HEAT EXCHANGER WITH HOLLOW CLOSING BARS INCLUDING INTERNAL STIFFNERS, AIR CONDITIONING SYSTEM AND VEHICLE

Abstract

HEAT EXCHANGER WITH HOLLOW CLOSING BAR INCLUDING INTERNAL STIFFENERS, AIR CONDITIONING SYSTEM AND VEHICLE The invention relates to a heat exchanger comprising a plate exchanger block comprising a plurality of plates arranged substantially parallel to each other, characterized in that it comprises a plurality of hollow closing bars (60), each hollow closing bar (60) extending mainly in a longitudinal direction and being arranged between two plates (13, 15), each hollow closing bar (60) having an internal cavity extending in said longitudinal direction, a first and a second contact faces (21, 22) that are flat and parallel to each other, a first side wall (23) having a generally concave outer edge (28), a second side wall (24) having a second generally convex outer edge (29) and at least one stiffener (25, 26,27) internal extending within said internal cavity (20). Figure for the abbreviation: figure 4,

Description

Title of the invention: HEAT EXCHANGER WITH HOLLOW CLOSING BARS INCLUDING INTERNAL STIFFENERS, AIR CONDITIONING SYSTEM AND VEHICLE Technical field of the invention

[0001] The invention relates to a plate heat exchanger, in particular for an aerial vehicle, comprising hollow closing bars including internal stiffeners. Technological background

[0002] Heat exchangers are used to allow heat transfer between at least two fluids, separated from each other by plates in contact with which heat exchange takes place in order to cool or heat one fluid with the help of another fluid.

[0003] Plate heat exchangers integrated into atmospheric vehicles are likely to be subjected to significant temperature gradients during their operating cycles. This is particularly the case, for example, of a heat exchanger intended to cool high-pressure bleed air taken from an aircraft propulsion engine or from an auxiliary power unit (commonly referred to as an APU).

[0004] These thermo-mechanical stresses experienced by plate heat exchangers can lead to deformations that may result in cracking or debonding of certain brazed parts. These phenomena create a risk of fluid leakage inside the exchanger, or even to the outside.

[0005] The sealing bars are a critical element for the cohesion and thermo-mechanical resistance of a heat exchanger, as they are positioned between each inner plate to delimit channels for the circulation of fluids passing through the exchanger. They are generally secured to the inner plates by brazing or welding. The alternating circulation channels for the hot and cold fluids maximize the heat exchange between the hot and cold fluids, thus forming a hot pass and a cold pass, respectively.

[0006] For example, US 2013 / 0140010 is known for a heat exchanger comprising closure bars having a C-shaped profile in which a recess is A gap is provided between the two wings of the C. The solid edge of the closure bars also includes slots. US 2013 / 0140010 specifies that such a shape provides flexibility to the bars, making them more resistant to cyclic thermal stresses.

[0007] However, the closing bars of such a heat exchanger according to US 2013 / 0140010 must have dimensions resulting in a significant mass reduction in order to maintain sufficient mechanical strength. Furthermore, such closing bars do not offer optimal aerodynamic performance. Objectives of the invention

[0008] The invention aims to provide a heat exchanger to overcome these drawbacks.

[0009] The invention aims in particular to provide a heat exchanger exhibiting excellent efficiency and excellent thermo-mechanical resistance while having a limited mass.

[0010] The invention also aims to provide a heat exchanger exhibiting excellent structural cohesion that is stable over time. Description of the invention

[0011] To this end, the invention relates to a heat exchanger comprising:

[0012] - a circulation chamber comprising a first inlet of a first fluid within the circulation area and a first exit of said first fluid outside the circulation area,

[0013] - a second inlet of a second fluid into the circulation chamber and a second outlet of said second fluid outside the circulation area,

[0014] - a plate heat exchanger block disposed in the circulation enclosure so as to be fluid communication with the inlets and outlets to allow the circulation of the first fluid and the second fluid in and through this exchanger block and the transfer of heat between them,

[0015] - said heat exchanger block comprising a plurality of plates arranged substantially parallel to each other,

[0016] characterized in that it comprises a plurality of hollow closing bars, each hollow closing bar extending mainly in a longitudinal direction and being arranged between two plates, each hollow closing bar having:

[0017] - an internal cavity extending along said longitudinal direction,

[0018] - a first contact face and a second contact face that are flat and parallel between them,

[0019] - a first lateral wall connecting said first contact face and said second contact face and presenting a generally concave outer edge,

[0020] - a second lateral wall connecting said first contact face and said second contact face and presenting a second overall convex outer edge,

[0021] - at least one internal stiffener extending within said internal cavity so as to connect said first side wall and said second side wall.

