Plate heat exchanger comprising a mixing device

Abstract

Described is a heat exchanger which includes a bundle of plates forming flow channels for a coolant, a coolant inlet manifold supplying the flow channels, and an inlet manifold with openings in the plates of the bundle of plates. The openings partially delimit a cylindrical region transversely to the bundle of plates. The heat exchanger includes a mixing device for mixing the coolant. The mixing device extends in the inlet manifold and is integral with a plate of the bundle of plates.

Description

[0001] The present invention relates to the field of thermodynamics and relates more specifically to a heat exchanger intended in particular to be used for cooling members of a vehicle.

[0002] In an electric or hybrid vehicle, it is common for the electric battery, the electric motor, and the power electronics of the vehicle to be cooled by a heat transfer liquid such as water, circulating in a heat transfer liquid circuit which passes through these components to be cooled, the heat transfer liquid itself being cooled by virtue of a heat exchanger which receives the heat transfer liquid and a refrigerant. The refrigerant undergoes a thermodynamic cycle in a separate refrigerant circuit using, for example, a compressor, a condenser, an internal heat exchanger, and an expansion member.

[0003] During rapid charging of the electric battery of an electric or hybrid vehicle, since the electrical current is high, the thermal power to be dissipated in order to cool the electric battery is significant, for example of the order of 10 000 watts. Similarly, when the electric or hybrid vehicle is running at high speed, the thermal power to be dissipated in the electric motor, the power electronics, and the electric battery is significant and therefore requires a heat exchanger which is dimensioned accordingly, referred to as a “high-performance” heat exchanger.

[0004] Since the heat exchanger is formed of a pack of stacked and brazed plates defining channels for circulating the refrigerant or the heat transfer liquid, the number of plates of the heat exchanger of the electric or hybrid vehicle is all the greater when it has to dissipate a high thermal power.

[0005] Nevertheless, when the electric or hybrid vehicle is being used in a way that consumes less energy, for example during slow charging of the electric battery of the electric vehicle, or when the electric vehicle is running at low speed, the thermal power of the electric battery that is to be dissipated is lower, for example of the order of 4000 watts. However, the efficiency of a “high-performance” heat exchanger is not optimal at medium or low load, because the number of plates and the dimensioning of the channels of such a heat exchanger have been optimized for high-load use. At medium or low load, the distribution of the liquid and gas phases of the refrigerant in the heat exchanger is therefore uneven and is inefficient.

[0006] There is therefore a need for a high-performance heat exchanger, in particular for an electric or hybrid vehicle, with improved thermal power and efficiency, particularly at low and medium load, making it possible to cool components of the vehicle. The vehicle components to be cooled preferably include the electric battery, the electric motor, and the power electronics, but also the interior of the vehicle.

[0007] The present invention at least partially overcomes the drawbacks of the prior art by providing a plate pack heat exchanger, in which the distribution of a refrigerant in the plate pack is improved.

[0008] To this end, the present invention proposes a heat exchanger comprising a plate pack forming a plurality of channels for circulating a refrigerant, and a refrigerant inlet header serving the circulation channels, the inlet header comprising openings in the plates of the plate pack, the openings at least partially defining a cylindrical zone in the inlet header, the heat exchanger comprising at least one device for mixing the refrigerant extending in the inlet header and integrally formed with at least one of the plates of the plate pack.

[0009] By virtue of the invention, the refrigerant, which is in the form of a separated two-phase flow before it enters the heat exchanger, flows in the inlet header in the form of a dispersed two-phase flow due to the mixing device. The refrigerant is made up of a gas phase, a liquid phase, and a small percentage of oil. Before it enters the heat exchanger, it flows in pockets or plugs. The pockets or plugs of refrigerant are atomized by contact with the mixing device, which forms singularities in the inlet header, and by a pressure reduction phenomenon each time the refrigerant passes through an opening in a plate of the plate pack, which makes it possible to mix the liquid phase and the gas phase of the refrigerant effectively.

