Heat transfer plate and a plate pack for a heat exchanger comprising a plurality of such heat transfer plates

A heat transfer plate comprises first, third and fourth guiding sections. The first and fourth guiding sections each comprise, as seen from a first side of the heat transfer plate, a male projection to engage the first adjacent heat transfer plate for aligning the plate and the first adjacent heat transfer plate, and, as seen from a second side of the heat transfer plate, a female recess to engage the second adjacent heat transfer plate for aligning the plate and the second adjacent heat transfer plate. The third guiding section comprises, as seen from the second side of the plate, a male projection to engage the second adjacent heat transfer plate for aligning the plate and the second adjacent plate, and, as seen from the first side of the plate, a female recess to engage the first adjacent heat transfer plate for aligning the plate and the first adjacent plate.

TECHNICAL FIELD

The invention relates to a heat transfer plate and its design. The invention also relates to a plate pack for a heat exchanger comprising a plurality of such heat transfer plates.

BACKGROUND ART

Plate heat exchangers, PHEs, typically consist of two end plates in 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 or different types and they may 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 other heat transfer plates, and every other heat transfer plate turned upside down in relation to the rest of the heat transfer plates. Typically, this is referred to as the heat transfer plates being “rotated” in relation 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 back side, respectively, of other heat transfer plates, and every other heat transfer plate turned upside down in relation to the rest of the heat transfer plates. Typically, this is referred to as the heat transfer plates being “flipped” in relation to each other.

In one type of well-known PHEs, the so called gasketed PHEs, gaskets are arranged between the heat transfer plates. The end plates, and therefore the heat transfer plates, are pressed towards each other by some kind of tightening means, whereby the gaskets seal 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 of initially different temperatures, which are fed to/from the PHE through inlets/outlets, can flow alternately through every second channel for transferring heat from one fluid to the other, which fluids enter/exit the channels through inlet/outlet port holes in the heat transfer plates communicating with the inlets/outlets of the PHE.

The end plates of a gasketed PHE are often referred to as frame plate and pressure plate. The frame plate is often fixed to a support surface such as the floor while the pressure plate is movable in relation to the frame plate. Often, an upper carrying bar for carrying the heat transfer plates, and possibly also the pressure plate, is fastened to the frame plate and extends from an upper part thereof, past the pressure plate and to a support column. Similarly, a lower guiding bar for guiding the heat transfer plates, and possibly also the pressure plate, is fastened to the frame plate and extends from a lower part thereof, on a distance from the ground, past the pressure plate and to the support column.

For a PHE to work properly, it is important that the heat transfer plates are aligned with each other in the stack since non-aligned heat transfer plates may result in a leaking PHE. Although the carrying and guiding bars of a heat exchanger may provide alignment of, by engagement with, the heat transfer plates, this alignment may be insufficient. Also, some PHEs may lack a carrying bar and/or a guiding bar. In view thereof, some heat transfer plates are provided with guiding sections wherein a guiding section of one heat transfer plate is arranged to engage with a guiding section of another heat transfer plate for alignment of the heat transfer plates. WO 2010/064975 discloses such heat transfer plates arranged in a stack wherein every other heat transfer plate is “rotated” in relation to the other heat transfer plates. Although WO 2010/064975 discloses a guiding solution that works very well, it is limited to alignment of heat transfer plates “rotated” in relation to each other.

SUMMARY

An object of the present invention is to provide a heat transfer plate which solves the above mentioned problem. The basic concept of the invention is to provide the heat transfer plate with a guiding solution which is more flexible than known solutions in that it enables alignment of the heat transfer plate and another heat transfer plate irrespective of whether the two heat transfer plates are “rotated” or “flipped” in relation to each other. Another object of the present invention is to provide a plate pack for a heat exchanger comprising a first, a second and a third such heat transfer plate. The heat transfer plate and the plate pack for achieving the objects above are defined in the appended claims and discussed below.

A heat transfer plate according to the present invention has opposing first and second sides, an outer edge and a central extension plane and includes an edge portion comprising corrugations. The corrugations extend between first and second planes which are parallel to the central extension plane, and the central extension plane is arranged between the first and second planes. The corrugations are arranged, at the first side of the heat transfer plate, to abut a first adjacent heat transfer plate, and at the second side of the heat transfer plate, to abut a second adjacent heat transfer plate, when the heat transfer plate is arranged in a plate heat exchanger. Longitudinal and transverse centre axes of the heat transfer plate extending parallel to the central extension plane and perpendicular to each other, define a first, a second, a third and a fourth plate area. The first and second plate areas are arranged on the same side of the transverse centre axis and the first and the third plate areas are arranged on the same side of the longitudinal centre axis. The first, third and fourth plate areas comprise a first, third and fourth guiding section, respectively. The heat transfer plate is characterized in that the first and fourth guiding sections each comprise, as seen from the first side of the heat transfer plate, a male projection projecting beyond the first plane and arranged to engage with the first adjacent heat transfer plate for alignment of the heat transfer plate and the first adjacent heat transfer plate, and, as seen from the second side of the heat transfer plate, a female recess arranged to engage with the second adjacent heat transfer plate for alignment of the heat transfer plate and the second adjacent heat transfer plate. Further, the third guiding section comprises, as seen from the second side of the heat transfer plate, a male projection projecting beyond the second plane and arranged to engage with the second adjacent heat transfer plate for alignment of the heat transfer plate and the second adjacent heat transfer plate, and, as seen from the first side of the heat transfer plate, a female recess arranged to engage with the first adjacent heat transfer plate for alignment of the heat transfer plate and the first adjacent heat transfer plate.

