Heat exchange device comprising flow restriction devices, air conditioning system and vehicle

Abstract

The invention relates to a heat-exchange device comprising: an exchanger block (12) arranged in a circulation chamber bounded by two external plates, said exchanger block comprising a first internal layer and a last internal layer allowing the circulation of the first heat-transfer fluid, said exchanger block comprising a plurality of internal plates (13, 14, 15, 16) arranged substantially in parallel with one another between two ends of said exchanger block, characterised in that each first internal layer and each last internal layer comprises at least one flow-limiting device (20) that is configured to be able to impede at least in part the circulation of said first fluid flow in said internal layer.

Description

Technical field of the invention

[0001] The invention relates to a heat exchange device, in particular a heat exchanger for an aircraft, comprising at least one flow limiting device.

[0002] The invention relates in particular to a plate heat exchange device, two different heat transfer fluids circulating between said plates so as to cool or heat a first fluid using a second fluid, the two fluids being separated from each other by plates in contact with which said heat exchange takes place.

[0003] Plate heat exchangers integrated into naturally aspirated vehicles are often subject to strong temperature gradients.

[0004] These repeated stresses create risks of premature rupture of the elements of the exchanger block (also called "bundle") and of the appearance of leaks of fluid circulating in the exchanger.

[0005] However, it is necessary to maintain structural continuity of the bundle of such heat exchangers, particularly during its manufacture, which may involve brazing steps. It is also desirable to maintain structural rigidity with respect to the forces induced by external constraints (forces at the interfaces, pressure, vibrations, etc.). Technological background

[0006] Various solutions have already been proposed to increase the thermomechanical resistance linked to the temperature gradients experienced by the heat exchange devices of atmospheric vehicles, and in particular aircraft.

[0007] EP 2 840 345 proposes, for example, a cross-flow heat exchanger in which the spacers arranged in the hot pass and the cold pass of the exchanger have slots intended to reinforce the mechanical resistance of the spacers and to limit the propagation of a crack which would be formed following thermal deformation.

[0008] Such a device does not allow the thermomechanical resistance of a heat exchange device to temperature gradients to be satisfactorily increased.

[0009] A heat exchanger according to EP 2 840 345 does not prevent deterioration of the elements of the exchanger block under the effect of the various stresses undergone by such a heat exchanger, in particular in an aircraft.

[0010] The invention therefore aims to propose a heat exchange device making it possible to overcome these drawbacks.

[0011] Also known from GB 654 395 is a plate heat exchanger comprising a casing inside which are arranged the plates forming cells for the circulation of a first fluid, another fluid circulating in the casing around said cells. Corrugated sheets on either side of a flat sheet may be provided in the cells so as to increase the heat transmitting surface, the corrugations of these sheets forming channels extending parallel to the direction of circulation of the fluid in said cells.

[0012] Also known from US 2013 / 191079 is a cross-flow plate and spacer heat exchanger comprising porous blocking bars arranged parallel to the direction in which the cold fluid flow is flowing, each blocking bar comprising pores making it possible to control the flow of hot fluid at the inlet of the hot pass. Objectives of the invention

[0013] The invention aims to provide a heat exchange device having very low sensitivity to temperature gradients.

[0014] The invention aims in particular to provide a heat exchange device having excellent structural cohesion which is stable over time.

[0015] The invention also aims to provide a heat exchange device having excellent efficiency. Statement of the invention

