Heat transfer plate

Abstract

A heat transfer plate comprises a first distribution area having a first distribution pattern, a second distribution area having a second distribution pattern, and a heat transfer area having a heat transfer pattern differing from the first and second distribution patterns. The first and second distribution patterns comprise distribution ridges and distribution valleys. Distribution ridges and distribution valleys of the first and second distribution patterns closest to the heat transfer area form end ridges and end valleys. The top portion of at least plural of the end ridges, along at least part of its longitudinal extension, has a second width exceeding a first width of the top portion of the remaining distribution ridges, and the bottom portion of at least plural of the end valleys, along at least part of its longitudinal extension, has a fourth width exceeding a third width of the bottom portion of the remaining distribution valleys.

Claims

1. A heat transfer plate comprising a first end portion, a center portion and a second end portion arranged in succession along a longitudinal center axis of the heat transfer plate, the first end portion comprising a first port hole and a second port hole and a first distribution area provided with a first distribution pattern, the second end portion comprising a third port hole and a fourth port hole and a second distribution area provided with a second distribution pattern, and the center portion comprising a heat transfer area provided with a heat transfer pattern differing from the first and second distribution patterns, the first end portion adjoining the center portion along a first borderline and the second end portion adjoining the center portion along a second borderline, wherein the first and second distribution patterns comprise distribution ridges and distribution valleys, a respective top portion of the distribution ridges extending in a first plane and a respective bottom portion of the distribution valleys extending in a second plane, which first and second planes are parallel to each other, the distribution ridges longitudinally extending along a number of separated imaginary ridge lines extending from the first borderline towards the first port hole in the first distribution area, and from the second borderline towards the third port hole in the second distribution area, the distribution ridge along each one of the imaginary ridge lines arranged closest to the center portion forming an end ridge, and the distribution valleys longitudinally extending along a number of separated imaginary valley lines extending from the first borderline towards the second port hole in the first distribution area, and from the second borderline towards the fourth port hole in the second distribution area, the distribution valley along each one of the imaginary valley lines arranged closest to the center portion forming an end valley, wherein the imaginary ridge lines and the imaginary valley lines form a grid within each of the first and second distribution areas, wherein the distribution valleys and distribution ridges defining each mesh of the grids enclose an area within which the heat transfer plate extends at a distance >0 from the first plane and a distance >0 from the second plane, wherein a width of the top portion of the distribution ridges and the bottom portion of the distribution valleys is measured perpendicular to the imaginary ridge lines and valley lines, wherein a top portion of at least a plurality of the end ridges, along at least part of a longitudinal extension of the end ridges, has a second width exceeding a first width of the top portion of the rest of the distribution ridges, and a bottom portion of at least a plurality of the end valleys, along at least part of a longitudinal extension of the end valleys, has a fourth width exceeding a third width of the bottom portion of the rest of the distribution valleys.

2. A heat transfer plate according to claim 1, wherein the first and third port holes are arranged on one side of the longitudinal center axis and the second and fourth port holes are arranged on the other side of the longitudinal center axis.

3. A heat transfer plate according to claim 1, wherein said at least a plurality of the end ridges comprise a respective projection to obtain the second width of the respective top portion, and said at least a plurality of the end valleys comprise a respective projection to obtain the fourth width of the respective bottom portion.

4. A heat transfer plate according to claim 3, wherein the projections of said at least a plurality of the end ridges project so as to face a first edge of the heat transfer plate, and the projections of said at least a plurality of the end valleys project so as to face an opposite second edge of the heat transfer plate.

5. A heat transfer plate according claim 1, wherein the top portion of said at least a plurality of the end ridges and the bottom portion of said at least a plurality of the end valleys each comprise a first part and a second part, which first and second parts are arranged in succession along the imaginary ridge and valley lines, the second part, along at least part of the respective longitudinal extension of the end ridges and the end valleys, being wider than the first part, the second part being closer to the first borderline than the first part in the first distribution area, and the second part being closer to the second borderline than the first part in the second distribution area.

6. A heat transfer plate according to claim 1, wherein said at least a plurality of the end ridges are inverts of said at least a plurality of the end valleys.

