SE2050094A1

SE2050094A1 - A brazed plate heat exchanger and use thereof

Info

Publication number: SE2050094A1
Application number: SE2050094A
Authority: SE
Inventors: Sven Andersson; Tomas Dahlberg
Original assignee: Swep Int Ab
Priority date: 2020-01-30
Filing date: 2020-01-30
Publication date: 2021-07-31
Also published as: CN114945789A; EP4097413A1; WO2021154152A1; SE545690C2; JP2023512425A; PL4097413T3; US20230036224A1; JP2025170375A; EP4617602A3; JP7736693B2; SI4097413T1; EP4617602A2; EP4097413B1

Abstract

A brazed plate heat exchanger (100) comprising a plurality of first and second heat exchanger plates (110, 120), wherein the first heat exchanger plates (110) are formed with a first pattern of ridges and grooves, and the second heat exchanger plates (120) are formed with a second pattern of ridges and grooves providing contact points between at least some crossing ridges and grooves of neighbouring plates under formation of interplate flow channels for fluids to exchange heat, said interplate flow channels being in selective fluid communication through port openings. The first pattern of ridges and grooves is different from the second pattern of ridges and grooves, so that an interplate flow channel volume on one side of the first heat exchanger plates (110) is different from an interplate flow channel volume on the opposite side of the first heat exchanger plates (110), and the first pattern of ridges and grooves exhibits a first angle (β1) and the second pattern of ridges and grooves exhibits a second angle (β2) different from the first angle (β1).

Description

A BRAZED PLATE HEAT EXCHANGER AND USE THEREOF FIELD OF THE INVENTION The present invention relates to a brazed plate heat exchanger comprising aplurality of heat exchanger plates having a pattern of ridges and grooves providingcontact points between at least some crossing ridges and grooves of neighbouring platesunder forrnation of interplate ﬂow channels for ﬂuids to exchange heat. The present invention is also related to the use of such a heat exchanger.

PRIOR ART Heat exchangers are used for exchanging heat between ﬂuid media. Theygenerally comprise a start plate, an end plate and a number of heat exchanger platesstacked onto one another in a manner forrning ﬂow channels between the heatexchanger plates. Usually, port openings are provided to allow selective ﬂuid flow inand out from the ﬂow channels in a way well known to persons skilled in the art.

A common way of manufacturing a plate heat exchanger is to braze the heatexchanger plates together to form the plate heat exchanger. Brazing a heat exchangermeans that a number of heat exchanger plates are provided with a brazing material, afterwhich the heat exchanger plates are stacked onto one another and placed in a fumacehaving a temperature suff1ciently hot to at least partially melt the brazing material. Afterthe temperature of the fumace has been lowered, the brazing material will solidify,whereupon the heat exchanger plates will be j oined to one another to form a compactand strong heat exchanger.

It is well known by persons skilled in the art that the ﬂow channels between theheat exchanger plates of a plate heat exchanger are created by providing the heatexchanger plates with a pressed pattem of ridges and grooves. A number of heatexchanger plates are typically stacked on one another, wherein the plates can beidentical to provide a symmetric plate heat exchanger or not identical to provide anasymmetric plate heat exchanger. When stacked, the ridges of a first heat exchangerplate contact the grooves of a neighboring heat exchanger plate and 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 arelead so that heat transfer is obtained between such media.

A plurality of brazed plate heat exchangers with a pressed corrugated pattemhaving ridges and grooves in a herringbone pattem is known in the prior art. However, there is a need to improve such prior art heat exchangers.

It is the object of the present invention to provide a plate heat exchanger with favourable ﬂow distribution, pressure drop and heat transfer between the ﬂuid media.