[0016] To do this, the invention relates to a heat exchange device comprising: a circulation enclosure delimited by at least a first side plate, called the first external plate, and at least a second side plate, called the second external plate, a first inlet for a first heat transfer fluid into the circulation enclosure, a first outlet for the first heat transfer fluid outside the enclosure, a second inlet for a second heat transfer fluid into the circulation enclosure, a second outlet for the second heat transfer fluid outside the enclosure, a plate exchanger block arranged in the circulation enclosure so as to be in fluid communication with the inlets and the outlets to allow the circulation of the first heat transfer fluid and the second heat transfer fluid in and through this exchanger block and the transfer of calories between them, said exchanger block being adapted to allow the circulation of a first flow of heat transfer fluid in said circulation enclosure in one direction,said main direction of circulation of the first fluid, between the first inlet and the first outlet, said exchanger block comprising a plurality of internal plates arranged substantially parallel to each other between two ends of said exchanger block, each space between two adjacent internal plates defining a layer, called internal layer, of circulation of one of said first heat transfer fluid and said second heat transfer fluid, said internal plates being arranged substantially parallel to the external plates, , characterized in that the first internal layer for circulation of said first heat transfer fluid and the last internal layer for circulation of said first heat transfer fluid, called internal end layers, each comprise at least one device, called a flow limiter device, configured to be able to at least partially hinder the circulation of said first flow of fluid in said internal layer end, while allowing the circulation of a non-zero fluid flow.

[0017] A heat exchange device according to the invention therefore makes it possible to limit the heat exchanges in at least one internal end layer, in particular a cold layer, of such a heat exchange device in order to limit the temperature drop in this layer compared to the temperature at the core of the exchanger block. A heat exchange device according to the invention therefore makes it possible to limit the temperature differences between the ends and the core of the bundle of such an exchanger as well as the resulting deformations. This results in better structural continuity of said heat exchange device over time as well as greater mechanical resistance to thermo-mechanical conditions. This thus makes it possible to avoid the breakage of certain parts, which may occur for example following a rotation of a closing bar of the bundle of a heat exchange device around its initial longitudinal axis.

[0018] Thus, advantageously and according to the invention, only said internal end layers comprise one (or more) flow limiting device(s). In other words, said flow limiting devices are only present in said internal end layers, i.e. the first internal circulation layer of said first heat transfer fluid and the last internal circulation layer of said first heat transfer fluid.

[0019] The heat exchange device according to the invention also comprises a passage, called the passage of the second heat transfer fluid, allowing the circulation of a flow of the second heat transfer fluid in the circulation enclosure between the second inlet and the second outlet.

[0020] The heat exchange device according to the invention is adapted to allow the circulation of the second heat transfer fluid in the passage of the second heat transfer fluid, in a direction, called the circulation direction of the second fluid, orthogonal to the circulation direction of the first fluid. Advantageously and according to the invention, the first heat transfer fluid circulates, in said circulation enclosure, in a direction, called the main circulation direction of the first fluid, extending between the first inlet and the first outlet, said circulation direction of the first fluid being orthogonal to the direction, called the circulation direction of the second fluid, in which the second heat transfer fluid circulates, in said circulation enclosure, between the second inlet and the second outlet.

[0021] Advantageously and according to the invention, the second heat transfer fluid is adapted to form a second flow of heat transfer fluid circulating, in said circulation enclosure, according to the direction of circulation of the second fluid, between the second inlet and the second outlet, said direction of circulation of the second fluid being orthogonal to the main direction of circulation of the first fluid.

[0022] The first heat transfer fluid and the second heat transfer fluid circulate in the spaces between the internal plates closed laterally by closing bars (or rods).

[0023] The second heat transfer fluid may correspond to the fluid whose temperature is higher than the temperature of the first heat transfer fluid or vice versa. Thus, advantageously and according to the invention, the second heat transfer fluid corresponds to the heat transfer fluid whose temperature is higher than the temperature of the first heat transfer fluid. In other words, the first heat transfer fluid may be called the “cold” fluid and the second heat transfer fluid may be called the “hot” fluid. Thus, each internal end layer is configured to allow the passage of a non-zero flow of said first heat transfer fluid, the temperature of said second heat transfer fluid being higher than the temperature of said first heat transfer fluid.

[0024] Advantageously and according to the invention, said internal end layers are layers inside which the “cold” fluid circulates, that is to say the first heat transfer fluid whose temperature is lower than the temperature of the second heat transfer fluid.

[0025] Advantageously and according to the invention, each heat transfer fluid may be in liquid or gaseous form. In particular, the state of the first heat transfer fluid may be identical to or different from the state of the second heat transfer fluid. Advantageously and according to the invention, the first heat transfer fluid and the second heat transfer fluid are in gaseous form.

