Heat Transfer Plates and Gaskets

Abstract

A heat transfer plate (1) and a gasket (2) are provided. The heat transfer plate (1) includes a front gasket groove (43) including an annular front groove part (45) extending around the heat transfer area (33), the upper and lower distribution areas (13, 25) and the first and third portholes (9, 21) of the heat transfer plate (1) and second and fourth ring groove parts (47, 49) surrounding the second and fourth portholes (11, 23) of the heat transfer plate (1). The heat transfer plate (1) further includes a second insulating area (17) extending between the annular front groove part (45) and the second ring groove part (47) and a fourth insulating area (29) extending between the annular front groove part (45) and the fourth ring groove part (49). The upper front groove portion (71) of the front gasket groove (43) extends between the second porthole (11) and the upper distribution area (13). The lower front groove portion (83) of the front gasket groove (43) extends between the fourth porthole (23) and the lower distribution area (25). The heat transfer plate (1) is characterized in that the bottom (67u, 69) of the upper front groove portion (71) is inclined such that the depth of the front gasket groove (43) increases in the upper front groove portion (71) in a direction toward the second insulating area (17) and the bottom (67l, 81) of the lower front groove portion (83) is inclined such that the depth of the front gasket groove (43) increases in the lower front groove portion (83) in a direction toward the fourth insulating area (29).

Description

[Technical field]

[0001] The present invention relates to a heat transfer plate and to a gasket for such a heat transfer plate. [Background technology]

[0002] A plate heat exchanger (PHE) typically includes two end plates between which a number of heat transfer plates are arranged in a stack or pack. The heat transfer plates of a PHE may be of the same type or of different types, and they can be stacked in different ways. In some PHEs, the heat transfer plates are stacked with the front side and the back side of one heat transfer plate facing the back side and the front side, respectively, of the other heat transfer plate, and with every other heat transfer plate being upside down with respect to the rest of the heat transfer plates. Typically, this is referred to as the heat transfer plates being "rotated" with respect to each other. In other PHEs, the heat transfer plates are stacked with the front side and the back side of one heat transfer plate facing the front side and the back side, respectively, of the other heat transfer plate, and with every other heat transfer plate being upside down with respect to the rest of the heat transfer plates. Typically, this is referred to as the heat transfer plates being "flipped" with respect to each other.

[0003] In one known type of PHE, the so-called gasketed PHE, a gasket is placed between the heat transfer plates in a gasket groove pressed into the heat transfer plate. The end plates (and thus the heat transfer plates) are pressed towards each other by some kind of clamping means, whereby the gasket seals between the heat transfer plates. Parallel flow channels are formed between the heat transfer plates, one channel between each pair of adjacent heat transfer plates. Two fluids, initially at different temperatures, which are pumped to / from the PHE through inlet / outlet ports, are allowed to flow alternately through each channel to transfer heat from one fluid to the other, the fluids entering / exiting the channels through inlet / outlet portholes in the heat transfer plates that communicate with the inlet / outlet ports of the PHE.

[0004] Typically, the heat transfer plate includes two end portions and an intermediate heat transfer portion. The end portions include inlet and outlet portholes, a distribution area pressed with a distribution pattern of ridges and valleys, and an intermediate insulation area pressed with an insulation pattern of ridges and valleys. Similarly, the heat transfer portion includes a heat transfer area pressed with a heat transfer pattern of ridges and valleys. The distribution pattern, insulation pattern, and heat transfer pattern of the heat transfer plate are arranged to contact (at the contact area) with the distribution pattern, insulation pattern, and heat transfer pattern of the adjacent heat transfer plate in the plate heat exchanger. The main task of the insulation area is to transport the fluid entering the channel to the distribution area and to transport the fluid from the distribution area out of the channel. The main task of the distribution area of ​​the heat transfer plate is to spread the fluid across the width of the heat transfer plate before it reaches the heat transfer area and to collect the fluid after it has passed through the heat transfer area. The main task of the heat transfer area is heat transfer. Since the insulation area, the distribution area and the heat transfer area have different main tasks, the insulation pattern, the distribution pattern and the heat transfer pattern are typically different from each other.

[0005] Thus, in a gasketed plate heat exchanger ready for operation, the heat transfer plates are aligned with each other in a plate pack with a gasket disposed between each two adjacent ones of the heat transfer plates. Typically, the gaskets on both sides of the same heat transfer plate are aligned with each other along most of their extension. However, to allow the alternate flow of two fluids through each channel of the plate heat exchanger as explained above, the gaskets on both sides of the same heat transfer plate are not aligned with each other along parts of their extension. Along these parts, there is a gasket support on only one side of the heat transfer plate.

[0006] For a plate heat exchanger to work properly, the heat transfer plates should be in contact with each other in the contact areas mentioned above to make the plate pack strong, while the heat transfer plates should be separated from each other in other areas to allow fluid to flow through the plate pack. However, depending on various factors such as the strength of the individual heat transfer plates, the tension between the heat transfer plates and the gasket, and the fluid pressure inside the channels between the heat transfer plates, the heat transfer plates may undergo deformation, especially near the areas where the gasket support is present on only one side of the heat transfer plates. Such deformation may prevent the desired contact and separation between the plates, which may result in a deterioration or failure of the plate heat exchanger. Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to provide a heat transfer plate and a gasket which at least partially solves the above-described problems of the prior art. The basic idea of ​​the present invention is to locally vary the pressing depth of the heat transfer plate and the thickness of the body of the gasket, making the heat transfer plate less susceptible to deformation. A heat transfer plate (which is also referred to simply as "plate" in this specification) and a gasket for achieving the above object are defined in the appended claims and described below. [Means for solving the problem]

[0008] The heat transfer plate according to the invention comprises an upper end portion, a central portion and a lower end portion arranged successively along a longitudinal central axis of the heat transfer plate. The upper end portion comprises a first and a second porthole and an upper distribution area having an upper distribution corrugation pattern. The lower end portion comprises a third and a fourth porthole and a lower distribution area having a lower distribution corrugation pattern. The central portion comprises a heat transfer area, the heat transfer area having a heat transfer corrugation pattern different from the upper and lower distribution corrugation patterns. At its front side, the heat transfer plate further comprises a front gasket groove, the front gasket groove comprising an annular front groove part extending around the heat transfer area, the upper and lower distribution areas and the first and third portholes, a second ring groove part surrounding the second porthole and a fourth ring groove part surrounding the fourth porthole. The upper end portion further includes a second insulating area extending between the annular front groove part and the second ring groove part. The lower end portion further includes a fourth insulating area extending between the annular front groove part and the fourth ring groove part. The upper front groove portion of the front gasket groove extends between the second porthole and the upper distribution area and includes a bottom. The lower front groove portion of the front gasket groove extends between the fourth porthole and the lower distribution area and includes a bottom. The heat transfer plate is characterized in that the bottom of the upper front groove portion is sloped or angled such that the depth of the front gasket groove increases in the upper front groove portion in a direction toward the second insulating area and the bottom of the lower front groove portion is sloped or angled such that the depth of the front gasket groove increases in the lower front groove portion in a direction toward the fourth insulating area.

[0009] Here, the depth is equal to the distance between the bottom of the groove and a reference plane parallel to the central extension plane of the heat transfer plate, the depth being measured perpendicular to the central extension plane.

[0010] The heat transfer plate is therefore characterized in that the depth of the front gasket groove increases in the upper and lower front groove portions from a first minimum depth to a first maximum depth along the transverse extension of the upper and lower front groove portions, with the first maximum depth being nearest the second and fourth insulating areas.

[0011] The imaginary upper and lower planes can define the extension of the heat transfer plate in the heat transfer area. The bottom of the front gasket groove can extend along more than half of its longitudinal extension into the imaginary lower plane. Such an embodiment can facilitate the permanent joining of the heat transfer plate and an underlying appropriately designed heat transfer plate (possibly another heat transfer plate according to the invention) into a cassette for use in so-called semi-welded plate heat exchangers. Alternatively, the bottom of the front gasket groove can extend along more than half of its longitudinal extension between the imaginary upper and lower planes (e.g. halfway between the imaginary upper and lower planes, etc.). Such an embodiment can enable the use of heat transfer plates in plate heat exchangers with the heat transfer plates rotated (and flipped) relative to each other and can also be suitable for so-called asymmetric heat transfer plates.