7. A heat transfer plate according to claim 1, wherein the top portion of at least a plurality of the distribution ridges not included in said at least a plurality of the end ridges, and the bottom portion of at least a plurality of the distribution valleys not included in said at least a plurality of the end valleys, have essentially the same width and an essentially uniform width along the respective longitudinal extension of the distribution ridges and the distribution valleys.

8. A heat transfer plate according to claim 1, wherein a length of the top portion of the distribution ridges and the bottom portion of the distribution valleys is measured parallel to the imaginary ridge lines and valley lines, the top portion of at least a plurality of the distribution ridges which are not end ridges and the bottom portion of at least a plurality of the distribution valleys which are not end valleys having essentially the same length.

9. A heat transfer plate according to claim 1, wherein a plurality of the distribution ridges are arranged along each one of at least a plurality of the imaginary ridge lines and a plurality of the distribution valleys are arranged along each one of at least a plurality of the imaginary valley lines.

10. A heat transfer plate according to claim 1, wherein the first and second borderlines are non-straight.

11. A heat transfer plate according to claim 1, wherein said at least a plurality of the end ridges each is arranged absolute adjacent to a respective one of said at least a plurality of the end valleys.

12. A heat transfer plate according to claim 1, wherein the top portion of each one of the end ridges extends only outside an imaginary circle in the first plane, which circle has a center coinciding with a closest point on the top portion of an adjacent one of the end ridges and a radius equal to a length of an imaginary line drawn from the center, perpendicular to the corresponding imaginary ridge line, to an edge of the top portion of said each one of the end ridges.

13. A heat transfer plate according to claim 1, wherein a number of the imaginary ridge lines within the first distribution area arranged closest to the second port hole are curved so as to bulge out as seen from the second porthole, a number of the imaginary ridge lines within the second distribution area arranged closest to the fourth port hole are curved so as to bulge out as seen from the fourth porthole, a number of the imaginary valley lines within the first distribution area arranged closest to the first port hole are curved so as to bulge out as seen from the first porthole, and a number of the imaginary valley lines within the second distribution area arranged closest to the third port hole are curved so as to bulge out as seen from the third port hole.

14. A heat transfer plate according to claim 1, wherein a first volume enclosed by the heat transfer plate and the first plane is different from a second volume enclosed by the heat transfer plate and the second plane within the first and second distribution areas and the heat transfer area.

15. A heat transfer plate according to claim 1, which within said area enclosed by the distribution ridges and distribution valleys at least partly extends in a third plane displaced from a center plane extending half way between the first and second planes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described in more detail with reference to the appended schematic drawings, in which

(2) FIG. 1 is a schematic plan view of a heat transfer plate,

(3) FIG. 2 illustrates abutting outer edges of adjacent heat transfer plates in a plate pack, as seen from the outside of the plate pack,

(4) FIG. 3 schematically illustrates a cross section through a heat transfer area of the heat transfer plate in FIG. 1,

(5) FIG. 4a contains an enlargement of a first distribution area of the heat transfer plate in FIG. 1,

(6) FIG. 4b contains an enlargement of a second distribution area of the heat transfer plate in FIG. 1,

(7) FIG. 5a schematically illustrates a cross section through the first or the second distribution area of the heat transfer plate in FIG. 1,

(8) FIG. 5b schematically illustrates another cross section through the first or the second distribution area of the heat transfer plate in FIG. 1,

(9) FIG. 6 contains an enlargement of a portion of the first distribution area of the heat transfer plate illustrated in FIG. 1, and

(10) FIG. 7 contains the enlargement of FIG. 6 and illustrates a limitation of an extension of end ridges of the first and second distribution areas.

DETAILED DESCRIPTION

(11) FIG. 1 shows a heat transfer plate 2a of a gasketed plate heat exchanger as described by way of introduction. The gasketed PHE, which is not illustrated in full, comprises a pack of heat transfer plates 2 like the heat transfer plate 2a, i.e. a pack of similar heat transfer plates, separated by gaskets, which also are similar and which are not illustrated. With reference to FIG. 2, in the plate pack, a front side 4 (illustrated in FIG. 1) of the plate 2a faces an adjacent plate 2b while a back side 6 (not visible in FIG. 1 but indicated in FIG. 2) of the plate 2a faces another adjacent plate 2c.

