introducing and removing the second fluid contained inside at least one plate in a uniform manner.

[0037] Advantageously, giving the collector an annular shape ensures a constant length of the first sub-collector and the second sub-collector relative to the first collector and the second collector, respectively.

[0038] In a specific embodiment, the first sub-collector and the second sub-collector are curved.

[0039] Advantageously, the diameters of the first sub-collector and the second sub-collector may be adjusted in order to equalize the pressure drop.

[0040] In an embodiment, the first sub-collector and the second sub-collector are made of a flexible material, which means that the sub-collectors have a certain degree of deformability / elasticity when the heat exchanger is in operating mode so as to adapt to the specific conditions of the heat exchanger of the present invention and to recover their original shape when the heat exchanger is not in operating mode. Advantageously, this helps to reduce the load transfer between the plate and the collector and avoid thermal buckling between the plates.

[0041] In a particular embodiment, the heat exchanger comprises a number of plates, preferably between 7 and 9 plates.

[0042] In an embodiment, when the second fluid is helium He, the heat exchanger comprises 7 plates.

[0043] In an embodiment, when the second fluid is nitrogen, the heat exchanger comprises 9 plates.

[0044] In a more specific embodiment, the plurality of plates are arranged according to the longitudinal direction XX' to be substantially parallel to each other and substantially perpendicular to a horizontal plane including the transverse direction YY'. In other words, the plurality of plates are arranged substantially in a vertical direction ZZ' perpendicular to a horizontal plane including the transverse direction YY'.

[0045] As is well known, a horizontal plane is a plane perpendicular to the direction of gravity.

[0046] Advantageously, by arranging a plurality of plates in substantially parallel directions, the distance between the plates is maintained along the entire longitudinal direction XX', thereby enhancing the heat transfer performance between the first fluid and the second fluid.

[0047] Advantageously, arranging the plurality of panels substantially perpendicularly relative to a horizontal plane including the transverse direction YY' minimizes vibration loads received by the plurality of panels and also prevents the plurality of panels from bending when receiving loads from a landing.

[0048] In a particular embodiment, the plurality of plates are arranged according to a stepped pattern and the area of ​​the plurality of plates decreases along the transverse direction YY'.

[0049] The plurality of plates are arranged according to a stepped pattern along the transverse direction Y-Y' so as to fit the plurality of plates inside the volume defined by the inner chamber of the liner. In some other embodiments, as much available volume as possible of the inner chamber of the liner is filled with plates so that heat transfer between the first fluid and the second fluid is enhanced.

[0050] In certain embodiments, the second fluid is nitrogen, helium, EGW (ethylene glycol water), oil or water.

[0051] In an embodiment, the first fluid is exhaust gas output from an engine, more specifically, exhaust gas output from an engine supplied with hydrogen H 2 .

[0052] In a particular embodiment, the at least one fluid outlet of the first collector and the at least one fluid inlet of the second collector are elbow-shaped.

[0053] Advantageously, the elbow shape of the at least one fluid outlet of the first collector and the at least one fluid inlet of the second collector facilitates thermal expansion of the absorber plate and the collectors.

[0054] In a particular embodiment, the at least one fluid outlet of the first collector and the at least one fluid inlet of the second collector are oriented in the same vertical direction ZZ' as the at least one plate.

[0055] In this particular embodiment, at least one fluid outlet and at least one fluid inlet are positioned in the lower part of the first collector and the second collector, respectively, and are positioned relative to at least one plate orientation, which is preferably perpendicular relative to a horizontal plane including the longitudinal direction XX'. Furthermore, at least one fluid outlet and at least one fluid inlet are oriented in the same direction as the inlet and outlet of the second fluid inside the at least one plate, i.e. along the vertical direction ZZ'.

[0056] In a particular embodiment, the at least one fluid outlet and the at least one fluid inlet are aligned with the center of the liner along the vertical direction ZZ'.

[0057] In a specific embodiment, the first collector and the second collector include two fluid outlets and two fluid inlets, respectively.

[0058] The two fluid outlets are in fluid communication and connected to each other, and

[0059] The two fluid inlets are in fluid communication and connected to each other, and the two fluid outlets and the two fluid inlets are located on opposite sides of the first collector and the second collector, respectively.

[0060] Advantageously, the first collector and the second collector have two fluid outlets and two fluid inlets, respectively, so that the second fluid is introduced into the interior of the first and second collectors and thus into the interior of at least one plate in a uniform and optimal manner, which enhances the overall performance of the heat exchanger of the present invention. In these embodiments, the two fluid outlets and the two fluid inlets are located on opposite sides of the collectors. The two fluid outlets and the two fluid inlets enhance the flow distribution of the second fluid.

[0061] In a particular embodiment, the attachment means are located on each side of the liner and are symmetrically arranged along the length of the liner with respect to the axis of symmetry and the longitudinal direction XX' of the liner.