[0010] In addition, since the mixing device is integrally formed with at least one of the plates of the plate pack, the heat exchanger according to the invention uses resources economically and allows rapid manufacturing, as the assembly of the mixing device is concurrent with the assembly of the heat exchanger by brazing the plate pack.

[0011] According to one advantageous feature of the heat exchanger according to the invention, the mixing device comprises at least one diversion means conveying the refrigerant toward an upper portion of the inlet header.

[0012] This upper portion of the inlet header is situated in the opposite direction to a portion of the heat exchanger comprising bends of the circulation channels of the heat exchanger, when these circulation channels are U-shaped, or is situated in the opposite direction to the outlets of the circulation channels when they provide circulation in one or three passes. In other words, this upper portion of the inlet header, which in the prior art receives little refrigerant, receives more refrigerant by virtue of the mixing device. In particular, when the mixing device takes the form of a coil, the coil radially diverts a peripheral portion of the stream of refrigerant arriving in the inlet header over the whole angular extent of the inlet header. As a result, the refrigerant flows more easily in an outer peripheral portion of the circulation channels, proximal to lateral walls of the heat exchanger formed by the edges of the plate pack. The refrigerant stream is thus better distributed inside each circulation channel, which improves the heat transfer coefficient of the heat exchanger and reduces the pressure variations in each circulation channel.

[0013] Preferably, the mixing device forms part of the edge of an opening of the plate, the mixing device protruding into the cylindrical zone, and extending radially toward a central axis of the cylindrical zone. In this embodiment, the mixing device comes into contact with the refrigerant stream in the inlet header in order to create singularities that make it possible to obtain a dispersed two-phase flow. In addition in this embodiment, the mixing device is for example obtained by stamping and / or half-shearing the edge of the opening. The mixing device can thus be produced easily without additional waste in relation to the prior art.

[0014] Preferably in this embodiment, the mixing device comprises a foot extending on an angular portion of the opening and connected to the plate, the mixing device also comprising a head continuing the foot and extending at a distance from a portion of the edge of the opening situated angularly level with the head. The head is therefore jutting out with respect to the rest of the opening and situated facing an intake orifice of the inlet header. This jutting head makes it possible to divert a portion of the refrigerant stream radially toward the circulation channels, in particular toward the upper portion of the inlet header.

[0015] For example, the mixing device extends over the entire edge of the opening and forms a helical coil the axis of which is coincident with the central axis of the cylindrical zone, a first angular portion of the helical coil forming the foot and a second angular portion of the helical coil forming the head. This feature imparts a rotating effect to the stream diverted by the mixing device, which facilitates the atomizing of refrigerant leaving the inlet header toward the circulation channels.

[0016] According to one advantageous feature of the heat exchanger according to the invention, the mixing device comprises at least a first mixing device formed on an edge of an opening of a first plate adjacent to a second plate, and a second mixing device formed on an edge of an opening of the second plate, the first and second mixing devices protruding between the first plate and the second plate. This arrangement angularly increases the zone for atomizing refrigerant leaving the inlet header toward the circulation channels, by increasing the number of diversion means between two adjacent plates of the plate pack.

[0017] In one embodiment of the invention, the first and second mixing devices meet and together form a helix portion the axis of which is coincident with the central axis of the cylindrical zone. In particular, the coil of the first plate comprises an angular end surface positioned orthogonally to the main plane of extension of the end face, in the same position as an angular end surface of the coil of the second plate. These surfaces are thus positioned against each other and brazed together during the brazing of the heat exchanger, in order to form the helix portion. This arrangement of the mixing devices makes it possible to distribute the refrigerant evenly in the plate pack, limiting pressure drops.

[0018] Preferably in this embodiment, the plate pack comprises alternating plates identical to the first plate and plates identical to the second plate, the first and second mixing devices of these alternating plates forming a helix extending over the length of the refrigerant inlet header facing the circulation channels. The refrigerant is thus evenly distributed in the whole plate pack.

