Heat exchanger comprising at least two closure bars placed side by side, air conditioning system, vehicle and manufacturing method

Abstract

The invention relates to a heat exchanger comprising: - a plate exchanger unit arranged in a circulation chamber so as to be in fluid communication with inlets (2, 6) and outlets (4) to allow the flow of a first fluid and a second fluid into and through this exchanger unit and the transfer of heat energy between them, the exchanger unit comprising a plurality of plates (10) arranged substantially parallel to one another and outer plates (12, 14), each space between two adjacent plates defining a layer for flow of a fluid, the plates being arranged substantially parallel to the outer plates (12, 14), characterized in that at least one outer layer for flow of at least either the first fluid and / or the second fluid comprises at least two closure bars (21, 22) placed longitudinally side by side.

Description

[0001] DESCRIPTION

[0002] TITLE OF THE INVENTION: HEAT EXCHANGER COMPRISING AT LEAST TWO JUXTAPOSED CLOSURE BARS, AIR CONDITIONING SYSTEM, VEHICLE AND MANUFACTURING METHOD

[0003] Technical field of the invention

[0004] The invention relates to a heat exchanger, in particular a heat exchanger for an aircraft, comprising at least two juxtaposed closing bars.

[0005] The invention relates in particular to a plate heat exchanger 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.

[0006] Technological background

[0007] Plate heat exchangers integrated into atmospheric vehicles are likely to be subjected to significant temperature gradients during their operating cycles. This is particularly true, for example, of a heat exchanger designed to cool high-pressure bleed air drawn from an aircraft propulsion engine or an auxiliary power unit (APU).

[0008] The sealing bars are a critical element for the cohesion and thermo-mechanical resistance of a heat exchanger, as they are positioned between each plate to define channels for the circulation of fluids passing through the exchanger. They are generally attached to the plates by brazing or welding. The alternating circulation channels for the hot and cold fluids maximize heat exchange between them, thus forming a hot pass and a cold pass, respectively.

[0009] The thermo-mechanical stresses experienced by plate heat exchangers are likely to cause deformations which may lead to cracking or debonding of some brazed parts during welding, particularly near the corners and end layers of the beam.

[0010] Various solutions have already been proposed to increase the thermo-mechanical resistance of heat exchangers in atmospheric vehicles, and in particular aircraft.

[0011] Document EP 4215 861 describes a plate heat exchanger in which each closure bar has a portion extending beyond the exchanger bundle such that the closure bars of each adjacent layer overlap, forming a wedge. Furthermore, the width of the plates varies, decreasing towards the center of the plate exchanger bundle.

[0012] However, such closure bars are complex to manufacture and involve a significant additional cost related to the design and manufacture of such a heat exchanger.

[0013] The invention therefore aims to provide a heat exchanger that overcomes these drawbacks.

[0014] Objectives of the invention

[0015] The invention aims to provide a heat exchanger exhibiting excellent thermomechanical resistance and whose manufacture is simple and does not involve significant additional cost.

[0016] The invention aims in particular to provide a heat exchanger exhibiting excellent structural resistance to pressure stresses.

[0017] The invention also aims to provide a heat exchanger exhibiting excellent structural cohesion that is stable over time.

[0018] Description of the invention

[0019] To this end, the invention relates to a heat exchanger comprising: - a circulation chamber delimited by at least one first external plate and at least one second external plate and comprising a first inlet of a first fluid into the circulation chamber and a first outlet of said first fluid outside the circulation chamber,

[0020] - a second inlet of a second fluid into the circulation chamber and a second outlet of said second fluid outside the circulation chamber, - a plate heat exchanger block arranged in the circulation chamber so as to be in fluid communication with the inlets and outlets 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,

[0021] said heat exchanger block comprising a plurality of plates arranged substantially parallel to each other between said first outer plate and said second outer plate, each space between two adjacent plates defining a circulation layer of one of said first fluid and said second fluid, said plates being arranged substantially parallel to said outer plates,

[0022] characterized in that said exchanger block comprises at least one layer, called the first outer layer, for the circulation of at least one of said first fluid and said second fluid, and at least one layer, called the second outer layer, for the circulation of at least one of said first fluid and said second fluid, said first outer layer and said second outer layer comprising at least two closure bars longitudinally juxtaposed with each other,

[0023] said exchanger block comprising a plurality of layers, called central layers, for the circulation of at least one of said first fluid and said second fluid arranged between said external layers, each central layer not comprising closure bars longitudinally juxtaposed between them, said central layers being arranged between said first external layer and said second external layer.

