METHOD FOR MANUFACTURING A PLATE HEAT EXCHANGER BY SUPERPOSING PLATES WITH ALIGNMENT MARKS

Abstract

The main subject matter of the invention is a method for manufacturing at least one heat exchanger (50) with plates (10) with at least two fluid circuits, characterised in that it comprises the following steps: a) formation of a plurality of plates (10) each comprising a reference pattern; b) formation of one or more alignment patterns (11) on each plate (10) by circular repetition of the reference pattern around an axis of revolution (X); c) formation of a plurality of grooves (12) on each plate (10). The method further comprises the following successive steps: d) assembling the plates (10) by superimposition with respect to each other, each reference pattern of a plate being superimposed on an alignment pattern (11) of an adjacent plate; e) carrying out an assembly treatment on the assembly obtained at the end of the preceding step d) by diffusion welding, by brazing and/or by diffusion brazing.

Claims

1. Method for manufacturing at least one heat exchanger with plates with at least two fluid circuits, comprising the following steps: a) formation of a plurality of constituent plates of the heat exchanger, each plate comprising a hollowed out pattern called “reference pattern”, b) formation of one or more hollowed out patterns, including the reference pattern, called “alignment patterns” on each plate by circular repetition of the reference pattern around an axis of revolution of the plate, the axes of revolution of the plates being coincident, c) formation of a plurality of grooves, intended to form the fluid circulation channels of the plate exchanger, on each plate, the grooves including at least one first plurality of grooves for the first fluid circuit and a second plurality of grooves for the second fluid circuit, and wherein it further comprises the following successive steps: d) assembling the plates by superimposition with respect to each other, each reference pattern of a first plate being superimposed on an alignment pattern of a second plate adjacent to the first plate, e) carrying out an assembly treatment on the assembly obtained at the end of the preceding step d) by diffusion welding, by brazing and/or by diffusion brazing.

2. Method according to claim 1, wherein step d) of assembling the plates comprises the following successive sub-steps: i) arranging a first plate on a support, ii) superimposing a second plate on the first plate by making the reference pattern of the second plate coincide with an alignment pattern of the first plate, iii) placing an alignment tool at the level of the coincident patterns formed by the reference pattern of the second plate and the alignment pattern of the first plate, the alignment tool making it possible to maintain the coincidence of said patterns, iv) optionally, placing another alignment tool at the level of two other coincident patterns formed by an alignment pattern of the first plate and an alignment pattern of the second plate, superimposed on each other and different from the patterns used at step ii), v) superimposing N plates, N being a whole number greater than or equal to 1, on the second plate, each N.sup.th plate being superimposed by coincidence of its reference pattern on an alignment pattern of the plate with which it is superimposed according to the principle of step ii), and by use of at least one alignment tool according to the principle of step iii).

3. Method according to claim 2, wherein the alignment tool(s) have a transversal dimension, substantially equal to the transversal dimension, of the alignment patterns of the plates.

4. Method according to claim 1, wherein step e) of carrying out an assembly treatment comprises diffusion welding and/or diffusion brazing.

5. Method according to claim 1, wherein step e) of carrying out an assembly treatment comprises brazing.

6. Method according to claim 1, wherein the angle of the circular repetition, called “angle of rotation”, of the reference pattern of each plate around the considered axis of revolution of the plate is identical for all the plates.

7. Method according to claim 1, wherein the angle of the circular repetition, called “angle of rotation”, of the reference pattern of each plate around the considered axis of revolution of the plate is different for at least two of the plates, notably the totality of the plates.

8. Method according to claim 7, wherein the value of each angle of rotation of the reference pattern to form one or more alignment patterns is a whole multiple of the value of the smallest angle of rotation among all of the angles of rotation forming the alignment patterns.

9. Method according to claim 1, wherein it is implemented for the manufacture of a plurality of elementary modules of plate heat exchanger, each elementary module of plate heat exchanger being obtained by means of steps a) to e), and wherein it comprises the following step: f) manufacturing a plate heat exchanger by combining together the elementary modules of plate heat exchanger.

10. Method according to claim 1, wherein the plates all have an identical shape.

11. Method according to claim 1, wherein the plates have different shapes.

12. Method according to claim 1, wherein the plates are made of metal.

13. Method according to claim 1, wherein each plate comprises a locating element to make it possible to know the position of said at least one reference pattern of the plate.