[0019] According to one advantageous feature of the heat exchanger according to the invention, the inlet header comprises a cylindrical passage transverse to the circulation channels, at least partially delimited by the mixing device. This cylindrical passage makes it possible to convey the refrigerant to the distribution channels furthest from the intake orifice of the inlet header.

[0020] Preferably, a diameter of the cylindrical passage is between 4 and 8 millimeters, the plate pack comprising between 30 and 70 plates. This smaller diameter than in the prior art accelerates the refrigerant and allows it to form a jet, improving the distribution of the refrigerant in the whole inlet header formed by a large number of plates. The invention thus provides an improvement in the distribution of refrigerant at low, medium or high load.

[0021] Other features and advantages of the invention will become more clearly apparent from the following description and from a number of exemplary embodiments provided by way of non-limiting indication with reference to the appended schematic drawings, in which:

[0022] FIG. 1 is a perspective view of a cross-section of a heat exchanger according to the invention, showing an inlet header of said heat exchanger, in a first embodiment of the invention,

[0023] FIG. 2 is an enlargement of a portion of the inlet header in FIG. 1, in which mixing portions extend,

[0024] FIG. 3 is a perspective view of two different plates of a plate pack of the heat exchanger in FIG. 1,

[0025] FIG. 4 is an enlargement of a portion of one of the plates in FIG. 3, comprising a mixing device,

[0026] FIG. 5 is an enlargement of a portion of the other of the plates in FIG. 3, comprising a mixing device,

[0027] FIG. 6 is a perspective view of a cross-section of a heat exchanger according to the invention, showing an inlet header of said heat exchanger, in a second embodiment of the invention,

[0028] FIG. 7 schematically shows the distribution of refrigerant on a plate of a plate pack without a mixing device, and

[0029] FIG. 8 schematically shows the distribution of refrigerant on a plate of the heat exchanger in FIG. 6, comprising mixing devices.

[0030] According to a first embodiment of the invention shown in FIG. 1, a heat exchanger 100 according to the invention comprises a plate pack 50 forming alternating circulation channels 51 in which a refrigerant FR circulates, and circulation channels 53 in which a heat transfer liquid such as glycol water circulates. In a known manner, the refrigerant FR is for example a hydrofluoroolefin (HFO) mixed with a small percentage of oil, less than 5% (percent), or even less than 3%.

[0031] The plate pack 50 is bounded at one end thereof comprising a refrigerant intake orifice 46 of the heat exchanger 100 by an end face 42, and at the other end thereof by a closing plate 44 of the plate pack 50.

[0032] The intake orifice 46 emerges into an inlet header 48 of the heat exchanger 100, extending around openings 541, 561 (marked in FIG. 2) formed in each of the plates of the plate pack 50, these openings defining a cylindrical zone 480 of central axis X passing through the plate pack 50. The inlet header 48 serves the refrigerant circulation channels 51.

[0033] As shown in FIG. 2, the plate pack 50 comprises two different types of plate, corresponding to the plates denoted54, which are all identical to each other, and to the plates denoted 56, which are all identical to each other. The plate pack 50 is formed by alternating plates 54 and 56 brazed to each other and in contact with each other in pairs on planar portions of the inlet header 48, that is, around the openings 541, 561 of the plates. Each pair of plates 54, 56 brazed to each other thus forms a partition between two circulation channels 51 at the inlet header 48 of the heat exchanger 100. The pairs of plates 54, 56 forming this partition separate beyond the inlet header 48 in order to form the heat transfer liquid circulation channels 53, sealed with respect to the refrigerant circulation channels 51.

[0034] Each plate 54 comprises a device 546 for mixing the refrigerant FR coming through the opening 541 of the plate 54. This mixing device 546 is integrally formed with the plate 54 and is more specifically obtained by stamping and half-shearing the opening 541. It forms an edge of this opening 541 and protrudes into a space allowing the refrigerant to enter the refrigerant circulation channel 51, this space being contained between the plate and a plate 56 situated facing the plate 54 but at a distance therefrom in the inlet header 48.