[0024] Adding closure bars alongside the initial closure bars in the layers closest to the outer plates of a heat exchanger block increases its thermomechanical resistance without requiring significant modification to the block. A heat exchanger according to the invention allows for a local reduction of thermomechanical stresses by minimizing the deformation of the closure bars through rotation around their longitudinal axis and by bending of the plates at the corners of the core. This results in an increased lifespan for the heat exchanger. Doubling or even tripling the number of closure bars in these outer circulation layers also strengthens the structural integrity of the heat exchanger and thus improves its pressure resistance.Furthermore, even if the brazed connection between a sealing bar and an external plate of the heat exchanger were to be altered during its cycles of use, the presence of this / these additional sealing bar(s), juxtaposed with another sealing bar, would then limit the impact of this alteration and thus prolong the life of the exchanger with respect to thermomechanical stresses.

[0025] In cases where the circulation layers of the first fluid have the same height (or thickness) as the circulation layers of the second fluid, a single type of sealing bar may be sufficient to manufacture a heat exchanger according to the invention, only the length of said sealing bars possibly needing to be adjusted according to the dimensions of the heat exchanger block. In cases where the circulation layers of the first fluid do not have the same height as the circulation layers of the second fluid, two types of sealing bars may be sufficient to manufacture the heat exchanger according to the invention. Thus, advantageously and according to the invention, all the sealing bars of the circulation layers of the first fluid of said heat exchanger have an identical cross-section.Similarly, all the closure bars of the circulation layers of the second fluid in said heat exchanger may also have an identical cross-section. In particular, each closure bar has a constant cross-section along its entire length and may be rectangular or any other suitable shape.

[0026] Thus, advantageously and according to the invention, each first outer layer and each second outer layer of said first fluid comprises two first closure bars longitudinally juxtaposed with each other and two second closure bars longitudinally juxtaposed with each other, each closure bar extending longitudinally between said first inlet and said first outlet so as to laterally close each outer layer. Advantageously and according to the invention, said heat exchanger comprises at least one first outer layer and at least one second outer layer of said first fluid, each comprising three first closure bars longitudinally juxtaposed with each other and three second closure bars longitudinally juxtaposed with each other, each closure bar extending longitudinally between said first inlet and said first outlet so as to laterally close each outer layer.

[0027] There is also nothing preventing the use of up to four or five closure bars placed longitudinally side by side.

[0028] Advantageously and according to the invention, said heat exchanger comprises at least one outer layer comprising three longitudinally juxtaposed closure bars and at least one outer layer comprising two longitudinally juxtaposed closure bars, said outer layer comprising three longitudinally juxtaposed closure bars being closer to said first outer plate than said outer layer comprising two longitudinally juxtaposed closure bars.

[0029] The second fluid can be the fluid whose temperature is higher than the temperature of the first fluid, or vice versa. Advantageously, according to the invention, the second fluid is the fluid whose temperature is higher than the temperature of the first fluid. In other words, the first fluid can be called the "cold" fluid and the second fluid the "hot" fluid. Each internal end layer is thus configured to allow the passage of a non-zero flow of the first fluid, the temperature of the second fluid being higher than that of the first fluid.

[0030] 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, both the first and second fluids are in gaseous form.

[0031] Each circulation layer of the first fluid and the second fluid can be equipped with any type of flow guide (or fins). Advantageously, according to the invention, each circulation layer comprises at least one flow guide having a corrugated shape. Such a flow guide can take various forms and be, for example, a corrugated sheet, a corrugated strip, or zigzag fins.

[0032] Each flow guide can be secured to the inner plates, for example, by brazing or welding. Each flow guide can be secured to the outer plates by a plurality of surface contacts. More specifically, the contact areas (external and internal) of each flow guide are advantageously brazed to the inner faces of an inner plate.