[0012] The front gasket groove is arranged to accommodate a gasket for sealing (and defining a front fluid channel) between the heat transfer plate and an upper appropriately designed heat transfer plate (possibly another heat transfer plate according to the invention). The front fluid channel can allow fluid flow between the first and third port holes of the heat transfer plate. The heat transfer plate is further arranged to cooperate with a lower appropriately designed heat transfer plate (possibly yet another heat transfer plate according to the invention) for defining a back fluid channel. The back fluid channel can allow fluid flow between the second and fourth port holes of the heat transfer plate, i.e., through a passage defined by the back sides of the upper and lower front groove portions of the front gasket groove of the heat transfer plate. To achieve the above fluid flow, there should be no gasket present on the back side, and only the front sides of the upper and lower front groove portions of the front gasket groove of the heat transfer plate. As described above, the heat transfer plate disposed in the plate heat exchanger may be easily deformed near the area with one-sided gasket support. By varying the depth of the upper and lower front groove portions of the front gasket groove of the heat transfer plate according to the present invention, the undesired deformation of the heat transfer plate near the upper and lower front groove portions of the front gasket groove can be minimized when the heat transfer plate is disposed in the plate heat exchanger together with the gasket and other heat transfer plates, which can ensure the proper performance of the plate heat exchanger.

[0013] In light of the above, the heat transfer plate may further include a back gasket groove at its back side, the back gasket groove further including an annular back groove part extending around the heat transfer area, the upper and lower distribution areas, and the second and fourth portholes, a first ring groove part surrounding the first porthole, and a third ring groove part surrounding the third porthole. Furthermore, the upper end portion may include a first insulating area extending between the annular back groove part and the first ring groove part, and the lower end portion may include a third insulating area extending between the annular back groove part and the third ring groove part. The upper back groove part of the back gasket groove may extend between the first porthole and the upper distribution area and may include a bottom. The lower back groove part of the back gasket groove may extend between the third porthole and the lower distribution area and may include a bottom. The bottom of the upper back groove portion can be sloped or angled such that the depth of the back gasket groove increases in the upper back groove portion in a direction toward the first insulation area, and the bottom of the lower back groove portion can be sloped or angled such that the depth of the back gasket groove increases in the lower back groove portion in a direction toward the third insulation area.

[0014] In this specification, "annular" does not necessarily mean a circular extension, but can mean any surrounding extension (e.g., an elliptical or polygonal extension, etc.). Thus, the annular front and back groove parts of the front and back gasket grooves do not have to be circular, but can have any shape suitable for the heat transfer plate. Similarly, the second and fourth ring groove parts of the front gasket groove and the first and third ring groove parts of the back gasket groove do not have to be circular, but can have any shape suitable for the heat transfer plate (and in particular the port holes thereof).

[0015] The first, second, third, and fourth insulating areas may have a first insulating corrugation pattern, a second insulating corrugation pattern, a third insulating corrugation pattern, and a fourth insulating corrugation pattern, respectively, which may be different from the upper and lower distribution corrugation pattern and the heat transfer corrugation pattern.

[0016] The depth of the front gasket groove (in the upper front groove portion and the lower front groove portion) and possibly the depth of the back gasket groove (in the upper back groove portion and the lower back groove portion) may gradually increase along the transverse extension of the upper and lower front groove portions of the front gasket groove and along the transverse extension of the upper and lower back groove portions of the back gasket groove, respectively. For example, the gradually increasing may be stepped or wavy. As another example, the depth may increase linearly, in which case the bottom of the upper front groove portion and the bottom of the lower front groove portion and possibly the bottom of the upper back groove portion and the bottom of the lower back groove portion may be flat. This configuration may allow a relatively simple design of the heat transfer plate.

[0017] The heat transfer plate can be designed such that the upper front groove portion of the front gasket groove is included in the upper oblique portion of the annular front groove part of the front gasket groove, the upper oblique portion extending between the second insulation area and the upper distribution area. Furthermore, said lower front groove portion of the front gasket groove can be included in the lower oblique portion of the annular front groove part of the front gasket groove, the lower oblique portion extending between the fourth insulation area and the lower distribution area. Thereby, the depth of the upper and lower front groove portions of the front gasket groove increases in the direction towards the second and fourth portholes. Such an embodiment can strengthen the heat transfer plate near the upper and lower oblique portions. As a result, deformation (due to fluid pressure) of the heat transfer plate near the upper and lower oblique portions can be prevented when the heat transfer plate is arranged in a plate heat exchanger. This can then ensure that a desired contact is achieved between the heat transfer plate in the plate heat exchanger and the adjacent heat transfer plate.

[0018] Alternatively / additionally, the heat transfer plate can be designed such that the upper front groove portion of the front gasket groove is included in the inner portion of the second ring groove part of the front gasket groove, the inner portion extending between the second port hole and the second insulation area. Furthermore, the lower front groove portion of the front gasket groove can be included in the inner portion of the fourth ring groove part of the front gasket groove, the inner portion extending between the fourth port hole and the fourth insulation area. Thereby, the depth of the upper and lower front groove portions of the front gasket groove increases in the direction away from the second and fourth port holes. The inner portion of the second ring groove part can be 25-65% of the second ring groove part. Similarly, the inner portion of the fourth ring groove part can be 25-65% of the fourth ring groove part. This embodiment can strengthen the heat transfer plate near the upper and lower oblique portions. As a result, deformation (due to fluid pressure) of the heat transfer plate near the inner portions of the second and fourth ring-groove parts can be prevented when the heat transfer plate is arranged in the plate heat exchanger, and this can ensure that desired contact is achieved between the heat transfer plate and adjacent heat transfer plates in the plate heat exchanger.

[0019] The portholes of the heat transfer plate are defined by inner plate edges, which may be corrugated or not. The heat transfer plate can be designed such that the bottom of the second ring groove part includes an annular second inner edge defining the second porthole, while the bottom of the fourth ring groove part includes an annular fourth inner edge defining the fourth porthole. According to this embodiment, the second and fourth ring groove parts extend to the second and fourth portholes, respectively. In case the bottoms of the second and fourth ring groove parts are planar, this embodiment means that the second and fourth portholes of the heat transfer plate are defined by planar (i.e. non-corrugated) inner plate edges. By omitting the corrugations around the second and fourth portholes, the cleanliness of the heat transfer plate can be improved and the plate surface available for heat transfer can be increased. According to the invention, by varying the depth of the front gasket groove in the inner part of the second and fourth ring groove parts on the heat transfer plate without corrugation around the porthole, the heat transfer plate can be "pre-deformed" in one direction. When the heat transfer plate is placed in a plate heat exchanger, the upper heat transfer plate and the intermediate gasket housed in the second and fourth ring groove parts of the heat transfer plate will deform the heat transfer plate in the opposite direction. This results in a reset of the "pre-deformation" and in the inner plate edges extending essentially parallel to the central extension plane of the heat transfer plate, at least along part of their extension, i.e. the desired separation between the heat transfer plate and the adjacent heat transfer plate in the plate heat exchanger. This in turn reduces the pressure drop for the fluid entering the channel defined by the backside of the heat transfer plate.

[0020] The heat transfer plate can be designed such that the first and third portholes are arranged on one side of the longitudinal central axis of the heat transfer plate, and the second and fourth portholes are arranged on another opposite side of the longitudinal central axis. Thereby, the heat transfer plate can be suitable for use in a so-called parallel flow type plate heat exchanger. Such a parallel flow heat exchanger can include only one plate type. Instead, if the first and fourth portholes are arranged on the same side of the longitudinal central axis, and the second and third portholes are arranged on the same other side (which is also possible according to the invention), the plate can be suitable for use in a so-called mixed flow type plate heat exchanger. Such mixed flow heat exchangers can typically include two or more plate types.

[0021] The heat transfer plate can be designed such that the upper front groove portion of the front gasket groove is a mirror image of the lower front groove portion of the front gasket groove parallel to the transverse central axis of the heat transfer plate, which can allow a plate pack including only heat transfer plates according to the invention.

[0022] Of course, different designs of back gasket grooves are contemplated that correspond to the different designs of front gasket grooves described above.