[0062] In certain embodiments, the liner is gas-tight and / or fire-proof.

[0063] In a second inventive aspect, the present invention provides a power unit for an aircraft, the power unit comprising:

[0064] a power unit inlet configured to supply a first fluid to the power unit,

[0065] an engine and a power unit outlet configured to discharge a first fluid from the engine,

[0066] in,

[0067] The power unit outlet comprises a heat exchanger according to any of the embodiments of the first inventive aspect, and

[0068] The heat exchanger further comprises two connection devices, one connection device being located at each end of said at least one plate, wherein one of the connection devices is configured for mounting the heat exchanger on a power unit outlet.

[0069] In the present application, the power unit outlet refers more specifically to the combustion gas outlet.

[0070] The heat exchanger of any embodiment or combination of the embodiments of the first inventive aspect is suitable for installation downstream of the outlet of a power unit of an aircraft so that the exhaust gas of the power unit, i.e. the exhaust gas of the engine implemented in the power unit, can be used as the first fluid flowing around at least one plate and inside the volume of the inner chamber defined by the liner.

[0071] Advantageously, the heat exchanger further comprises a connection device at each end of at least one plate and liner, such that one end of the heat exchanger is configured to be mounted downstream of the power unit outlet and the other end of the heat exchanger is configured for connection to another device downstream, such as a muffler.

[0072] Furthermore, the heat exchanger of the present invention is mounted at the outlet of the power unit so that the connection means located on the first end side of at least one plate and the liner is a connection means mounted directly to the outlet of the power unit. In this way, the first fluid output from the outlet of the power unit has a first temperature when it enters the interior of the heat exchanger, which is higher than its temperature when the first fluid reaches the other end of the second end of at least one plate. Therefore, by mounting the heat exchanger in the said direction, along the longitudinal direction XX' and along the said orientation, the present invention allows the first fluid and the second fluid to have a countercurrent flow arrangement. Therefore, the present invention helps to provide a progressive heat transfer from the first fluid to the second fluid, thereby enhancing the performance and capacity of the heat exchanger of the present invention, and thus enhancing the performance and capacity of the power unit of the second invention aspect.

[0073] In a particular embodiment of the power unit according to the second inventive aspect and the heat exchanger according to any embodiment of the first inventive aspect having an attachment device, the attachment device:

[0074] fixed along the longitudinal direction XX' and the vertical direction ZZ', or

[0075] fixed along the longitudinal direction XX' and free along the vertical direction ZZ', or

[0076] free along the longitudinal direction XX' and fixed along the vertical direction ZZ', or

[0077] Free along the longitudinal direction XX' and the vertical direction ZZ'.

[0078] In this document the term "free along" should be taken such that a limited degree of movement along one or more directions is allowed, with the element not being completely free to move but having room for providing the attachment means with a certain amount of movement along said directions.

[0079] Furthermore, the vertical direction ZZ' is perpendicular to a horizontal plane including both directions XX' and YY'.

[0080] Advantageously, by virtue of the different configurations of the attachment means of this embodiment of the power unit, the invention provides an optimal way of fixing the liner and allows some freedom of said liner in certain directions due to the thermal expansion of at least one plate located inside the inner chamber of the liner.

[0081] In some embodiments, the heat exchanger has four attachment means, two attachment means being positioned at each end of the liner.In addition, at each end of the liner, the attachment means of each respective end of the liner are preferably arranged symmetrically with respect to the longitudinal direction XX'.

[0082] In some preferred embodiments, the heat exchanger has four attachment devices, and each of the attachment devices has one of the configurations selected from the list of configurations:

[0083] fixed along the longitudinal direction XX' and the vertical direction ZZ', or

[0084] fixed along the longitudinal direction XX' and free along the vertical direction ZZ', or

[0085] free along the longitudinal direction XX' and fixed along the vertical direction ZZ', or

[0086] Free along the longitudinal direction XX' and the vertical direction ZZ'.

[0087] In a particular embodiment of the power unit according to any embodiment of the second inventive aspect and any embodiment of the heat exchanger according to the first inventive aspect with an attachment device, wherein the attachment device and / or the collector and sub-collector:

[0088] is sealed relative to the power unit outlet, or

[0089] is enclosed and sealed relative to the power unit outlet, or

[0090] is enclosed and further includes a blocking device configured to open or close fluid communication with the power unit outlet, or

[0091] Enclosed and in fluid communication with the power unit outlet.

[0092] Advantageously, the configuration in which the attachment means, collector and sub-collector are enclosed and in fluid communication with the power unit outlet, i.e. the configuration of the first fluid flow, provides uniform temperature between the at least one plate, the first sub-collector and the second sub-collector, and the first collector and the second collector by allowing exhaust gases to enter the collector area. Thus, the collector and sub-collector are protected from thermal stresses present during power unit operation.

[0093] In an embodiment, the blocking means has two substantially semicircular sections.