14. Method according to claim 13, wherein the locating element is in the form of a notch produced on the periphery of the plate.

15. Plate heat exchanger with at least two fluid circuits, obtained by means of the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0075] The invention will be able to be better understood on reading the detailed description that follows of non-limiting exemplary embodiments thereof, and by examining the figures, schematic and partial, of the appended drawings, in which:

[0076] FIG. 1 represents an isometric view of an example of circular metal plate of a plate heat exchanger with two fluid circuits conforming to a first embodiment of the invention,

[0077] FIG. 1A is a detail view along A of the plate of FIG. 1,

[0078] FIGS. 18 and 1C are detail views along B′ of the plate of FIG. 1 seen from above, differently referenced,

[0079] FIG. 2 represents, schematically in perspective, an example of alignment tool of the plate heat exchanger conforming to the first embodiment of the invention, constituted of a plurality of plates according to FIG. 1,

[0080] FIG. 3 represents a negative view of the alignment patterns of the plate of FIG. 1, as well as a row of grooves of the first fluid and a row of grooves of the second fluid,

[0081] FIGS. 4A and 4B represent, partially in perspective, a case of heat exchanger conforming to the first embodiment of the invention in which the reference pattern of an upper plate is aligned with that of the lower plate, the axis of rotation of the upper plate also being aligned with the axis of rotation of the lower plate, FIG. 4B making it possible to visualise in partial transparency the lower plate,

[0082] FIG. 5 represents a negative view, similar to that of FIG. 3, illustrating the configuration of FIGS. 4A and 4B,

[0083] FIG. 5A is a view of the assembly of FIG. 5 along the plane C′,

[0084] FIGS. 6A and 6B represent, partially in perspective, a case of heat exchanger conforming to the first embodiment of the invention in which the reference pattern of an upper plate is shifted right (clockwise rotation of one step) of the reference pattern of the lower plate, the axis of rotation of the upper plate being aligned with the axis of rotation of the lower plate, FIG. 5B making it possible to visualise in partial transparency the lower plate,

[0085] FIG. 7 represents a negative view, similar to that of FIG. 3, illustrating the configuration of FIGS. 5A and 5B,

[0086] FIG. 7A is a view of the assembly of FIG. 7 along the plane D,

[0087] FIG. 8 represents a negative view, similar to that of FIG. 3, in the case of a heat exchanger conforming to the first embodiment of the invention in which a shift of the reference patterns is carried out during the stacking of the plates by carrying out three clockwise rotations of one step, then three anticlockwise rotations of one step, on all 21 plates, all the axes of rotation of all the plates being co-linear,

[0088] FIG. 8A is a view of the assembly of FIG. 8 along the plane E,

[0089] FIG. 9 represents an isometric view of an example of first hexagonal metal plate of a plate heat exchanger with two fluid circuits conforming to a second embodiment of the invention,

[0090] FIG. 9A is a partial top view of FIG. 9,

[0091] FIG. 9B is a closer view from the centre of FIG. 9,

[0092] FIG. 10 represents an isometric view of a second intermediate plate of the plate heat exchanger conforming to the second embodiment of the invention, making it possible to make the connection between two plates of the type of that presented in FIG. 9,

[0093] FIG. 10A is a partial top view of FIG. 10,

[0094] FIG. 11 represents an isometric view of a third plate of the plate heat exchanger conforming to the second embodiment of the invention, making it possible to form a first closing plate,

[0095] FIG. 12 represents an isometric view of a fourth plate of the plate heat exchanger conforming to the second embodiment of the invention, making it possible to form a second closing plate,

[0096] FIG. 13 represents, schematically in perspective, an example of alignment tool of the plate heat exchanger conforming to the second embodiment of the invention, constituted of the plates of FIGS. 9, 10, 11 and 12,

[0097] FIG. 14 represents an exploded view of a heat exchanger conforming to the second embodiment of the invention, or an elementary module of a heat exchanger conforming to the second embodiment of the invention, constituted of the plates of FIGS. 9, 10, 11 and 12,

[0098] FIG. 14A represents the stack of FIG. 14 according to an assembled view, showing the orientation of the plates with respect to each other,

[0099] FIG. 15 represents the heat exchanger conforming to the second embodiment of the invention, or the elementary module of a heat exchanger conforming to the second embodiment of the invention, of FIG. 14, after the final steps of manufacture and machining,

[0100] FIG. 16 represents a negative view of the alignment patterns and grooves of FIG. 9,

[0101] FIG. 17 represents the superimposition of two plates of FIG. 9, one being reversed with respect to the other, seen in negative, and

[0102] FIG. 17A represents a negative view of the stack of FIG. 17 with the plate of FIG. 10.