[0022] Thus, the hollow sealing bars of a heat exchanger according to the invention make it possible to improve both the thermomechanical behavior and the aerodynamics of the exchanger (and therefore the performance of the heat exchanger) without resulting in a mass gain. In particular, since such bars are not only hollow, which contributes to reducing their mass, but also have at least one internal stiffener connecting the side walls of each hollow sealing bar, they exhibit increased mechanical strength, allowing their mass to be reduced while maximizing the contact surfaces with the plates of the exchanger block (greater brazed joint length), which improves the thermomechanical resistance of the heat exchanger.Furthermore, the concave outer profile of the first side wall also contributes to improving the thermomechanical resistance of the heat exchanger by providing connection areas for the plates, similar to a radius of contact. This prevents excessive stress in the contact or junction areas between the flat upper and lower contact faces of the hollow sealing bars and the plates, particularly in the brazing areas between these elements. Moreover, the increased contact area between each hollow sealing bar and the plates of the heat exchanger block allows for greater structural stability of the heat exchanger block, without any increase in mass, thanks to the structure of the hollow sealing bars.

[0023] The heat exchanger according to the invention may comprise different materials and is in particular formed of at least one material selected from metallic materials and their composite materials. In particular, in a particularly advantageous embodiment of a heat exchanger according to the invention, the plates of the exchanger block are formed of metallic material, in particular of at least one material selected from the group consisting of steels, copper, aluminum, metal alloys (in particular superalloys) and mixtures thereof.

[0024] Advantageously and according to the invention, each hollow closure bar comprises at least one material selected from metallic materials. Advantageously and according to the invention, each hollow closure bar is formed from a single piece, that is, from a single unit. Advantageously and according to the invention, each hollow closure bar is manufactured by additive manufacturing. Additive manufacturing makes it possible to optimally obtain the geometries of the stiffeners and internal partitions of the hollow closure bars according to the invention. Advantageously and according to the invention, Each hollow closure bar is manufactured by powder bed fusion, in particular by selective laser fusion. Specifically, advantageously and according to the invention, each hollow closure bar is manufactured by a process commonly referred to as LPBF (for "Laser Powder Bed Fusion").

[0025] The invention also relates to a method of manufacturing at least one closing bar of such a heat exchanger.

[0026] The first side wall of each hollow sealing bar connects the first and second contact faces of a bar and has an outer edge with a generally concave external surface (facing the interior of the heat exchanger block). This external surface of the outer edge may, of course, have certain recessed or raised features. Advantageously, according to the invention, said generally concave outer edge of the first side wall has a curvature in a constant direction. The configuration of such a first side wall of each hollow sealing bar provides large, maximized contact surfaces with the plates of the heat exchanger block, which contributes to improving the thermomechanical resistance of the heat exchanger.The portions of the first side wall closest to the plates of the heat exchanger block against which they are positioned form fins, the cross-section of such a first side wall being substantially C-shaped. These fins reduce the geometric break between each hollow closing bar and each plate of the heat exchanger block, the fins being tapered, i.e., thinned, towards their free ends (wings of the C) and forming a gradual geometric transition up to each (thin) plate of the heat exchanger block according to the invention. This provides better structural stability of the heat exchanger block while limiting the mass of the hollow closing bars.