SUMMARY OF THE INVENTION According to the invention, the above object is achieved by a brazed plate heatexchanger (BPHE) comprising a plurality of first and second heat exchanger plates,wherein the first heat exchanger plates are formed with a first pattem of ridges andgrooves, and the second heat exchanger plates are formed with a second pattem ofridges and grooves providing contact points between at least some crossing ridges andgrooves of neighbouring plates under formation of interplate ﬂow channels for ﬂuids toexchange heat, said interplate ﬂow channels being in selective ﬂuid communicationthrough port openings, characterised in that the first pattem of ridges and grooves isdifferent from the second pattem of ridges and grooves, so that an interplate ﬂowchannel volume on one side of the first heat exchanger plates is different from aninterplate ﬂow channel volume on the opposite side of the first heat exchanger plates,and the first pattem of ridges and grooves exhibits a first angle and the second pattem ofridges and grooves exhibits a second angle different from the first angle. Thecombination of different interplate ﬂow channel volumes on opposite sides of the platesand at least two different plate patterns having different angles result in a BPHE withfavourable properties for ﬂuid distribution, wherein the ﬂuid ﬂow distribution andpressure drop can be balanced to achieve efficient heat exchange. This makes it possibleto achieve different properties in interplate ﬂow channels on opposite sides of the sameplate, wherein the ﬂow and pressure drop on one side can be different from the oppositeside. Also, the different ﬂow channel volumes on opposite sides of the plates can be used for different types of medias, such as a liquid in one and a gas in the other.

When a refrigerant start to evaporate it is transferred from a liquid state to avapour state. The liquid has a density that is much higher than the vapour density. Forexample R4l0A at Tdew=5°C has 32 times higher density for the liquid than thevapour. This also mean that the vapour will move in a channel at velocities that are 32times higher than the liquid. This will automatically lead to the dynamic pressure dropfor the vapour being 32 times higher than for the liquid, i.e. vapour creates much higher pressure drop for all kind of refrigerants.

The performance (Temperature Approach, TA) of a heat exchanger is definedas the water outlet temperature (at the inlet of the heat exchanger channel) minus theevaporation temperature (Tdew) at the outlet of the heat exchanger channel. A highpressure drop along the heat exchanger surface results in different local saturationtemperatures that will result in a relatively large total difference in refrigeranttemperature between the inlet and outlet of the channel. The temperature will be higherat the inlet of the channel. This will have a direct, detrimental impact on theperformance of the heat exchanger, since a higher inlet refrigerant temperature (due totoo high channel pressure drop) makes it harder to cool the outlet water to the correcttemperature. The only way for the system to compensate for the too high refrigerantinlet temperature is by lowering the evaporation temperature until correct water outlettemperature can be reached. By creating pattem for heat exchanger channels that havehigh heat transfer characteristics and at the same time have low pressure dropcharacteristics, a higher performance can be reached for the heat exchanger. A loweroverall refrigerant pressure drop in the channel will not only improve the heatexchanger performance it will also have a positive impact on the total system performance and, hence, the energy consumption.

At least one of the first and second heat exchanger plates can be an asymmetricheat exchanger plate. Altematively, the first heat exchanger plates are formed withanother corrugation width than the second heat exchanger plates. The first heatexchanger plate can be a symmetric heat exchanger plate, wherein the second heatexchanger plate can be an asymmetric heat exchanger plate. Hence, first grooves of the second heat exchanger plates can be formed with a first depth, and second grooves of the second heat exchanger plates can be formed with a second depth different from thefirst depth. Through the combination of different angles and corrugation depth pattems,the ﬂuid ﬂow distribution and pressure drop can be customized for the application toachieve efficient heat exchange. The pattems of ridges and grooves can be herringbone pattems, wherein the angles of the pattem of ridges and grooves are chevron angles.

Furthermore, the depths of the first and second heat exchanger plates maydiffer from each other in a way that the interplate ﬂow channels have different sizesseen in cross section, wherein the interplate ﬂow channels have different volumes onopposite sides of the plates. Hence, the interplate flow channels can have different crosssection areas on opposite sides of the plates. This provides an asymmetric plate heatexchanger that combines favourable heat transfer with low pressure drop to achieve amore efficient heat exchanger for various purposes, such as for heating, refrigeration or a reversible refrigeration system.

The first and second angles, such as first and second chevron angles, can be 0-90°, 25-70° or 30-45°. Hence, the angles can be selected to achieve favourable ﬂuiddistribution. The difference between the first and second angles can be 2-35°.

Disclosed is also the use of a brazed plate heat exchanger according to the present invention for evaporation or condensation of media.