[0103] In all of these figures, identical references may designate identical or analogous elements.

[0104] In addition, the different parts represented in the figures are not necessarily according to a uniform scale, to make the figures more legible.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

Example 1

[0105] With reference to FIGS. 1 to 8A, a first embodiment of a plate heat exchanger 50 including two fluid circuits C1 and C2, respectively constituted of 130 channels and 150 channels, will be described hereafter.

[0106] In this first embodiment of the invention, the method for manufacturing the heat exchanger 50 implements an assembly of a plurality of plates 10, such as that represented in FIG. 1, by diffusion welding obtained by the technique of hot isostatic pressing (HIP).

[0107] In this example, the heat exchanger 50 comprises a plurality of plates 10 all identical and similar to that represented in FIG. 1.

[0108] Thus, the plate 10, represented in FIG. 1, has a disc shape of diameter d1 and of thickness e1. It comprises, on its periphery, a plurality of alignment patterns 11, to be specific 130 alignment patterns 11 including the reference pattern 11a, as well as a plurality of grooves 12 between these alignment patterns 11 and the axis of central revolution X.

[0109] FIG. 1A is a detail view along A of the plate 10 of FIG. 1, making it possible to visualise better the alignment patterns 11 of the plate 10.

[0110] Thus, each alignment pattern 11 has a disc shape going through the plate 10 and having a diameter d2.

[0111] In order to be able to locate the reference pattern 11a with respect to the other alignment patterns 11 of the plate 10, a notch 13, forming a locating element 13, has been produced on the periphery of the plate 10 at the level of the reference pattern 11a.

[0112] Furthermore, FIGS. 1B and 1C are detail views along B′ of the plate 10 of FIG. 1 seen from above.

[0113] FIG. 1B thus shows the grooves 121 of the fluid C1 and the grooves 122 of the fluid C2. With respect to the centre O of the plate 10, situated on the axis of central revolution X, the first ring of grooves 121 of the fluid C1 begins at a distance r′1 from the centre O and ends at a distance r′2 from the centre O, such that the thickness of this first ring is equal to r′2−r′1. The first ring of grooves 122 of the fluid C2 begins for its part at a distance r′3 from the centre O and ends at a distance r′4 from the centre O, such that the thickness of this first ring is equal to r′4−r′3. Thus, the separation between the first ring of grooves 121 of the fluid C1 and the first ring of grooves 122 of the fluid C2 is equal to r′1-r′4. Then, the following grooves 121 and 122 of the fluids C1 and C2 are arranged in successive concentric rings.

[0114] It is thus to be noted that, in this first exemplary embodiment of the invention, the grooves 12, including the grooves 121 and 122, are pieces of ring having two opposite edges in arc of circle of which the centre is the centre O of the plate 10, the two other opposite edges being straight and aligned following a radius of the plate 10. The alignment patterns 11 are for their part situated on a circle of centre O and of radius R3, as represented in FIG. 1B.

[0115] Moreover, FIG. 1C represents the angles θ1, θ2, θ2′ and θ3 of the circular repetitions of the alignment patterns 11 and the grooves 12.

[0116] Thus, starting from the centre O of the plate 10, the grooves 121 of the fluid C1 being repeated with an angle θ1 and the grooves 122 of the fluid C2 being repeated with an angle θ2+θ2′. With regard to the alignment patterns 11, they are repeated with an angle θ3.

[0117] FIG. 2 represents for its part, schematically in perspective, an example of alignment tool 20 of the heat exchanger 50 with plates 10 conforming to the first embodiment of the invention.

[0118] Thus, in order to enable the alignment of the plates 10 together, a plurality of alignment tools 20 is used, each being in the form of a cylindrical rod 20 of nominal diameter d2 equal to that of the alignment patterns 11 and of length L1, as may be seen in FIG. 2.

