A heat exchanger plate and a brazed plate heat exchanger comprising such plates

Abstract

A heat exchanger plate (110, 120) for a plate heat exchanger (100), wherein the heat exchanger plate (110, 120) extends in a general plane, has a first center axis (A) and a second center axis (B) perpendicular to the first center axis (A), wherein the heat exchanger plate (110, 120) is formed with through port openings (O1-O4) and a main heat exchanging area having at least first and second patterns (180, 190) of ridges and grooves. The first pattern (180) of ridges and grooves comprises only first ridges (R1) formed with a first height (H1), and the second pattern (190) of ridges and grooves comprises first ridges (R1) and second ridges (R2), wherein the second ridges (R2) are formed with a second height (H2) lower than the first height (H1). Disclosed is also a plate heat exchanger (100) comprising such heat exchanger plates (110, 120).

Description

[0001] A HEAT EXCHANGER PLATE AND A BRAZED PLATE HEAT EXCHANGER

[0002] COMPRISING SUCH PLATES

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to a heat exchanger plate for a brazed plate heat exchanger, wherein the heat exchanger plate extends in a general plane, has a first center axis and a second center axis perpendicular to the first center axis, wherein the heat exchanger plate is formed with through port openings and a heat exchanging surface having at least first and second pressed patterns of ridges and grooves. The present invention is also related to a brazed plate heat exchanger comprising a plurality of such heat exchanger plates stacked to provide contact points between at least some crossing ridges and grooves of adjacent heat exchanger plates under formation of interplate flow channels for fluids to exchange heat, wherein the interplate flow channels are in selective fluid communication through the port openings.

[0005] PRIOR ART

[0006] Heat exchangers are used for exchanging heat between fluid media. They generally comprise a start plate, an end plate and a plurality of heat exchanger plates stacked onto one another in a manner forming flow channels between the heat exchanger plates by means of ridges of the heat exchanger plates contacting each other in contact points. The heat exchanger plates are provided with brazing material at least at or close to some of the contact points. Port openings are provided to allow selective fluid flow in and out from the flow channels in a way well known to persons skilled in the art. For example, two fluids are alternatingly guided into the flow channels for exchange of heat between them. For example, port openings are arranged on different levels in relation to a general plane of the heat exchanger plates to alternatingly form an opening for fluid and alternatingly being closed by areas surrounding the port openings and contacting each other. Areas surrounding port openings and contacting each other can be connected by a brazing joint.

[0007] Before brazing a plurality of heat exchanger plates are provided with a brazing material, after which the heat exchanger plates are stacked onto one another and placed in a furnace, wherein the heat exchanger plates are heated to a temperature sufficient to at least partially melt the brazing material or to connect the heat exchanger plates by diffusion bonding. After the temperature of the furnace has been lowered, the brazing material, if at least partly melted, will solidify, whereupon the heat exchanger plates will be joined to one another to form a compact and strong heat exchanger.

[0008] It is well known by persons skilled in the art that the flow channels between the heat exchanger plates of a plate heat exchanger are created by providing the heat exchanger plates with a pressed pattern of ridges and grooves. A plurality of heat exchanger plates are typically stacked on one another, wherein the ridges of a first heat exchanger plate contact the grooves of a neighboring heat exchanger plate and general planes of the plates are thus kept at a distance from each other through contact points. Hence, flow channels are formed. In these flow channels, fluid media, such as a first and second fluid media are lead so that heat transfer is obtained between such media.

[0009] A plurality of brazed plate heat exchangers and heat exchanger plates with a pressed corrugated pattern having ridges and grooves is known in the prior art. One type of such prior art heat exchangers comprises first and second heat exchanger plates, wherein the first plates have constant corrugation depth and the second heat exchanger plates have first and second ridges with different heights. Heat exchanger plates with a constant corrugation depth, i.e. all ridges have the same height, are also called symmetrical heat exchanger plates. Heat exchanger plates with a varying corrugation depth, i.e. having first ridges with a first height and second ridges with a second height arranged altematingly or in a repeating pattern, are also called asymmetrical heat exchanger plates. A heat exchanger comprising symmetric and asymmetric plates arranged altematingly results in interplate flow channels with different volumes.

[0010] One problem with prior art plate heat exchangers is that they are difficult to produce. Also, the production thereof may result in a relatively complicated brazing process and ultimately may increase the risk of leakage of fluids from the heat exchanger. SUMMARY OF THE INVENTION

[0011] One object of the present invention is to mitigate the problems of prior art heat exchangers and provide a heat exchanger plate with favourable flow distribution, pressure drop and / or heat transfer between the fluid media which is easy to produce.

[0012] According to the invention, the above object is achieved by a heat exchanger plate for a plate heat exchanger, wherein the heat exchanger plate extends in a general plane, has a first center axis and a second center axis perpendicular to the first center axis, wherein the heat exchanger plate is formed with through port openings and a main heat exchanging area having at least first and second pressed patterns of ridges and grooves, characterised in that the first pattern of ridges and grooves comprises only first ridges formed with a first height, and the second pattern of ridges and grooves comprises first ridges and second ridges, wherein the second ridges are formed with a second height lower than the first height. The first pattern comprising only the first ridges with the first height forms a symmetric pattern and the second pattern comprising first and second ridges, wherein the second ridges are formed with a second height lower than the first height, forms an asymmetric pattern. When stacked, the heat exchanger plates form an asymmetric heat exchanger wherein the first and second patterns of ridges and grooves provide contact points between at least some crossing ridges and grooves of adjacent heat exchanger plates under formation of interplate flow channels for fluids to exchange heat. The interplate flow channels are in selective fluid communication through the port openings. The first and second patterns result in interplate flow channels with different volumes or portions with different volumes. Also, as the second ridges are free ridges that are not contacting any adjacent heat exchanger plate, the second pattern results in areas with fewer contact points and thus also fewer brazing joints in some of the interplate flow channels. It has been found that pressing both the first and second patterns in the same heat exchanger plate compared to pressing symmetric and asymmetric patterns in different plates result in improved tolerances and a better fit between heat exchange plates when stacked. Also, a better fit results in a more efficient and reliable brazing process to provide a brazed plate heat exchanger. Pressing both the first and second patterns in the same plate equalizes the press force, facilitates use of similar types of press lines and reduces tolerances to provide a better fit and improved brazing.