[0094] In an embodiment, the blocking device comprises two parts and coupling means, such as rivets, which allow assembly and disassembly of the two parts of the blocking device. The blocking device is preferably positioned along the liner and between the sub-collectors so that it helps to minimize aerodynamic flow leakage from the enclosed volume inside the liner.

[0095] Preferably, the blocking device is made of Inconel, corrosion resistant stainless steel, or any material that is both corrosion and high temperature resistant.

[0096] In a third inventive aspect, the invention provides an aircraft comprising a power unit according to any embodiment of the second inventive aspect.

[0097] All of the features described in this application document (including claims, description and drawings) and / or all of the steps of the described methods may be combined in any combination, except for mutually exclusive combinations of features and / or steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] These and other features and advantages of the present invention will be clearly understood in view of the detailed description of the present invention which will become apparent from the preferred embodiments of the present invention, which are given by way of example only and not limited thereto, with reference to the accompanying drawings.

[0099] Figure 1a to Figure 1b : These figures show embodiments of the distribution of at least one plate of a heat exchanger according to the invention.

[0100] Figure 2 : The figure shows an embodiment of a heat exchanger according to the present invention.

[0101] Figures 3a to 3e : These figures show an embodiment of a collector according to the invention.

[0102] Figure 4 : The figure shows a cross-sectional view of an embodiment of an attachment device for a heat exchanger according to the present invention.

[0103] Figure 5a to Figure 5d : These figures show embodiments of an attachment device for a heat exchanger according to the invention.

[0104] Figures 6a to 6d : These figures show an integrated embodiment of an attachment device, a collector and a sub-collector according to an embodiment of the present invention.

[0105] Figure 7: This figure shows a power unit according to an embodiment of the second inventive aspect of the present invention.

[0106] Figure 8 : The figure shows an aircraft according to an embodiment of the third inventive aspect of the present invention.

[0107] Fig. 9 : The figure shows a schematic representation of a conventional plate according to the prior art. DETAILED DESCRIPTION

[0108] Figure 1a and Figure 1b An embodiment of the distribution of at least one plate 2 of the heat exchanger 1 according to the invention is shown.

[0109] Figure 1a An embodiment is depicted in which the heat exchanger has seven plates 2, each plate having a first end 2.1 and a second end 2.2 distributed in parallel according to a longitudinal direction XX'. Each plate 2 is separated from the other plates so that when the heat exchanger 1 is in operating mode, a first fluid flows between said plates 2. Each of the plates 2 comprises an internal hollow volume configured to accommodate a second fluid. Due to the plates 2, the heat exchanger 1 allows heat to be transferred from a first fluid located outside at least one plate 2 to a second fluid located inside at least one plate 2.

[0110] Preferably, the first fluid is exhaust gas, preferably exhaust gas of an engine of the power unit, more preferably exhaust gas of the engine supplied with hydrogen.

[0111] Preferably, the second fluid is nitrogen, helium, EGW (ethylene glycol water), oil or water.

[0112] The heat exchanger 1 has a first collector 3.1 at the first end 2.1 of the plate 2 and a second collector 3.2 at the second end 2.2 of the plate. In this particular embodiment, the first collector 3.1 and the second collector 3.2 are circular in shape.

[0113] The second collector 3.2 allows the introduction of a second fluid into the interior of the plate 2, and the first collector 3.1 allows the second fluid to be withdrawn from the plate 2. Figure 1a In the embodiment of the first collector 3.1 has two fluid outlets 4.1 on opposite sides of the circular shape of the first collector 3.1 and the second collector 3.2 has two fluid outlets 4.2 on opposite sides of the circular shape of the second collector 3.2.

[0114] The first collector 3.1 and the second collector 3.2 are configured to be in fluid communication with the inner hollow volume of the plate 2, the fluid outlet 4.1 and the fluid inlet 4.2. By means of the fluid inlet 4.2, the second fluid is introduced into the interior of the second collector 3.2 at the second end 2.2 of the plate 2 and thus into the interior of the plate 2. By means of the fluid outlet 4.1, the second fluid is introduced into the interior of the first collector 3.1 at the first end 2.1 of the plate 2 and thus into the interior of the plate 2.

[0115] Furthermore, the heat exchanger 1 has a first sub-collector 5.1 which connects the first collector 3.1 one after another to each of the plates 2, in particular to each of the first ends 2.1 of the plates 2. At the opposite ends of the plates 2, the heat exchanger 1 also has a second sub-collector 5.2 which connects the second collector 3.2 one after another to each of the plates 2, in particular to each of the second ends 2.2 of the plates 2.

[0116] In this particular embodiment, if Figure 1b As shown in FIG. 1 , the sub-collector 5.1 and the corresponding sub-collector 5.2 at the other end of the plate 2 are curved. The curved sub-collectors 5.1 , 5.2 are preferably made of a flexible material to absorb vertical displacement and thermal expansion. In some preferred embodiments, the sub-collectors are made of stainless steel 316.