(12) With reference to FIG. 1, the heat transfer plate 2a is an essentially rectangular sheet of stainless steel. It comprises a first end portion 8, which in turn comprises a first port hole 10, a second port hole 12 and a first distribution area 14. The plate 2a further comprises a second end portion 16, which in turn comprises a third port hole 18, a fourth port hole 20 and a second distribution area 22. The plate 2a further comprises a center portion 24, which in turn comprises a heat transfer area 26, and an outer edge portion 28 extending around the first and second end portions 8 and 16 and the center portion 24. The first end portion 8 adjoins the center portion 24 along a first borderline 30 while the second end portion 16 adjoins the center portion 24 along a second borderline 32. The first and second borderlines 30 and 32 are arched so as to bulge towards each other. As is clear from FIG. 1, the first end portion 8, the center portion 24 and the second end portion 16 are arranged in succession along a longitudinal center axis L of the plate 2a, which extends perpendicular to a transverse center axis T of the plate 2a. As is also clear from FIG. 1, the first and third port holes 10 and 18 are arranged on one and the same side of the longitudinal center axis L, while the second and fourth port holes 12 and 20 are arranged on one and the other side of the longitudinal center axis L. Also, the heat transfer plate 2a comprises, as seen from the front side 4, a front gasket groove 34 and, as seen from the back side 6, a back gasket groove (not illustrated). The front and back gasket grooves are partly aligned with each other and arranged to receive a respective gasket.

(13) The heat transfer plate 2a is pressed, in a conventional manner, in a pressing tool, to be given a desired structure, more particularly different corrugation patterns within different portions of the heat transfer plate. As was discussed by way of introduction, the corrugation patterns are optimized for the specific functions of the respective plate portions. Accordingly, the first distribution area 14 is provided with a first distribution pattern, the second distribution area 22 is provided with a second distribution pattern and the heat transfer area 26 is provided with a heat transfer pattern. Further, the outer edge portion 28 comprises corrugations 36 which make the outer edge portion stiffer and, thus, the heat transfer plate 2a more resistant to deformation. Further, the corrugations 36 form a support structure in that they are arranged to abut corrugations of the adjacent heat transfer plates in the plate pack of the PHE. With reference again to FIG. 2, illustrating the peripheral contact between the heat transfer plate 2a and the two adjacent heat transfer plates 2b and 2c of the plate pack, the corrugations 36 extend between and in a first plane 38 and a second plane 40, which are parallel to the figure plane of FIG. 1. A center plane 42 extends half way between the first and second planes 38 and 40, and a respective bottom of the front gasket groove 34 and back gasket groove extends in this center plane 42, i.e. in so called half plane.

(14) The heat transfer pattern is of so-called herringbone type and comprises V-shaped heat transfer ridges 44 and heat transfer valleys 46 alternately arranged along the longitudinal center axis L. With reference to FIG. 3 schematically illustrating a cross section of the plate 2a within the heat transfer area 26, taken perpendicular to a longitudinal extension of the heat transfer ridges and valleys 44 and 46, the heat transfer ridges 44 and valleys 46 extend between and in the first plane 38 and the second plane 40. As is illustrated in FIG. 3, the heat transfer ridges and valleys 44 and 46 are not symmetrical with respect to the center plane 42. Instead, the heat transfer valleys 46 are wider or less pointed than the heat transfer ridges 44. Consequently, within the heat transfer area 26, a first volume V1 enclosed by the plate 2a and the first plane 38 will be larger than a second volume V2 enclosed by the plate 2a and the second plane 40.