[0013] The main heat exchanging area is an area that is understood by a skilled person. The main heat exchanging area is the area of the heat exchanger providing the substantial heat exchange and is arranged between the port openings or pairs of port openings. Areas in the vicinity of the port openings and around the port openings can have a different pattern. Hence, for a rectangular heat exchanger having port openings close to the corners, the main heat exchanging area is the area between an inlet port opening and an outlet port opening in the longitudinal direction, wherein the main heat exchanging area can extend from one side of the heat exchanger plates to the opposite side thereof in the lateral direction.

[0014] The first pattern can comprise at least four of the first ridges arranged consecutively one after the other, wherein the second pattern can comprise at least two of the first ridges and at least two of the second ridges grouped together. The first pattern can continuously cover a first section of the main heat exchanging area, wherein the second pattern can continuously cover a second section of the heat exchanging area. Hence, the first pattern covers the first section uninterrupted, wherein the second pattern covers the second section uninterrupted. Hence, the first section comprises only the first pattern, wherein the second section comprises only the second pattern. The first and second sections can be arranged alternatingly over the heat exchanging plate, such as in a longitudinal direction from an inlet port opening to an outlet port opening. Hence, a plurality of first and second sections can be arranged alternatingly. The first section can cover at least 10% of the main heat exchanging area. The second section can cover at least 10% of the main heat exchanging area. Hence, the first and second patterns are arranged alternatingly over the heat exchanger plate. The first and second sections can extend from one side of the heat exchanger plate to the opposite side thereof, such as from one long side to the other. The second pattern can continuously cover 30-70% of the main heat exchanging area. The first pattern can continuously cover the remaining part of the main heat exchanging area.For example, the second pattern can continuously cover approximately half of the main heat exchanging area of the heat exchanger plate, wherein the first pattern continuously covers the other half. Hence, the press force is equalized while resulting in an asymmetric heat exchanger, i.e. a heat exchanger where at least some neighbouring interplate flow channels have different volumes, at least in portions thereof, so that the volumes varies at least locally between neighbouring interplate flow channels. Alternatively, the first and second sections are arranged alternatingly, e.g. so that each section covers 25% of the main heat exchanging area. Hence, a first quarter of the heat exchanging area is only formed with the first pattern, followed by a second quarter formed only with the second pattern, followed by a third quarter formed with only the first pattern and a fourth quarter formed with only the second pattern. When stacked, the first pattern of one plate is substantially facing the second pattern of adjacent plates. Alternatively, the first pattern of one plate is substantially facing the first pattern of adjacent plates or both the first pattern and the second pattern of adjacent plates.

[0015] The first pattern can extend from a first side of the heat exchanger plate to the opposite second side thereof. Also the second pattern can extend from the first side of the heat exchanger plate to the second side thereof. For example, the first and second patterns can extend continuously across the heat exchanger plate or continuously along the heat exchanger plate from the first side to the second side. The first pattern can be arranged adjacent to the second pattern. The first pattern can be arranged substantially in a first half, such as a bottom half or a left half, of the main heat exchanging area of the first heat exchanger plates, wherein the second pattern can be arranged substantially in a second half, such as a top half or a right half, of the main heat exchanging area of the first heat exchanger plates. Then, the first pattern of the second heat exchanger plates can be arranged substantially in the second half, such as the top half or right half, wherein the second pattern thereof can be arranged substantially in the first half, such as the bottom half or the left half. When stacked, the first pattern will substantially face the second pattern of the adjacent plates. Hence, the first pattern can be arranged only on one side of the first center axis and the second pattern can be arranged only on the opposite side of the first center axis. Alternatively, the first pattern can be arranged substantially on one side of the second center axis and the second pattern can be arranged substantially on the opposite side of the second center axis. The press force for pressing the first and second heat exchanger plates is thus efficiently equalized while providing favorable flow distribution, pressure drop and / or heat transfer between the fluids to exchange heat. The heat exchanger plate can be elongated, wherein the first center axis is a longitudinal center axis and the second center axis is a lateral center axis. Since the ridges and grooves are arranged at an angle, parts of some of the ridges and grooves, particularly of the ones closest to the second center axis, can be arranged on both sides of the second center axis. The heat exchanger plate can be rectangular. For example, the interplate flow channel portion having bigger volume can be arranged adjacent to an inlet port opening of a heat exchange medium, such as a medium for condensation or evaporation, to provide favorable pressure drop. The port openings can be arranged at corners of the heat exchanger plate in a conventional manner.

[0016] The ridges can extend continuously from one side of the heat exchanger plates to the opposite side thereof and can be inclined in relation to sides of the heat exchanger plate. The ridges can be arranged as chevrons. Each chevron can have a single apex, optionally coinciding with the first center axis (which may be the longitudinal center axis of the heat exchanger plate). Alternatively, the ridges can be arranged as oblique straight lines, optionally extending continuously from one side of the heat exchanger plate to the opposite side. Alternatively, the ridges can be arranged intermittently in a corresponding pattern, such as said chevrons or obliquely straight lines.