[0033] The use of such flow guides between the plates of the heat exchanger block is optional but improves the efficiency of heat exchange.

[0034] 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.

[0035] 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 supply or discharge line for the first fluid.

[0036] Advantageously, and according to the invention, the path of the first fluid flow and the path of the second fluid flow within the heat exchanger block can be substantially straight. It is, of course, also possible to use any other type of plate heat exchanger block, for example, in which the flow of one or both of the first and second fluids follows a U-shaped or S-shaped path. Thus, advantageously, and according to the invention, the principal direction of flow of the second fluid is orthogonal to the principal direction of flow of the first fluid.

[0037] The heat exchanger according to the invention can be formed from at least one material selected from metallic materials, composite materials, polymer materials, ceramic materials, in particular graphite, glass... In particular, in a particularly advantageous embodiment of a heat exchanger according to the invention, the plates are formed from metallic material, in particular from at least one material selected from the group consisting of steels, copper, aluminum, metallic alloys (in particular superalloys) and mixtures thereof.

[0038] The invention extends to an air conditioning system comprising at least one heat exchanger according to the invention. This may in particular be a non-contact, cross-flow heat exchanger.

[0039] The invention extends to a vehicle, in particular an aircraft, comprising at least one air conditioning system according to the invention.

[0040] The invention also extends to a method for manufacturing such a heat exchanger in which:

[0041] - at least two longitudinally juxtaposed closing bars are arranged in said first outer layer and said second outer layer, said exchanger block comprising at least one layer, said first outer layer, for the circulation of at least one of said first fluid and said second fluid, and at least one layer, said second outer layer, for the circulation of at least one of said first fluid and said second fluid,

[0042] - said exchanger block comprising a plurality of layers, called central layers, for the circulation of at least one of said first fluid and said second fluid arranged between said external layers, closure bars are arranged in each central layer in such a way that each central layer does not include closure bars longitudinally juxtaposed with each other, said central layers being arranged between said first external layer and said second external layer.

[0043] The invention also relates to 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.

[0044] List of figures

[0045] 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:

[0046] [Fig. 1] is a schematic perspective view of a heat exchanger block according to a first embodiment of the invention, [Fig. 2] is a schematic front view of a detail of a heat exchanger block according to a first embodiment of the invention,

[0047] [Fig. 3] is a schematic front view of a detail of a heat exchanger block of a heat exchange device according to a second embodiment of the invention.

[0048] Detailed description of an embodiment of the invention. In the figures, scales and proportions are not strictly respected for the purposes of illustration and clarity.

[0049] In addition, identical, similar or analogous elements are designated by the same references in all figures.

[0050] Figures 1 and 2 schematically illustrate an exchanger block of a heat exchanger according to a first embodiment of the invention.

[0051] The plate heat exchanger block may for example include a stack of flat plates 10 arranged parallel to each other between a first outer plate 12 and a second outer plate 14.

[0052] The plate heat exchanger block is configured to allow the circulation of a first and a second fluid in the spaces between each of the plates 10 closed laterally by closing bars 20, 21, 22, 30.

[0053] The plates 10 are arranged parallel to each other. Each inner plate 10 is arranged parallel to the first outer plate 12 and the second outer plate 14. Each space between two adjacent plates 10 defines a circulation layer for the first fluid or the second fluid. The first fluid, called the "cold" fluid, can, for example, flow along a principal flow direction between a first inlet 6 and a first outlet (not shown). The second fluid, called the "hot" fluid, can flow along a principal flow direction between a second inlet 2 and a second outlet 4.

[0054] In the first embodiment of a heat exchanger according to the invention, illustrated in Figures 1 and 2, in the first and last circulation layers of the heat exchanger block, which are circulation layers for the first fluid, the first closing bar 21 is doubled by a second closing bar 22. The heat exchanger block thus comprises a first outer circulation layer for the first fluid and a second outer circulation layer for the first fluid comprising two closing bars 21, 22 longitudinally juxtaposed at each lateral edge of the layer. The first outer circulation layer for the first fluid therefore comprises a total of four closing bars 21, 22. Similarly, the second outer circulation layer for the first fluid (or last circulation layer of the heat exchanger block) also comprises a total of four closing bars 21, 22 (joined in pairs).Each closing bar 21, 22 extends longitudinally between the first inlet 6 and the first outlet so as to laterally close the outer layer.