[0023] A gasket for a plate heat exchanger according to the invention comprises an annular gasket part, an annular second ring gasket part and an annular fourth ring gasket part. The second and fourth ring gasket parts are arranged on the outside of the annular gasket part and on both sides of the annular gasket part. The second ring gasket part and the annular gasket part are separated by a second intermediate space and the fourth ring gasket part and the annular gasket part are separated by a fourth intermediate space. An upper gasket part of the gasket limits, defines or extends along the second intermediate space. A lower gasket part of the gasket limits, defines or extends along the fourth intermediate space. The gasket comprises a body part, the body part extends along the complete annular gasket part and the second and fourth ring gasket parts and includes an upper side and an opposite lower side. The upper and lower sides of the gasket body define a body thickness, the gasket being characterized in that the thickness of the gasket body increases in the upper gasket portion in a direction toward the second intermediate space and increases in the lower gasket portion in a direction toward the fourth intermediate space.

[0024] The thickness of the body of the gasket can increase gradually (possibly linearly) within the upper and lower gasket portions along the transverse extension of the upper and lower gasket portions of the gasket.

[0025] The upper and lower sides of the gasket body can be essentially planar.

[0026] The upper gasket portion of the gasket can be contained within an upper angled portion of the annular gasket part of the gasket, the upper angled portion extending inside the second ring gasket part of the gasket, and the lower gasket portion of the gasket can be contained within a lower angled portion of the annular gasket part of the gasket, the lower angled portion extending inside the fourth ring gasket part of the gasket.

[0027] Alternatively / additionally, the upper gasket portion of the gasket can be included within an inner portion of a second ring gasket part of the gasket, the inner portion extending between an outer portion of the second ring gasket part of the gasket and an upper beveled portion of the annular gasket part of the gasket, the upper beveled portion extending inwardly of the second ring gasket part of the gasket, and the lower gasket portion of the gasket can be included within an inner portion of a fourth ring gasket part of the gasket, the inner portion extending between an outer portion of the fourth ring gasket part of the gasket and a lower beveled portion of the annular gasket part of the gasket, the lower beveled portion extending inwardly of the fourth ring gasket part of the gasket.

[0028] The gasket may further include at least one elongated protrusion protruding from one of the upper and lower sides of the body and extending along at least the upper and lower gasket portions of the gasket, such protrusions may improve the sealing capabilities of the gasket.

[0029] The at least one elongate projection may be disposed offset from the second mid-plane of the body, whereby the sealing function of the gasket may be optimized.

[0030] The gasket can be configured such that the second central plane of the body of the gasket is disposed between the at least one protrusion and the second intermediate space in the upper gasket portion, and between the at least one protrusion and the fourth intermediate space in the lower gasket portion. Such an arrangement can position the protrusion relatively close to the fluid when the gasket is disposed between two heat transfer plates in the plate heat exchanger, which can enable early prevention of fluid leakage.

[0031] The gasket may have a design such that the second and fourth ring gasket parts of the gasket are located on the same side of the central longitudinal axis of the gasket.

[0032] The upper gasket portion of the gasket can be a mirror image of the lower gasket portion of the gasket parallel to the transverse center axis of the gasket.

[0033] The heat transfer plate and the gasket according to the invention are adapted to be used together, and the design of the gasket is adapted to the design of the heat transfer plate and vice versa. Thus, the above-mentioned different embodiments of the gasket according to the invention correspond to the above-mentioned different embodiments of the heat transfer plate according to the invention. Thus, the advantages of the above-mentioned different embodiments of the heat transfer plate are transferable to the above-mentioned different embodiments of the gasket. Naturally, these advantages first appear when the heat transfer plate and the gasket cooperate with each other and with other appropriately designed heat transfer plates and gaskets in the plate heat exchanger.

[0034] Further objects, features, aspects, and advantages of the present invention will become apparent from the following detailed description and from the drawings.

[0035] The invention will now be explained in more detail with reference to the accompanying schematic drawings. [Brief description of the drawings]

[0036] [Figure 1] FIG. 2 is a schematic plan view of a heat transfer plate according to the present invention, illustrating its front side. [Diagram 2] FIG. 2 is an enlarged view of a portion of the diagram in FIG. [Diagram 3] 3 illustrates a cross-section of the heat transfer plate of FIG. 1 taken along line AA of FIG. 2. [Figure 4] 2. FIG. 4 illustrates another cross-section of the heat transfer plate of FIG. 1 taken along line BB of FIG. [Diagram 5] FIG. 2 is an enlarged view of another portion of the view in FIG. [Figure 6] 6 illustrates another cross-section of the heat transfer plate of FIG. 1 taken along line CC of FIG. 5. [Figure 7] 6 illustrates yet another cross-section of the heat transfer plate of FIG. 1 taken along line DD of FIG. 5. [Figure 8] FIG. 2 is a schematic plan view of a gasket according to the present invention, illustrating its upper side. [Figure 9] 9 illustrates a cross-section of the gasket of FIG. 8 taken along line AA of FIG. 8. [Figure 10] 9 illustrates a cross-section of the gasket of FIG. 8 taken along line BB of FIG. 8. [Figure 11] 9 illustrates a cross-section of the gasket of FIG. 8 taken along line CC of FIG. 8. [Figure 12] 9 illustrates a cross-section of the gasket of FIG. 8 taken along line DD of FIG. 8. [Figure 13] FIG. 2 is a schematic plan view of another gasket according to the present invention, illustrating its upper side. [Figure 14] 14 illustrates a cross-section of the gasket of FIG. 13 taken along line AA of FIG. 13. [Figure 15] 14 illustrates a cross-section of the gasket of FIG. 13 taken along line BB of FIG. 13. [Figure 16] 14 illustrates a cross-section of the gasket of FIG. 13 taken along line CC of FIG. 13. [Figure 17] 14 illustrates a cross-section of the gasket of FIG. 13 taken along line DD of FIG. 13. [Figure 18] 14 illustrates a cross-section of the gasket of FIG. 13 taken along line EE of FIG. 13. [Figure 19] FIG. 2 illustrates two adjacent heat transfer plates and an intermediate gasket of a plate pack according to the prior art prior to compression of the plate pack. [Figure 20] FIG. 20 illustrates the heat transfer plates and gaskets of FIG. 19 after compression of the plate pack. [Figure 21] FIG. 2 illustrates two adjacent heat transfer plates and an intermediate gasket of a plate pack according to the invention prior to compression of the plate pack. [Figure 22] FIG. 22 illustrates the heat transfer plates and gaskets of FIG. 21 after compression of the plate pack. [Figure 23] 3 is a view corresponding to FIG. 2 for a plate according to an alternative embodiment of the invention; [Figure 24] 4 is a view corresponding to FIG. 3 for a plate according to an alternative embodiment of the invention; FIG. [Diagram 25] 5 is a view corresponding to FIG. 4 for a plate according to an alternative embodiment of the invention. [Figure 26] 6 is a view corresponding to FIG. 5 for a plate according to an alternative embodiment of the invention; [Figure 27] 7 is a view corresponding to FIG. 6 for a plate according to an alternative embodiment of the invention. [Figure 28] 8 is a view corresponding to FIG. 7, but for a plate according to an alternative embodiment of the invention. [Figure 29] 13A-13C illustrate cross sections of a gasket according to an alternative embodiment of the present invention. [Diagram 30] FIG. 13 illustrates another cross-section of a gasket according to an alternative embodiment of the present invention. [Diagram 31] 23 is a view corresponding to FIG. 22 for a plate and gasket according to an alternative embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Figures 1 to 7 show a heat transfer plate 1 (hereinafter also simply referred to as "plate") for a gasketed plate heat exchanger as described by the introduction, in which a number of heat transfer plates such as heat transfer plate 1 (i.e. a number of similar heat transfer plates) are aligned in a plate pack.