[0035] This plate 56 also comprises a device 566 for mixing the refrigerant FR obtained by stamping and half-shearing an edge of the opening 561 of the plate 56, and protruding into a space allowing the refrigerant to enter the refrigerant circulation channel 51, this space being delimited by the plate 54 and this plate 56.

[0036] Each mixing device 546, 566 of a plate 54 or 56 takes the form of a helical coil the axis of which is the central axis X of the cylindrical zone 480. A first angular portion 5662 (marked in FIG. 4) of the helical coil 566 forms an edge of the opening 561 of the plate 56, extending in the inlet header 48 in the direction of the central axis X while remaining attached to the plate 56, that is, without offering radial access to the refrigerant between this first angular portion 5662 and the rest of the plate 56. A second angular portion 5664 (marked in FIG. 4) of the helical coil 566, continuing the first angular portion 5662, forms an edge of the opening 561 of the plate 56, extending in the inlet header 48 in the direction of the central axis X while being detached from the plate 56, that is, the refrigerant FR can pass radially between the second angular portion 5664 and the rest of the plate 56.

[0037] Similarly, a first angular portion 5462 (marked in FIG. 5) of the helical coil 546 forms an edge of the opening 541 of the plate 54, extending in the inlet header 48 in the direction of the central axis X while remaining attached to the plate 54, that is, without offering radial access to the refrigerant between this first angular portion 5462 and the rest of the plate 54. A second angular portion 5464 (marked in FIG. 5) of the helical coil 546, continuing the first angular portion 5462, forms an edge of the opening 541 of the plate 54, extending in the inlet header 48 in the direction of the central axis X while being detached from the plate 54, that is, the refrigerant FR can pass radially between the second angular portion 5464 and the rest of the plate 54.

[0038] At the angular end thereof detached from the plate 54, each helical coil 546 of a plate 54 meets an angular end of a helical coil 566 of a plate 56 detached from the plate 56. These two coils 546 and 566 that meet are brazed to each other at these angular ends, more specifically on respective angular end surfaces 5465, 5665 (marked in FIGS. 4 and 5) positioned orthogonally to the main plane of extension of the end face 42, and form a helix portion.

[0039] The helical coil 546 of the plate 54 thus imparts a rotating movement to a portion of the refrigerant FR arriving up against this helical coil 546. The second angular portion 5464 of this helical coil 546 makes it possible to radially and angularly divert a portion of the refrigerant FR, in particular toward an upper portion 482 (marked in FIG. 1) of the inlet header 48, situated in the opposite direction to bent ends of the refrigerant circulation channels 51 as described hereinafter with reference to FIG. 3. The helical coil 566 also receives a portion of refrigerant FR arriving up against this helical coil 566 or driven by the aforementioned rotating movement, and also makes it possible to radially and angularly divert a portion of the refrigerant FR about the central axis X.

[0040] Since each plate 54, 56 is provided with a helical coil 546, 566, these coils 546, 566 of the assembly of plates of the plate pack 50 form a helix that extends in the inlet header 48 along the central axis X.

[0041] FIG. 3 shows a plate 54 and a plate 56 as a whole and makes it easier to understand the structure of the stack of plates forming the plate pack 50. In FIG. 3, the plate 54 has a face 540 intended to be brazed to a face 560 (marked in FIG. 2) of the plate 56, on the opposite side from a face 562 of the plate 56 shown in FIG. 3. In other words, the plate 56 is stacked and brazed on top of and in contact with the plate 54. Thus positioned, the pair of plates 54, 56 forms a partition between two refrigerant circulation channels 51.