[0117] In addition, Figure 1a In the embodiment shown in , the panels 2 are arranged according to a stepped pattern, wherein a central panel 2.3 is located between two adjacent panels 2.4, 2.5 located on each side of the central panel 2.3, and the area of ​​the panels 2 decreases from the central panel 2.3 along the transverse direction Y-Y'. Figure 2 As shown in FIG. 1 , the liner 6 has a generally cylindrical shape extending along a length according to a longitudinal direction XX′, defining an inner chamber, the inner chamber limiting plate 2, the first and second collectors 3.1, 3.2 and the first and second sub-collectors 5.1, 5.2.

[0118] Figure 2 A view of a heat exchanger 1 and an exploded view in which the elements covering the plate 2, the collectors 3.1, 3.2 and the sub-collectors 5.1, 5.2 are shown. In particular, the plate 2, the collectors 3.1, 3.2 and the sub-collectors 5.1, 5.2 are covered by a liner 6 positioned along the length of the plate 2. In this embodiment, these elements are covered by two substantially semi-cylindrical portions 6.1, 6.2 and attachment means 7 configured for fixing both substantially semi-cylindrical portions 6.1, 6.2 of the liner 6 to each other.

[0119] The heat exchanger comprises connection means 14 on both ends, a first end 2.1 and a second end 2.2 of the plate 2, making it suitable for installation at the outlet of a power unit, for example. The connection means 14 also comprise baffles which provide support for the plates 2 and hold them in an arrangement ensuring a sufficient distance between the plates 2 so that the first fluid can flow, thereby enhancing the heat transfer between the first fluid and the second fluid.

[0120] Figures 3a to 3e Embodiments of the distribution of the fluid outlets 4.1 of the first collector 3.1 and of the fluid inlets 4.2 of the second collector 3.2 are depicted. In these figures, these embodiments of the collectors 3.1, 3.2 are represented independently of their position inside the heat exchanger of the invention, i.e. Figures 3a to 3e Each embodiment of is applicable to both ends 2.1, 2.2 of each of the plates 2. Thus, reference numerals, for example 3.1 and 5.1, may be replaced by reference numerals 3.2 and 5.2.

[0121] Figures 3a to 3e The distribution of parallel plates 2 is shown and is distributed substantially perpendicularly relative to a horizontal plane comprising both the longitudinal direction X-X' and the transverse direction Y-Y'. The plates 2 are arranged in a stepped pattern in which the central plate 2.3 has a larger surface area relative to the remaining plates of the plates 2 and the surface areas of the adjacent plates 2.4, 2.5 decrease from the central plate 2.3 and along the transverse direction Y-Y'. Thus, the plates 2 located farther from the central plate 2.3 have the smallest surface area relative to the remaining plates of the plates 2.

[0122] exist Figure 3a In the embodiment, the first collector 3.1 has two fluid outlets 4.1, both of which are symmetrically positioned on opposite sides of the first collector 3.1 relative to the center of the first collector 3.1, so that the introduction of fluid inside the collector and the extraction of fluid from the collector are performed in a uniform manner. The two fluid outlets 4.1 are unified into one and only fluid outlet.

[0123] exist Figure 3b In the embodiment of the invention, the first collector 3.1 is in the shape of an open ring and the fluid outlet 4.1 is located on the opposite side with respect to the open side of the first collector 3.1.

[0124] exist Figure 3c In the embodiment of , the fluid outlet 4 . 1 of the first collector 3 . 1 is located on the lower side of the collector and is oriented in the same vertical direction as the at least one plate 2 , ie perpendicularly with respect to the transverse direction YY′.

[0125] Figure 3d The embodiment shows Figure 3aAn alternative to the embodiment depicted in , in which the two fluid outlets 4.1 are positioned symmetrically with respect to the center of the collector 3.1 on the top side and the lower side of the collector.

[0126] exist Figure 3e In the embodiment of the present invention, the fluid outlet 4.1 is located at one side of the first collector 3.1, and the outlet 4.1 has a straight shape.

[0127] exist Figure 3a , Figure 3b and Figure 3d In some embodiments, the fluid outlet 4.1 of the first collector 3.1 is elbow-shaped. Accordingly, in some embodiments, the fluid inlet 4.2 of the second collector 3.2 is also elbow-shaped.

[0128] Figure 4 The distribution of the attachment means 7.1, 7.2, 7.3, 7.4 of a heat exchanger 1 according to an embodiment of the invention is depicted.

[0129] exist Figure 4 In the embodiment of the present invention, the liner 6 is attached due to four attachment means 7.1, 7.2, 7.3, 7.4 respectively located at the lower left side, upper left side, lower right side and upper right side of the liner 6. The liner 6 extends along the longitudinal direction XX' and the plates 2 (only one plate 2 is shown in this cross-sectional view) are accommodated inside the liner 6. At the same time, the first collector 3.1 and the second collector 3.2 and the first sub-collector 5.1 and the second sub-collector 5.2 are located outside the liner 6 and penetrate the inside of the liner 6 due to the sub-collectors 5.1, 5.2 so as to be connected with the corresponding ends 2.1, 2.2 of the plates 2.