[0119] By way of non-limiting examples, each plate 10 may be made of metal, notably stainless steel, for example of the type X2CrNiMo17-12-02 1.4404 according to the European standard EN 10027, with a thickness e1 of the order of 0.5 mm for a diameter d1 of the order of 100 mm.

[0120] The alignment patterns 11 and/or the grooves 12 may be produced by laser cutting and, unless stated otherwise, the tolerances on the final dimensions may be of the order of ±0.05 mm. In addition, the alignment patterns 11, here 130 in number, may have a diameter d2 of the order of 2 mm, being distributed on a circle of diameter equal to around 96 mm, the angle θ3 being equal to (360/130)°.

[0121] Furthermore, for the first ring of grooves 122 of the fluid C2, the distances r′3 and r′4 may respectively be equal to around 5 mm and 8 mm, i.e. a thickness of around 3 mm. The five rings of grooves 122 of the fluid C2 all have advantageously a thickness of around 3 mm.

[0122] Moreover, for the first ring of grooves 121 of the fluid C1, the distances r′1 and r′2 may respectively be equal to around 9 mm and 13 mm, i.e. a thickness of around 4 mm. The four rings of grooves 121 of the fluid C1 all have advantageously a thickness of around 4 mm.

[0123] In addition, the separation between a ring of grooves 121 of the fluid C1 and a ring of grooves 122 of the fluid C2 is preferentially identical for the entire plate 10, i.e. r′1-r′4=1 mm. The values of the angles of repetition may then be such that ½*θ1=θ2=θ2′=6°.

[0124] In order to better visualise the stacks, said stacks will hereafter be represented with diagrams of plates 10 seen in “negative”, that is to say that the grooves 12 and the alignment patterns 11 appear in thickness whereas the remainder is empty.

[0125] Thus, by way of illustration, FIG. 3 represents a negative view of the alignment patterns 11, forming channels 11′, of FIG. 1 with a row of grooves 121 of the fluid C1, forming channels 121′, and a row of grooves 122 of the fluid C2, forming channels 122′, comprising the geometric characteristics described previously.

[0126] Different sub-examples of assembly of the plates 10 according to the method of manufacture of the invention, to obtain various configurations of heat exchangers 50 will be described hereafter, with reference to FIGS. 4A to 8.

[0127] It is considered that each heat exchanger 50 obtained is formed by the assembly of 21 identical plates 10 superimposed on each other, with the geometric characteristics described previously. Thus, the total length L of these heat exchangers 50 after manufacture is around 10.5 mm.

[0128] In the first sub-example described with reference to FIGS. 4A to 5A, all of the reference patterns 11a of the plates 10 that constitute the stack forming the heat exchanger 50 are aligned with each other. FIGS. 4A and 4B make it possible to visualise this first sub-example where only the superimposition of two plates 10 is represented for reasons of clarity.

[0129] Then, once the stack finished, the channels 11a′ formed by the reference patterns 11a are all aligned, as illustrated in FIG. 5A, and consequently, the channels 121′ of the fluid C1 and the channels 122′ of the fluid C2 formed respectively by stacking of the grooves 121 and 122 are all oriented vertically, as illustrated in FIG. 5.

[0130] In the second sub-example described now with reference to FIGS. 6A to 7A, all of the reference patterns 11a of the plates 10 that constitute the stack forming the heat exchanger 50 are shifted by an angle θ3 in the clockwise direction (lower plate with respect to that situated above in the assembly). FIGS. 6A and 6B make it possible to visualise this second sub-example where only the superimposition of two plates 10 is represented for reasons of clarity.

[0131] Then, once the stack finished, the channels 121′ and 122′ formed by the grooves 121 of the fluid C1 and 122 of the fluid C2 form steps in a same direction of rotation, as illustrated in FIG. 7. By then observing the stack along the plane D, as according to FIG. 7A, the channel 11a′ formed by the reference pattern 11a of a plate 10 is superimposed with the channels 11′ of the alignment patterns 11 of all of the plates 10 of the mounting but shifted by an angle step θ3 with respect to the upper and/or lower plate.

[0132] In the third sub-example described now with reference to FIGS. 8 and 8A, just as for the second sub-example, a stack of plates 10 is employed with a shift of the reference patterns 11a according to a repeated sequence of the type θ3, θ3, −θ3, −θ3, etc. This alternation of shifts following the clockwise direction and the anticlockwise direction makes it possible to obtain a stack of 21 plates 10 as represented in FIGS. 8 and 8A, showing views respectively similar to those of FIGS. 7 and 7A.