[0026] Advantageously and according to the invention, each flow limiting device comprises at least one portion extending substantially along a plane intersecting (non-parallel) to the main direction of circulation of the first fluid so as to be able to at least partially hinder the circulation of said first flow of fluid in said internal end layer. Advantageously and according to the invention, each flow limiting device comprises at least one flat portion (or face) extending substantially orthogonally to the main direction of circulation of the first fluid.

[0027] Advantageously and according to the invention, each flow limiting device comprises at least one flow guide adapted to be in the form of a plurality of channels substantially parallel to each other, each flow guide being arranged in each first internal layer and in each last internal layer so that said channels extend in a direction substantially orthogonal to the main direction of circulation of the first fluid. The channels of each flow guide are at least partly formed by side walls, these walls forming said flat portions extending mainly in a direction not substantially parallel to the main direction of circulation of the first fluid so as to be able to at least partly hinder the circulation of said first flow of fluid in said end internal layer. Such a flow guide can extend throughout said first internal layer and said last internal layer of the exchanger block.Advantageously and according to the invention, each flow limiting device extends throughout said first internal layer and said last internal layer of the exchanger block. Such a flow guide may also extend only in one or more portions of said first internal layer and said last internal layer of the exchanger block.

[0028] It is also possible to arrange each flow limiting device consisting of a flow guide so that the channels are arranged forming an angle of less than 90° with the main direction of circulation of the first fluid in the end layer, in particular an angle of between 35° and 90°.

[0029] Advantageously and according to the invention, said flow limiting device comprises at least one flow guide having a corrugated shape. Such a flow guide can take various forms and be presented for example in the form of a corrugated sheet or a corrugated strip or even zig-zag fins.

[0030] According to a particularly advantageous variant of a heat exchange device according to the invention, each flow guide is formed from a plurality of successive sections each having a crenellated profile, so as to form guide walls and surface contact zones with the plates. In such a flow guide, commonly called an “offset” flow guide, two successive sections are laterally offset, so 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 exchanger block) relative to the guide walls of the latter.

[0031] Each flux guide may be secured to the inner plates, for example by brazing or welding. Each flux guide may be secured to the outer plates by a plurality of surface contacts. More particularly, the contact zones (external and internal) of each flux guide are advantageously brazed to the inner faces of an inner plate and of the first or second inner plate (end plates).

[0032] Advantageously and according to the invention, the flow limiting device comprises at least one bar, called a flow limiting bar, extending mainly in a longitudinal direction, said bar being arranged so that the longitudinal direction of said bar is orthogonal to the main direction of circulation of said first fluid, said bar having at least one through opening, in particular at least two through openings, adapted to allow the passage of a flow of said first heat transfer fluid through said through openings. Said flow limiting bar may be arranged at the inlet or at the outlet of the internal end layer (the inlet and the outlet being defined relative to the direction of circulation of the heat transfer fluid in said internal layer) or in any intermediate position between the inlet and the outlet of said internal end layer.Advantageously and according to the invention, said flow limiting bar is arranged at the inlet of each internal end layer. However, nothing prevents the provision (as a variant or in combination) of two flow limiting bars within each internal end layer, for example a first flow limiting bar at the inlet and a second flow limiting bar at the outlet of said internal layer. More particularly, said flow limiting bar partially or completely closes the heat transfer fluid passage section of the first internal end layer and / or of the last internal end layer, with the exception of said through openings. Furthermore, the number, distribution, size and shape of said through openings provided in each flow limiting bar may vary.

[0033] It is therefore possible to optimize the geometric parameters of such flow limiting devices of a heat exchange device according to the invention and to modulate the flow of heat transfer fluid (in particular the flow of so-called cold fluid) and thus to optimize the reduction of the thermal gradient at the ends of the bundle of a heat exchange device according to the invention. With regard to a flow limiting device in the form of a flow guide, it is possible to choose, depending on the case, the height of the corrugations, the pitch of each flow guide, the offset pitch between each section ("offset"), etc.