(15) With reference to FIGS. 4a and 4b which show enlargements of parts of the plate 2a, the first and second distribution patterns, which are similar, each comprise elongate distribution ridges 50 and elongate distribution valleys 52. The distribution ridges 50 are divided into sets. The distribution ridges 50 of each set are arranged, longitudinally extending, along one of a number of separated imaginary ridge lines 54, of which only a few are illustrated by broken lines in FIGS. 4a and 4b. Similarly, the distribution valleys 52 are divided into sets. The distribution valleys 52 of each set are arranged, longitudinally extending, along one of a number of separated imaginary valley lines 56, of which only a few are illustrated by broken lines in FIGS. 4a and 4b. As is illustrated in FIG. 4a, in the first distribution area 14 the imaginary ridge lines 54 extend from the first borderline 30 towards the first porthole 10 while the imaginary valley lines 56 extend from the first borderline 30 towards the second porthole 12. Similarly, as is illustrated in FIG. 4b, in the second distribution area 22 the imaginary ridge lines 54 extend from the second borderline 32 towards the third porthole 18 while the imaginary valley lines 56 extend from the second borderline 32 towards the fourth porthole 20. As is shown in FIGS. 4a and 4b, the imaginary ridge and valley lines 54 and 56 with the largest sets of distribution ridges and valleys are curved so as to bulge out towards the respective one of the first and second borderlines 30 and 32, while the rest of, i.e. the imaginary ridge and valley lines 54 and 56 with the smallest sets of distribution ridges and valleys, are essentially straight. The imaginary ridge and valley lines 54 and 56 cross each other so as to form an imaginary grid within each of the first and second distribution areas 14 and 22. These grids comprises meshes, wherein the meshes immediately adjacent the first and second borderlines 30 and 32 are open and the rest of the meshes are closed.

(16) FIG. 5a schematically illustrates a cross section of the first and second distribution areas 14 and 22 taken between two adjacent ones of the imaginary valley lines 56, while FIG. 5b schematically illustrates a cross section of the first and second distribution areas 14 and 22 taken between two adjacent ones of the imaginary ridge lines 54. As is clear from FIGS. 5a and 5b, a respective top portion 58 of the distribution ridges 50 extend in the first plane 38, while a respective bottom portion 60 of the distribution valleys 52 extend in the second plane 40. Further, the distribution ridges 50 and distribution valleys 52 defining each mesh of the grids enclose, completely in the case of a closed mesh and partly in the case of an open mesh, a triangular or quadrangular area 62, as is also illustrated in FIGS. 4a and 4b. This area 62 extends in a third plane 64 arranged between the second plane 40 and center plane 42. Since the third plane 64 is displaced from the center plane 42, the first volume V1 enclosed by the plate 2a and the first plane 38 will be larger than the second volume V2 enclosed by the plate 2a and the second plane 40, within the first and second distribution areas 14 and 22.

(17) Between two adjacent ones of the distribution ridges 50 along one and the same one of the imaginary ridge lines 54, and between two adjacent ones of the distribution valleys 52 along one and the same one of the imaginary valley lines 56, the plate 2a here extends in the center plane 42 (but this could be different in other embodiments).

(18) The distribution ridge 50 along each of the imaginary ridge lines 54 that is arranged closest to the first borderline 30 in the first distribution area 14, and closest to the second borderline 32 in the second distribution area 22, forms a respective end ridge 66. In a corresponding way, the distribution valley 52 along each of the imaginary valley lines 56 that is arranged closest to the second borderline 30 in the first distribution area 14, and closest to the second borderline 32 in the second distribution area 22, forms a respective end valley 68. The end ridges 66 as seen from the front side 4 of the plate 2a and the end valleys 68 as seen from the opposite back side of the plate 2a, where they form end ridges, have the same shape. This means that the end ridges 66 are inverts of the end valleys 68. Each of the end ridges 66 is arranged right beside a respective one of the end valleys 68.