The first and second sides of the heat transfer plate may also be referred to as front and back side.

The central extension plane may be arranged half way between the first and second planes.

The longitudinal centre axis may extend along opposing long sides of the heat transfer plate, while the transverse centre axis may extend along opposing short sides of the heat transfer plate.

The edge portion may be an outer peripheral edge portion of the heat transfer plate or an inner edge portion such as an edge portion defining a port hole of the heat transfer plate. Further, the complete edge portion, or only one or more portions thereof, may comprise corrugations. The corrugations may be evenly or unevenly distributed along the edge portion, and they may, or may not, all look the same. The edge portion may comprise further corrugations extending within or outside the first and second planes.

The corrugations define ridges and valleys which may give the edge portion a wave-like design. As seen from the first side of the plate, when the heat transfer plate is arranged in a plate heat exchanger, the ridges are arranged to abut the first adjacent plate while the valleys are arranged to abut the second adjacent heat transfer plate.

The heat transfer plate may be essentially rectangular, and the longitudinal and transverse centre axes essentially perpendicular to each other so as to define four essentially rectangular plate areas.

“As seen from the first side of the heat transfer plate” means when the first side of the heat transfer plate is viewed at a distance. Similarly, “as seen from the second side of the heat transfer plate” means when the second side of the heat transfer plate is viewed at a distance.

The heat transfer plate and the first and second adjacent heat transfer plates may all be of the same type. Alternatively, the heat transfer plate and the first and second adjacent heat transfer plates may be of different types. For example, the heat transfer plate and the first and second adjacent heat transfer plates may all comprise guiding sections as defined in the claims but otherwise be differently designed.

The above configuration of the guiding sections may enable alignment of the heat transfer plate and an adjacent heat transfer plate irrespective of whether the adjacent heat transfer plate is rotated or flipped with respect to the heat transfer plate. Further, alignment of the heat transfer plate and the adjacent heat transfer plate by means of at least two of the guiding sections of the heat transfer plate may be enabled, which improves the alignment. Moreover, alignment of the heat transfer plate and two adjacent heat transfer plates, e.g. the first and second adjacent heat transfer plates referred to above, by means of each of said at least two of the guiding sections of the heat transfer plate may be enabled, which improves the alignment. The alignment enablement is naturally dependent on the design of the adjacent heat transfer plate(s).

The second plate area may comprise a second guiding section comprising, as seen from the second side of the heat transfer plate, a male projection projecting beyond the second plane and arranged to engage with the second adjacent heat transfer plate for alignment of the heat transfer plate and the second adjacent heat transfer plate, and, as seen from the first side of the heat transfer plate, a female recess arranged to engage with the first adjacent heat transfer plate for alignment of the heat transfer plate and the first adjacent heat transfer plate. Thereby, alignment of the heat transfer plate and the adjacent heat transfer plate by means of all of the guiding sections of the heat transfer plate may be enabled, which improves the alignment. Moreover, alignment of the heat transfer plate and two adjacent heat transfer plates, e.g. the first and second adjacent heat transfer plates referred to above, by means of each of all the guiding sections of the heat transfer plate may be enabled, which improves the alignment. Again, the alignment enablement is naturally dependent on the design of the adjacent heat transfer plate(s).

A respective top of the male projections of the first and second guiding sections may extend from a distance ML1to a distance ML2from the transverse centre axis and from a distance MW1to a distance MW2from the longitudinal centre axis, and a respective opening or root of the female recesses of the third and fourth guiding sections may extend from a distance FL1to a distance FL2from the transverse centre axis and from a distance FW1to a distance FW2from the longitudinal centre axis, wherein FL1<ML1<ML2<FL2and FW1<MW1<MW2<FW2. Further, (each of) the male projections of the first and second guiding sections may fit into (each of) the female recesses of the third and fourth guiding sections. By “fit” is meant that the male projections at least partly could be received in the female recesses. For example, the male projections could have outer circumferences which are smaller than inner circumferences of the female recesses and/or outer surfaces of the male projections could define volumes which are smaller than volumes defined by inner surfaces of the female recesses. Naturally, reception of the male projections of a heat transfer plate in the female recesses of the same heat transfer plate is not relevant and impossible without deforming or cutting the heat transfer plate. However, this embodiment may enable alignment of the heat transfer plate and first and second adjacent heat transfer plates of the same type as the heat transfer plate, or at least comprising guiding sections as above defined, by insertion of the male projections of the first and second guiding sections of the heat transfer plate in the female recesses of the third and fourth guiding sections of the first and second adjacent heat transfer plates, and reception, of the male projections of the first and second guiding sections of the first and second adjacent heat transfer plates, by the female recesses of the third and fourth guiding sections of the heat transfer plate.