[0042] The plate 56 comprises, on a main portion 57, flow disruptors 569 protruding from a planar surface of the face 560. These flow disruptors 569 extend orthogonally with respect to this planar surface, to the same level as a planar portion 59 of the plate 56 around the opening 561 of the inlet header 48. In other words, the main portion 57 is raised on the face 562 with respect to the planar portion 59 around the opening 561 comprising the helical coil 566. A ridge 5622 delimits the raised main portion 57 from the planar portion 59. The helical coil 566 extends orthogonally from this planar portion 59 to the same level as a planar surface of the main portion 57 situated on the same side as the face 562. When the plate 56 is pressed against the plate 54, the planar portion 59 around the opening 561 is in contact with a corresponding planar portion 58 of the plate 54 around the opening 541 of the inlet header 48. The helical coils 561 and 541 of the respective plates 56 and 54 protrude on either side of these planar portions 58, 59 in contact with each other. The refrigerant FR cannot therefore flow between the plates 54 and 56.

[0043] Similarly, a perimeter of an opening 543 of the plate 54 forming part of an outlet header of the heat exchanger 100 is sealingly brazed to a perimeter of an opening 563 of the plate 56 forming part of this outlet header. The refrigerant FR cannot therefore pass from the outlet header toward a heat transfer fluid circulation channel 53, situated between the plate 54 and the plate 56. This contact between the perimeters of the openings 543 and 563 is permitted because the refrigerant outlet opening 563 is situated on a portion of the plate 56 at the same level as the planar portion 59 comprising the opening 561 with respect to the main portion 57 of the plate 56, while the opening 543 is situated in the continuation of the main portion 61 of the plate 54 without diverging orthogonally from it.

[0044] The plate 54 also comprises, on a main portion 61, flow disruptors 549 protruding from a planar surface of a face 542 (marked in FIG. 2) of the plate 54, on the opposite side from the face 540 of the plate 54. These flow disruptors 549 extend orthogonally with respect to this planar surface, at the same distance as the helical coil 546 of the plate 54 also protruding on the same side as the face 542. Other types of disrupting element can of course be provided instead of or in addition to these flow disruptors 549.

[0045] Unlike the plate 56, the planar portion 58 of the plate 54 around the opening 541 of the inlet header 48 is in the same plane as the main portion 61 taken without its protruding elements (in particular the flow disruptors 549). This main portion 61 is however raised on the face 540 with respect to a planar portion of the plate 54 comprising an opening 545 of a heat transfer liquid inlet header of the heat exchanger 100, and with respect to a planar portion of the plate 54 comprising an opening 547 of a heat transfer liquid outlet header of the heat exchanger 100. The plate 56 comprises, facing the opening 545, an opening 565 of the heat transfer liquid inlet header, and facing the opening 547, an opening 567 of the heat transfer liquid outlet header. These openings 565 and 567 on the plate 56 are situated in the continuation of the main portion 57 of the plate 56 without diverging orthogonally from it. In other words, the heat transfer liquid inlet openings 565 and 545 are situated at a distance from each other and the heat transfer liquid outlet openings 567 and 547 are situated at a distance from each other. When the plate 56 is brazed onto the plate 54, the heat transfer liquid arriving in the heat transfer liquid inlet header can thus circulate in the circulation channel 53 between the plates 54 and 56, and between the flow disruptors 569 of the plate 56, which impose a distance between the planar surface of the main portion 57 of the plate 56 situated on the same side as the face 560 and the planar surface of the main portion 61 of the plate 54 situated on the same side as the face 540. A groove 568 arranged on the face 562 of the plate 56 separates the heat transfer liquid inlet opening 565 and the heat transfer liquid outlet opening 567, extending from the middle of one edge of the plate 56 toward the opposite edge but not reaching it. The heat transfer liquid arriving through the heat transfer liquid inlet opening 545 of the plate 54 is thus forced to go around the groove 568 before leaving through the heat transfer liquid outlet opening 547 of the plate 54, which makes it travel along the entire length of the plate 54, the circulation channel 53 being U-shaped, the bend of the U being positioned at an opposite longitudinal end of the plate 56 from the heat transfer liquid openings 565, 567 of the plate 56. The refrigerant inlet header 48 and the refrigerant outlet header are situated on the other longitudinal end of the plate 56.