[0130] The first attachment device 7 . 1 located at the lower left side of the liner tube 6 is fixed along the longitudinal direction XX′ and the vertical direction ZZ′ so that this particular attachment device 7 . 1 has no degrees of freedom in these two directions at this particular point of the liner tube 6 . Figure 5a An embodiment of the attachment means 7 . 1 is shown in which the attachment means, such as a bolt, is locked and has no degrees of freedom.

[0131] The second attachment means 7.2, located on the upper left side of the liner 6, is fixed along the longitudinal direction XX' and free to move along the vertical direction ZZ'. The degree of freedom provided to the second attachment means 7.2 along the vertical direction ZZ' is due to the fact that compression means such as springs allow the liner 6 and the attachment means 7.2 to adapt to the thermal expansion of the plate 2 in this particular direction ZZ'. Figure 5b One embodiment of the second attachment means 7.2 and compression means, such as a spring, which allows such a degree of freedom along the vertical direction ZZ' is shown.

[0132] The term "free along" should be taken such that a limited degree of movement along one or more directions is allowed, with the element not being completely free to move but having room to provide the attachment means with a certain amount of movement along said directions.

[0133] The third attachment means 7.3 located at the lower right side of the liner 6 is free to move along the longitudinal direction XX' and is fixed along the vertical direction ZZ'. The degree of freedom provided to the third attachment means 7.3 along the longitudinal direction XX' is achieved by sliding means, such as bolts mounted in slotted holes, which are usually rectangular holes with rounded ends, and the sliding means allow a certain degree of displacement of the bolts along the longitudinal direction XX', such as Figure 5c As depicted in .

[0134] Finally, the fourth attachment means 7.4, located on the upper right side of the liner 6, is free to move in the longitudinal direction XX' and in the vertical direction ZZ'. The fourth attachment means 7.4 comprises both compression means and sliding means, which provide it with degrees of freedom in both the longitudinal direction XX' and in the vertical direction ZZ'. Figure 5d An embodiment of the fourth attachment means 7.4 is shown in FIG.

[0135] like Figure 4 The combination of all these attachment means 7.1, 7.2, 7.3, 7.4 provides a solution for the thermal expansion of the plate 2 inside the liner 6 as shown in the embodiment of FIG.

[0136] Figures 6a to 6d An embodiment is depicted in which the collectors 3.1, 3.2 and the sub-collectors 5.1, 5.2 are integrated with the liner 6. Each of these embodiments can be applied to two collectors, namely the first collector 3.1 and the second collector 3.2.

[0137] exist Figure 6a In the embodiment of the invention, on the one hand, the attachment device 7 is enclosed, and on the other hand, the first collector 3.1 and the first sub-collector 5.1 are sealed relative to the inner chamber of the liner 6, in which the first fluid flows out from the power unit outlet. That is, the volume defined by the enclosure of the attachment device 7 is in fluid communication with the inner chamber of the liner 6, and the volume defined by the enclosure is freely filled with the first fluid.

[0138] Several arrows show how the first fluid circulates inside the inner chamber of the liner 6 and enters inside the volume defined by the enclosure of the attachment device 7 .

[0139] exist Figure 6bIn an embodiment of the present invention, the attachment device 7 is enclosed and the first collector 3.1 is also enclosed together with the first sub-collector 5.1. In this embodiment, the first collector 3.1 and the first sub-collector 5.1 are sealed relative to the inner chamber of the liner 6, in which the first fluid flows out from the power unit outlet. In other words, the volume defined by the enclosure of the attachment device 7 is in fluid communication with the inner chamber of the liner 6, and the volume is freely filled with the first fluid. On the other hand, the volume defined by the enclosure of the first collector 3.1 and the first sub-collector 5.1 is sealed so that the first fluid cannot penetrate the volume.

[0140] Several arrows show how the first fluid circulates inside the inner chamber of the liner 6 and enters inside the volume defined by the enclosure of the attachment device 7. However, it can also be seen that no first fluid penetrates inside the volume defined by the enclosures of the first collector 3.1 and the first sub-collector 5.1.

[0141] exist Figure 6c In an embodiment, the attachment device 7 is enclosed, the collector 3.1 and the sub-collector 5.1 are also enclosed, and the liner 6 further comprises a blocking device 16, such as a layer providing a certain degree of permeability between the enclosed volume and the inner chamber of the liner 6. The blocking device 16 is configured to open or close the fluid communication with the inner chamber filled with the first fluid, i.e., the fluid coming out of the power unit outlet. The blocking device 16 is installed along the liner 6 and is located between the first sub-collector 5.1 and the second sub-collector 5.2. Figure 6c As shown in FIG. 1 , the blocking device 16 may comprise two parts 16.1, 16.2 attached to each other by means of coupling means 16.3, such as rivets, which allow the two parts 16.1, 16.2 of the blocking device to be disassembled. Preferably, the blocking device 16 is made of Inconel, corrosion-resistant stainless steel or any material that is both corrosion-resistant and temperature-resistant. Advantageously, the blocking device 16 helps to minimize aerodynamic flow leakage inside the liner 6.