A respective top of the male projections of the third and fourth guiding sections may extend from a distance ML3to a distance ML4from the transverse centre axis and from a distance MW3to a distance MW4from the longitudinal centre axis, and a respective opening or root of the female recesses of the first and second guiding sections may extend from a distance FL3to a distance FL4from the transverse centre axis and from a distance FW3to a distance FW4from the longitudinal centre axis, wherein FL3<ML3<ML4<FL4and FW3<MW3<MW4<FW4. Further, (each of) the male projections of the third and fourth guiding sections may fit into (each of) the female recesses of the first and second guiding sections. The meaning of “fit” is as defined above. This embodiment may enable alignment of the heat transfer plate and first and second adjacent heat transfer plates of the same type as the heat transfer plate, or at least comprising guiding sections as above defined, by insertion of the male projections of the third and fourth guiding sections of the heat transfer plate in the female recesses of the first and second guiding sections of the first and second adjacent heat transfer plates, and reception, of the male projections of the third and fourth guiding sections of the first and second adjacent heat transfer plates, by the female recesses of the first and second guiding sections of the heat transfer plate.

The first and fourth guiding sections may each comprise a first plane portion extending between the outer edge of the heat transfer plate and the male projection, or even surrounding the male projection, and extending parallel to the central extension plane. Further, the second and third guiding sections may each comprise a second plane portion extending between the outer edge of the heat transfer plate and the male projection, or even surrounding the male projection, and extending parallel to the central extension plane. This embodiment excludes arrangement of the male projections immediately at an outer edge portion of the heat transfer plate which may improve the stability of the guiding sections.

Similarly, the first and fourth guiding sections may each comprise a second plane portion extending between the outer edge of the heat transfer plate and the female recess, or even surrounding the female recess, and extending parallel to the central extension plane, and the second and third guiding sections may each comprise a first plane portion extending between the outer edge of the heat transfer plate and the female recess, or even surrounding the female recess, and extending parallel to the central extension plane. This embodiment excludes arrangement of the female recesses immediately at an outer edge portion of the heat transfer plate which may improve the stability of the guiding sections.

The first and second plane portions referred to above may extend in different planes. For example, they may extend in the first and the second plane, respectively, of the heat transfer plate. The first and second plane portions may then be arranged to abut the first and the second adjacent heat transfer plate, respectively, which may improve the stability of the guiding sections.

Each of the first plane portions of the first, second, third and fourth guiding sections may “branch” towards the outer edge of the heat transfer plate so as to define and at least partly enclose a respective third plane portion extending in the second plane.

The heat transfer plate may be such that, as seen from the first side of the heat transfer plate, two reinforcement recesses, in relation to the first plane portions, are arranged on opposite sides of each of the first plane portions, and two reinforcement projections, in relation to the second plane portions, are arranged on opposite sides of each of the second plane portions. The reinforcement recesses and projections may be arranged in succession along the outer edge of the heat transfer plate. As implied by the names, the reinforcement recesses and projections are arranged to reinforce and stiffen the heat transfer plate so as to reduce the risk of deformation of the guiding sections of the heat transfer plate when this engages with the first and second adjacent heat transfer plates, which could affect the alignment of the three heat transfer plates negatively. Bottoms of the reinforcement recesses may extend in the second plane while tops of the reinforcement projections may extend in the first plane. The reinforcement recesses and projections may then be arranged to abut the first and the second adjacent heat transfer plate, respectively, which may improve the stability of the guiding sections. For example, one or more of the reinforcement recesses and projections could comprise a respective one of the corrugations of the edge portion of the heat transfer plates.

The first, second, third and fourth guiding sections may be arranged at a respective one of four corners of the heat transfer plate. Then, the guiding sections may be arranged as far from each other as is possible and suitable which may result in an optimized alignment between the heat transfer plate and the first and second adjacent heat transfer plates.

The heat transfer plate may comprise two opposing long sides extending parallel to the longitudinal centre axis and two opposing short sides extending parallel to the transverse centre axis. Within each of the first, second, third and fourth guiding sections, the female recess and the male projection may be arranged on opposite sides of an imaginary straight line extending with an angle of 45 degrees in relation to one of the long sides and one of the short sides of the heat transfer plate. This may result in an optimized alignment between the heat transfer plate and the first and second adjacent heat transfer plates.