[0017] The first and second ridges of the second pattern can be arranged alternatingly, wherein every other ridge is the first ridge and every other ridges is the second ridge. Alternatively, every second or every third ridge is the first ridge or the second ridge. Alternatively, one, two or three of the first ridges is followed by one, two or three of the second ridges in any suitable pattern.

[0018] The second height, i.e. the height of the second ridges, is so much lower than the first height so that the second ridges are not contacting the adjacent plate. For example, the second ridges can be 30-80% of the first height to provide the desired pressure drop.

[0019] The present invention is also related to a plate heat exchanger, such as a brazed plate heat exchanger, comprising a plurality of stacked heat exchanger plates as set out above according to the invention, wherein the first and second patterns of ridges and grooves provide contact points between at least some crossing ridges of adjacent heat exchanger plates under formation of interplate flow channels for fluids to exchange heat, and wherein the interplate flow channels are in selective fluid communication through the port openings. The plate heat exchanger can comprise first and second heat exchanger plates arranged altematingly, wherein only the first ridges of the first and second patterns are contacting an adjacent heat exchange plate. Hence, the second ridges are not contacting an adjacent plate. The first and second heat exchanger plates can be identical, wherein every other heat exchanger plate is rotated 180 degrees in relation to the others. Alternatively, the first and second heat exchanger plates are different, e.g. in ridge angle, corrugation frequency or corrugation depth. The ridges of the first heat exchanger plates are arranged in a first direction in a first angle, wherein the ridges of the second heat exchanger plate are arranged in an opposite second direction in a second angle, wherein the second angle optionally is different to the first angle. The difference between the first and second angles can be 2-35°. The first and second heat exchanger plates can be stacked so that the first pattem(s) of the first heat exchanger plates is (are) facing the second pattern(s) of the second heat exchanger plate and so that the second pattern(s) of the first heat exchanger plates is (are) facing the first pattern(s) of the second heat exchanger plates. The present invention results in interplate flow channels having first and second portions with different volumes. For example, a portion with bigger volume is arranged adjacent to an inlet port opening for media to evaporate or condensate. Hence, the present invention combines at least one symmetric area and at least one asymmetric area in the same heat exchanger plate to facilitate production of the heat exchanger plates as well as a brazed heat exchanger comprising a plurality of such heat exchanger plates in a stack. The first pattern, or the first section(s), of one heat exchanger plate can face the second pattern, or second section(s), of adjacent heat exchanger plates entirely or substantially.

[0020] Further characteristics and advantages of the present invention will become apparent from the description of the embodiments below, the appended drawings and the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In the following, the invention will be described with reference to appended drawings, wherein:

[0022] Fig. l is a schematic and exploded perspective view of a plate heat exchanger comprising first and second heat exchanger plates according to one example,

[0023] Fig. 2 is schematic view of a first heat exchanger plate with first and second patterns of ridges and grooves according to a first embodiment,

[0024] Fig. 3 is a schematic view of a second heat exchanger plate with the first and second patterns of ridges and grooves according to one embodiment,

[0025] Fig. 4 is a schematic view of the second heat exchanger plate according to another embodiment,

[0026] Fig. 5 is a schematic section view of a part of a heat exchanger plate illustrating the first pattern of ridges and grooves,

[0027] Fig. 6 is a schematic section view of a part of a heat exchanger plate illustrating the second pattern of ridges and grooves,

[0028] Fig. 7 is a schematic section view of a stack of first and second heat exchanger plates arranged so that the first and second patterns of ridges and grooves are facing each other,

[0029] Fig. 8 is a schematic view of the first heat exchanger plate with first and second patterns of ridges and grooves according to a second embodiment,

[0030] Fig. 9 is a schematic view of the second heat exchanger plate of the second embodiment,

[0031] Fig. 10 is a schematic section view of a center part of a stack of first heat exchanger plates according to Fig. 8 and second heat exchanger plates according to Fig. 9, illustrating interplate flow channels between the first and second heat exchanger plates,

[0032] Fig. 11 is a schematic view of a heat exchanger plate with first and second patterns of ridges and grooves according to a third embodiment,

[0033] Fig. 12 is a schematic view of a heat exchanger plate with first and second patterns of ridges and grooves according to a fourth embodiment,

[0034] Fig. 13 is a schematic view of a heat exchanger plate with first and second patterns of ridges and grooves according to a fifth embodiment, Fig. 14 is a schematic view of a heat exchanger plate with first and second patterns of ridges and grooves according to a sixth embodiment, and

[0035] Fig. 15 is a schematic view of a heat exchanger plate with first and second patterns of ridges and grooves according to an seventh embodiment.

[0036] DESCRIPTION OF EMBODIMENTS

[0037] With reference to Fig. 1 an exploded view of a brazed plate heat exchanger 100 is illustrated according to a general example. The heat exchanger 100 comprises a plurality of first heat exchanger plates 110 and a plurality of second heat exchanger plates 120 stacked in a stack to form the heat exchanger 100. The first and second heat exchanger plates 110, 120 are arranged altematingly, wherein every other plate is a first heat exchanger plate 110 and every other plate is a second heat exchanger plate 120. The first and second heat exchanger plates 110, 120 may be similar, wherein one of the first and second heat exchanger plates 110, 120 has been rotated 180 degrees in relation to the other. Alternatively, the first and second heat exchanger plates 110, 120 are different. In an alternative example (not illustrated), the first and second heat exchanger plates are arranged in another configuration together with additional heat exchanger plates, such as a third heat exchanger plate different from the first and second heat exchanger plates 110, 120. The heat exchanger plates 110, 120 are arranged to form interplate flow channels for fluids exchanging heat with each other.