[0027] The second lateral wall of each hollow sealing bar connects the first and second contact faces of a bar and has an external edge with an overall convex external surface (facing outwards from the heat exchanger block) so as to present a profiled shape. This external surface of the outer edge may, of course, have certain recessed or raised features. Advantageously, according to the invention, said overall convex external edge of the second lateral wall has a curvature in a constant direction. If the hollow sealing bars are arranged at the first inlet of the first fluid and / or at the second inlet of the second fluid in the circulation chamber, the external surface of the second lateral wall of each hollow sealing bar thus forms a leading edge with respect to the first and / or second fluid entering the heat exchanger block.If the hollow closure bars are arranged at the first outlet of said first fluid and / or at the second outlet of said second fluid outside the enclosure. During circulation, the external surface of the second lateral wall of each hollow sealing bar forms a trailing edge with respect to the first and / or second fluid exiting the heat exchanger block. The configuration of such an external edge of the second lateral wall of each hollow sealing bar ensures a significant reduction in pressure losses due to the grid effect in the relevant flow path.

[0028] Each internal stiffener of a hollow closure bar according to the invention provides significant mechanical resistance to said bar. Each internal stiffener of a hollow closure bar according to the invention may have a rod-like or profile-like shape and may be curved or straight. The cross-sectional area of ​​an internal stiffener may be constant or vary from one end to the other. Advantageously, and according to the invention, each internal stiffener extends in a straight line. Each internal stiffener then extends like beams inside the internal cavity of a hollow closure bar. Each hollow closure bar can thus comprise a plurality of parallel internal stiffeners, each internal stiffener extending longitudinally primarily in a direction substantially orthogonal or intersecting to the longitudinal direction of said hollow closure bar.

[0029] Advantageously and according to the invention, each internal stiffener extends substantially along a plane. Such an internal stiffener can then extend along the entire length of said hollow closing bar, within said internal cavity, without interruption or in the form of several portions of planes.

[0030] Advantageously and according to the invention, each closing bar comprises at least one internal stiffener extending substantially parallel to said first contact face and to said second contact face.

[0031] Advantageously, and according to the invention, each hollow closure bar comprises a plurality of internal stiffeners, said internal stiffeners having at least one point at which said internal stiffeners are connected to each other. The internal stiffeners can therefore intersect, each intersection forming a node. Each hollow closure bar can thus have an internal structure resembling a truss or a triangulated system. Such hollow closure bars thus exhibit significant mechanical strength, in particular high stiffness and modulus of elasticity, and high tensile strength, relative to their mass.

[0032] Advantageously and according to the invention, each internal stiffener extends over the entire length of said hollow closing bar.

[0033] The second overall convex outer edge of the hollow closing bars may further have surface concavities (without affecting the overall convex shape of said second outer edge between the two flat faces of the bar hollow closure bars), arranged close enough to one of the flat contact faces of the bar to collect brazing material. These surface concavities, forming brazing reservoirs, are therefore shallower than the thickness of the second lateral wall. This prevents the brazing material from being drawn ("sucked") into the heat exchanger block. Such brazing reservoirs can be distributed in various ways along the second, generally convex outer edge of the hollow closure bars and can take different hollow forms (point or elongated). Advantageously, according to the invention, the second, generally convex outer edge has at least one brazing reserve groove. In particular, each brazing reserve groove extends longitudinally substantially parallel to the longitudinal direction of the hollow closure bar.The second, generally convex, outer edge has, for example, two longitudinal solder reserve grooves, each located in the immediate vicinity of the second contact face and the first contact face of the hollow closing bar, respectively.

[0034] The heat exchanger according to the invention may comprise both hollow and solid sealing bars. Hollow and solid sealing bars may be used for different layers on the same face of the exchanger block or on different faces. The hollow sealing bars may be used for each circulation layer of said first fluid and / or for each circulation layer of said second fluid, at the first inlet of the first fluid into the circulation chamber and / or at the first outlet of said first fluid and / or at the second inlet of the second fluid into the circulation chamber and / or at the second outlet of said second fluid from the circulation chamber.

[0035] Advantageously and according to the invention, said heat exchanger comprises closure bars for each circulation layer of said first fluid, at least one closure bar being disposed between two circulation plates of the second fluid.

[0036] Advantageously and according to the invention, said heat exchanger comprises closure bars for each circulation layer of said second fluid, at least one closure bar being disposed between two circulation plates of the first fluid.