[0142] exist Figure 6c In some embodiments not shown in FIG. 1 , the blocking device 16 has two substantially semicircular sections.

[0143] In this Figure 6c In FIG. 1 , some arrows depict how the first fluid circulates inside the inner chamber of the liner 6 , while when the blocking device 16 closes the fluid communication with the inner chamber of the liner 6 , the flow of the first fluid is not shown inside the two enclosures.

[0144] exist Figure 6dIn the embodiment of the invention, the attachment device 7 is enclosed, the collector 3.1 and the sub-collector 5.1 are also enclosed and the two volumes defined by the two packages are in fluid communication with the power unit outlet, i.e. in fluid communication with the inner chamber of the liner 6, in which the first fluid flows. This provides a uniform temperature between the plate, the first sub-collector 5.1 and the second sub-collector 5.2 and the first collector 3.1 and the second collector 3.2 by allowing the first fluid, the exhaust gas from the power unit outlet, to enter the collector area. Thus, the collectors 3.1, 3.2 and the sub-collectors 5.1, 5.2 are protected from the thermal stresses present during the operation of the power unit.

[0145] exist Figure 6d In FIG. 1 , several arrows show how the first fluid circulates inside the inner chamber of the liner 6 and how the first fluid permeates the interior of the volume defined by the two enclosures.

[0146] Power Unit

[0147] Figure 7 An embodiment of a power unit 10 for an aircraft is shown, the power unit 10 having a power unit inlet 11 supplying fluid to an engine 12 of the power unit 10, and a power unit outlet 13. A heat exchanger 1 of any of the embodiments of the invention is mounted downstream of the power unit outlet 13 by means of a first connection device 14.1 located at a first end of at least one plate included in the heat exchanger 1. Then, a muffler 15 is mounted downstream of the heat exchanger 1 by means of a second connection device 14.2 located at a second end of at least one plate included in the heat exchanger 1.

[0148] Aircraft

[0149] Figure 8 An embodiment of an aircraft is shown implementing any embodiment of a power unit 10 according to the second inventive aspect of the invention, comprising any previously described embodiment of the inventive heat exchanger 1 or any combined embodiment previously described.

[0150] Preferred Embodiments of the Invention

[0151] In a preferred embodiment, as shown in FIG. 1 , the heat exchanger of the present invention comprises seven plates 2, and these plates 2 have different widths, said plates 2 being located inside the liner 6, which is installed at the outlet of the power unit. The plates 2 are presented in a stepped pattern, which helps to comply with the size constraints provided by the liner shape and the installation position. By providing said design of the plates 2, the present invention allows to recover as much available heat as possible from the exhaust gas by transferring said heat to the fluid located inside the plates 2.

[0152] Inside the plates 2, the fluid flows in the opposite direction to the exhaust gases so as to provide a counter-current heat exchange and to increase the efficiency of the entire heat exchanger by an increasing temperature gradient along the plates.

[0153] The heat exchanger of the preferred embodiment has two collectors 3.1, 3.2, namely a first collector 3.1 and a second collector 3.2, the first collector 3.1 having a fluid outlet 4.1 and the second collector 3.2 having a fluid inlet 4.2. Each collector 3.1, 3.2 is in fluid communication with the inner chamber of the plate 2 due to a first sub-collector 5.1 connecting the first collector 3.1 to each first end 2.1 of the plate 2 and due to a second sub-collector 5.2 connecting the second collector 3.2 to each second end 2.2 of the plate 2.

[0154] The exhaust gases of the power unit 10 flow between the plates 2 at high speed and due to the shape of the plates, ie the pillow shape, the heat transfer with the fluid located inside the plates is increased.

[0155] The plate 2 comprises two sheets defining a watertight and airtight inner chamber, the sheets being joined to each other on their corresponding contours by means of discrete spot welds joining respective portions of each sheet and by means of continuous welding.

[0156] The plate 2 has specific geometrical parameters which provide the heat exchanger of the invention with relevant advantages.

[0157] In the preferred embodiment, the fluid flowing inside the plate is nitrogen N2.

[0158] Each plate 2 is hydraulically expanded using water by means of a hydrostatic pump. The hydraulic expansion process is a safe expansion process. However, other expansion processes may be used depending on the application. The expansion process pressurizes the two sheets, which allows the material to deform between the discrete spot welds and results in the creation of cavities, enabling fluid to flow inside the created interior chamber.