[0034] Such flow guides may also be interposed between the so-called central internal plates, distinct from the end internal plates, i.e. arranged between the first and last end internal plates of the exchanger block. Advantageously and according to the invention, each internal layer, called the central internal layer, arranged between said first internal layer and said last internal layer of said exchanger block, is provided with at least one flow guide adapted to form a plurality of channels substantially parallel to each other, each flow guide being arranged in said central internal layer so that said channels extend in a direction substantially parallel to the main direction of circulation of the heat transfer fluid in said central internal layer. Each flow guide may have a corrugated shape, the height of the corrugations being substantially equal to the distance between central internal plates.Thus, each flow guide has a plurality of external zones and internal zones in surface contact with the inner face of the internal plates. Each flow guide may have a plurality of undulations so as to form a plurality of circulation channels for the first heat transfer fluid and the second heat transfer fluid in the circulation enclosure. Each flow guide may have a regularly undulated profile in a periodic shape, for example of the sinusoidal or crenellated type.

[0035] Each flow guide may be secured to the central internal plates by a plurality of surface contacts. In particular, each flow guide may be secured to the central internal plates, for example by brazing or welding.

[0036] The use of such flow guides between the central internal plates of the exchanger block is optional but improves the efficiency of heat exchange. Fluted internal plates can also be used.

[0037] Advantageously and according to the invention, the internal layers, called central internal layers, arranged between said first internal layer and said last internal layer are devoid of a flow limiting device. The flow guides possibly provided within said internal layers and arranged in such a way that the circulation channels of said flow guides are oriented substantially parallel to the direction of circulation of the fluid in the internal layer, are not considered as flow limiting within the meaning of the present invention. In this way, the heat exchanges being reduced only within the internal end layers of the exchanger block, this makes it possible to limit the thermal gradient between the internal end layers and the central internal layers of such an exchanger block.

[0038] The circulation enclosure has a closed periphery that is impervious to heat transfer fluids (at least in operation and without taking into account the inlets and outlets for the first heat transfer fluid and for the second heat transfer fluid).

[0039] Advantageously and according to the invention, the first inlet has an inlet for the first heat transfer fluid into the circulation enclosure. Advantageously and according to the invention, the first outlet has an outlet for the first heat transfer fluid out of the circulation enclosure. In a particularly advantageous variant and according to the invention, each outlet has a single orifice forming an inlet or outlet, an opening towards the circulation enclosure and / or towards the plate exchanger block, and a solid peripheral wall between this orifice and this opening. Each orifice of each outlet can be connected to an inlet or outlet conduit for the first heat transfer fluid.

[0040] Advantageously and according to the invention, the path of the first flow of heat transfer fluid and the path of the second flow of heat transfer fluid inside the exchanger block can be substantially rectilinear. 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 heat transfer fluid follows a U-shaped or S-shaped path.

[0041] The heat exchange device according to the invention can be formed from at least one material chosen from metallic materials, composite materials, polymer materials, ceramic materials, in particular graphite, glass, etc. In particular, in a particularly advantageous embodiment of a heat exchange device according to the invention, the plates are formed from metallic material, in particular from at least one material chosen from the group formed from steels, copper, aluminum, metal alloys (superalloys in particular) and mixtures thereof.

[0042] The invention extends to an air conditioning system comprising at least one heat exchange device according to the invention. It may in particular be a non-contact cross-flow exchanger.

[0043] The invention extends to a vehicle, in particular an aircraft, comprising at least one air conditioning system according to the invention.

[0044] The invention also relates to a heat exchange device, 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

[0045] Other aims, characteristics and advantages of the invention will appear on reading the following description given solely for non-limiting purposes and which refers to the appended figures in which: [ Fig. 1 ] is a schematic view of an exchanger block of a heat exchange device according to a first embodiment of the invention, [ Fig. 2 ] is a schematic sectional view of an exchanger block of a heat exchange device according to the first embodiment of the invention, [ Fig. 3 ] is a schematic perspective view of a detail of an exchanger block of a heat exchange device according to the invention, [ Fig. 4 ] is a schematic sectional view of an exchanger block of a heat exchange device according to a second embodiment of the invention, [ Fig. 5 ] is a graph illustrating the temperature gradient within an exchanger block of a heat exchange device according to the second embodiment of the invention, [ Fig. 6 ] is a graph illustrating the temperature gradient within an exchanger block of a heat exchange device not in accordance with the invention. Detailed description of an embodiment of the invention

[0046] In the figures, scales and proportions are not strictly respected, for the purposes of illustration and clarity.