The heat transfer plate may be so designed that a depth of the female recesses of the third and fourth guiding sections is a ≥height of the male projections of the first and second guiding sections, and a depth of the female recesses of the first and second guiding sections is a ≥height of the male projections of the third and fourth guiding sections. Such an embodiment may enable that the complete male projections of the heat transfer plate may be received in recesses of first and second adjacent heat transfer plates of the same type as the heat transfer plate, or at least comprising guiding sections as above defined, and that the female recesses of the heat transfer plate completely may receive male projections of the first and second adjacent heat transfer plates. In turn, this enables an optimized alignment of the heat transfer plate and the first and second adjacent heat transfer plates.

At least one of the male projections of the first and second guiding sections and at least one of the female recesses of the third and fourth guiding sections may have an at least partly uniform cross section parallel to the central extension plane. Similarly, at least one of the female recesses of the first and second guiding sections and at least one of the male projections of the third and fourth guiding sections may have an at least partly uniform cross section parallel to the central extension plane. Thereby, a good fit between the male projections and the female recesses of the heat transfer plate and first and second adjacent heat transfer plates of the same type as the heat transfer plate, or at least comprising guiding sections as above defined, may be enabled.

At least one of the male projections of the first and second guiding sections and at least one of the female recesses of the third and fourth guiding sections may have a cross section parallel to the central extension plane comprising two perpendicular portions, i.e. two portions that are perpendicular to each other, each. Similarly, at least one of the female recesses of the first and second guiding sections and at least one of the male projections of the third and fourth guiding sections may have a cross section parallel to the central extension plane comprising two perpendicular portions each. Thereby, alignment, in two perpendicular directions, i.e. optimum alignment, of the heat transfer plate and first and second adjacent heat transfer plates of the same type as the heat transfer plate, or at least comprising guiding sections as above defined, may be enabled.

A plate pack for a heat exchanger according to the invention comprises a first, a second and a third heat transfer plate as described above, which heat transfer plates may or may not be similar. The second heat transfer plate is arranged between the first and third heat transfer plates. When the first and second sides of the second heat transfer plate abut the second side of the first heat transfer plate and the first side of the third heat transfer plate, respectively, and the second heat transfer plate is rotated 180 degrees in relation to the first and third heat transfer plates about an axis extending parallel to a normal of the central extension plane, and through a cross point between the longitudinal and transverse centre axes, of the second heat transfer plate, i.e. when the heat transfer plates are rotated in relation to each other with the above definition,the male projections of the first and fourth guiding sections of the second heat transfer plate are received in the female recesses of the fourth and first guiding sections, respectively, of the first heat transfer plate,the male projections of the second and third guiding portions of the first heat transfer plate are received in the female recesses of the third and second guiding sections, respectively, of the second heat transfer plate,the male projections of the fourth and first guiding sections of the third heat transfer plate are received in the female recesses of the first and fourth guiding sections, respectively, of the second heat transfer plate, andthe male projections of the second and third guiding portions of the second heat transfer plate are received in the female recesses of the third and second guiding sections, respectively, of the third heat transfer plate.

Further, when the first and second sides of the second heat transfer plate abut the first side of the first heat transfer plate and the second side of the third heat transfer plate, respectively, and the second heat transfer plate is rotated 180 degrees in relation to the first and third heat transfer plates about an axis coinciding with the transverse centre axis of the second heat transfer plate, i.e. when the heat transfer plates are flipped in relation to each other with the above definition,the male projections of the first and fourth guiding sections of the second heat transfer plate are received in the female recesses of the third and second guiding sections, respectively, of the first heat transfer plate,the male projections of the first and fourth guiding sections of the first heat transfer plate are received in the female recesses of the third and second guiding sections, respectively, of the second heat transfer plate,the male projections of the second and third guiding sections of the third heat transfer plate are received in the female recesses of the fourth and first guiding sections, respectively, of the second heat transfer plate, andthe male projections of the second and third guiding sections of the second heat transfer plate are received in the female recesses of the fourth and first guiding sections, respectively, of the third heat transfer plate.

Still other objectives, features, aspects and advantages of the invention will appear from the following detailed description as well as from the drawings.

DETAILED DESCRIPTION

With reference toFIG.1, a plate pack2for a gasketed plate heat exchanger comprising a plurality of heat transfer plates is shown. All of the heat transfer plates are of the same type. InFIGS.4a-4d, which will be further discussed below, a first, a second and a third heat transfer plate4a,4band4c, respectively, of this plurality of heat transfer plates are illustrated. The first heat transfer plate4ais also visible inFIG.1. The design and function of a gasketed plate heat exchanger are well known and were discussed by way of introduction and, therefore, no further description is given here.

The heat transfer plate4awill now be further described with reference toFIGS.1,2a-2dand3a-3gwhich illustrate the heat transfer plate and portions and cross sections of the heat transfer plate, respectively. The heat transfer plate4ais an essentially rectangular sheet of stainless steel having opposing first and second sides6and8, respectively, which also may be referred to as front and back sides. InFIG.1, only the first side6is visible. The heat transfer plate4acomprises two opposing long sides10and two opposing short sides12.