[0046] Conversely, when a plate 54 is positioned on a plate 56, that is, when the face 542 of the plate 54 is brazed onto the face 562 of the plate 56, the planar portion 58 of the plate 54 around the opening 541 of the inlet header 48 is at a distance from the planar portion 59 of the plate 56 around the opening 561 of the inlet header 48, and the coils 546 and 561 of the two plates 54, 56 meet at their angular end surfaces 5465 and 5665. The refrigerant FR arriving through the opening 541 can therefore circulate between these plates 54 and 56 in a circulation channel 51 formed between these plates 54 and 56. In this case, the refrigerant FR circulates between the flow disruptors 549 of the plate 54, which impose a distance between the planar surface of the main portion 61 of the plate 54 situated on the same side as the face 542 and the planar surface of the main portion 57 of the plate 56 situated on the same side as the face 562.

[0047] A groove 548 arranged on the face 540 of the plate 54 separates the opening 541 of the refrigerant inlet header 48 from the opening 543 of the refrigerant outlet header, extending from the middle of one edge of the plate 54 toward the opposite edge but not reaching it. The refrigerant arriving through the refrigerant inlet opening 541 is thus forced to go around the groove 548 before leaving through the refrigerant outlet opening 543 of the plate 54, which makes it travel along the entire length of the plate 54, the circulation channel 51 being U-shaped, the bend of the U being positioned at an opposite longitudinal end of the plate 54 from the refrigerant openings 541 and 543, this longitudinal end being proximal to the edge of the plate 54 from which the groove 548 extends. The heat transfer liquid openings 545 and 547 of the plate 54 are situated at an opposite longitudinal end of the plate 54.

[0048] The dimension of the flow disruptors 549 in a direction orthogonal to the end face 42 is identical to the level change in this orthogonal direction, between the portions of the plate 54 comprising the heat transfer liquid openings 545, 547 and the planar surface of the main portion 61 of the plate 54 situated on the same side as the face 542. As a result, the perimeters of the heat transfer liquid openings 545, 547 of the plate 54 are fully in contact with corresponding perimeters of the respective heat transfer liquid openings 565, 567 of the plate 56 that are situated in the continuation of the main portion 57 of the plate 56 without diverging orthogonally from it. As a result, the heat transfer liquid entering through the opening 545 of the plate 54 cannot pass into the refrigerant circulation channel 51, and the heat transfer liquid leaving through opening 547 of the plate 54 likewise cannot pass into the circulation channel 51.

[0049] It will be noted that the dimensions of the coils orthogonally to the planar portions 58 and 59 can be slightly different from those stated here, given that the mixing devices 546, 566 work even if they do not meet exactly on their respective angular end surfaces 5465 and 5665.

[0050] Returning to FIG. 1, the refrigerant FR arriving from a refrigerant connection block 40 brazed to the end face 42 of the heat exchanger 100, into the intake orifice 46, is made up of a small percentage of oil, and a refrigerant compound that is 30% gas phase and 70% liquid phase. The refrigerant FR entering the intake orifice 46 reaches the inlet header 48 through an opening made in a first plate 52 brazed to a first plate 54 of the plate pack 50, proximal to the end face 42 of the heat exchanger 100. This plate 52 makes it possible to form a first circulation channel 53 between this plate 52 and the first plate 54, without a helical coil protruding from the plate 52 toward the end face 42. In other words, the plate 52 is structurally identical to a plate 56 with the exception that it does not comprise a mixing device.

[0051] One portion of the refrigerant FR arriving in the inlet header 48 passes through this opening in the plate 52 and the openings 541 and 561 made in the plates 54, 56 of the plate pack 50, to the closing plate 44. This portion of the refrigerant FR passing directly through the inlet header 48 circulates in a cylindrical passage 60 (marked in FIG. 2) delimited by inner contours 544, 564 (marked in FIGS. 4 and 5) of the respective helical coils 546 and 566 of each respective plate 54, 56.