[0038] Referring to FIG. 1, plate 1 is an essentially rectangular sheet of stainless steel having a front side 3 (illustrated in FIGS. 1, 2, and 5) and an opposing back side 5 (illustrated in FIGS. 3, 4, 6, and 7). Plate 1 includes upper end portion 7 and lower end portion 19, with upper end portion 7 including first porthole 9, second porthole 11, upper distribution area 13, first insulation area 15, and second insulation area 17, and lower end portion 19 including third porthole 21, fourth porthole 23, lower distribution area 25, third insulation area 27, and fourth insulation area 29. Plate 1 further includes a central portion 31 and an outer edge portion 35, with central portion 31 including a heat transfer area 33 and outer edge portion 35 extending around upper and lower end portions 7 and 19 and central portion 31. The upper end portion 7 adjoins the central portion 31 along an upper boundary 37, while the lower end portion 19 adjoins the central portion 31 along a lower boundary 39. The upper end portion 7, the central portion 31 and the lower end portion 19 are arranged in succession along a central longitudinal axis LP of the plate 1, which extends perpendicularly to a central transverse axis TP of the plate 1. The first and third portholes 9 and 21 are arranged on the same side of the central longitudinal axis LP, while the second and fourth portholes 11 and 23 are arranged on the other side of the central longitudinal axis LP. The upper end portion 7 is a mirror image of the lower end portion 19, parallel to the central transverse axis TP of the heat transfer plate 1.

[0039] The heat transfer plate 1 is pressed in a pressing tool in a conventional manner to give it the desired structure (e.g. different corrugation patterns in different parts of the heat transfer plate). As explained by the introduction, the corrugation patterns are optimized for the specific function of the respective plate part. Thus, the upper and lower distribution areas 13 and 25 have a chocolate bar type distribution pattern, while the heat transfer area 33 has a herringbone type heat transfer pattern. The first, second, third and fourth insulating areas 15, 17, 27 and 29 include corrugations adapted to transport fluids with minimized heat transfer. Furthermore, the outer edge portion 35 includes corrugations 41, which make the outer edge portion 35 harder and therefore the heat transfer plate 1 more resistant to deformation. Furthermore, the corrugations 41 form support structures in that they are arranged to abut corrugations in the outer edge portions of adjacent heat transfer plates in the plate pack of the heat exchanger. The corrugations 41 extend between and in imaginary lower and upper planes P1 and P2 (FIGS. 3, 4, 6 and 7), which are parallel to the drawing planes of FIGS. 1 and 2.

[0040] With reference to FIG. 1 , the front gasket groove 43 is also pressed into the front side 3 of the heat transfer plate 1, the extension of which is partially illustrated by dashed lines in FIG. 1 . The front gasket groove 43 comprises an annular front groove part 45, a second ring groove part 47 and a fourth ring groove part 49. The annular front groove part 45 surrounds the heat transfer area 33, the upper and lower distribution areas 13 and 25, the first and third insulation areas 15 and 27, and the first and third portholes 9 and 21. The second ring groove part 47 surrounds the second porthole 11, while the fourth ring groove part 49 surrounds the fourth porthole 23. The upper half of the front gasket groove 43 is a mirror image of the lower half of the front gasket groove 43, parallel to the transverse central axis TP of the heat transfer plate 1. Further, referring to Figures 2 to 7, the plate 1 further includes, at its back side 5, a back gasket groove 51, the extension of which is partially illustrated by dashed lines in Figures 2 and 5. The back gasket groove 51 includes an annular back groove part 53, a first ring groove part 55, and a third ring groove part 57. The annular back groove part 53 surrounds the heat transfer area 33, the upper and lower distribution areas 13 and 25, the second and fourth insulation areas 17 and 29, and the second and fourth portholes 11 and 23. The first ring groove part 55 surrounds the first porthole 9, while the third ring groove part 57 surrounds the third porthole 21. The upper half of the back gasket groove 51 is a mirror image of the lower half of the back gasket groove 51, parallel to the transverse central axis TP of the heat transfer plate 1. Along the heat transfer area 33, the front gasket groove 43 (or, more specifically, its annular front groove part 45) is aligned in the back gasket groove 51 (or, more specifically, its annular back groove part 53).

[0041] 1, 2 and 5, the first ring groove part 55 and the third ring groove part 57 of the back gasket groove 51 each include an annular first inner edge 59 that defines the first porthole 9 of the plate 1, and an annular third inner edge 61 that defines the third porthole 21. Similarly, the second ring groove part 47 and the fourth ring groove part 49 of the front gasket groove 43 each include an annular second inner edge 63 that defines the second porthole 11 of the plate 1, and an annular fourth inner edge 65 that defines the fourth porthole 23.

[0042] 2 and 5 (which illustrate the front side of the front gasket groove 43) and 4 and 7 (which illustrate local cross sections of the front gasket groove 43), the bottom 67 of the annular front groove part 45 is planar and extends in an imaginary plane P3 that is located between an imaginary lower plane P1 and an upper plane P2. Thereby, essentially along the entire length of the annular front groove part 45, the depth of the front gasket groove 43 is essentially constant along the transverse extension of the front gasket groove 43, even though the depth may vary in different longitudinal cross sections of the annular front groove part 45. By way of example, the depth of the front gasket groove 43 along the two opposing long sides of the heat transfer plate 1 can be different from the depth of the front gasket groove 43 along the upper and lower oblique parts 45u and 45l of the annular front groove part 45 that extend inside the second and fourth ring groove parts 47 and 49. Furthermore, the bottom 69 of the upper front groove portion 71 of the front gasket groove 43 (here the inner portion 73 of the second ring groove part 47) is plane and is inclined by an angle α (which here is equal to 3 degrees) relative to the plane P3. This angle can have other values ​​in alternative embodiments of the invention. Thereby, the depth of the second ring groove part 47 (in its inner portion 73) increases linearly and gradually in the direction away from the second porthole 11. The bottom 75 of the outer portion 77 of the second ring groove part 47 (which outer portion 77 is arranged between the two transition portions 79 of the second ring groove part 47) is plane and extends in the plane P3. Thereby, along the outer portion 77 of the second ring groove part 47, the depth of the front gasket groove 43 is essentially constant along the transverse extension of the front gasket groove 43. Similarly, the bottom 81 of the lower front groove portion 83 of the front gasket groove 43 (here the inner portion 85 of the fourth ring groove part 49) is plane and is inclined with respect to the plane P3 by an angle β (which here is equal to 3 degrees). This angle can have other values ​​in alternative embodiments of the invention.Thereby, the depth of the fourth ring groove part 49 (in its inner portion 85) gradually increases linearly in the direction away from the fourth porthole 23. The bottom 87 of the outer portion 89 of the fourth ring groove part 49 (which outer portion 89 is arranged between the two transition portions 91 of the fourth ring groove part 49) is planar and extends in the plane P3. Along the outer portion 89 of the fourth ring groove part 49, the depth of the front gasket groove 43 is thereby essentially constant along the transverse extension of the front gasket groove 43. Here, the depth is equal to the distance between the groove bottom and the plane P2, measured perpendicularly to the plane P2.

[0043] 2 and 5 (which illustrate the back side of the back gasket groove 51) and 3 and 6 (which illustrate local cross sections of the back gasket groove 51), the bottom 93 of the annular back groove part 53 is planar and lies in the plane P3. Thereby, essentially along the entire length of the annular back groove part 53, the depth of the back gasket groove 51 is essentially constant along the transverse extension of the back gasket groove 51, even though the depth may vary in different longitudinal cross sections of the annular back groove part 53. As an example, the depth of the back gasket groove 51 along the two opposing long sides of the heat transfer plate 1 can be different from the depth of the back gasket groove 51 along the upper and lower oblique portions 53u and 53l of the annular back groove part 53 extending inside the first and third ring groove parts 55 and 57. Furthermore, the bottom 95 of the upper back groove portion 97 of the back gasket groove 51 (here the inner portion 99 of the first ring groove part 55) is plane and is inclined by an angle γ (which here is equal to 3 degrees) with respect to the plane P3. This angle can have other values ​​in alternative embodiments of the invention. Thereby, the depth of the first ring groove part 55 (in its inner portion 99) increases linearly and gradually in the direction away from the first porthole 9. The bottom 101 of the outer portion 103 of the first ring groove part 55 (which outer portion 103 is arranged between the two transition portions 105 of the first ring groove part 55) is plane and extends into the plane P3. Thereby, along the outer portion 103 of the first ring groove part 55, the depth of the back gasket groove 51 is essentially constant along the transverse extension of the back gasket groove 51. Similarly, the bottom 107 of the lower back groove portion 109 of the back gasket groove 51 (here the inner portion 111 of the third ring groove part 57) is planar and is inclined with respect to the plane P3 by an angle Ω (which here is equal to 3 degrees). This angle can have other values ​​in alternative embodiments of the invention.Thereby, the depth of the third ring groove part 57 (in its inner portion 111) gradually increases linearly in the direction away from the third porthole 21. The bottom 113 of the outer portion 115 of the third ring groove part 57 (which outer portion 115 is arranged between the two transition portions 117 of the third ring groove part 57) is planar and extends in the plane P3. Thereby, along the outer portion 115 of the third ring groove part 57, the depth of the back gasket groove 51 is essentially constant along the transverse extension of the back gasket groove 51. Here, the depth is equal to the distance between the groove bottom and the plane P1, measured perpendicularly to the plane P1.