The heat transfer plate further has a longitudinal centre axis20extending parallel to, and half way between, the long sides10, and a transverse centre axis22extending parallel to, and half way between, the short sides12, and thus perpendicular to the longitudinal centre axis20(FIG.1). The longitudinal and transverse centre axes divide the heat transfer plate4ainto four equally large first, second, third and four plate areas,24,26,28and30, respectively. The first and second plate areas24and26are arranged on the same side of the transverse centre axis22while the first and the third plate areas24and28are arranged on the same side of the longitudinal centre axis20.

The heat transfer plate4acomprises four port holes32arranged at a respective one of four corners34,36,38and40of the heat transfer plate, and recesses42extending from a respective one of the short sides12of the heat transfer plate4aand arranged to receive carrying and guiding bars of the plate heat exchanger.

The heat transfer plate4ais 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. The corrugation patterns are optimized for the specific functions of the respective plate portions. Accordingly, the heat transfer plate4acomprises two distribution areas44which each is provided with a distribution pattern adapted for optimized fluid distribution across the heat transfer plate. Further, the heat transfer plate4acomprises a heat transfer area46arranged between the distribution areas44and provided with a heat transfer pattern adapted for optimized heat transfer between two fluids flowing on opposite sides of the heat transfer plate. Moreover, the heat transfer plate4acomprises inner edge portions48surrounding the port holes32and an outer edge portion50extending along an outer edge51of the heat transfer plate4a. The inner and outer edge portions48and50comprises corrugations52which make the inner and outer edge portions stiffer and, thus, the heat transfer plate4amore resistant to deformation. Further, the corrugations52form a support structure in that they are arranged to abut adjacent heat transfer plates when the heat transfer plate4ais arranged in the plate heat exchanger. Depending on the design of the distribution and heat transfer patterns, the heat transfer plate4amay also be arranged to abut adjacent heat transfer plates within the distribution and heat transfer areas44and46, respectively, when the heat transfer plate is arranged in the plate heat exchanger. However, this is not further discussed herein. Also, the heat transfer plate4acomprises a groove53arranged to receive a gasket.

With reference especially toFIGS.2d,3eand3f, the corrugations52extend within and between a first plane54and a second plane56, which are parallel to a central extension plane58and to the figure plane ofFIG.1. The central extension plane58extends half way between the first and second planes54and56, respectively, and a bottom of the groove53extends in the central extension plane, i.e. in so called half plane.

The first, second, third and fourth plate areas24,26,28and30comprise a first, second, third and fourth guiding section60,62,64and66, respectively, arranged at a respective one of the four corners34,36,38and40of the heat transfer plate4a. With reference especially toFIGS.2a,3a,2d,3dand3f, the first and fourth guiding sections60and66comprise, as seen from the first side6of the heat transfer plate4a, a respective male projection68and70. The male projections68and70project from a respective first plane portion72and74of the first and fourth guiding sections60and66surrounding the respective male projections68and70and extending in the first plane54. Thus, the male projections68and70project from the first plane54, to a third plane76arranged on the opposite side of the first plane54than the central extension plane58. Further, the first and fourth guiding sections60and66comprise, as seen from the second side8of the heat transfer plate4a, a respective female recess78and80. The female recesses78and80extend from a respective second plane portion82and84of the first and fourth guiding sections60and66surrounding the respective female recesses78and80and extending in the second plane56. Thus, the female recesses78and80extend from the second plane56, to a fourth plane86arranged on the same side of the central extension plane58as the first plane54.

Similarly, with reference especially toFIGS.2b,3b,2cand3cthe second and third guiding sections62and64comprise, as seen from the second side8of the heat transfer plate4a, a respective male projection88and90. The male projections88and90project from a respective second plane portion92and94of the second and third guiding sections62and64surrounding the respective male projections88and90and extending in the second plane56. Thus, the male projections88and90projects from the second plane56, to a fifth plane96arranged on the opposite side of the second plane56than the central extension plane58. Further, the second and third guiding sections62and64comprise, as seen from the first side6of the heat transfer plate4a, a respective female recess98and100. The female recesses98and100extend from a respective first plane portion102and104of the second and third guiding sections62and64surrounding the respective female recesses98and100and extending in the first plane54. Thus, the female recesses102and104extends from the first plane54, to a sixth plane106arranged on the same side of the central extension plane58as the second plane56.

Naturally, the male projections as seen from one side of the heat transfer plate forms female recesses as seen from the other side of the plate, and vice versa.

Thus, as is clear fromFIGS.2a,2b,2cand2d, each of the first, second, third and fourth guiding sections60,62,64and66comprises a male projection and a female recess. Within each of the first, second, third and fourth guiding sections, the female recess and the male projection are arranged on opposite sides of an imaginary straight line108extending from the respective one of the corners34,36,38and40with an angle of 45 degrees in relation to the long side and the short side defining the respective one of the corners.