[0047] Furthermore, identical, similar or analogous elements are designated by the same references in all figures.

[0048] There Figure 1schematically illustrates an exchanger block 12 of a heat exchange device according to a first embodiment of the invention.

[0049] The plate exchanger block may, for example, comprise a stack of flat internal plates. The internal plates of the exchanger block comprise: at least two central internal plates 13, 15 arranged between a first external plate 2 and a second external plate 2, at least one first internal end plate 14 arranged between the central internal plates 13, 15 and the first external plate 2, and at least one second internal end plate 16, distinct from the first internal end plate 14 and arranged between the central internal plates 13, 15 and the second external plate 2.

[0050] A first and a second heat transfer fluid circulate in the spaces between the internal plates 13, 14, 15, 16 and closed laterally by closing bars 60, 62.

[0051] The internal plates 13, 14, 15, 16 are arranged parallel to each other. The first heat transfer fluid, called the “cold” fluid, circulates in circulation zones of the first heat transfer fluid according to a main direction of circulation of the first fluid between a first inlet 4 and a first outlet 6. The second heat transfer fluid circulates in circulation zones of the second heat transfer fluid, distinct from the circulation zones of the first heat transfer fluid, between a second inlet 8 and a second outlet 10.

[0052] The internal plates 13, 14, 15, 16 are arranged parallel to the external plates 2. A first internal layer allows the circulation of the first heat transfer fluid between the first internal end plate 14 and an internal plate 18 adjacent to said first internal end plate (the internal plate 18 being the second internal plate of the exchanger block 12), and a last internal layer allows the circulation of the first heat transfer fluid between the last internal plate 16 of the exchanger block and an internal plate adjacent to said last internal plate.

[0053] At least one flow limiting device is arranged in each end layer, i.e. in the first inner layer and in the last inner layer, the latter extending substantially orthogonally to the main direction of circulation of the first fluid, so as to at least partially hinder the circulation of the first fluid flow in the first inner layer and in the last inner layer. However, of course, each flow limiting device continues to allow the circulation of a non-zero fluid flow in the first inner layer and in the last inner layer.Only the end inner layers comprise a flow limiting device, the flow limiting devices being exclusively present in the end inner layers, i.e. the first inner layer for circulation of said first heat transfer fluid and the last inner layer for circulation of said first heat transfer fluid, so as to hinder the circulation of the first heat transfer fluid in each end inner layer more significantly than in the central inner layers.

[0054] In a heat exchange device, such an exchanger block is placed in a circulation enclosure delimited by at least two external side plates 2.

[0055] In a heat exchange device not in accordance with the invention, each end layer being in contact with a single other internal heat exchange plate, it only contributes to cooling one internal layer, unlike the central internal layers which cool two. The temperature within the cold end internal layers is therefore lower than that within the other central internal layers of the exchanger block.

[0056] Limiting the heat exchanges in the internal end layers relative to the central internal layers within an exchanger block 12 therefore makes it possible to limit this usual temperature gradient.

[0057] In the first embodiment of a heat exchange device according to the invention illustrated in figures 1 to 3, the flow limiting device consists of a flow guide 20, 25 forming a plurality of channels parallel to each other, but arranged transversely to the flow of the first heat transfer fluid. Each flow guide 20, 25 is therefore arranged in the first internal layer (see Figure 2 ) and in the last inner layer so that said channels extend in a direction substantially orthogonal to the main direction of circulation of the first fluid. It is also possible to arrange each flow limiting device consisting of a flow guide so that the channels are arranged forming an angle of less than 90° with the main direction of circulation of the first fluid in the end layer, for example an angle of between 35° and 90°.