[0044] As mentioned above, in a gasketed plate heat exchanger, a number of heat transfer plates, such as the heat transfer plate 1, are aligned in a plate pack (here "rotated" relative to one another). Between each two adjacent ones of the heat transfer plates, a rubber gasket 2 is arranged as illustrated in Figs. 8-12. The gasket 2 as oriented in Fig. 8 is arranged on the heat transfer plate 1 as oriented in Fig. 1. More specifically, the gasket 2 is accommodated in the front gasket groove 43 of the plate 1, such that the annular gasket part 4 of the gasket 2 is received in the annular front groove part 45, while the annular second ring gasket part 6 and the annular fourth ring gasket part 8 of the gasket 2 are received in the second ring groove part 47 and the fourth ring groove part 49, respectively. 8, the annular gasket part 4 and the second ring gasket part 6 are separated by a second intermediate space 10, while the annular gasket part 4 and the fourth ring gasket part 8 are separated by a fourth intermediate space 12. However, as illustrated in FIG. 8, the second and fourth ring gasket parts 6 and 8 are connected to the annular gasket part 4 by a number of joints 14 that bridge the second and fourth intermediate spaces 10 and 12. The joints 14 can be omitted in alternative embodiments of the invention. The upper half of the annular gasket part 4 and the second ring gasket part 6 are mirror images of the lower half of the annular gasket part 4 and the fourth ring gasket part 8 parallel to the transverse central axis TG of the gasket 2.

[0045] 9-12, which illustrate local transverse cross sections of the gasket 2, the gasket 2 includes an elongated body portion 16 extending along the annular gasket part 4, the second ring gasket part 6, and the fourth ring gasket part 8. The body portion 16 includes an essentially planar upper side 18 and an opposing essentially planar lower side 20, the lower side 20 being disposed to face the front side 3 of the plate 1. The thickness of the gasket body portion 16 is equal to the distance between the upper side 18 and the lower side 20 of the body portion 16.

[0046] The design of the gasket 2 is adapted to the design of the plate 1 and vice versa. Thus, the upper and lower sides 18 and 20 of the gasket body 16 extend essentially along the entire length of the annular gasket part 4 parallel to each other and to the first central plane C1 of the gasket body 16. Thereby, essentially along the entire length of the annular gasket part 4, the thickness of the gasket body 16 is essentially constant along the transverse extension of the gasket body 16, even though the thickness may vary among different longitudinal sections of the annular gasket part 4. By way of example, the thickness of the gasket body 16 along the portions of the annular gasket part 4 that are arranged to extend along two opposing long sides of the heat transfer plate 1 can be different from the thickness of the gasket body 16 along the upper and lower oblique portions 22 and 24 of the annular gasket part 4 that extend inside the second and fourth ring gasket parts 6 and 8. Furthermore, along the upper gasket portion 26 (here the inner portion 28 of the second ring gasket part 6 (bold reference number in FIG. 8 )) that defines the second intermediate space 10, the upper side 18 of the gasket body 16 is inclined by an angle θ (here equal to 2 degrees) relative to the first mid-plane C1, while the lower side 20 of the gasket body 16 is inclined by an angle μ (here equal to 2 degrees) relative to the first mid-plane C1. Thereby, the thickness of the gasket body 16 (in the inner portion 28 of the second ring gasket part 6) gradually increases linearly in the direction towards the upper oblique portion 22. Along the outer portion 30 of the second ring gasket part 6 (which outer portion 30 is disposed between two transition portions 32 of the second ring gasket part 6), the upper and lower sides 18 and 20 of the gasket body 16 extend parallel to one another so as to give the gasket body 16 an essentially constant thickness along the transverse extension of the gasket body 16.Furthermore, along the lower gasket portion 34 (here the inner portion 36 of the fourth ring gasket part 8 (bold reference number in FIG. 8 )) that defines the fourth intermediate space 12, the upper side 18 of the gasket body 16 is inclined by an angle Φ (which here is equal to 2 degrees) relative to the first mid-plane C1, while the lower side 20 of the gasket body 16 is inclined by an angle π (which here is equal to 2 degrees) relative to the first mid-plane C1. Thereby, the thickness of the gasket body 16 (in the inner portion 36 of the fourth ring gasket part 8) gradually increases linearly in the direction towards the lower oblique portion 24. Along the outer portion 38 of the fourth ring gasket part 8 (which outer portion 38 is disposed between two transition portions 40 of the fourth ring gasket part 8), the upper and lower sides 18 and 20 of the gasket body 16 extend parallel to one another so as to give the gasket body 16 an essentially constant thickness along the transverse extension of the gasket body 16.

[0047] Besides the body portion 16, the gasket 2 further includes an elongated upper projection 42 projecting from the upper side 18 of the body portion 16 and an elongated lower projection 44 projecting from the lower side 20 of the body portion 16. The upper projection 42 extends along the annular gasket part 4, the second ring gasket part 6 and the fourth ring gasket part 8, while the lower projection 44 extends only along the inner portions 28 and 36 of the second and fourth ring gasket parts 6, 8. The opposing upper and lower projections 42 and 44 are disposed offset from a second mid-plane C2, which is orthogonal to the first mid-plane C1. In the annular gasket part 4 of the gasket 2, the upper protrusion 42 is displaced toward the inner circumference 46 of the annular gasket part 4, in the second ring gasket part 6 of the gasket 2, the upper and lower protrusions 42 and 44 are displaced toward the inner circumference 48 of the second ring gasket part 6, and in the fourth ring gasket part 8 of the gasket 2, the upper and lower protrusions 42 and 44 are displaced toward the inner circumference 50 of the fourth ring gasket part 8.

[0048] Figures 21 and 22 illustrate how the gasket 2 according to the invention looks in cross section at the inner part 28 of the second ring gasket part 6 when the gasket 2 is placed between two heat transfer plates 1 according to the invention, with one of the heat transfer plates rotated relative to the other. Now referring to Figures 1, 2, 5 and 8, the inner part 28 of the second ring gasket part 6 of the gasket 2 is placed between the inner part 73 of the second ring groove part 47 of the front gasket groove 43 of the lower heat transfer plate 1 and the inner part 111 of the third ring groove part 57 of the back gasket groove 51 of the upper heat transfer plate 1. Figure 21 illustrates how the plates 1 look when they are not pressed against each other, the varying gasket groove depth of the plates and the varying thickness of the gasket body. Figure 22 illustrates what the plates look like when pressed against one another, the plate deformation resulting from compensating for the varying gasket groove depth, and the gasket deformation resulting from compensating for the varying gasket body thickness. Figures 19 and 20 illustrate the same as Figures 21 and 22, but for a prior art gasket and two prior art plates. The prior art gasket and plates are not "pre-deformed," which results in unwanted deformation of the gasket and plates as the plates are pressed against one another, resulting in a change in the distance between the plates on either side of the gasket.