[0133] It should be noted that the three sub-examples described previously are only presented for illustrative purposes and in a non-limiting manner for the invention. The combinations of stack of plates 10 to obtain heat exchangers 50, as well as the number of these plates 10, make it possible to produce a very large number of different assemblies. In particular, it may be noted that the characteristics of the channels that can be obtained with a single type of plate 10 are very varied. In the three sub-examples described, the lengths of channel are different as are the sections of passage. It is possible to provide the channels with a geometric complexity able to improve the efficiency of heat exchanges by introducing turbulence. This geometric complexity may also have an interest for mixing in the case of exchanger-reactors described previously.

Example 2

[0134] With reference now to FIGS. 9 to 17A, a second embodiment of a plate heat exchanger 50 including two fluid circuits C1 and C2, each constituted of a single channel will be described hereafter.

[0135] In this second embodiment of the invention, the method for manufacturing the heat exchanger 50 implements an assembly of a plurality of plates 10a, 10a′, 10b, 10c, 10d by diffusion welding obtained by the hot uniaxial pressing (HUP) technique.

[0136] In this second example, unlike the first example described beforehand, the heat exchanger 50 comprises plates 10a, 10a′, 10b, 10c and 10d having different patterns. More specifically, the heat exchanger 50 comprises four types of plates.

[0137] FIG. 9 represents the first model of plate 10a of the heat exchanger 50.

[0138] Thus, the plate 10a, represented in FIG. 9, has a hexagonal shape, a thickness e2 and a width L2, corresponding to the distance between two opposite sides. The plate 10a comprises six alignment patterns 11 near to each angle, including the reference pattern 11a. The reference pattern 11a is located by means of an indexing mark 13, forming a locating element 13. Furthermore, a plurality of grooves 12 is formed on the plate 10a around the axis of central revolution X. These grooves 12 include grooves 121 for the fluid C1 and grooves 122 for the fluid C2.

[0139] FIG. 9A shows a top view of half of the plate 10a of FIG. 9. In this FIG. 9A, it may be seen that the indexing mark 13 is in the form of a lozenge shaped notch 13 in the corner bearing the reference pattern 11a. The reference pattern 11a, like the other alignment patterns 11, are in the form of through cylindrical patterns of diameter d3, and are situated at a distance d4 from the edge of the plate 10a.

[0140] In addition, the grooves 121 and 122 have an identical shape, namely a straight through port shape with circular ends of a diameter equal to the width of the channel.

[0141] Taking as reference the triangle of material between the centre O of the plate 10a and two consecutive tops B and C of the plate 10a, namely the equilateral triangle OBC represented in FIG. 9A, the grooves 122 are pierced parallel to the side BC starting from the straight line OB up to the height OH, H being the middle of the segment BC, and the grooves 121 are pierced parallel to the side BC starting from the straight line OC up to the height OH. In addition, starting from the centre O of the plate 10a following the straight line OH, the first groove 121 is distant by a length d1′ from the centre O of the plate 10a, the first groove 122 is distant by a length d2′ from the first groove 121 and the second groove 121 is distant by a length d3′ from the first groove 122. The distance between a groove 121 and the following groove 122 then remains set at d2′, and between a groove 122 and the following groove 121 at d3′.

[0142] These grooves 121 and 122 are next reproduced by central symmetry six times by an angle of 60° with respect to the central axis X of the plate 10a. For the final symmetry, the ends of the grooves 121 and 122 do not end following the straight line OH′, as represented in FIG. 9A, but at a distance d5 on either side of the straight line OH′.

[0143] Furthermore, as may be seen in FIG. 9B, the grooves 121 have a width d6 and the grooves 122 have a width d7. The central hexagonal pattern M has equal sides and a width L3.

[0144] With reference now to FIGS. 10 and 10A, the second model of plate 10b of the heat exchanger 50 according to the second embodiment of the invention is represented.

[0145] The second model of plate 10b is of same dimension as the first model of plate 10a, namely with a hexagonal shape with equal sides of width L2. Similarly, the plate 10b comprises six alignment patterns 11 situated at the corners of the hexagon, the reference pattern 11a being located by an indexing mark 13 similar to that of the plate 10a, the plate 10b here having a thickness e3.