The male projections68,70,88and90and the female recesses78,80,98and100all have, parallel to the central extension plane58, an essentially uniform rectangular cross section, with a cross section of the female recesses being larger than the cross section of the male projections. All the female recesses have essentially the same cross section while all the male projections have essentially the same cross section. Thus, the male projections fit into the female recesses. Further, all the female recesses have essentially the same depth d while all the male projections have essentially the same height h, and d is essentially equal to h. The depth d and height h of the female recess78and the male projection68of the first guiding section60is illustrated inFIG.2a.

As is clear fromFIG.1in combination withFIGS.2a,2b,2cand2d, an opening78′ and98′ of each of the female recesses78and98of the first and second guiding sections60and62, respectively, extends from a distance FL3to a distance FL4from the transverse centre axis22, and from a distance FW3to a distance FW4from the longitudinal centre axis20. Further, a top90′ and70′ of each of the male projections90and70of the third and fourth guiding sections64and66, respectively, extends from a distance ML3to a distance ML4from the transverse centre axis22, and from a distance MW3to a distance MW4from the longitudinal centre axis20. FL3<ML3<ML4<FL4and FW3<MW3<MW4<FW4. Furthermore, a top68′ and88′ of each of the male projections68and88of the first and second guiding sections60and62, respectively, extends from a distance ML1to a distance ML2from the transverse centre axis22, and from a distance MW1to MW2from the longitudinal centre axis20. Further, an opening100′ and80′ of each of the female recesses100and80of the third and fourth guiding sections64and66, respectively, extends from a distance FL1to a distance FL2from the transverse centre axis22, and from a distance FW1to a distance FW2from the longitudinal centre axis20. FL1<ML1<ML2<FL2and FW1<MW1<MW2<FW2.

With reference especially toFIGS.2a,2b,2c,2d,3e,3fand3g, in order to stiffen the corners34,36,38and40of the heat transfer plate4a, each of the first plane portions72,102,104and74of the first, second, third and fourth guiding sections60,62,64and66, respectively, “branches” towards the outer edge51of the heat transfer plate4aso as to define and partly enclose a third plane portion110′,112′,114′ and116′, respectively, extending in the second plane56. More particularly, the first plane portions72,102,104and74each comprises a “branch” or sub portion forming a first reinforcement projection72′,102′,104′ and74′ on one side of the respective one of the second plane portions82,92,94and84. The respective most adjacent one of the corrugations52on the other opposing side of the second plane portions82,92,94and84forms second reinforcement projections52A,52B,52C and52D. Each of the third plane portions110′,112′,114′ and116′ forms a bottom of a respective first reinforcement recesses110,112,114and116arranged on one side of the respective one of the first plane portions72,102,104and74. The respective most adjacent one of the corrugations52on the other opposing side of the first plane portions72,102,104and74forms second reinforcement recesses52a,52b,52cand52d.

FIGS.4a-4dillustrate cross sections of the first, second and third heat transfer plates4a,4band4cof the plate pack2ofFIG.1. The second heat transfer plate4bis arranged between the first and third heat transfer plates4aand4c. Further, the second heat transfer plate4bis rotated 180 degrees about an axis perpendicular to, and extending through a cross point between, its transverse and longitudinal centre axes20and22, in relation to the first and third heat transfer plates4aand4c. Thereby, the first and second sides6and8of the second heat transfer plate4babut the second side8of the first heat transfer plate4aand the first side6of the third heat transfer plate4c, respectively. More particularly, portions of the second heat transfer plate4bextending in the first plane54contact opposing portions of the first heat transfer plate4aextending in the second plane56, and portions of the second heat transfer plate4bextending in the second plane56contact opposing portions of the third heat transfer plate4cextending in the first plane54. For example, as schematically illustrated inFIG.6for the outer edge portions of the heat transfer plates4a,4band4c, the corrugations52of the inner and outer edge portions48and50(FIG.1) of the second heat transfer plate4babut the corrugations52of the inner and outer edge portions48and50of the first and third heat transfer plates4aand4cat the first side6and the second side8, respectively, of the second heat transfer plate4b. Further, the first reinforcement projections72′,102′,104′,74′ and the third plane portions110′,112′,114′,116′ of the second heat transfer plate4bpartly abut the third plane portions116′,114′,112′,110′ of the first heat transfer plate4aand the first reinforcement projections74′,104′,102′,72′ of the third heat transfer plate4c, respectively.

Further, the fourth guiding section66of the second heat transfer plate4bengages with the first guiding sections60of the first and third heat transfer plates4aand4c(FIG.4a). More particularly, the male projection70of the second heat transfer plate4bis received in the female recess78of the first heat transfer plate4aand the first plane portion74of the second heat transfer plate4babuts the second plane portion82of the first heat transfer plate4a. Further, the male projection68of the third heat transfer plate4cis received in the female recess80of the second heat transfer plate4band the first plane portion72of the third heat transfer plate4cabuts the second plane portion84of the second heat transfer plate4b.