[0058] Each flow guide 20, 25, 51 is formed from a plurality of successive sections each having a crenellated profile, so as to form guide walls and surface contact zones with the internal plates. In such a flow guide, commonly called an “offset” flow guide as illustrated in Figure 3two successive sections are offset laterally by a distance called half-pitch 52, so that the guide walls of a section located directly adjacent to another section are offset laterally (in a direction parallel to the external plates of the exchanger block) relative to the guide walls of the latter. It is therefore possible to choose, depending on the case, the height of the corrugations, the pitch 53 of each flow guide or even the pitch 54 of offset between each section ("offset"). For a flow guide with identical offset, the 90° arrangement with the main direction of circulation of the first fluid makes it possible to limit as much as possible the flow rate of the heat transfer fluid flow in the end layer, and therefore limits as much as possible the temperature gradients in the exchanger block 12. Thus, the closer said angle is to 90° with respect to the main direction of circulation of the first fluid, the more the flow rate of the heat transfer fluid flow is hindered.

[0059] The path that the first heat transfer fluid must then take in a circulation channel of the first internal layer and the last internal layer of the exchanger block 12 provided with such an offset flow guide then follows the form of a succession of S shapes arranged one after the other or of notches.

[0060] In the embodiment shown, the flow guide 20, 25 extends throughout the first internal layer and the last internal layer of the exchanger block 12. This has the particular advantage of making it possible to maintain the structural continuity of the exchanger block.

[0061] However, it is also possible to arrange the flow guide 20, 25 only in certain areas of the first internal layer and the last internal layer of the exchanger block 12.

[0062] In the first embodiment, the heat exchange device comprises only two end layers, i.e. the first inner layer and the last inner layer provided with a flow limiting device (only the first cold inner layer from each end). However, it is also possible to provide that the heat exchange device further comprises a flow limiting device in the third inner layer and / or in the antepenultimate inner layer (i.e. the second cold inner layer from each end of the exchanger block 12).

[0063] In a second embodiment of a heat exchange device according to the invention illustrated in Figure 4, the flow limiting device consists of a flow limiting bar 30 arranged so that its longitudinal direction is orthogonal to the main direction of circulation of said first fluid. Each flow limiting bar 30 has through openings 32 adapted to allow the passage of a flow of the first heat transfer fluid through said through openings. The flow limiting bar 30 may be arranged at the inlet and / or outlet of the inner end layer or in any intermediate position between the inlet and the outlet of the inner end layer. In the present second embodiment, the flow limiting bar 30 is arranged at the inlet of the first inner end layer ( Figure 4 ) and at the entrance of the last internal end layer, i.e. along an edge of each of the internal plates 14, 18, 16 defining the internal end layers.

[0064] In the examples shown, the path of the first and second heat transfer fluid flows inside the exchanger block is substantially rectilinear (without considering any possible sinuosities in the case of a flow guide used as a flow limiting device according to the invention in the end layers). 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 heat transfer fluid follows a U-shaped or S-shaped path.

[0065] In each embodiment, each inner layer, called the central inner layer, arranged between said first inner layer and said last inner layer of said exchanger block, may also comprise at least one flow guide 50 arranged so that said channels extend in a direction substantially parallel to the main direction of circulation of the heat transfer fluid in this central inner layer. Such a flow guide 50 may extend throughout the entire inner layer or only in certain portions. In the embodiments shown, flow guides 50 extend in each of the central inner layers and in the integrity of each central inner layer.

[0066] There Figure 5represents the variation of the temperature in an exchanger block such as that described according to the second embodiment, under conditions of use in an aircraft, the temperature in °C of each internal plate of the exchanger block 12 being represented along the ordinate axis and the number of internal plates of the exchanger block along the abscissa axis (here 42 internal plates, each point represented on the Figure 5 corresponding to an internal plate).

[0067] There Figure 6 also represents the variation in temperature in °C of each internal plate in an exchanger block of a heat exchange device distinct from a heat exchange device according to the invention, without a flow limiter device in the end layers. In comparison with the curve obtained by the same measurement methods represented in Figure 5, we can see that there is a significant temperature gradient at the ends of the exchanger block in the case of the curve represented in Figure 6 unlike the Figure 5 .