[0038] In the illustrated embodiment, each of the heat exchanger plates 110, 120 comprises a skirt S, which extends generally perpendicular to a plane of the heat exchanger plate and is adapted to contact skirts of neighbouring heat exchanger plates in order to provide a seal along the circumference of the heat exchanger 100. For example, the skirt S extends around the entire periphery of the heat exchanger pates 110, 120. Alternatively, the skirt S extends along at least two opposite sides of the heat exchanger plates 110, 120, such as long sides thereof, wherein the other sides may be connected through surfaces extending in the plane of the heat exchanger plates 110, 120. For example, the skirt S may be arranged in a conventional manner.

[0039] The heat exchanger plates 110, 120 are arranged with port openings O1-O4 for letting fluids to exchange heat into and out of the interplate flow channels. In the illustrated embodiment, the heat exchanger plates 110, 120 are arranged with a first port opening 01, a second port opening 02, a third port opening 03 and a fourth port opening 04. Areas surrounding the port openings 01 to 04 are provided at different heights such that selective communication between the port openings and the interplate flow channels is achieved. In the heat exchanger 100, the areas surrounding the port openings 01-04 are arranged such that the first and second port openings 01 and 02 are in fluid communication with one another through some interplate flow channels, whereas the third and fourth port openings 03 and 04 are in fluid communication with one another by other interplate flow channels. In the illustrated embodiment, the heat exchanger plates 110, 120 are rectangular with rounded corners, wherein the port openings 01-04 are arranged near the corners. Alternatively, the heat exchanger plates 110, 120 are square, e.g. with rounded corners. Alternatively, the heat exchanger plates 110, 120 are circular, oval or arranged with other suitable shape, wherein the port openings 01-04 are distributed in a suitable manner. In the illustrated embodiment, each of the heat exchanger plates 110, 120 is formed with four port openings 01-04. However in other embodiments of the invention (not illustrated), the number of port openings may be larger than four, i.e. six, eight or ten. For example, the number of port openings is at least six, wherein the heat exchanger is configured for providing heat exchange between at least three fluids. For example, the ports 01-04 are arranged in a a conventional manner. Apart from the skirt S and ports 01-04 practically the remaining part of the heat exchanger plates 110, 120 forms a heat exchanging area 130, 140. For example, at least a central main portion of the heat exchanger plates 110, 120 between the port openings 01-04 forms the main heat exchanging area 130, 140 in a manner familiar to the skilled person.

[0040] In the illustrated embodiment, the heat exchanger 100 also comprises a start plate 150 and an end plate 160. The start plate 150 is formed with openings corresponding to the port openings 01-04 for letting fluids into and out of the interplate flow channels formed by the first and second heat exchanger plates 110, 120. The start plate 150 may be provided with port connections 170 for connecting pipes to the heat exchanger 100 for fluids to exchange heat. For example, the start plate 150 is a conventional start plate 150. The end plate 160 is a plate without openings in the illustrated embodiment. Alternatively, the end plate 160 has inlet and / or outlet openings for fluids. For example, the end plate 160 is a conventional end plate.

[0041] With reference to Fig. 2 a first heat exchanger plate 110 according to a first embodiment is illustrated schematically, wherein a second heat exchanger pate 120 is illustrated in Fig. 3. The heat exchanger plates 110, 120 are, e.g., made from sheet metal, such as steel, aluminum, copper or other suitable metals or alloys depending on the use of the heat exchanger. Each heat exchanger plate 110, 120 extends in a general plane and has a first face and an opposite second face, wherein the first and second faces or main portions thereof form the heat exchanging areas 130, 140. The heat exchanger plates 110, 120 each has a first center axis A and a second center axis B extending perpendicular to the first center axis A. For example, the first center axis A is a longitudinal center axis and the second center axis B is a lateral center axis.

[0042] Each of the heat exchanger plates 110, 120 is provided with at least a first pressed pattern 180 of ridges and grooves and second pressed pattern 190 of ridges and grooves. Hence, each of the first heat exchanger plates 110 comprises at least the first pattern 180 of ridges and grooves and the second pattern 190 of ridges and grooves, wherein each of the second heat exchanger plates 120 comprises at least the first pattern 180 of ridges and grooves and the second pattern 190 of ridges and grooves. The heat exchanging area 130 of the first heat exchanger plates 110 comprises both the first and second patterns 180, 190 of ridges and grooves, wherein the heat exchanging area 140 of the second heat exchanger plate 120 comprises both the first and second pattern 180, 190 of ridges and groves. The first pattern 180 is different from the second pattern 190. The first pattern 180 comprises only first ridges R1 and thus only first grooves Gl. The second pattern 190 comprises first and second ridges Rl, R2, wherein the second ridges R2 are different from the first ridges Rl . The second ridges R2 are illustrate with a double line in the drawings for illustration purposes only. In the embodiment of Fig. 2, the first pattern 190 is arranged only on one side of the second center line B, wherein the second pattern 190 is arranged only on the other side of the center line B. Hence, around half of the heat exchanging area 140 is formed with the first pattern 180, wherein the other half is formed with the second pattern 190. For example, the first pattern 180 extends from one side of the heat exchanger plates 110, 120 to the opposite side thereof. For example, the first pattern 180 extends from one long side of the heat exchanger plates 110, 120 to the opposite long side thereof in a lateral direction. For example, the first pattern 180 substantially covers an area from the lateral center line B to the first and third port openings 01, 03. The second pattern 190 is, e.g. arranged in a similar manner on the opposite side of the lateral center line B. For example, the second pattern 190 mirrors the first pattern 180. For example, 30-70% of the heat exchanging area 130 is formed with the first pattern 180, wherein the rest is formed with the second pattern 190. Hence, the heat exchanger plates 110, 120 are formed with at least one symmetric area and at least one asymmetric area, wherein the first pattern 180 forms the symmetric area(s) and the second pattern 190 forms the asymmetric area(s).