[0146] FIG. 10A, a top view of half of plate 10b of FIG. 10, shows that this model of plate 10b comprises circular shaped and oblong shaped grooves 12. Firstly, the plate 10b comprises grooves 121 of circular shape for the fluid C1 and grooves 122 of circular shape for the fluid C2. The grooves 121 have a diameter d6 and the grooves 122 have a diameter d7. These grooves 121 and 122 are produced following the diagonals of the hexagon and following the heights OH presented previously with reference to FIG. 10A. In addition, the spacing between the grooves 121 and 122 is identical to that of the grooves 121 and 122 of the first model of hexagonal plate 10a, namely the distances d1′, d2′ and d3′.

[0147] Furthermore, on one of the sides of the hexagon, the circular grooves are replaced by grooves in the form of oblong holes 123 for the fluid C1 and 124 for the fluid C2, respectively of width d6 and d7, centred following the straight line OH′. The distance following the straight line OH′ between two consecutive oblong holes 123 or 124 is d2′+d3′, and the width of these holes 123 and 124 following the normal to the straight line OH′ is 2×d5.

[0148] The third 10c and fourth 10d types of plates used in the heat exchanger 50 according to the second embodiment of the invention will now be described with reference to FIGS. 11 and 12 respectively.

[0149] These two plates 10c and 10d have the same dimensions as the preceding plates 10a and 10b, namely a hexagonal shape with equal sides of width L2. The alignment patterns 11, including the reference pattern 11a, and the indexing mark 13 are identical to those described previously for the plates 10a and 10b.

[0150] The respective thicknesses of the plates 10c and 10d are e4 and e5. In addition, the plates 10c and 10d also comprise a hexagonal central pattern M of width L3.

[0151] The plate 10c comprises a groove 12, in the form of a circular groove 12a, with a diameter d7, which is going to be superimposed on the final groove 122 of the plate 10a.

[0152] The plate 10d comprises for its part a groove 12, in the form of a circular groove 12b, of diameter d6, which is going to be superimposed on the first groove 122 of the plate 10a.

[0153] Furthermore, FIG. 13 represents, schematically in perspective, an example of alignment tool 20 of the heat exchanger 50 with plates 10a, 10b, 10c, 10d, in the form of an alignment pad 13 that is going to serve as guide during the mounting. This alignment pad 13 has the shape of a chamfered cylinder of length L3 and of diameter d3.

[0154] By way of non-limiting examples, each plate 10a, 10b, 10c and 10d may be made of metal, notably stainless steel, for example of the type X2CrNiMo17-12-02 1.4404 according to the European standard EN 10027, with a thickness e2=e3=e4=e5 of the order of 0.5 mm for a width L2 of the order of 84 mm.

[0155] The alignment patterns 11 and/or the grooves 12 may be produced by laser cutting and, unless stated otherwise, the tolerances on the final dimensions may be of the order of ±0.05 mm. In addition, the alignment patterns 11, here 6 in number, may have a diameter d2 of the order of 2 mm, being situated at a distance d3 of the order of 2 mm from the edge of the plates.

[0156] Furthermore, the grooves 121 and 122 may be of respective width d6 of the order of 1 mm and d7 of the order of 1.6 mm. The remaining dimensions may be the following: d1′=2.7 mm; d2′=d3′=2.3 mm; d5=2.6 mm; and L3=3.4 mm.

[0157] FIG. 14 represents the final stack, according to an exploded view, of the heat exchanger 50 obtained by means of a plate 10a, a plate 10b, a plate 10c, a plate 10d and a plate referenced 10a′ because it corresponds to a turned over plate 10a.

[0158] More precisely, the stack represented in FIG. 14 is constituted from bottom to top by a plate 10c, a plate 10a, a plate 10b, a second turned over plate 10a, noted 10a′, and a plate 10d. Thus, all the plates are arranged with a top view identical to FIGS. 9, 10, 11 and 12, except for the second plate 10a′. Indeed, to enable the formation of channels from the grooves 121 and 122, the latter have to be turned over, the top face shown in FIG. 9 being located below in the stack.

[0159] The reference patterns 11a are thus superimposed for all the plates, apart from the second plate 10a′ for which the indexing mark 13 is then situated on another top of the hexagonal stack.