Further characteristics and advantages of the present invention will becomeapparent from the description of the embodiments below, the appended drawings and the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGSIn the following, the invention will be described with reference to appended drawings, wherein: Fig. l is a schematic and exploded perspective view of a heat exchanger according to one embodiment of the present invention, Fig. 2 is an exploded perspective view of a part of the heat exchanger of Fig. 1,illustrating a first heat exchanger plate and a second heat exchanger plate of the heat exchanger, Fig. 3 is a schen1atic section view of a part of the first heat exchanger plateaccording to one en1bodin1ent, illustrating identical depth of grooves of the first heat exchanger plate, Fig. 4 is a schen1atic section view of a part of the second heat exchanger plateaccording to one en1bodin1ent, illustrating an alternating depth of grooves of the second heat exchanger plate, Fig 5 is a schen1atic section view of a part of a heat exchanger con1prising firstand second heat exchanger plates according to one en1bodin1ent, wherein the first and second heat exchanger plates are alternatingly arranged, Fig. 6a is a schen1atic front view of the first heat exchanger plate according toone en1bodin1ent, illustrating a corrugated herringbone pattern thereof having a first chevron angle, Fig. 6b is a schen1atic front view of the first heat exchanger plate according toan alternative en1bodin1ent, illustrating a corrugated pattern thereof having a first angle, Fig. 7a is a schen1atic front view of the second heat exchanger plate accordingto one en1bodin1ent, illustrating a corrugated herringbone pattern thereof having a second chevron angle, Fig. 7b is a schen1atic front view of the second heat exchanger plate accordingto an alternative en1bodin1ent, illustrating a corrugated pattern thereof having a second angle, Fig. 8 is a schen1atic view of the first heat exchanger plate arranged on thesecond heat exchanger plate, illustrating contact points between then1 according to theexample of Fig. 5, Fig. 9 is a schen1atic view of the second heat exchanger plate arranged on thefirst heat exchanger plate, illustrating contact points between then1 according to theexample of Fig. 5, Fig. 10 is a scheniatic cross section view of a part of a heat exchanger coniprising f1rst and second heat exchanger plates according to another en1bodin1ent, Fig. 11 is a scheniatic cross section view of a part of a heat exchanger coniprising f1rst and second heat exchanger plates according to another en1bodin1ent, Fig. 12 is a scheniatic cross section view of a part of a heat exchangerconiprising f1rst and second heat exchanger plates according to yet another en1bodin1ent, and Fig. 13 is a scheniatic cross section view of a part of a stack of heat exchangerplates of f1rst and second heat exchanger plates having different corrugation depths according to another en1bodin1ent.

DESCRIPTION OF EMBODIMENTS With reference to Fig. 1 a brazed plate heat exchanger 100 is illustratedaccording to one en1bodin1ent, wherein a part thereof is illustrated more in detail in Fig.2. The heat exchanger 100 con1prises a plurality of f1rst heat exchanger plates 110 and aplurality of second heat exchanger plates 120 stacked in a stack to forrn the heatexchanger 100. The first and second heat exchanger plates 110, 120 are arrangedalternatingly, wherein every other plate is a f1rst heat exchanger plate 110 and everyother plate is a second heat exchanger plate 120. Alternatively, the f1rst and second heatexchanger plates are arranged in another configuration together with additional heat exchanger plates. The heat exchanger 100 is an asyn1n1etric plate heat exchanger.

The heat exchanger plates 110, 120 are n1ade from sheet n1eta1 and areprovided with a pressed pattern of ridges R1, R2a, R2b and grooves G1, G2a, G2b suchthat interplate flow channels for ﬂuids to exchange heat are forrned between the plateswhen the plates are stacked in a stack to forrn the heat exchanger 100 by providingcontact points between at least son1e crossing ridges and grooves of neighbouring plates110, 120 under forrnation of the interplate flow channels for ﬂuids to exchange heat.The pressed pattern of Figs. 1 and 2 is a herringbone pattern. However, the pressedpattern n1ay also be in the forrn of obliquely extending straight lines. In any case , the pressed pattern of ridges and grooves is a corrugated pattern. The pressed pattern is adapted to keep the plates 110, 120 on a distance from one another, except from the contact points, to form the interplate ﬂoW channels.

In the illustrated embodiment, each of the heat exchanger plates 110, 120 issurrounded by a skirt S, Which extends generally perpendicular to a plane of the heatexchanger plate and is adapted to contact skirts of neighbouring plates in order toprovide a seal along the circumference of the heat exchanger. Apart from the skirt S andports 01-04 practically the remaining part of the heat exchanger plates 110, 120 forrnsa heat exchanging surface 130, 140.