(19) The width of the distribution ridges 50 and distribution valleys 52, and especially the top and bottom portions 58, 60 thereof, is measured perpendicular to the imaginary ridge lines 54 and the imaginary valley lines 56, respectively. The top portion 58 of the distribution ridges 50 not being end ridges 66, and the bottom portion 60 of the distribution valleys 52 not being end valleys 68 have the same width w1=w3 (FIGS. 5a and 5b), and the width is constant along essentially their complete longitudinal extension. The length of the top portion 58 of the distribution ridges 50 and the bottom portion 60 of the distribution valleys 52 is their longitudinal extension, and this is measured parallel to the respective imaginary ridge lines and valley lines 54 and 56. As is clear from FIGS. 4a and 4b, the top and bottom portions 58, 60 of most of the distribution ridges 50 and distribution valleys 52 (not the ones most adjacent to the portholes 10, 12, 18 and 20) not being end ridges 66 and end valleys 68 have essentially the same length.

(20) The end ridges 66 and end valleys 68 have a shape deviating from the shape of the rest of the distribution ridges 50 and distribution valleys 52. FIG. 6 contains an enlargement of the first distribution area 14 within the box drawn with ghost lines in FIG. 1. As is clear from FIG. 6, the top portion 58 of the end ridges 66 and the bottom portion 60 of the end valleys 68 each comprise a first part 70 and a second part 72 arranged in succession along the corresponding one of the imaginary ridge and valley lines 54 and 56. Within the first distribution area 14 the second part 72 is the part most adjacent to the first borderline 30, and within the second distribution area 22 the second part 72 is the part most adjacent to the second borderline 32 (borderlines 30 and 32 illustrated in FIG. 1). The width of the first parts is w1=w3. The second parts 72 each comprise an outside heel or projection, denoted 74 for the end ridges 66 and 76 for the end valleys 68, which results in a local widening of the corresponding end ridge 66 or end valley 68, and the top and bottom portions 58, 60 thereof. Thus, along part of their longitudinal extension, the second parts have a width w2=w4 which is larger than w1=w3.

(21) As is clear from the figures, the projections 74 of the end ridges 66 project so as to face a first edge 73 (FIG. 1) of the heat transfer plate 2, and the projections 76 of the end valleys 68 project so as to face an opposite second edge 75 (FIG. 1) of the heat transfer plate 2.

(22) As is indicated by FIG. 1, the first porthole 10, the second porthole 12, the first borderline 30 and the first distribution area 14 including the first distribution pattern, on the one hand, and the third porthole 18, the fourth port hole 20, the second borderline 32 and the second distribution area 22 including the second distribution pattern, on the other hand, are symmetrical, or mirrorings of each other, with reference to the transverse center axis T.

(23) As previously said, in the plate pack, the plate 2a is arranged between the plates 2b and 2c. The plates 2b and 2c may be arranged either “flipped” or “rotated” in relation to the plate 2a.

(24) If the plates 2b and 2c are arranged “flipped” in relation to the plate 2a, the front side 4 and back side 6 of plate 2a face the front side 4 of plate 2b and the back side 6 of plate 2c, respectively. This means that the ridges of plate 2a will abut the ridges of plate 2b while the valleys of plate 2a will abut the valleys of plate 2c. More particularly, the heat transfer ridges 44 and heat transfer valleys of the plate 2a will abut, in pointlike contact areas, the heat transfer ridges 44 of the plate 2b and the heat transfer valleys 46 of the plate 2c, respectively. Further, the top portions 58 of the distribution ridges 50 and the bottom portions 60 of the distribution valleys 52 of the plate 2a will abut, in elongate contact areas, the top portions 58 of the distribution ridges 50 of the plate 2b and the bottom portions 60 of the distribution valleys 52 of the plate 2c, respectively. Because of the heels 74 and 76 of the end ridges 66 and end valleys, the contact areas closest to the first and second border lines 30 and 32 will be locally widened to provide extra strength to the plate pack close to the transitions between the heat transfer and distribution areas 26, 14 and 22. The plates 2a and 2b will form a channel of volume 2×V1, while the plates 2a and 2b will form a channel of volume 2×V2, i.e. two assymetric channels since V1>V2.