[0043] In the embodiment of Figs. 2 to 4, the first and second ridges Rl, R2 are formed in a herringbone pattern as chevrons, wherein each chevron has a single apex optionally arranged on the first center line A. For example, the Ridges Rl, R2 extend from one side of the heat exchanger plates 110, 120 to the opposite side thereof, such as from one long side to the other. Optionally, the first ridges Rl extend continuously from one side to the other of the heat exchanger plates 110, 120, wherein the second ridges R2 extend continuously from one side to the other of the heat exchanger plates 110, 120. The first and second patterns 180, 190 of Figs. 2 to 4 are herringbone patterns. However, the first and second patterns 180, 190 may also be in the form of obliquely extending straight lines. In any case, the first and second patterns 180, 190 are adapted to keep the planes of the plates 110, 120 on a distance from one another to form the interplate flow channels.

[0044] With reference to Fig. 3, the second heat exchanger plate 120 is illustrated according to one example, wherein the first and second patterns 180, 190 are arranged in corresponding positions as in the first heat exchanger plate 110. When stacked, the first pattern 180 of the first heat exchanger plate 110 is facing and contacting the first pattern 180 of the second heat exchanger plate 120, wherein the second patterns 190 of the heat exchanger plates 110, 120 will face and contact each other. The chevron shaped ridges Rl, R2 of the first heat exchanger pates 110 point in a first direction, wherein the chevron shaped ridges Rl, R2 of the second heat exchanger plates 120 point in an opposite second direction. The first and second heat exchanger plates 110, 120 of Figs, 2 and 3 are produced by different pressing tools. For example, the second heat exchanger pates 120 are formed with a different corrugation depth or corrugation frequency compared to the first heat exchanger plates 110.

[0045] With reference to Fig. 4, the second heat exchanger plates 120 are similar as the first heat exchanger plates 110 and rotated 180 degrees in its plane before stacking with the first heat exchanger plates 110. Hence, every other plate is rotated 180 degrees, so that the ridges Rl, R2 of the first heat exchanger plates 110 point in the first direction and the ridges Rl, R2 of the second heat exchanger plates point in the opposite second direction. The first and second heat exchanger plates 110, 120 of Figs, 2 and 4 may be produced by the same pressing tool. Alternatively, the second heat exchanger pates 120 are formed with a different corrugation depth or corrugation frequency compared to the first heat exchanger plates 110, wherein the first and second heat exchanger plates 110, 120 of Figs, 2 and 4 are produced by different pressing tools.

[0046] The first heat exchanger plates 110 are formed with the ridges Rl, R2 and grooves Gl, G2 in a first chevron angle 1. The chevron angle is the angle between legs of the ridge Rl, R2 connected in the apex. The legs of the ridge Rl, R2 are inclined and extend from the apex towards opposite sides of the heat exchanger plate 110, 120, such as the long sides thereof. Optionally, the first and second patterns of ridges and grooves of the first heat exchanger plates 110 are formed with the first chevron angle 01 throughout the heat exchanging area 130 of the plate. For example, the first chevron angle 01 is 50°-140°, such as 80°-130°.

[0047] The second heat exchanger plates 120 are formed with a second chevron angle 02. Optionally, the second chevron angle 02 is different from the first chevron angle 01. Hence, the second heat exchanger plates 120 are arranged with a herringbone pattern having a different angle than the first heat exchanger plate 110. For example, the second chevron angle 02 is 50°-140°, such as 80°-130°. Optionally, the second heat exchanger plates 120 are formed with the second chevron angle 02 throughout the heat exchanging area 140 of the plate. An optional difference between the first and second angles 01, 02 is, e.g. 2-35°.

[0048] According to various embodiments, the first pattern 180 of ridges and grooves is formed with a different chevron angle than the second pattern 190 of ridges and grooves. Alternatively or in addition, the first pattern 180 of ridges and grooves is formed with a different corrugation frequency than the second pattern 190.

[0049] With reference also to Figs 5 to 7 the first and second patterns 180, 190 are illustrated schematically in section view. In Fig. 5, the first pattern 180 is illustrated schematically according to one embodiment, wherein the second pattern 190 is illustrated schematically according to one embodiment in Fig. 6. A portion of a stack of first and second plates 110, 120 is illustrated schematically in Fig. 7 to illustrate the resulting interplate flow channels when the first pattern 180 is facing the second pattern 190.

[0050] The ridges Rl, R2 in the first face of the heat exchanger plate 110, 120 form the grooves Gl, G2 in the opposite second face of the heat exchanger plate 110, 120. The first pattern 180 of ridges and grooves, which is illustrated in Fig. 5, comprises only ridges of the same height, i.e. the first ridges Rl. The first ridges Rl are all formed with a first height Hl. Hence, the height of all the first ridges Rl is the same. Consequently, the grooves Gl of the first pattern 180 are similar and they all have a first depth DI. Hence, all grooves Gl of the first pattern 180 are formed with the same depth DI. For example, the first height Hl is the same as the first depth DI, i.e. H1=D1. For example, the depth DI is 0.5-5 mm, such as 1-3 mm or 1.5-3 mm. In other words, the corrugation depth of the first pattern 180 is symmetrical and similar throughout the area of the first pattern 180. For example, tops of all the first ridges Rl are arranged in a common plane parallel to the general plane of the heat exchanger plate 110, 120.