[0068] A heat exchange device according to the invention therefore effectively limits temperature gradients likely to damage the exchanger block.

[0069] The invention is not limited to the embodiments described. In particular, the flow guides or the openings provided through the closing bar may be of different shapes, etc.

Claims

1. Heat-exchange device comprising: - a flow enclosure defined by at least one first lateral plate, referred to as first external plate (2), and at least one second lateral plate, referred to as second external plate (2), - a first inlet (4) for a first heat-transfer fluid into the flow enclosure, - a first outlet (6) for said first heat-transfer fluid out of the flow enclosure, - a second inlet (8) for a second heat-transfer fluid into the flow enclosure, - a second outlet (10) for said second heat-transfer fluid out of the flow enclosure, - a plate exchanger block (12) disposed in the flow enclosure so as to be in fluid communication with the inlets (4, 8) and the outlets (6, 10) in order to allow the flow of the first heat-transfer fluid and of the second heat-transfer fluid in and through this exchanger block and the transfer of calories therebetween, said exchanger block being adapted to allow the flow of a first stream of heat-transfer fluid in said flow enclosure in a direction, referred to as main flow direction of the first fluid, between the first inlet (4) and the first outlet (6), - said exchanger block comprising a plurality of internal plates (13, 14, 15, 16) disposed substantially in parallel with each other between two ends of said exchanger block, each space between two adjacent internal plates defining a layer, referred to as internal layer, for flow of one of said first heat-transfer fluid and of said second heat-transfer fluid, said internal plates being disposed substantially in parallel with said external plates (2), characterized in that the first internal layer for flow of said first heat-transfer fluid and the last internal layer for flow of said first heat-transfer fluid, referred to as end internal layers, each comprise at least one device, referred to as flow-limiting device, configured to be able to impede, at least in part, the flow of said first stream of fluid in said end internal layer, while allowing the flow of a non-zero stream of fluid in said end internal layer, the internal layers, referred to as central internal layers, disposed between said first internal layer and said last internal layer having no flow limiting device, and each flow limiting device comprising at least one planar portion extending substantially orthogonally to said main flow direction of the first fluid.

2. Device as claimed in claim 1, characterized in that each end internal layer is configured to allow the passage of a non-zero stream of said first heat-transfer fluid, the temperature of said second heat-transfer fluid being higher than the temperature of said first heat-transfer fluid.

3. Device as claimed in any one of claims 1 or 2, characterized in that each flow limiting device comprises at least one flow guide (20, 25) adapted to be in the form of a plurality of channels which are substantially in parallel with each other, each flow guide being disposed in each end internal layer so that said channels extend in a direction substantially orthogonal to the main flow direction of the first fluid.

4. Device as claimed in claim 3, characterized in that each flow guide (20, 25) extends throughout said first internal layer and throughout said last internal layer for flow of said first heat-transfer fluid of the exchanger block (12).

5. Device as claimed in any one of claims 1 to 4, characterized in that each flow limiting device comprises at least one bar (30) extending mainly in a longitudinal direction, said bar being disposed so that the longitudinal direction of said bar is orthogonal to the main flow direction of the first heat-transfer fluid, said bar (30) having at least two through-openings (32) adapted to allow the passage of a stream of said first heat-transfer fluid through said through-openings.

6. Device as claimed in any one of claims 1 to 5, characterized in that each internal layer, referred to as central internal layer, disposed between said first internal layer and said last internal layer of said exchanger block, is provided with at least one flow guide (50) adapted to form a plurality of channels which are substantially in parallel with each other, each flow guide being disposed in said central internal layer so that said channels extend in a direction substantially in parallel with the main flow direction of the heat-transfer fluid in said central internal layer.

7. Air-conditioning system characterized in that it comprises at least one heat-exchange device as claimed in any one of claims 1 to 6.

8. Vehicle - in particular an aircraft - characterized in that it comprises at least one air-conditioning system as claimed in claim 7.

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