[0049] The gasket 2 shown in Figures 8 to 12 is arranged to be positioned between two heat transfer plates 1 according to Figure 1, whereas the gasket 52 as shown in Figures 13 to 18 is arranged to be positioned between the outermost heat transfer plate 1 of the plate pack and the end plate of the gasketed plate heat exchanger. The gaskets 2 and 52 are similar in many aspects, and most of the above description is also valid for the gasket 52, with appropriate adjustments. However, there are some differences between the gaskets 2 and 52. For example, the extension of the annular gasket part 4 is different between the gaskets 2 and 52, the annular gasket part 4 of the gasket 52 lacks a protrusion protruding from the gasket body part 16, the gasket body part 16 of the gasket 52 is similar to half of the gasket body part 16 of the gasket 2, and the gasket 52 includes first and third ring gasket parts 54 and 56 in addition to the second and fourth ring gasket parts 6 and 8. In what follows, the last difference will be the focus.

[0050] Along the inner portion 58 of the first ring gasket part 54, the lower side 20 of the gasket body 16 is inclined at an angle (here, 2 degrees) relative to the upper side 18 of the gasket body 16. Thereby, the thickness of the gasket body 16 (in the inner portion 58 of the first ring gasket part 54) gradually increases linearly in a direction toward the outer portion 60 of the first ring gasket part 54. In the outer portion 60 of the first ring gasket part 54, the upper and lower sides 18 and 20 of the gasket body 16 extend parallel to one another, so as to give the gasket body 16 an essentially constant thickness along the transverse extension of the gasket body 16. Furthermore, along the inner portion 62 of the third ring gasket part 56, the lower side 20 of the gasket body 16 is inclined at an angle (here, 2 degrees) relative to the upper side 18 of the gasket body 16. Thereby, the thickness of the gasket body 16 (in the inner portion 62 of the third ring gasket part 56) gradually increases linearly in a direction towards the outer portion 64 of the third ring gasket part 56. In the outer portion 64 of the third ring gasket part 56, the upper and lower sides 18 and 20 of the gasket body 16 extend parallel to one another, so as to give the gasket body 16 an essentially constant thickness along the transverse extension of the gasket body 16. The upper projection 42 extends inwardly offset along the first and third ring gasket parts 54 and 56, and the lower projection 44 extends inwardly offset along the inner portions 58 and 62 of the first and third ring gasket parts 54 and 56.

[0051] As mentioned above, the pressing depth of the heat transfer plate is varied around the porthole to realize a ring groove part with a partially inclined bottom. Furthermore, the design of the gasket is varied to realize a ring gasket body part with a partially radial tapered. Instead of or in addition to varying the ring groove part pressing depth and the ring gasket body part thickness, the pressing depth and the gasket body part thickness can be varied in other plate areas and gasket areas, respectively, according to the invention. Hereafter, a heat transfer plate 1 and a gasket 2 according to an alternative embodiment of the invention will be described. This plate and this gasket (which are essentially designed as shown in Fig. 1 and Fig. 8, respectively) are in many aspects similar to the plate 1 and gasket 2 described above, and most of the above description is also valid for this plate and this gasket. Therefore, in order to avoid unnecessary repetition, the differences of the alternative embodiment are focused on below.

[0052] 23-28 illustrate a plate 1 according to an alternative embodiment. More specifically, FIGS. 23 and 26 illustrate the front side of the front gasket groove 43, and FIGS. 25 and 28 illustrate local cross sections of the front gasket groove 43. The bottom 67u of the upper front groove portion 71 of the front gasket groove 43 (here the upper oblique portion 45u of the annular front groove part 45) is plane and is inclined by an angle α (here equal to 4 degrees) with respect to a virtual plane P3 that is located between the virtual lower plane P1 and the upper plane P2. Similarly, the bottom 67l of the lower front groove portion 83 of the front gasket groove 43 (here the lower oblique portion 45l of the annular front groove part 45) is plane and is inclined by an angle β (here equal to 4 degrees) with respect to the plane P3. Thereby, the depth of the annular front groove part 45 (in its upper and lower oblique portions 45u and 45l) gradually increases linearly in the direction towards the second and fourth portholes 11 and 23. The bottom 67 of the annular front groove part 45 outside the upper and lower oblique portions 45u and 45l, as well as transition portions not shown or further described herein, are planar and extend in the plane P3, giving the annular front groove part 45 an essentially constant depth along the transverse extension of the front gasket groove 43. Furthermore, the bottoms 69 and 75 of the inner and outer portions 73 and 77 of the second ring groove part 47 as well as the bottoms 81 and 87 of the inner and outer portions 85 and 89 of the fourth ring groove part 49 are planar and extend in the plane P3. Thereby, along the second and fourth ring groove parts 47 and 49 , the depth of the front gasket groove 43 is essentially constant along the transverse extension of the front gasket groove 43 .

[0053] 23 and 26 illustrate the back side of the back gasket groove 51, and 24 and 27 illustrate local cross sections of the back gasket groove 51. The bottom 93u of the upper back groove portion 97 of the back gasket groove 51 (here the upper oblique portion 53u of the annular back groove part 53) is plane and is inclined by an angle γ (which is here equal to 4 degrees) with respect to the plane P3. Similarly, the bottom 93l of the lower back groove portion 109 of the back gasket groove 51 (here the lower oblique portion 53l of the annular back groove part 53) is plane and is inclined by an angle Ω (which is here equal to 4 degrees) with respect to the inclined plane P3. Thereby, the depth of the annular back groove part 53 (in its upper and lower oblique portions 53u and 53l) increases linearly and gradually in the direction towards the first and third portholes 9 and 21. The bottom 93 of the annular back groove part 53 outside the upper and lower oblique portions 53u and 53l, as well as transition portions not shown or further described herein, are planar and extend in the plane P3, giving the annular back groove part 53 an essentially constant depth along the transverse extension of the back gasket groove 51. Furthermore, the bottoms 95 and 101 of the inner and outer portions 99 and 103 of the first ring groove part 55, as well as the bottoms 107 and 113 of the inner and outer portions 111 and 115 of the third ring groove part 57, are planar and extend in the plane P3. Thereby, along the first and third ring groove parts 55 and 57, the depth of the back gasket groove 51 is essentially constant along the transverse extension of the back gasket groove 51.

[0054] Figures 29 and 30 show local transverse sections of a gasket 2 according to an alternative embodiment. Figure 29 illustrates a section through the upper and lower oblique portions 22 and 24 of the annular gasket part 4 of the gasket 2, while Figure 30 illustrates a section through essentially the remaining portion of the gasket 2. The design of the gasket 2 shown in Figures 29 and 30 is adapted to the design of the plate 1 shown in Figures 23 to 28 and vice versa. Thus, referring also to FIG. 8, as illustrated in FIG. 29, along the upper gasket portion 26 defining the second intermediate space 10 (here the upper oblique portion 22 of the annular gasket part 4 (non-bold reference number in FIG. 8)), the upper side 18 of the gasket body 16 is inclined by an angle θ (here equal to 6 degrees) relative to the first mid-plane C1, while the lower side 20 of the gasket body 16 is inclined by an angle μ (here equal to 4 degrees) relative to the first mid-plane C1. Similarly, as illustrated in Fig. 29, along the lower gasket portion 34 defining the fourth intermediate space 12 (here the lower beveled portion 24 of the annular gasket part 4 (non-bold reference number in Fig. 8)), the upper side 18 of the gasket body 16 is inclined by an angle Φ (here equal to 6 degrees) relative to the first mid-plane C1, while the lower side 20 of the gasket body 16 is inclined by an angle π (which is equal to 4 degrees) relative to the first mid-plane C1. Thereby, the thickness of the gasket body 16 (in the upper and lower beveled portions 22 and 24 of the annular gasket part 4) gradually increases linearly in the direction towards the second and fourth ring gasket parts 6 and 8 (Fig. 8). As shown in FIG. 30, outside the upper and lower angled portions 22 and 24 of the annular gasket part 4, as well as in transition portions not shown or further described herein, the upper and lower sides 18 and 20 of the gasket body 16 extend parallel to one another and to a first mid-plane C1 of the gasket body 16, giving the gasket body 16 an essentially constant thickness along its transverse extension.Further, along the second and fourth ring gasket parts 6 and 8, the upper and lower sides 18 and 20 of the gasket body 16 extend parallel to each other and to the first mid-plane C1 of the gasket body 16, giving the gasket body 16 an essentially constant thickness along the transverse extension of the gasket body 16.