Further, the third guiding section64of the second heat transfer plate4bengages with the second guiding sections62of the first and third heat transfer plates4aand4c(FIG.4b). More particularly, the male projection88of the first heat transfer plate4ais received in the female recess100of the second heat transfer plate4band the second plane portion92of the first heat transfer plate4aabuts the first plane portion104of the second heat transfer plate4b. Further, the male projection90of the second heat transfer plate4bis received in the female recess98of the third heat transfer plate4cand the second plane portion94of the second heat transfer plate4babuts the first plane portion102of the third heat transfer plate4c.

Further, the second guiding section62of the second heat transfer plate4bengages with the third guiding sections64of the first and third heat transfer plates4aand4c(FIG.4c). More particularly, the male projection90of the first heat transfer plate4ais received in the female recess98of the second heat transfer plate4band the second plane portion94of the first heat transfer plate4aabuts the first plane portion102of the second heat transfer plate4b. Further, the male projection88of the second heat transfer plate4bis received in the female recess100of the third heat transfer plate4cand the second plane portion92of the second heat transfer plate4babuts the first plane portion104of the third heat transfer plate4c.

Further, the first guiding section60of the second heat transfer plate4bengages with the fourth guiding sections66of the first and third heat transfer plates4aand4c(FIG.4d). More particularly, the male projection68of the second heat transfer plate4bis received in the female recess80of the first heat transfer plate4aand the first plane portion72of the second heat transfer plate4babuts the second plane portion84of the first heat transfer plate4a. Further, the male projection70of the third heat transfer plate4cis received in the female recess78of the second heat transfer plate4band the first plane portion74of the third heat transfer plate4cabuts the second plane portion82of the second heat transfer plate4b.

Thereby, in the plate pack2, the second heat transfer plate4bengages, at all four of its guiding sections60,62,64and66, with both the first and the third heat transfer plate4a,4c, which results in a reliable and effective alignment of the first, second and third heat transfer plates.

In the above described plate pack2, the heat transfer plates are “rotated” in relation to each other. In an alternative plate pack according to the invention, the heat transfer plates are instead “flipped” in relation to each other. Accordingly, the second heat transfer plate4bis arranged between the first and third heat transfer plates4aand4c. Further, the first and third heat transfer plates4aand4bare both rotated 180 degrees about their respective transverse centre axis22, in relation to the second heat transfer plate4b. Thereby, the first and second sides6and8of the second heat transfer plate4babut the first side6of the first heat transfer plate4aand the second side8of the third heat transfer plate4c, respectively. More particularly, portions of the second heat transfer plate4bextending in the first plane54contact opposing portions of the first heat transfer plate4aextending in the first plane54, and portions of the second heat transfer plate4bextending in the second plane56contact opposing portions of the third heat transfer plate4cextending in the second plane56. For example, as schematically illustrated inFIG.6for the outer edge portions of the heat transfer plates4a,4band4c, the corrugations52of the inner and outer edge portions48and50(FIG.1) of the second heat transfer plate4babut the corrugations52of the inner and outer edge portions48and50of the first and third heat transfer plates4aand4cat the first side6and the second side8, respectively, of the second heat transfer plate4b. Further, the first reinforcement projections72′,102′,104′,74′ and the third plane portions110′,112′,114′,116′ of the second heat transfer plate4bpartly abut first reinforcement projections104′,74′,72′,102′ of the first heat transfer plate4aand the third plane portions114′,116′,110′,112′ of the third heat transfer plate4c, respectively.

Further, the third guiding section64of the second heat transfer plate4bengages with the first guiding sections60of the first and third heat transfer plates4aand4c(FIG.5a). More particularly, the male projection68of the first heat transfer plate4ais received in the female recess100of the second heat transfer plate4band the first plane portion72of the first heat transfer plate4aabuts the first plane portion104of the second heat transfer plate4b. Further, the male projection90of the second heat transfer plate4bis received in the female recess78of the third heat transfer plate4cand the second plane portion94of the second heat transfer plate4babuts the second plane portion82of the third heat transfer plate4c.

Further, the fourth guiding section66of the second heat transfer plate4bengages with the second guiding sections62of the first and third heat transfer plates4aand4c(FIG.5b). More particularly, the male projection70of the second heat transfer plate4bis received in the female recess98of the first heat transfer plate4aand the first plane portion74of the second heat transfer plate4babuts the first plane portion102of the first heat transfer plate4a. Further, the male projection88of the third heat transfer plate4cis received in the female recess80of the second heat transfer plate4band the second plane portion92of the third heat transfer plate4cabuts the second plane portion84of the second heat transfer plate4b.

Further, the first guiding section60of the second heat transfer plate4bengages with the third guiding sections64of the first and third heat transfer plates4aand4c(FIG.5c). More particularly, the male projection68of the second heat transfer plate4bis received in the female recess100of the first heat transfer plate4aand the first plane portion72of the second heat transfer plate4babuts the first plane portion104of the first heat transfer plate4a. Further, the male projection90of the third heat transfer plate4cis received in the female recess78of the second heat transfer plate4band the second plane portion94of the third heat transfer plate4cabuts the second plane portion82of the second heat transfer plate4b.