[0055] In the first embodiment, the heat exchanger comprises only two external layers, i.e. the first and last circulation layers of the exchanger block, provided laterally on either side with two juxtaposed closure bars 21, 22.

[0056] The heat exchanger block also includes a plurality of central circulation layers for the first and second fluids arranged between the outer layers. Each central layer is also laterally closed by closure bars 20, 30, but these bars are not juxtaposed; each closure bar 20, 30 of a central layer is isolated (individually) at each lateral edge of said central layer. The central circulation layers thus comprise a single closure bar 20, 30 at each lateral edge (of the heat exchanger block), the closure bars 20, 30 of the same central layer being spaced apart by the width of that layer and arranged parallel to each other in the crossflow embodiment shown in Figures 1 to 3.

[0057] In both embodiments of the heat exchanger illustrated in Figures 1 to 3, each outer and inner layer comprises a flow guide 40 formed by a plurality of successive sections, each with a serrated profile, so as to form guide walls and surface contact areas with the plates. Alternatively, so-called "offset" flow guides can be used, consisting of two successive sections offset laterally by a distance known as half-step, such that the guide walls of a section directly adjacent to another section are offset laterally. Any other type of flow guide can also be used within each circulation layer of the first or second fluid of the heat exchanger.

[0058] In a second embodiment illustrated in Figure 3, the heat exchanger comprises three interlocking closure bars 25, 26, 27 in the first and second outer layers (or last circulation layer of the exchanger block), which are circulation layers for the first fluid, and two interlocking closure bars 23, 24 in the next outer layer, located further from the outer plate than the first (or second) outer layer. Each closure bar 25, 26, 27 extends longitudinally between the first inlet 6 and the first outlet so as to laterally close off the outer layer. The outer layer comprising three longitudinally interlocking closure bars 25, 26, 27 is closer to a first outer plate 17 than the outer layer comprising two longitudinally interlocking closure bars 23, 24.We thus observe a progression in the number of closure bars juxtaposed with each other from the centre of the exchanger block towards the external plates 17 of the exchanger block.

[0059] It is also possible to provide that the heat exchanger comprises more than two external layers including two closure bars 21, 22 juxtaposed two by two at each lateral border, for example 4 or 6 external layers in total for a heat exchanger block. In the two embodiments of the heat exchanger illustrated in Figures 1 to 3, only the external layers of the first fluid are provided with bars juxtaposed to each other, but it is also possible to provide such bars juxtaposed both in the external circulation layers of the first fluid and in the external circulation layers of the second fluid, or even only in the external circulation layers of the second fluid.

[0060] In both embodiments of the heat exchanger illustrated in Figures 1 to 3, each closing bar 20, 21, 22, 23, 24, 25, 26, 27 has a generally parallelepiped shape. However, there is nothing preventing the use of a different geometry for the closing bars.

[0061] The circulation layers of the first fluid may have a different height than the circulation layers of the second fluid, so two types of sealing bars may suffice to manufacture the heat exchanger. In both embodiments of the heat exchanger illustrated in Figures 1 to 3, all the sealing bars 20, 21, 22, 23, 24, 25, 26, 27 of the circulation layers of the first fluid of the heat exchanger have an identical cross-section. The sealing bars 20, 21, 22, 23, 24, 25, 26, 27 are identical to each other. The sealing bars 20, 21, 22, 23, 24, 25, 26, 27 and the sealing bars 30 differ, where applicable, in their height and length (depending on the dimensions of the exchanger block and the plates that compose it). This presents an undeniable advantage in terms of the manufacturing and cost of such a heat exchanger.

[0062] The inventors evaluated the structural integrity of a heat exchanger according to the invention under pressure loads and demonstrated the advantages of the closure bar configuration according to the invention. An analysis of the thermomechanical stresses of a heat exchanger according to the invention also showed an improvement in fatigue resistance related to thermal cycling.