(25) If the plates 2b and 2c are arranged “rotated” in relation to the plate 2a, the front side 4 and back side 6 of plate 2a face the back side 6 of plate 2b and the front side 4 of plate 2c, respectively. This means that the ridges of plate 2a will abut the valleys of plate 2b while the valleys of plate 2a will abut the ridges of plate 2c. More particularly, the heat transfer ridges 44 and heat transfer valleys of the plate 2a will abut, in pointlike contact areas, the heat transfer valleys 46 of the plate 2b and the heat transfer ridges 44 of the plate 2c, respectively. Further, the top portions 58 of the distribution ridges 50 and the bottom portions 60 of the distribution valleys 52 of the plate 2a will abut, in elongate contact areas, the bottom portions 60 of the distribution valleys 52 of the plate 2b and the top portions 58 of the distribution ridges 50 of the plate 2c, respectively. Because of the heels 74 and 76 of the end ridges 66 and end valleys, the contact areas closest to the first and second border lines 30 and 32 will be locally widened to provide extra strength to the plate pack close to the transitions between the heat transfer and distribution areas 26, 14 and 22. The plates 2a and 2b will form a channel of volume V1+V2, while the plates 2a and 2b will form a channel of volume V1+V2, i.e. two symmetric channels.

(26) The above described embodiment of the present invention should only be seen as an example. A person skilled in the art realizes that the embodiment discussed can be varied in a number of ways without deviating from the inventive conception.

(27) For example, the heat transfer area may comprise other heat transfer patterns, both symmetric and asymmetric, and both of herringbone-type and other types, than the one described above.

(28) Similarly, the first and second distribution areas may comprise other distribution patterns than the one described above. As an example, the third plane could be arranged closer to, or more distant from, the first plane than illustrated in the drawings. As another example, the first and second distribution patterns need not be asymmetric, i.e. the third plane could coincide with the center plane.

(29) The plate pack described above contains only plates of one type. The plate pack could instead comprise plates of two or more different types, such as plates having differently configurated heat transfer patterns.

(30) The end ridges and end valleys need not all be provided with heels. The heels of some or all of the end ridges may differ in form and/or size from the heels of some or all of the end valleys. Further, alternative designs of the distribution ridges and distribution valleys are possible. For example, all the distribution ridges and valleys could be straight, and/or they could have a varying design such as different lengths and widths.

(31) The heels need not be designed as illustrated in the drawings but could, for example, be larger or smaller. FIG. 7 illustrates a possible maximum extension of the heels. Preferably, the top portion 58 of a first end ridge 66a should not extend inside a certain imaginary circle 78 (of which only a circle sector 78′ is illustrated) in the first plane 38. This imaginary circle 78 has a center C coinciding with a point P on the top portion 58 of an adjacent second end ridge 66b, which point is closest to the first end ridge 66. Further, the imaginary circle 78 has a radius r equal to the length of an imaginary line drawn from the center C of the imaginary circle 78, perpendicular to the imaginary ridge line 54 along which the second end ridge 66b is arranged, to an edge 80 of the top portion 58 of the first end ridge 66a.

(32) The first and second borderlines need not be curved but could have other forms. For example, they could be straight or zig-zag shaped.

(33) The heat transfer plate could additionally comprise a transition band, like the ones described in EP 2957851, EP 2728292 or EP 1899671, between the heat transfer and distribution areas. Such a plate may not be “flippable” as well as “rotatable”.

(34) The present invention is not limited to gasketed plate heat exchangers but could also be used in welded, semi-welded, brazed and fusion-bonded plate heat exchangers.

(35) The heat transfer plate need not be rectangular but may have other shapes, such as essentially rectangular with rounded corners instead of right corners, circular or oval. The heat transfer plate need not be made of stainless steel but could be of other materials, such as titanium or aluminium.

(36) The triangular and quadrangular areas enclosed by the distribution ridges and valleys need not be flat and extend completely in the third plane.

(37) It should be stressed that the attributes front, back, first, second, third, etc. is used herein just to distinguish between details and not to express any kind of orientation or mutual order between the details.

(38) Further, it should be stressed that a description of details not relevant to the present invention has been omitted and that the figures are just schematic and not drawn according to scale. It should also be said that some of the figures have been more simplified than others. Therefore, some components may be illustrated in one figure but left out on another figure.