[0052] The diameter of the cylindrical passage 60 is approximately 5 millimeters, the plate pack 50 comprising 60 plates in this first embodiment of the invention. As a variant, the diameter of the cylindrical passage has a different value, of between 4 and 8 millimeters, and the plate pack comprises between 30 and 70 plates. This diameter is smaller than the average diameter of an opening of an inlet header of the prior art, in order to allow the refrigerant to easily reach the opposite end of inlet header 48 from the end face 42 of the heat exchanger 100.

[0053] Other portions of refrigerant FR diverge from the direction parallel to the central axis X and arrive in each of the refrigerant circulation channels 51. This diversion of portions of the stream of refrigerant FR is facilitated by the respective helical coils 546 and 566 at the inlet of each circulation channel 51.

[0054] According to a second embodiment of the invention illustrated in FIGS. 6 and 8, a heat exchanger 10 according to the invention comprises a plate pack 20 bounded by an end face 14 and a closing plate 16. A connection block 12 is rigidly connected to the end face 14 and allows a refrigerant FR to enter an intake orifice 18 arranged in the end face 14. This intake orifice 18 emerges into an inlet header 11 of the heat exchanger 10. The plate pack 20 comprises two types of alternating plate, namely plates 24 and plates 26, which form alternating channels 23 for circulating heat transfer liquid and channels 21 for circulating refrigerant. This arrangement of the heat exchanger 10 is structurally identical to the arrangement of the heat exchanger 100, and only the mixing devices 31 formed in the openings 30 of the plates 24, 26 have different structures from the mixing devices 546, 466 of the first embodiment of the invention.

[0055] In particular, the inlet header 11 comprises a cylindrical zone 110 at least partially delimited by the openings 30, and an upper portion 112 in the opposite direction to the bends of the circulation channels 21, 23, these bends themselves being positioned at a longitudinal end of the plates 24, 26. In addition, an inlet plate 22 that does not comprise a mixing device 31 is positioned against the end face 14, similarly to the plate 52 of the first embodiment of the invention.

[0056] The mixing device 31 of a plate 24 protrudes into a space contained between this plate 24 and a plate 26, this space allowing the refrigerant FR to enter a refrigerant circulation channel 21. The mixing device 31 of the plate 26 protrudes into the same space. The mixing devices 31 of the plates 24 and 26 therefore face each other in each circulation channel 21.

[0057] Each mixing device 31 comprises a foot 33 rigidly connected to the rest of the plate 24, 26 to which it belongs, by one end thereof, the other end thereof being connected to a head 35 of the mixing device jutting out with respect to the rest of the plate 24, 26. The heads 35 of the mixing devices 31 make it possible to divert the refrigerant FR arriving through the intake orifice 18 toward the circulation channels 21 or toward the upper portion 112 of the header 11 as shown by the arrows orthogonal to the direction given by the axis X, which is the central axis of the cylindrical zone 110.

[0058] The heads 35 leave a cylindrical passage 15 in the cylindrical zone 110 that allows the refrigerant FR to pass unobstructed through the inlet header 11 to the closing plate 16. This cylindrical passage 15 is for example 5 mm in diameter, the plates 24, 26 being approximately 60 in number.

[0059] Compared to a plate 2 without a mixing device as shown in FIG. 7, the distribution of refrigerant FR on a plate 24 (or 26) is improved, as shown in FIG. 8. In FIG. 7, the refrigerant FR enters a refrigerant circulation channel delimited by the plate 2, through an opening 4 in the plate 2, goes around a groove 6 separating this opening 4 from a refrigerant outlet opening 8, and then leaves the plate 2 through this outlet opening 8. The arrows formed by dashed and dotted lines show the stream of refrigerant FR on this plate 2, the arrows being thicker the greater the flow rate of the stream. It will be noted that at the periphery of the plate 2 and in the vicinity of the groove 6, the refrigerant stream has a very low flow rate. The refrigerant is not therefore evenly distributed in the circulation channel defined by the plate 2.