[0159] Expansion height of the board b i is the maximum internal expansion of the plate, such as Fig. 9 This specific parameter is responsible for the optimum point of the heat transfer coefficient and the intermediate fluid pressure drop inside the heat exchanger. In a preferred embodiment, the expansion height is between 3 mm and 6 mm, preferably 3,5 mm.

[0160] like Fig. 9The distance b between the plates, shown in , is a parameter that allows controlling the exhaust gas velocity flowing inside the heat exchanger and therefore also the pressure drop that has a great influence on the performance of the power unit 10. In a preferred embodiment, the optimal distance between the plates is between 16 mm and 30 mm, more preferably between 19,5 mm and 23 mm, so that the exhaust gas velocity is controlled and the pressure drop criterion is met, while not affecting the overall performance of the machine and avoiding higher consumption.

[0161] like Fig. 9 As shown in the figure, the longitudinal distance between two discrete solder joints is 2S L and the lateral distance S between two discrete solder joints T A small area of ​​fluid is defined within the inner chamber of the plate. The correct size of the longitudinal distance between two points and the correct size of the lateral distance between two points help to reduce the pressure drop, increase the heat transfer coefficient and provide uniform heat redistribution along the plate to avoid overstress and creep damage. In a preferred embodiment, the coefficient a is referred to as d Ratio 2S L / S T Preferably it is equal to 1, and both the longitudinal distance and the transverse distance are preferably equal to 42 mm.

[0162] Diameter of welding point d SP The control of provides stability to the plate as well as influences the path of the fluid located inside the plate. This parameter does influence the pressure drop, heat transfer coefficient and total stress inside the plate, therefore, this parameter directly affects the overall performance of the heat exchanger. Increasing the diameter of the discrete points helps to increase the convection coefficient inside the plate, which increases the total heat transfer capacity. In a preferred embodiment, the diameter of the weld point is 7,14 mm.

[0163] It is called coefficient b d The ratio d SP / S T Preferably equal to 0,17 and said parameters ensure that the compressor power, heat transfer area and pressure drop are controlled and provide the best performance for the heat exchanger of the invention when in operation.

[0164] It is called coefficient c d The ratio b i / S T Preferably equal to 0,0849 and said parameter affects compressor power, heat transfer area and fluid and exhaust gas velocities.

[0165] In a preferred embodiment, the first collector 3.1 and the second collector 3.2 are annular in shape in order to avoid possible problems related to thermal expansion and also provide uniform distribution of the fluid to the plates. Furthermore, the sub-collectors 5.1 , 5.2 are preferably curved to avoid potential stresses of expansion.

[0166] In a preferred embodiment, the plate 2 is made of Inconel 625 for providing thermal resistance and ensuring optimal conditions for heat transfer between the exhaust gases and the fluid located inside the plate, preferably nitrogen.

[0167] Additionally, in this preferred embodiment, the heat exchanger has a maximum length of 591 mm and a maximum diameter of 260 mm.

[0168] In another preferred embodiment, the fluid flowing inside the plates is helium He and the following parameters are set with respect to the plates of the heat exchanger of the present invention:

[0169] - Expansion height b of the plate i equal to 5,26mm, in order to minimize the heat transfer area,

[0170] - the distance b between the plates is between 19,5 mm and 23 mm,

[0171] - The longitudinal distance between two discrete welding points is 2S L and the lateral distance S between two discrete solder joints T Equal to 42mm,

[0172] -Diameter of the soldering point d SP equal to 7,14mm,

[0173] -Parameter a d is equal to 1,

[0174] -Parameter b d is equal to 0,17,

[0175] -Parameter c d Equals 0,0849.

[0176] In this preferred embodiment, when the fluid inside the plates is helium, the diameter of the muffler downstream of the heat exchanger must be increased and the preferred diameter is 0,2849 m.

Claims

1. A heat exchanger (1) for an aircraft, the heat exchanger (1) being arranged along a longitudinal direction XX' and comprising: at least one plate (2), said at least one plate (2) having a first end (2.1) and a second end (2.2) according to said longitudinal direction XX', said at least one plate (2) comprising an internal hollow volume configured to accommodate a second fluid for transferring heat from a first fluid located outside said at least one plate (2) to said second fluid located inside said at least one plate (2) in an operating mode of said heat exchanger (1), A first collector (3.1) and a second collector (3.2), the first collector (3.1) and the second collector (3.2) being configured to output the second fluid from the at least one plate (2) and to input the second fluid into the at least one plate (2), respectively, wherein: The first collector (3.1) is located at the first end (2.1) of the at least one plate (2), and the second collector (3.2) is located at the second end (2.2) of the at least one plate (2), The first collector (3.1) comprises at least one fluid outlet (4.1), and the The second collector (3.2) comprises at least one fluid inlet (4.2), and The first collector (3.1) and the second collector (3.2) are configured to be in fluid communication with the inner hollow volume of the at least one plate (2), the at least one fluid outlet (4.1) and the at least one fluid inlet (4.2), at least one first sub-collector (5.1) configured to connect the first collector (3.1) to the first end (2.1) of the at least one plate (2); at least one second sub-collector (5.2) configured to connect the second collector (3.2) to the second end (2.2) of the at least one plate (2), The liner (6) has a length L according to the longitudinal direction XX'. T The liner (6) is configured to define an inner chamber, the inner chamber confining the at least one plate (2), the first collector (3.1) and the second collector (3.2) and the first sub-collector (5.1) and the second sub-collector (5.2), and in, The at least one plate (2) comprises at least two sheets defining a watertight and airtight inner chamber, the sheets being coupled to each other by means of discrete spot welds joining respective portions of each sheet and by means of continuous welding on corresponding contours of the sheets.