[0037] Advantageously and according to the invention, all of the closing bars of said heat exchanger are hollow closing bars according to the invention, that is to say that said hollow closing bars are arranged between each circulation plate of the first fluid and between each circulation plate of the second fluid.

[0038] Advantageously and according to the invention, said plates of said exchanger block comprise two external plates delimiting said circulation chamber and arranged substantially parallel to the plates, said internal plates.

[0039] The space between each of said plates of the heat exchanger block, forming internal layers, may be left free or fitted with flow guides (or fins). Advantageously, and according to the invention, a heat exchanger according to the invention further comprises at least one flow guide disposed between each of said plates of said heat exchanger block, each flow guide being adapted to form a plurality of substantially parallel channels. Advantageously, and according to the invention, each internal layer is fitted with at least one flow guide adapted to form a plurality of substantially parallel channels.

[0040] Advantageously, and according to the invention, each flow guide is formed of a plurality of successive sections, each having a serrated profile, so as to form guide walls and surface contact areas with the plates. These are, for example, so-called "offset" flow guides in which two successive sections are laterally offset, such that the guide walls of a section located directly adjacent to another section are laterally offset (in a direction parallel to the external plates of the heat exchanger block) relative to the guide walls of the latter. Each flow guide can be secured to the plates, for example, by brazing or welding.

[0041] The use of such flow guides between the plates of the exchanger block is optional but allows for improved heat exchange efficiency.

[0042] A heat exchanger according to the invention may be cross-flow or counter-current (single-pass or multi-pass). Advantageously, according to the invention, the path of the first fluid flow and the path of the second fluid flow within the exchanger block may each be substantially straight. Advantageously, according to the invention, said heat exchanger is said to be cross-flow. The heat exchanger according to the invention is adapted to allow the circulation of the second fluid in a second fluid passage, along a direction, referred to as the second fluid flow direction, orthogonal to the main flow direction of the first fluid.

[0043] It is of course also possible to use any other type of plate exchanger block, for example in which the flow of one and / or the other of the first or second fluid follows a U-shaped path or an S-shaped or Z-shaped path or any more complex circuit in which closing bars are used.

[0044] Advantageously and according to the invention, the circulation enclosure has a closed periphery that is sealed against fluids (at least in operation and without taking into account the inlets and outlets for the first fluid and for the second fluid).

[0045] Advantageously, and according to the invention, each fluid can be in liquid or gaseous form. In particular, the state of the first fluid can be the same as or different from the state of the second fluid. Advantageously, and according to the invention, the first fluid and the second fluid are in gaseous form.

[0046] Advantageously, according to the invention, the first inlet has an inlet port for the first fluid into the circulation chamber. Advantageously, according to the invention, the first outlet has an outlet port for the first fluid out of the circulation chamber. In a particularly advantageous embodiment of the invention, each outlet has a single orifice forming an inlet or outlet, an opening to the circulation chamber and / or to the plate heat exchanger block, and a solid peripheral wall between this orifice and this opening. Each orifice of each outlet can be connected to a fluid supply or discharge conduit.

[0047] The invention also relates to a heat exchanger, a method for manufacturing at least one closing bar of such a heat exchanger, an air conditioning system and a vehicle comprising at least one such air conditioning system characterized in combination by all or part of the characteristics mentioned above or below. List of figures

[0048] Other objects, features and advantages of the invention will become apparent from the following description, given by way of non-limiting example only, and which refers to the accompanying figures in which:

[0049] [Fig. 1] is a schematic perspective view of a heat exchanger block according to a first embodiment of the invention,

[0050] [Fig.2] is a schematic perspective view of a detail of the exchanger block of a heat exchanger according to the invention as shown in [Fig.1],

[0051] [Fig.3] is a schematic perspective view of a closing bar of a heat exchanger according to the first variant of the invention.

[0052] [Fig.4] is a schematic cross-sectional view of a closing bar of a heat exchanger according to a second embodiment of the invention.

[0053] Detailed description of an embodiment of the invention

[0054] In the figures, scales and proportions are not strictly observed for illustrative and clarity purposes. Identical, similar, or analogous elements are designated by the same reference numerals in all figures.