[0051] The second pattern 190 of ridges and grooves, which is illustrated in Fig. 6, comprises the first ridges Rl and second ridges R2, wherein the second ridges R2 are formed with a second height H2 lower than the first height Hl. Hence, the second pattern 190 of ridges and grooves comprises both the first ridges Rl and the second ridges R2. Consequently, the second pattern 190 comprises first and second grooves Gl, G2, wherein the first grooves Gl have the first depth DI and the second grooves G2 have a second depth D2 smaller than the first depth DI. For example, H1=D1 and H2=D2. For example, the first depth DI is 0.5-5 mm, such as 0.5-3 mm, wherein the second depth D2 is 30-80% of the first depth DI, such as 40-60% thereof. The ridges Rl, R2 have different heights Hl, H2 in a corresponding manner. The first depth DI is larger than the second depth D2. The first and second grooves Gl, G2 are arranged alternatingly. Alternatively, the first and second grooves Gl, G2, and optionally further grooves having other depths, are arranged in a suitable pattern to provide the asymmetric second pattern 190. Hence, the second pattern 190 of ridges and grooves is asymmetrical and forms an asymmetric heat exchanger when stacked with other heat exchanger plates 110, 120. The first and second ridges Rl, R2 extend from the first face of the heat exchanger plate 110, 120. Tops of the first ridges Rl are arranged in a first common plane, wherein tops of the second ridges R2 are arranged in a second common plane parallel to the general plane of the heat exchanger plate. Tops of ridges extending from the second face are all arranged in a single plane parallel to the general plane of the heat exchanger plate.

[0052] With reference to Fig. 7 a plurality of the first and second heat exchanger plates 110, 120 have been stacked to schematically illustrate formation of first and second interplate flow channels 200, 210 according to one embodiment. In the illustrated embodiment, every other plate is a first heat exchanger plate 110 and the remaining plates are second heat exchanger plates 120, wherein the first and second heat exchanger plates 110, 120 are arranged alternatingly to form the heat exchanger 100. The first and second heat exchanger plates 110, 120 contact each other in contact points between the first ridges Rl, such that the interplate flow channels 200, 210 for fluids to exchange heat are formed between the heat exchanger plates 110, 120 when the heat exchanger plates 10, 120 are stacked in a stack to form the heat exchanger 100. Hence, contact points are provided between at least some crossing ridges Rl and grooves Gl of neighbouring and adjacent plates 110, 120 under formation of the interplate flow channels 200, 210 for fluids to exchange heat. The second ridges R2 are not contacting any neighbouring plate 110, 120.

[0053] In Fig. 7 the first and second heat exchanger plates 110, 120 are arranged so that the first pattern 180 faces the second pattern 190. The first and second patterns 180, 190 are arranged to alternatingly form different volume profiles of the interplate flow channels 200, 210 on opposite sides of the heat exchanger plates 110, 120. Hence, at least a first portion of each of the interplate flow channels 200, 210 is formed with a bigger volume than at least a second portion thereof. An interplate flow channel portion formed between the first pattern 180 and the second pattern 190 (i.e. when the first pattern 180 is placed on top of the second pattern 190) has bigger volume than an interplate flow channel portion formed between the second pattern 190 and the first pattern 180 (i.e. when the second pattern 190 is placed on top of the first pattern 180). Thus, each of the first and second interplate flow channels 200, 210 have the first portion and the second portion, wherein the first portion has a profile with bigger volume than the second portion. The same interplate flow channel 200, 210 has the first portion and the second portion next to each other in different sections of the same interplate flow channel 200, 210. Optionally, the first portion is 30%-70% or around 50% of the heat exchanging area 130, 140, wherein the second portion is the rest. In the heat exchanger 100, the heat exchanger plates 110, 120 are arranged so that the first and second portions are arranged alternatingly. Hence, in a first part of the heat exchanger 100, such as a first half, the first and second portions of the interplate flow channels 200, 210 are arranged alternatingly starting with the first portion, wherein in a second part of the heat exchanger 100, such as a second half, the second and first portions are arranged alternatingly starting with the second portion. For example, the first heat exchanger plates 110 has the first pattern 180 in an area between the second center line B and the second and fourth port openings 02, 04, wherein the second heat exchanger plates 120 has the first pattern 180 between the second center line B and the first and third port openings 01, 03 of the heat exchanger 100. Simultaneously, the first heat exchanger plates 110 has the second pattern 190 in an area between the second center line B and the first and third port openings 01, 03, wherein the second heat exchanger plates 120 has the second pattern 190 between the second center line B and the second and fourth port openings 01, 03 of the heat exchanger 100.

[0054] With reference also to Figs. 8 to 10 the first and second heat exchanger plates 110, 120 are illustrated according to a second embodiment. The first heat exchanger plate 110 is illustrated in Fig. 8 and the second heat exchanger plate 120 is illustrated in Fig. 9, wherein a stack of the first and second heat exchanger plates 110, 120 is illustrated in Fig. 10. The heat exchanger plates 110, 120 comprises the first and second patterns 180, 190 of ridges and grooves in a similar manner as described above, wherein the first pattern 180 only has the first ridges R1 with the first height Hl and the second pattern 190 has both the first and second ridges Rl, R2, wherein the second ridges R2 are formed with the lower second height H2. The ridges Rl of the second embodiment are arranged as chevrons, wherein one leg of some of the chevrons forms the second ridges R2 with the lower second height H2. The chevrons of the first and second heat exchanger plates 110, 120 point in opposite directions. Optionally, the first and second ridges Rl, R2 are arranged alternatingly in the second pattern 190, wherein every other ridge is the first ridge Rl and every other ridge is the second ridge R2. Other patterns can be used. For example, one, two or three of the first ridges Rl are arranged in a row followed by one, two or three of the second ridges R2 in a repeated or desired pattern.