[0063] The invention is not limited to the embodiments described. In particular, the heat exchanger block may have a different architecture and configuration, etc.

Claims

DEMANDS 1. Heat exchanger comprising: - a circulation enclosure delimited by at least one first external plate (12, 17) and at least one second external plate (14) and comprising a first inlet (6) of a first fluid into the circulation enclosure and a first outlet of said first fluid out of the circulation enclosure, - a second inlet (2) of a second fluid into the circulation chamber and a second outlet (4) of said second fluid out of the circulation chamber, - a plate heat exchanger block disposed in the circulation chamber so as to be in fluid communication with the inlets (2, 6) and the outlets (4) 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 exchanger block comprising a plurality of plates (10) arranged substantially parallel to each other between said first outer plate (12) and said second outer plate (14), each space between two adjacent plates defining a circulation layer of one of said first fluid and said second fluid, said plates being arranged substantially parallel to said outer plates (12, 17, 14), characterized in that said exchanger block comprises at least one layer, called first outer layer, for the circulation of at least one of said first fluid and said second fluid, and at least one layer, called second outer layer, for the circulation of at least one of said first fluid and said second fluid, said first outer layer and said second outer layer comprising at least two closure bars (21, 22) longitudinally juxtaposed with each other, said exchanger block comprising a plurality of layers, called central layers, for the circulation of at least one of said first fluid and said second fluid arranged between said outer layers, each central layer not comprising closure bars longitudinally juxtaposed with each other, said central layers being arranged between said first outer layer and said second outer layer.2.Heat exchanger according to claim 1, characterized in that all the closing bars (20, 21, 22, 23, 24, 25, 26, 27) of the circulation layers of said first fluid have an identical transverse cross-section.

3. Heat exchanger according to any one of claims 1 or 2, characterized in that each first outer layer and each second outer layer of said first fluid comprises two first closure bars (21, 22, 23, 24) longitudinally juxtaposed with each other and two second closure bars longitudinally juxtaposed with each other, each closure bar (21, 22, 23, 24) extending longitudinally between said first inlet (6) and said first outlet so as to laterally close said outer layer.

4. Heat exchanger according to any one of claims 1 to 3, characterized in that it comprises at least a first outer layer and at least a second outer layer of said first fluid, each comprising three first closure bars (25, 26, 27) longitudinally juxtaposed with each other and three second closure bars longitudinally juxtaposed with each other, each closure bar (25, 26, 27) extending longitudinally between said first inlet (6) and said first outlet so as to laterally close each outer layer.

5. Heat exchanger according to any one of claims 1 to 4, characterized in that it comprises at least one outer layer comprising three longitudinally juxtaposed closure bars (25, 26, 27) and at least one outer layer comprising two longitudinally juxtaposed closure bars (21, 22, 23, 24), said outer layer comprising three longitudinally juxtaposed closure bars (25, 26, 27) being closer to said first outer plate (17) than said outer layer comprising two longitudinally juxtaposed closure bars (21, 22, 23, 24).

6. Heat exchanger according to any one of claims 1 to 5, characterized in that each circulation layer of said first fluid and said second fluid comprises at least one flow guide (40, 42).

7. Air conditioning system characterized in that it comprises at least one heat exchanger according to any one of claims 1 to 6.

8. Vehicle - in particular aircraft - characterized in that it comprises at least one air conditioning system according to claim 7.

9. A method for manufacturing a heat exchanger according to any one of claims 1 to 6, wherein: - at least two closure bars (21, 22) are arranged longitudinally juxtaposed in said first outer layer and said second outer layer, said exchanger block comprising at least one layer, said first outer layer, for the circulation of at least one of said first fluid and said second fluid, and at least one layer, said second outer layer, for the circulation of at least one of said first fluid and said second fluid, - said exchanger block comprising a plurality of layers, said central layers, for the circulation of at least one of said first fluid and said second fluid arranged between said outer layers, closure bars (20, 30) are arranged in each central layer such that each central layer does not include closure bars longitudinally juxtaposed, said central layers being arranged between said first outer layer and said second outer layer.

Images