[0055] Figures 1 to 3 illustrate a first embodiment of a heat exchanger according to the invention. [Fig. 1] schematically illustrates a heat exchanger block 12 of a heat exchanger according to the invention, a detail of which is shown in [Fig. 2].

[0056] Such a heat exchanger comprises a circulation chamber delimited by two external plates 14 and 16, the exchanger block comprising internal plates 13, 15, 18 arranged substantially parallel to each other between the outer plates 14, 16.

[0057] The heat exchanger includes a first inlet 4 and a first outlet 6 of a first fluid in the circulation chamber, as well as a second inlet 8 and a second outlet 10 of a second fluid in the circulation chamber.

[0058] The plate heat exchanger block 12 therefore allows the circulation of the first heat transfer fluid and the second heat transfer fluid in and through this heat exchanger block 12 and the transfer of heat between them.

[0059] The first fluid, called the "cold" fluid, circulates in the circulation zones of the first fluid along a main direction of circulation of the first fluid between the first inlet 4 and the first outlet 6. The second fluid, called the "hot" fluid, circulates in the circulation zones of the second fluid, distinct from the circulation zones of the first fluid, between the second inlet 8 and the second outlet 10.

[0060] Fig. 2 represents a portion of an edge of the exchanger block 12 between the first outlet 6 and the second outlet 10.

[0061] The exchanger block 12 includes parallelepiped (solid) closure bars 62 arranged along the length of the cold pass to define the cold fluid circulation channels.

[0062] The heat exchanger block 12 also includes a plurality of hollow sealing bars 60 at the first outlet 6 of the first fluid, arranged along the length of the hot pass to define the hot fluid circulation channels. Each hollow sealing bar 60 extends primarily in a longitudinal direction. Each hollow sealing bar has an internal cavity 20 extending in the longitudinal direction. Each hollow sealing bar 60 has a flat and parallel upper contact face 21 and lower contact face 22, as well as a first lateral wall 23 and a second lateral wall 24. The first lateral wall 23 connects the upper contact face 21 and the lower contact face 22 and has a generally concave outer edge 28.The second lateral wall 24 connects the upper contact face 21 and the lower contact face 22 and has a second overall convex external edge 29.

[0063] Each hollow closing bar 60 comprises internal stiffeners 25, 26, 27 extending within the internal cavity 20 so as to connect the first lateral wall 23 and the second lateral wall 24. In the embodiments shown in Figures 1 to 4, each closing bar 60 comprises three internal stiffeners 25, 26, 27, connected to each other at the contact with the first lateral wall 23 of the hollow closing bar. A central internal stiffener 25 extends longitudinally within the cavity 20 in a plane parallel to the upper contact faces 21 and lower contact faces 22 of the bar and located equidistant from the upper and lower faces of the bar. Two oblique internal stiffeners 26, 27 extend from the first side wall 23 to the second side wall 24, each forming a non-zero angle with the central internal stiffener 25. The internal stiffeners 25, 26, 27 are assembled in a truss structure, also known as a triangulated system in architecture. This configuration offers significant stiffness and modulus of elasticity and allows for a reduction in the mass of the bars. In the embodiments shown in the figures, the three internal stiffeners 25, 26, 27 extend along the entire length of the hollow closing bar 60.

[0064] The hollow closure bars of a heat exchanger according to the invention make it possible to improve both the thermomechanical behavior and the aerodynamics of the exchanger without resulting in a mass gain.

[0065] Each hollow closure bar 60 is manufactured by additive manufacturing by powder bed fusion, such as by selective laser melting according to the LPBF process.

[0066] The first side wall 23 of each hollow closing bar 60 connects the upper contact face 21 and the lower contact face 22 and has an outer edge with a concave external surface 28 (facing the interior of the heat exchanger block) whose cross-section is in the shape of an arc of a circle (or a C). This shape increases the contact areas of the closing bars with the plates 13, 14, 15, 16, 18 of the heat exchanger block, which helps to improve the thermomechanical resistance of the heat exchanger. This also has the advantage of further stabilizing the heat exchanger block structurally while limiting the mass of the heat exchanger.