Further, the second guiding section62of the second heat transfer plate4bengages with the fourth guiding sections66of the first and third heat transfer plates4aand4c(FIG.5d). More particularly, the male projection70of the first heat transfer plate4ais received in the female recess98of the second heat transfer plate4band the first plane portion74of the first heat transfer plate4aabuts the first plane portion102of the second heat transfer plate4b. Further, the male projection88of the second heat transfer plate4bis received in the female recess80of the third heat transfer plate4cand the second plane portion92of the second heat transfer plate4babuts the second plane portion84of the third heat transfer plate4c.

Thereby, in the plate pack above, the second heat transfer plate4bengages, at all four of its guiding sections60,62,64and66, with both the first and the third heat transfer plate4a,4c, which results in a reliable and effective alignment of the first, second and third heat transfer plates.

Thus, due to the inventive construction of the first, second, third and fourth guiding sections60,62,64and66, the heat transfer plates4a,4band4care properly aligned with each other in a plate pack irrespective of whether they are rotated or flipped in relation to each other. Due to the design, and location on the heat transfer plates, of the female recesses and male projections, the actual alignment of the heat transfer plates is performed by means of outer portions of the female recesses and the male projections, i.e. portions of the female recesses and the male projections facing the respective outer edges51of the heat transfer plates. Thus, when the heat transfer plates are aligned, the outer portions of the female recesses and the male projections of one heat transfer plate engage with the outer portions of the male projections and the female recesses, respectively, of the adjacent plates. Inner portions of the female recesses and the male projections, i.e. portions of the female recesses and the male projections facing away from the respective outer edges51of the heat transfer plates, do not engage with each other.

In that the first and second plane portions72,74,102,104and82,84,92and94extend in the first and second planes54and56, and the depth of the female recesses78,80,98and100is equal to the height of the male projections68,70,88and90, the first and second plate portions, just like inside bottom surfaces of the female recesses and outside top surfaces of the male projections, will abut each other in the plate pack and so make the plate pack more stable.

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

For example, the female recesses and the male projections need not have a rectangular cross section. As an example, they may have a round, triangular or pentagonal cross section, such as the cross section illustrated inFIG.7, which defines a right angle and comprises two outer portions118and120which are perpendicular to each other for optimum heat transfer plate alignment. Since the alignment function resides within the outer portions118and120, the inner portions can be cut or shortened so as to enable space efficient female recesses and male projections with large alignment capability.

Further, the female recesses need not all have the same cross section and the same depth. Similarly, the male projections need not all have the same cross section and the same height. Also, the depth of the female recesses need not be equal to the height of the male projections but could be larger or even smaller. Also, one or more of the first plane portions of the guiding sections may extend in a plane different from the first plane. Similarly, one or more of the second plane portions of the guiding sections may extend in a plane different from the second plane.

Also, the alignment function need not reside solely within the outer portions of the female recesses and the male projections but could instead reside solely within the inner portions of the female recesses and the male projections, or within one or more of the outer portions and/or one or more of the inner portions of the female recesses and the male projections.

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.

The guiding sections of the heat transfer plate need not be arranged at a respective corner of the heat transfer plate but could be arranged closer to the longitudinal centre axis and/or closer to the transverse centre axis. Also, within each of the guiding sections, the female recess and the male projection need not be arranged on opposite sides, but could instead be arranged on the same side, of the imaginary straight line108illustrated inFIGS.2a,2b,2cand2d. Further, the distance between the female recess and the male projection of each of the guiding section could vary. Typically, the female recesses and the male projections are arranged where there is room available on the heat transfer plate, e.g. in the corners and/or at the centre of the short sides, close to the outer edge, of the heat transfer plate.

The plate packs described above comprises one plate type only. Naturally, the plate packs could instead comprise two or more different types of alternately arranged heat transfer plates, for example heat transfer plates with different heat transfer patterns and/or guiding sections as long as the heat transfer patterns and/or the guiding sections are compatible with each other.

The present invention could be used in connection with other types of plate heat exchangers than gasketed ones, such as brazed, all-welded and semi-welded (heat transfer plates pairwise welded to each other in cassettes, which cassettes are separated by gaskets) plate heat exchangers. The present invention could also be used with plate heat exchangers lacking carrying and guiding bars, i.e. for heat transfer plates lacking recesses for receiving such carrying and guiding bars.

The locations of the first, second, central extension, third, fourth, fifth and sixth planes54,56,58,76,86,96and106need not be as above defined but could vary. As an example, with reference toFIGS.3a,3dand4a, the fourth plane86could instead extend between the second plane56and the central extension plane58, and the third plane76could consequently extend closer to the first plane54. As another example, the fourth plane86could instead extend between the first plane54and the third plane76, and the third plane76could consequently extend farther away from the first plane54.

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.