[0055] In addition to the body portion 16, the gasket 2 according to the alternative embodiment further includes three elongated upper protrusions 42a, 42b, and 42c protruding from the upper side 18 of the body portion 16, but none protruding from the lower side 20 of the body portion 16. The upper protrusions 42a, 42b, and 42c extend along each other and along the entire length of the body portion 16. One of the upper protrusions 42b is disposed in alignment with the second mid-plane C2 of the gasket body portion 16, while the remaining two upper protrusions 42a and 42c are disposed on either side of the upper protrusion 42b.

[0056] Figure 31 illustrates how the gasket 2 according to the alternative embodiment looks in cross section at the upper beveled part 22 when the gasket 2 is pressed between two heat transfer plates 1 according to the alternative embodiment, with one of the heat transfer plates rotated relative to the other. Now, referring to Figures 8, 23 and 26, the upper beveled part 22 of the gasket 2 is located between the upper beveled part 45u of the annular front groove part 45 of the front gasket groove 43 of the lower heat transfer plate 1 and the lower beveled part 53l of the annular back groove part 53 of the back gasket groove 51 of the upper heat transfer plate 1. The beveled gasket groove bottom and the tapered gasket body, present before and remaining after the pressing, make it possible to ensure contact between the two heat transfer plates in the desired contact area, especially at the point P where the risk of plate separation is particularly high due to the medium pressure inside the channel formed between the heat transfer plates.

[0057] The above-described embodiments of the present invention should be seen as examples only, and those skilled in the art will recognize that the described embodiments can be modified and combined in multiple ways without departing from the inventive concept.

[0058] In the embodiment described above, both the upper and lower sides 18 and 20 of the gasket body 16 are tapered in the upper and lower gasket portions 26 and 34 of the gasket 2 to achieve a varying thickness of the gasket body 16. Of course, a varying body thickness could instead be achieved by tapering only one of the upper and lower sides 18 and 20.

[0059] Additionally, while in the embodiments described above the upper and lower sides of the gasket body are beveled at the same angle / angles in the upper and lower gasket portions of the gasket, this need not be the case in alternative embodiments.

[0060] In the embodiments described above, the bottoms of the upper and lower front groove portions and the bottoms of the upper and lower back groove portions are all sloped to achieve a varying groove depth. According to an alternative embodiment, only the bottoms of either the upper and lower front groove portions or the upper and lower back groove portions are sloped.

[0061] Furthermore, while in the embodiment described above the bottoms of the upper and lower front groove portions and the bottoms of the upper and lower back groove portions are all sloped at the same angle, this need not be the case in alternative embodiments.

[0062] The imaginary plane P3 used above to define the gasket groove depth may or may not be located midway between the planes P1 and P2. According to an alternative embodiment, the plane P3 may also coincide with the imaginary lower plane P1.

[0063] The boundaries of the upper and lower front groove portions, upper and lower back groove portions, and upper and lower gasket portions can be infinitely varied to reposition, reduce, or expand the areas where groove depth and gasket body thickness are varied. As an example, groove depth and gasket body thickness can be varied throughout the ring groove part and ring gasket part, respectively.

[0064] The number, extension, design, and / or positioning of the upper and lower protrusions of the gasket can be infinitely varied.

[0065] In the embodiments described above, the heat transfer plates of the plate packs and the gaskets between the heat transfer plates are all similar, but this is not necessary. For example, different types of plates can be combined in alternative plate packs, such as plates with differently configured heat transfer patterns.

[0066] The heat transfer plates do not have to be rectangular, but can have other shapes, such as essentially rectangular with rounded corners instead of right angles, circular, or elliptical. The port holes in the plates can have other shapes than those shown in the drawings, such as, for example, circular shapes. The heat transfer plates do not have to be made from stainless steel, but can be made from other materials, such as, for example, titanium or aluminum. Similarly, the gaskets do not have to be made from rubber.

[0067] The heat transfer plates of the present invention can be used with types of plate heat exchangers other than those with gaskets (e.g. semi-welded plate heat exchangers). Furthermore, the plates in the plate pack can be "flipped" instead of "rotated" relative to each other.

[0068] The heat transfer plate does not have to have a herringbone type heat transfer pattern and a chocolate bar type distribution pattern, but can have other patterns (both symmetrical and asymmetrical).

[0069] It is emphasized that the attributes front, back, top, bottom, first, second, third, etc. are used merely to distinguish between details and not to express any kind of orientation or ordering of the details with respect to each other.

[0070] It is further emphasized that details not relevant to the present invention have been omitted and that the figures are merely schematic and not drawn to scale. It is also to be noted that some of the figures are more simplified than others. Thus, some components may be shown in one figure but omitted in another. [Explanation of symbols]

[0071] 1 Plate 2 Gasket 3 Front side 4 Annular gasket parts 5 Backside 6 Second Ring Gasket Part 7 Upper end part 8 4th Ring Gasket Part 9. First Porthole 10 Second Intermediate Space 11 Second Porthole 12 Fourth Intermediate Space 13 Upper distribution area 14 Joint 15 First insulation area 16 Gasket body 17 Second insulation area 18 Upper Side 19 Lower end part 20 Lower Side 21 Third Porthole 22 Upper diagonal part 23 Fourth Porthole 24 Lower diagonal part 25 Lower distribution area 26 Upper gasket part 27 Third Insulation Area 28 Inner part 29 Fourth Insulation Area 30 outer part 31 Central part 32 Transition Section 33 Heat Transfer Area 34 Lower gasket part 35 Outer edge part 36 Inner part 37 Upper Border 38 Outer part 39 Lower Border 40 Transition Section 41 Corrugation 42 Upper protrusion 42a, 42b, 42c Upper protrusion 43 Front gasket groove 44 Lower protrusion 45 Circular front groove part 45u Upper diagonal part 45l Lower diagonal part 46 Inner circumference 47 Second ring groove part 48 Inner circumference 49 4th ring groove part 50 Inner circumference 51 Back gasket groove 52 Gasket 53 Circular back groove part 53u Upper diagonal part 53l Lower diagonal part 54 1st Ring Gasket Part 55 First ring groove part 56 3rd Ring Gasket Part 57 3rd ring groove part 58 Inner part 59 Annular first inner edge 60 outer part 61 Third inner edge 62 Inner part 63 Annular second inner edge 64 Outer part 65 Annular fourth inner edge 67 Bottom 67u bottom 67l bottom 69 Bottom 71 Upper front groove part 73 Inner part 75 Bottom 77 Outer part 79 Transition Section 81 Bottom 83 Lower front groove part 85 Inner part 87 Bottom 89 Outer part 91 Transition Section 93 Bottom 93u bottom 93l bottom 95 Bottom 97 Upper back groove part 99 Inner part 101 Bottom 103 Outer part 105 Transition 107 Bottom 109 Lower back groove part 111 Inner part 113 Bottom 115 Outer part 117 Transition C1 First midplane C2 Second midplane LP Plate Longitudinal Center Axis Points where the risk of P-plate separation is particularly high P1 Virtual lower plane P2 Virtual upper plane P3 Virtual Plane Transverse center axis of TP plate TG Gasket Transverse Center Axis α Angle β angle γ Angle Ω Angle θ Angle μ Angle Φ Angle π Angle

Claims

1. A heat transfer plate (1), comprising an upper end portion (7), a central portion (31) and a lower end portion (19) arranged successively along a longitudinal central axis (LP) of the heat transfer plate (1), the upper end portion (7) comprising a first porthole (9) and a second porthole (11) and an upper distribution area (13) having an upper distribution corrugation pattern, and the lower end portion (19) comprising a third porthole (21) and a fourth porthole (23) and a lower distribution corrugation pattern. and a lower distribution area (25) having a corrugated heat transfer pattern different from the upper distribution corrugation pattern and the lower distribution corrugation pattern, the central portion (31) includes a heat transfer area (33) having a corrugated heat transfer pattern different from the upper distribution corrugation pattern and the lower distribution corrugation pattern, the heat transfer plate (1) further includes, at its front side (3), a front gasket groove (43) which is adapted to connect the heat transfer area (33), the upper distribution area (13) and the lower distribution area (25), and the first port (11). a first porthole (9) and a second porthole (21), a second ring groove part (47) surrounding the second porthole (11), and a fourth ring groove part (49) surrounding the fourth porthole (23), the upper end portion (7) further comprising a second insulating area (17) extending between the annular front groove part (45) and the second ring groove part (47), and the lower end portion (19) further comprising a second insulating area (17) extending between the annular front groove part (45) and the second ring groove part (47), and a fourth insulating area (29) extending between the second porthole (11) and the upper distribution area (13), an upper front groove portion (71) of the front gasket groove (43) extending between the second porthole (11) and the upper distribution area (13) and including a bottom portion (67u, 69), and a lower front groove portion (83) of the front gasket groove (43) extending between the fourth porthole (23) and the lower distribution area (25) and including a bottom portion (67l, 81),a bottom (67l, 81) of the lower front groove portion (83) is inclined such that a depth of the front gasket groove (43) increases in the upper front groove portion (71) in a direction toward the second insulating area (17), and the bottom (67l, 81) of the lower front groove portion (83) is inclined such that a depth of the front gasket groove (43) increases in the lower front groove portion (83) in a direction toward the fourth insulating area (29).