[0067] The second lateral wall 24 of each hollow sealing bar 60 has a second external edge having a generally convex external surface 29 (facing outwards from the heat exchanger block) with a transverse cross-section in the shape of an arc. Since the hollow sealing bars 60 are located at the first outlet 6 of the first fluid from the circulation chamber, the external surface of the second lateral wall 24 of each hollow sealing bar 60 forms a trailing edge that helps to reduce pressure losses. Hollow sealing bars can also be located at the inlet of the heat exchanger block, in which case the second convex external edge 29 of the second lateral wall 24 acts as the leading edge with respect to the fluid.

[0068] Such a heat exchanger therefore not only improves the thermomechanical behavior and aerodynamics of the exchanger, without mass gain, but also reduces pressure losses in order to achieve optimal efficiency.

[0069] In the embodiment shown here, the first fluid and the second fluid flow in a simple cross-flow configuration. Other types of Circulation configurations of the first fluid and the second fluid are also conceivable.

[0070] Fins 51 (or flow guides) are arranged in each circulation layer of the first fluid and the second fluid. The fins 51 can be formed of corrugated plates forming circulation channels which can have various geometries such as rectangular ([Fig.4]).

[0071] Fig. 4 illustrates a second embodiment of hollow closure bars of a heat exchanger according to the invention in which each closure bar 60 further has, on its second overall convex outer edge 29, two grooves 41, 42 for brazing reserve.

Claims

Demands

1. Heat exchanger (1) comprising: - a circulation chamber including a first inlet (4) of a first fluid into the circulation chamber and a first outlet (6) of said first fluid out of the circulation chamber, - a second inlet (8) of a second fluid into the circulation chamber and a second outlet (10) of said second fluid out of the circulation chamber, - a plate heat exchanger block (12) arranged in the circulation chamber so as to be in fluid communication with the inlets (4, 8) and the outlets (6, 10) to allow the circulation of the first fluid and the second fluid in and through this heat exchanger block and the transfer of heat between them, - said heat exchanger block comprising a plurality of plates (13, 14, 15, 16, 18) arranged substantially parallel to each other, characterized in that it comprises a plurality of hollow closing bars (60),Each hollow closure bar (60) extending primarily in a longitudinal direction and being disposed between two plates (13, 14, 15, 16, 18), each hollow closure bar (60) having: - an internal cavity (20) extending in said longitudinal direction, - a first contact face (21) and a second contact face (22) that are flat and parallel to each other, - a first lateral wall (23) connecting said first contact face (21) and said second contact face (22) and having a generally concave outer edge (28), - a second lateral wall (24) connecting said first contact face (21) and said second contact face (22) and having a generally convex second outer edge (29), - at least one internal stiffener (25, 26, 27) extending within said internal cavity (20) so as to connect said first lateral wall (23) and said second lateral wall (24).,

2. Heat exchanger according to claim 1, characterized in that said overall concave outer edge (28) of the first side wall (23) has a curvature of constant direction.

3. Heat exchanger according to any one of claims 1 or 2, characterized in that each internal stiffener (25, 26, 27) extends in a straight line.

4. Heat exchanger according to any one of claims 1 to 3, characterized in that each internal stiffener (25, 26, 27) extends substantially along a plane.

5. Heat exchanger according to any one of claims 1 to 4, characterized in that each closing bar (60) comprises at least one internal stiffener (25) extending substantially parallel to said first contact face (21) and said second contact face (22).

6. Heat exchanger according to any one of claims 1 to 5, characterized in that each closing bar (60) comprises a plurality of internal stiffeners (25, 26, 27), said internal stiffeners (25, 26, 27) having at least one point at which said internal stiffeners (25, 26, 27) are connected to each other.

7. Heat exchanger according to any one of claims 1 to 6, characterized in that each internal stiffener (25, 26, 27) extends over the entire length of said hollow closing bar (60).

8. Heat exchanger according to any one of claims 1 to 7, characterized in that said second overall convex outer edge (29) has at least one groove (41, 42) for brazing reserve.

9. Air conditioning system characterized in that it comprises at least one heat exchanger according to any one of claims 1 to Q

10. o. Vehicle -in particular aircraft- characterized in that it comprises at least one air conditioning system according to claim 9.

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