2. Heat exchanger (1) according to the preceding claim, wherein: The liner (6) comprises at least two parts (6.1, 6.2) and attachment means (7) configured for fixing the parts (6.1, 6.2) of the liner (6) together.

3. A heat exchanger (1) according to any one of the preceding claims, wherein: The first collector (3.1) and the second collector (3.2) are annular or open-ring shaped, preferably circular shaped.

4. A heat exchanger (1) according to any one of the preceding claims, wherein: The first sub-collector (5.1) and the second sub-collector (5.2) are curved.

5. A heat exchanger (1) according to any one of the preceding claims, wherein: The heat exchanger (1) comprises a plurality of plates (2), preferably between 7 and 9 plates.

6. The heat exchanger (1) according to claim 5, wherein: The plurality of plates (2) are arranged substantially parallel to each other according to the longitudinal direction XX' and substantially perpendicular with respect to a horizontal plane including the transverse direction YY'.

7. The heat exchanger (1) according to claim 6, wherein: The plurality of plates (2) are arranged according to a stepped pattern, wherein the area of ​​the plurality of plates (2) decreases along the transverse direction YY'.

8. A heat exchanger (1) according to any one of the preceding claims, wherein: The second fluid is nitrogen, helium, ethylene glycol water, oil or water.

9. A heat exchanger (1) according to any one of the preceding claims, wherein: At least one of the fluid outlets (4.1) of the first collector (3.1) and at least one of the fluid inlet (4.2) of the second collector (3.2) are elbow-shaped.

10. A heat exchanger (1) according to any one of the preceding claims, wherein The at least one fluid outlet (4.1) of the first collector (3.1) and the at least one fluid inlet (4.2) of the second collector (3.2) are oriented in the same vertical direction as the at least one plate (2).

11. A heat exchanger (1) according to any one of the preceding claims, wherein: The first collector (3.1) and the second collector (3.2) respectively include two fluid outlets (4.1) and two fluid inlets (4.2), The two fluid outlets (4.1) are in fluid communication and connected to each other, and The two fluid inlets (4.2) are in fluid communication and connected to each other, and The two fluid outlets (4.1) and the two fluid inlets (4.2) are located on opposite sides of the first collector (3.1) and the second collector (3.2), respectively.

12. The heat exchanger (1) according to any one of claims 2 to 11, wherein: The attachment means (7) are located on each side of the liner (6) and are symmetrically arranged along the length of the liner (6) relative to an axis of symmetry of the liner (6).

13. A heat exchanger (1) according to any one of the preceding claims, wherein: The liner (6) is gas-tight and / or fireproof.

14. A power unit (10) for an aircraft, comprising: a power unit inlet (11), the power unit inlet (11) being configured to supply a first fluid to the power unit (10), an engine (12) and a power unit outlet (13), the power unit outlet (13) being configured to discharge the first fluid from the engine (12), in, The power unit outlet (13) comprises a heat exchanger (1) according to any one of the preceding claims, and The heat exchanger (1) further comprises two connection devices (14.1, 14.2), one connection device being positioned at each end of the at least one plate (2), wherein one of the connection devices (14.1, 14.2) is configured for mounting the heat exchanger (1) on the power unit outlet (13).

15. The power unit (10) according to claim 14, and the heat exchanger (1) according to claims 2 to 13, wherein: The attachment device (7): fixed along the longitudinal direction XX' and the vertical direction ZZ', or fixed along said longitudinal direction XX' and free along said vertical direction ZZ', or free along said longitudinal direction XX' and fixed along said vertical direction ZZ', or Free along the longitudinal direction XX' and the vertical direction ZZ'.

16. A power unit (10) according to any one of claims 14 or 15, and a heat exchanger according to claims 2 to 13, wherein: The attachment device (7) and / or the collector (3.1, 3.2) and the sub-collector (5.1, 5.2): is sealed relative to the power unit outlet (10), or is enclosed and sealed relative to the power unit outlet (10), or is enclosed and further comprises a blocking device (16) configured to open or close fluid communication with the power unit outlet (10), or Enclosed and in fluid communication with the power unit outlet (10).

17. An aircraft (100) comprising a power unit (10) according to any one of claims 14 to 16.

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