2. The heat transfer plate (1) further includes a back gasket groove (51) on its back side (5), the back gasket groove (51) including an annular back groove part (53) extending around the heat transfer area (33), the upper distribution area (13) and the lower distribution area (25), the second porthole (11) and the fourth porthole (23), and a first ring groove part (54) surrounding the first porthole (9). 5) and a third ring groove part (57) surrounding the third porthole (21), the upper end portion (7) further comprises a first insulating area (15) extending between the annular back groove part (53) and the first ring groove part (55), the lower end portion (19) further comprises a third insulating area (27) extending between the annular back groove part (53) and the third ring groove part (57), and the back gasket groove an upper back groove portion (97) of the back gasket groove (51) extends between the first porthole (9) and the upper distribution area (13) and includes a bottom portion (93u, 95); a lower back groove portion (109) of the back gasket groove (51) extends between the third porthole (21) and the lower distribution area (25) and includes a bottom portion (93l, 107); the bottom portion (93u, 95) of the upper back groove portion (97) is inclined, and the back gasket groove (51) extends between the third porthole (21) and the lower distribution area (25) and includes a bottom portion (93l, 107); 2. The heat transfer plate (1) according to claim 1, wherein the depth of the back gasket groove (51) increases in the upper back groove portion (97) in a direction toward the first insulating area (15), and the bottom (93l, 107) of the lower back groove portion (109) is inclined such that the depth of the back gasket groove (51) increases in the lower back groove portion (109) in a direction toward the third insulating area (27).

3. 3. The heat transfer plate (1) according to claim 1 or 2, wherein the depth of the front gasket groove (43) gradually increases within the upper front groove portion (71) and the lower front groove portion (83) along a transverse extension of the upper front groove portion (71) and the lower front groove portion (83) of the front gasket groove (43).

4. 3. The heat transfer plate (1) according to claim 1 or 2, wherein the bottom (67u, 69) of the upper front groove portion (71) and the bottom (67l, 81) of the lower front groove portion (83) are flat.

5. 3. The heat transfer plate (1) according to claim 1 or 2, wherein the upper front groove portion (71) of the front gasket groove (43) is included in an upper oblique portion (45u) of the annular front groove part (45) of the front gasket groove (43), the upper oblique portion (45u) extending between the second insulation area (17) and the upper distribution area (13), and the lower front groove portion (83) of the front gasket groove (43) is included in a lower oblique portion (45l) of the annular front groove part (45) of the front gasket groove (43), the lower oblique portion (45l) extending between the fourth insulation area (29) and the lower distribution area (25).

6. 3. The heat transfer plate (1) according to claim 1 or 2, wherein the upper front groove portion (71) of the front gasket groove (43) is contained within an inner portion (73) of the second ring groove part (47) of the front gasket groove (43), the inner portion (73) extending between the second porthole (11) and the second insulation area (17), and the lower front groove portion (83) of the front gasket groove (43) is contained within an inner portion (85) of the fourth ring groove part (49) of the front gasket groove (43), the inner portion (85) extending between the fourth porthole (23) and the fourth insulation area (29).

7. 3. The heat transfer plate (1) according to claim 1 or 2, wherein the bottom (69, 75) of the second ring groove part (47) comprises an annular second inner edge (63) that defines the second porthole (11) and the bottom (81, 87) of the fourth ring groove part (49) comprises an annular fourth inner edge (65) that defines the fourth porthole (23).

8. A gasket (2) for a plate heat exchanger, the gasket (2) comprising an annular gasket part (4), an annular second ring gasket part (6) and an annular fourth ring gasket part (8), the second ring gasket part (6) and the fourth ring gasket part (8) being arranged outside the annular gasket part (4) and on both sides of the annular gasket part (4), the second ring gasket part (6) and the annular gasket part (4) being separated by a second intermediate space (10), the fourth ring gasket part (8) and the annular gasket part (4) being separated by a fourth intermediate space (12), and an upper gasket part (26) of the gasket (2) defining the second intermediate space (10). a lower gasket portion (34) of the gasket (2) defining the fourth intermediate space (12), the gasket (2) including a body portion (16) extending along a complete annular second ring and fourth ring gasket parts (4, 6, 8) and including a first side (18) and an opposing second side (20), the first side (18) and the second side (20) defining a thickness of the body portion (16), the thickness of the body portion (16) of the gasket (2) increasing in the upper gasket portion (26) in a direction toward the second intermediate space (10) and increasing in the lower gasket portion (34) in a direction toward the fourth intermediate space (12).

9. 9. The gasket (2) of claim 8, wherein the thickness of the body portion (16) of the gasket (2) gradually increases within the upper gasket portion (26) and the lower gasket portion (34) along a transverse extension of the upper gasket portion (26) and the lower gasket portion (34) of the gasket (2).

10. 10. The gasket (2) of claim 8 or 9, wherein the first side (18) and the second side (20) of the body portion (16) are essentially planar.

11. 10. The gasket (2) according to claim 8 or 9, wherein the upper gasket portion (26) of the gasket (2) is included in an upper beveled portion (22) of the annular gasket part (4) of the gasket (2), the upper beveled portion (22) extending inside the second ring gasket part (6) of the gasket (2), and the lower gasket portion (34) of the gasket (2) is included in a lower beveled portion (24) of the annular gasket part (4) of the gasket (2), the lower beveled portion (24) extending inside the fourth ring gasket part (8) of the gasket (2).

12. The upper gasket portion (26) of the gasket (2) is contained within an inner portion (28) of the second ring gasket part (6) of the gasket (2), the inner portion (28) extending between an outer portion (30) of the second ring gasket part (6) of the gasket (2) and an upper beveled portion (22) of the annular gasket part (4) of the gasket (2), the upper beveled portion (22) extending inside the second ring gasket part (6) of the gasket (2), 10. The gasket (2) according to claim 8 or 9, wherein the lower gasket portion (34) is included in an inner portion (36) of the fourth ring gasket part (8) of the gasket (2), the inner portion (36) extending between an outer portion (38) of the fourth ring gasket part (8) of the gasket (2) and a lower beveled portion (24) of the annular gasket part (4) of the gasket (2), the lower beveled portion (24) extending inside the fourth ring gasket part (8) of the gasket (2).

13. 10. The gasket (2) of claim 8 or 9, wherein the gasket (2) further comprises at least one elongated protrusion (42, 42a, 42b, 42c, 44), the at least one elongated protrusion (42, 42a, 42b, 42c, 44) protruding from one of the first side (18) and the second side (20) of the body portion (16) and extending along at least the upper gasket portion (26) and the lower gasket portion (34) of the gasket (2).

14. 14. The gasket (2) of claim 13, wherein the at least one elongated protrusion (42, 42a, 42c, 44) is offset from a second mid-plane (C2) of the body portion (16), the second mid-plane (C2) extending through the first side (18) and the second side (20) of the body portion (16).

15. 15. The gasket (2) of claim 14, wherein the second central plane (C2) of the body portion (16) of the gasket (2) is disposed between the at least one protrusion (42, 42a, 42b, 42c, 44) and the second intermediate space (10) in the upper gasket portion (26), and is disposed between the at least one protrusion (42, 42a, 42b, 42c, 44) and the fourth intermediate space (12) in the lower gasket portion (34).

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