[0055] In the embodiment of Figs. 8 to 10 the first pattern 180 is arranged on one side of the first center axis A, whereas the second pattern 190 is arranged on the opposite side of the first center axis A. For example, a first leg of the chevrons form the first pattern 180, wherein the second leg of the chevrons form the second pattern 190. Hence, the first leg of the chevrons from the first ridges Rl with the first height Hl, wherein some of the second legs, such as every other second leg, form the second ridges R2 with the lower height H2. Optionally, first and second ridges Rl, R2 extend continuously from one side of the heat exchanger plates 110, 120 to the apex of the chevrons and then continues with the first ridge Rl from the apex. For example, the first pattern 180 extends between the first and second port openings 01, 02, wherein the second pattern 190 extends between the third and fourth port openings 03, 04. Optionally, the first pattern 180 extends continuously substantially from the first port opening 01 to the second port opening 02, wherein the second pattern 190 extends continuously substantially from the third port opening 03 to the fourth port opening 04. For example, the first and second patterns 180, 190 extend in parallel. In the embodiment of Figs. 8 to 10 the heat exchanger plates 110, 120 are elongated, wherein the first and second patterns 180, 190 extend in the longitudinal direction of the heat exchanger plates 110, 120. For example, a left half of the first heat exchanger plates 110, or at least a substantial portion of the heat exchanging area 130 thereof, is formed with the first pattern 180, wherein a right half, or at least a substantial portion of the heat exchanging area 130 thereof, is formed with the second pattern 190. Then, a left half of the second heat exchanger plates 120, or at least a substantial portion of the heat exchanging area 140 thereof, is formed with the second pattern 190, wherein a right half, or at least a substantial portion of the heat exchanging area 140 thereof, is formed with the first pattern 180.

[0056] The ridges Rl, R2 of the second embodiment are arranged as chevrons as set out above for the first embodiment, wherein the chevron angles of the first and second heat exchanger plates 110, 120 may be similar or different. Also, a corrugation depth and / or corrugation frequency of the first and second heat exchanger plates 110, 120 may be similar or may be different.

[0057] With reference particularly to Fig. 10 the interplate flow channels 200, 210 resulting from a stack of first and second heat exchanger plates 110, 120 of the second embodiment are illustrated schematically. In Fig. 10 an axial center plane through the stack from the first center axis A is illustrated by the line C. As can be seen in Fig. 10 the first and second patterns 180, 190 are arranged alternatingly to form the bigger first portions and smaller second portions of each of the interplate flow channels 200, 210. In Fig. 10, the first pattern 180 of the first heat exchanger plates 110 are arranged on one side (right side) of the center plane C, wherein the second pattern 190 of the first heat exchanger plates 110 are arranged on the other side of the center plane C (left side) and vice versa for the second heat exchange plates 120. The first interplate flow channels 200 have the bigger first portion on a first side of the center plane C and the smaller second portion on the opposite second side thereof. At the same time, the second interplate flow channels 210 have the bigger first portion on the second side of the center plane C and the smaller second portion on the first side thereof. Hence, smaller and bigger portions of the interplate flow channels 200, 210 are arranged alternatingly throughout the heat exchanger 100, starting with the smaller portion on one side of the center plane C and starting with the bigger portion on the other side of the center plane C. For example, the bigger first portion of the interplate flow channels 200, 210 changes into the smaller second portion at the axial center plane C of the heat exchanger 100.

[0058] With reference to Figs. 11 to 13 various embodiments are illustrated, wherein the ridges Rl, R2 are arranged as oblique straight lines instead of chevrons. With reference to Fig. 11, the first ridges Rl (or a majority thereof) extend continuously from one side of the heat exchanger plate 110 to the opposite side thereof, whereas the second ridges R2 extend from one side of the heat exchanger plate 110 to the first center axis, which may be a longitudinal center axis as describe above, to form the first pattern 180 on one side of the first center axis A and the second pattern 190 on the other side thereof. Optionally, the first and second ridges Rl, R2 are arranged alternatingly in the second pattern 190 or in another suitable pattern as described above. The first ridges Rl are formed with the first height Hl and the second ridges R2 are formed with the second height H2 smaller than the first height Hl as described above.

[0059] With reference to Fig. 12 the first pattern 180 is arranged on one side of the second center axis B, wherein the second pattern 190 is arranged on the opposite side of the second center axis B. In the embodiment of Fig. 12, the first ridges Rl transitions into the second ridges R2 at the second center line B, wherein the first pattern 180 is arranged on one side and the second pattern 190 is arranged on the other side of the second center line B. Similar may apply for ridges Rl, R2 arranged as chevrons. Alternatively, the second ridges R2 continues from one side of the heat exchanger plate 110 to the opposite side thereof even though the second center line B is crossed, which is illustrated in Fig. 13. Similar may apply for ridges Rl, R2 arranged as chevrons. The heat exchanger plates 110 of figs. 11 to 13 are stacked with second heat exchanger plates with corresponding but opposite first and second patterns in a similar manner as described above and having the ridges Rl, R2 extending obliquely in the opposite direction, optionally at a different angle.