[0060] On the plate 24 shown in FIG. 8, the refrigerant FR enters a refrigerant circulation channel 21 delimited by the plate 24, through the opening 30 of the plate 24, goes around a groove 34 separating this opening 30 from a refrigerant outlet opening 32, and then leaves the plate 24 through this outlet opening 32. The arrows formed by dashed and dotted lines also show the stream of refrigerant FR on this plate 24, the arrows being thicker the greater the flow rate of the stream.

[0061] It will be noted that the heads 35 make it possible to divert one portion of the stream of refrigerant FR toward the upper portion 112 of the inlet header 11, angularly distributing this diversion evenly around the opening 30 of the plate 24. As a result, the stream of refrigerant FR at the periphery of the plate 24 has a higher flow rate compared to that of the plate 2, and the stream of refrigerant FR in the vicinity of the groove 34 has a higher flow rate compared to that of the plate 2. The refrigerant FR is therefore more evenly distributed in the circulation channel 21 delimited by the plate 24 than the refrigerant FR in the circulation channel delimited by the plate 2. The heat transfer of the heat exchanger 10 is therefore better than that of a heat exchanger of the prior art.

[0062] Of course, the invention is not limited to the examples that have just been described, and numerous modifications can be made to these examples without departing from the scope of the invention. In particular, the features of the different embodiments or variants can be combined to carry out the invention, provided that these embodiments or variants are not mutually incompatible.

Claims

1. A heat exchanger, comprising:a plate pack forming a plurality of circulation channels for circulating a refrigerant;a refrigerant inlet header serving the plurality of circulation channels, the refrigerant inlet header comprising openings in plates of the plate pack, the openings at least partially defining a cylindrical zone in the refrigerant inlet header; andat least one mixing device for mixing the refrigerant extending in the refrigerant inlet header and integrally formed with at least one plate of the plate pack.

2. The heat exchanger as claimed in claim 1, wherein the at least one mixing device comprises at least one diversion means conveying the refrigerant toward an upper portion of the inlet header.

3. The heat exchanger as claimed in claim 1, wherein the at least one mixing device forms part of an edge of an opening of the at least one plate, the at least one mixing device protruding into the cylindrical zone, and extending radially toward a central axis of the cylindrical zone.

4. The heat exchanger as claimed in claim 3, wherein the at least one mixing device is obtained by stamping and / or half shearing the edge of the opening.

5. The heat exchanger as claimed in claim 3, wherein the at least one mixing device comprises a foot extending on an angular portion of the opening and connected to the plate, the at least one mixing device also comprising a head continuing the foot and extending at a distance from a portion of the edge of the opening situated angularly level with the head.

6. The heat exchanger as claimed in claim 5, wherein the at least one mixing device extends over the entire edge of the opening and forms a helical coil, the axis of which is coincident with the central axis of the cylindrical zone, a first angular portion of the helical coil forming the foot and a second angular portion of the helical coil forming the head.

7. The heat exchanger as claimed in claim 3, wherein the at least one mixing device comprises at least a first mixing device formed on an edge of an opening of a first plate adjacent to a second plate, and a second mixing device formed on an edge of an opening of the second plate, the first and second mixing devices protruding between the first plate and the second plate.

8. The heat exchanger as claimed in claim 7, wherein the first and second mixing devices meet and together form a helix portion, the axis of which is coincident with the central axis of the cylindrical zone.

9. The heat exchanger as claimed in claim 8, wherein the plate pack comprises alternating plates identical to the first plate and plates identical to the second plate, the first and second mixing devices of these alternating plates forming a helix extending over a length of the refrigerant inlet header facing the plurality of circulation channels.

10. The heat exchanger as claimed in claim 1, wherein the refrigerant inlet header comprises a cylindrical passage transverse to the plurality of circulation channels, at least partially delimited by the at least one mixing device.

11. The heat exchanger as claimed in claim 10, wherein a diameter of the cylindrical passage is between 4 and 8 millimeters, the plate pack comprising between 30 and 70 plates.

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