[0160] The mounting is carried out such that the straight lines OH′ described previously are all parallel with each other. Two alignment tools 20 are necessary in order to conserve the alignment of the plates together during the remainder of the manufacture.

[0161] The remainder of the manufacture of the heat exchanger 50 from the stack of FIG. 14A will now be described.

[0162] The leak tightness of the plates of the heat exchanger 50 with respect to each other is achieved by diffusion welding assisted by hot uniaxial pressing (HUP).

[0163] To do so, it is necessary to have available a press making it possible to work at high temperature under vacuum or under neutral gas.

[0164] An example of procedure of diffusion welding assisted by HUP for the examples presented above in stainless steel 316L is described below: [0165] once the stack of plates produced and correctly aligned with each other, the assembly is placed between the two pressure plates of the press, [0166] pumping makes it possible to produce a sufficiently high vacuum at the level of the stack, i.e. around a minimum pressure of 10.sup.−3 mbars; it is also possible to work under neutral gas (of the type argon, nitrogen): to do so, it is necessary to alternate phases of degassing and filling in order to obtain an atmosphere as clean as possible, [0167] the stack next undergoes the cycle of hot uniaxial pressing (HUP) which includes heating for 3 hours at a temperature of 1020° C. with a load increase up to 10 MPa, a plateau of 3 hours at a temperature of 1020° C. under 10 MPa, then cooling over several hours, and finally unloading.

[0168] Obviously, this procedure is only given by way of an example in precise cases. It is in no way limiting with regard to the possible embodiments using this assembly technique.

[0169] As may be seen in FIG. 15, once the heat exchanger 50 manufactured using diffusion welding assisted by hot uniaxial pressing (HUP) in this example, a notch 30 is produced at the centre of the lateral face of the heat exchanger 50 situated between indexing marks 13 of the plate 10a′ and the plates 10a, 10b, 10c and 10d.

[0170] With reference to FIGS. 16, 17 and 17A, as for the first embodiment of the invention according to FIG. 3 for example, the plates 10a, 10a′ and 10b are shown in negative to better understand the stack, the channels 11′ formed by the alignment patterns 11, and the channels 121′ and 122′ formed by the grooves 121 and 122 being in relief, the remainder of the plates being transparent.

[0171] FIG. 16 thus shows the plate 10a in negative view. When the two plates 10a and 10a′ are superimposed, the plate 10a′ being reversed with respect to the other plate 10a, as according to FIG. 17, the straight lines OH′ being parallel, the formation of the channels 121′ and 122′ from the grooves 121 and 122 is visible over the whole circumference of the mounting except at the level of the straight line OH′. Thus, the addition of a plate 10b, as according to FIG. 17A, makes it possible to offset this problem and to achieve the continuity of the grooves. The present invention thus makes it possible to use a single model of plate, namely the first model of plate 10a, in two different configurations to produce a plate heat exchanger 50.

[0172] Obviously, the invention is not limited to the exemplary embodiments that have just been described. Various modifications may be made thereto by those skilled in the art.

[0173] In particular, the invention may be applied for the production of a plate heat exchanger with changing channel geometry. In particular, it is possible to make the geometry of the fluid circulation channels change over the whole length of the heat exchanger. Indeed, it is possible to modify the angle of repetition θ3, or shift step, of the alignment patterns 11 over the whole length of the heat exchanger 50, as long as the grooves 12 of a plate are slightly facing those of adjacent plates to form a channel. This has the advantage in certain cases of intensifying the exchanges in certain critical zones whereas others do not require it.

[0174] Furthermore, the compactness and the integrity of the heat exchanger after manufacture may also be optimised by integrating the fluid collectors C1 and C2 circulating in the channels formed from the grooves 121 and 122 respectively directly during the phases of mounting the heat exchanger.

[0175] Furthermore, the hollowed out patterns represented in the examples described above correspond to through hollows formed notably by removal of material. In an alternative, the hollowed out patterns may also correspond, in totality or partially, to hollows formed without removal of material, for example by stamping. At least one continuous channel may then be formed by superimposition of at least two plates comprising such hollowed out stamped patterns, one of the plates being turned over with respect to the other and if need be shifted by a predetermined angle with respect to the other to place the stamped hollowed out patterns in at least partial superimposition.