[0060] With reference to Figs. 14 and 15 further embodiments are illustrated schematically, wherein the first and second ridges Rl, R2 are distributed to form the first and second patterns 180, 190 in different sections of the heat exchanger plate 110. In Fig. 14 a plurality of sections of the first and second patterns 180, 190 is arranged alternatingly along the first center axis A, wherein the patterns 180, 190 in one side of the first center axis A are mirrored in the opposite side. Only a few ridges are illustrated schematically and many more ridges are present in a real heat exchanger plate. In Fig. 15 a plurality of sections of the first and second patterns 180, 190 is arranged alternatingly along the first center axis A, wherein the sections of the first patterns 180 on one side of the first center axis A are displaced in relation to the first patterns 180 on the opposite side of the first center axis A, optionally so that the second ridges R2 transitions into the first ridges R1 at the first center axis A. The heat exchanger plates 110 of figs. 14 and 15 are stacked with second heat exchanger plates with corresponding but opposite first and second patterns in a similar manner as described above.

[0061] The heat exchanger according to the present invention is, e.g. used for condensation or evaporation, wherein at least one media at some point is in gaseous phase. For example, the heat exchanger is used for heat exchange, wherein condensation or evaporation primarily takes place in the bigger interplate flow channel portions.

[0062] The present invention has been described with at least two patterns, i.e. the first pattern 180 and the second pattern 190, wherein the first pattern 180 is symmetric and the second pattern 190 is asymmetric. However, it is understood that each heat exchanger plate 110, 120 can comprise further symmetric and asymmetric patterns, such as a symmetric third pattern and an asymmetric fourth pattern, etc. Alternatively, the first pattern 180 can be divided into a first symmetric section and a second symmetric section of different symmetric patterns, wherein the second pattern 190 can be divided into a first asymmetric section and a second asymmetric section of different asymmetric patterns, wherein the difference can be in height of the second ridges R2, ridge frequency and / or angle of the ridges (such as chevron angle or angle of the obliquely extending ridges in relation to the first or second center axes A, B).

Claims

CLAIMS1. A heat exchanger plate (110, 120) for a plate heat exchanger (100), wherein the heat exchanger plate (110, 120) extends in a general plane, has a first center axis (A) and a second center axis (B) perpendicular to the first center axis (A), wherein the heat exchanger plate (110, 120) is formed with through port openings (O1-O4) and a main heat exchanging area having at least first and second patterns (180, 190) of ridges and grooves, characterised in that the first pattern (180) of ridges and grooves comprises only first ridges (Rl) formed with a first height (Hl), and the second pattern (190) of ridges and grooves comprises first ridges (Rl) and second ridges (R2), wherein the second ridges (R2) are formed with a second height (H2) lower than the first height (Hl).

2. The heat exchanger plate of claim 1, wherein the first pattern (180) continuously covers a first section of at least 10% of the main heat exchanging area, wherein the second pattern (190) continuously covers a second section of at least 10% of the main heat exchanging area.

3. The heat exchanger plate of claim 2, wherein said first and second sections extend from one side of the heat exchanger plate (110, 120) to the opposite side thereof.

4. The heat exchanger plate of any claim 1 or 2, wherein said first and second sections are arranged alternatingly.

5. The heat exchanger plate of any of claims 1-3, wherein the second pattern (190) continuously covers at least 30% and not more than 70% of the main heat exchanging area of the heat exchanger plate (110, 120).

6. The heat exchanger plate of claim 5, wherein the first pattern (180) continuously covers the remaining part of the main heat exchanging area.

7. The heat exchanger plate of claim 5 or 6, wherein the first pattern (180) is substantially or only arranged on one side of the first center axis (A) and the second pattern (190) is substantially or only arranged on the opposite side of the first center axis (A).

8. The heat exchanger plate of claim 5 or 6, wherein the first pattern (180) is substantially arranged on one side of the second center axis (B) and the second pattern (190) is substantially arranged on the opposite side of the second center axis (B).

9. The heat exchanger plate of any of the preceding claims, wherein heat exchanger plate (110), 120) is elongated and the first center axis (A) is a longitudinal center axis and the second center axis (B) is a lateral center axis.

10. The heat exchanger plate of any of the preceding claims, wherein the ridges (Rl, R2) extend continuously from one side of the heat exchanger plates (110, 120) to the opposite side thereof and are inclined in relation to sides of the heat exchanger plate (110, 120).

11. The heat exchanger plate of any of the preceding claims, wherein the ridges (Rl, R2) are arranged as chevrons, each chevron having a single apex, optionally coinciding with the first center axis (A).

12. The heat exchanger plate of any of the preceding claims, wherein the first and second ridges (Rl, R2) of the second pattern (190) are arranged alternatingly.

13. The heat exchanger plate of any of the preceding claims, wherein the second height (H2) is in the range of 30-80% of the first height.

14. A plate heat exchanger (100) comprising a plurality of stacked heat exchanger plates (110, 120) according to any of the preceding claims, wherein the first and secondpatterns (180, 190) of ridges and grooves provide contact points between at least some crossing ridges and grooves of adjacent heat exchanger plates (110, 120) under formation of interplate flow channels (200, 210) for fluids to exchange heat, and wherein the interplate flow channels (200, 210) are in selective fluid communication through the port openings (O1-O4).

15. The plate heat exchanger of claim 14, wherein only the first ridges (Rl) are contacting an adjacent heat exchange plate (110, 120).

16. The plate heat exchanger of claim 14 or 15, wherein the heat exchanger plates (110, 120) are similar and every other heat exchanger plate (110, 120) is rotated 180 degrees its plane, and wherein the first pattern (180) of one heat exchanger plate (110, 120) is mainly facing the second pattern (190) of adjacent heat exchanger plates (110, 120).

17. The plate heat exchanger of claim 14 or 15, comprising first heat exchanger plates (110) and second heat exchange plates (120) different from the first heat exchanger plates (120), wherein the first pattern (180) of one heat exchanger plate (110, 120) is contacting the first or second pattern (180, 190) of an adjacent heat exchanger plate (110, 120).

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