The heat exchanger plates 110, 120 are arranged With port openings 01-04 forletting fluids to exchange heat into and out of the interplate ﬂoW channels. In theillustrated embodiment, the heat exchanger plates 110, 120 are arranged With a first portopening 01, a second port opening 02, a third port opening 03 and a fourth portopening 04. Areas surrounding the port openings 01 to 04 are provided at differentheights such that selective communication between the port openings and the interplateﬂoW channels is achieved. In the heat exchanger 100, the areas surrounding the portopenings 01-04 are arranged such that the first and second port openings 01 and 02are 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 Withone another by neighboring interplate ﬂoW channels. In the illustrated embodiment, theheat exchanger plates 110, 120 are rectangular With rounded comers, Wherein the portopenings 01-04 are arranged near the comers. Altematively, the heat exchanger plates110, 120 are square, e.g. With rounded comers. Altematively, the heat exchanger plates110, 120 are circular, oval or arranged With other suitable shape, Wherein the portopenings 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.

Please note that in other embodiments of the invention, the number of portopenings may be larger than four, i.e. six, eight or ten. For example, the number of portopenings is at least six, Wherein the heat exchanger is conf1gured for providing heatexchange between at least three ﬂuids. Hence, according to one embodiment, the heat exchanger is a three circuit heat exchanger having at least six port openings and in addition being arranged With or Without at least one integrated suction gas heatexchanger. Altematively, the number of port openings is at least six, Wherein the heat exchanger includes one or more integrated suction gas heat exchangers.

In the illustrated embodiment, the heat exchanger 100 comprises only the firstand second heat exchanger plates 110, 120. Altematively, the heat exchanger 100comprises a third and optionally also a fourth heat exchanger plate, Wherein the thirdand optional fourth heat exchanger plates are arranged With different pressed patternsthan the first and second heat exchanger plates 110, 120, and Wherein the heat exchanger plates are arranged in a suitable order.

In the illustrated embodiment, the heat exchanger 100 also comprises a startplate 150 and an end plate 160. The start plate 150 is forrned With openingscorresponding to the port openings O1-O4 for letting ﬂuids into and out of the interplateﬂoW channels forrned by the first and second heat exchanger plates 110, 120. For example, the end plate 160 is a conventional end plate.

With reference to Fig. 3, a section View of the first heat exchanger plate 110according to one embodiment is illustrated schematically. The first heat exchangerplates 110 are forrned With a first pattern of ridges R1 and grooves G1. The grooves G1of the first heat exchanger plates are forrned With identical depth Dl. Hence, all groovesG1 are forrned With the same depth D1. For example, the depth D1 is 0.5-5 mm, such as1-3 mm or 1.5-3 mm. For example, all ridges R1 are forrned With the same height in acorresponding manner. In other Words, the corrugation depth of the first heat exchangerplates 110 is symmetrical and similar throughout the plate or at least substantially throughout the plate.

With reference to Fig. 4, a section View of the second heat exchanger plate 120is illustrated schematically according to one embodiment. For example, all second heatexchanger plates 120 are identical. The second heat exchanger plates 120 are forrnedWith a second pattem of first and second ridges R2a, R2b and first and second groovesG2a, G2b. The first and second grooves G2a, G2b of the second heat exchanger plates120 are forrned With different depths, Wherein the first grooves G2a are forrned With a first depth D2a, and the second grooves G2b are forrned With a second depth D2b, wherein the second depth D2b is different from the first depth D2a, For example, thefirst depth D2a is 05-5 mm, such as 0.5-3 mm, wherein the second depth D2b is 30-80% of the first depth D2a, such as 40-60% thereof. The ridges R2a, R2b have differentheights in a corresponding manner. In the illustrated embodiment, the first depth D2a islarger than the second depth D2b. The first and second grooves G2a, G2b are arrangedaltematingly. Altematively, the first and second grooves G2a, G2b, and optionallyfurther grooves having other depths, are arranged in any desired pattem. For example,the pattem of ridges and grooves of the second heat exchanger plates 120 isasymmetrical, i.e. the second heat exchanger plates 120 would form an asymmetric heatexchanger when combined with first heat exchanger plates 110 such as shown belowwith reference to Fig. 5. According to one embodiment, the entire heat exchangingsurface of the second heat exchanger plates 120 is formed with the second pattem ofridges and grooves having at least two different corrugation depths D2a, D2b of the grooves.

With reference to Fig. 5 a plurality of the first and second heat exchangerplates 110, 120 have been stacked to schematically illustrate formation of interplateﬂow channels according to one embodiment, In the illustrated embodiment, every otherplate is a first heat exchanger plate 110 and the remaining plates are second heatexchanger plates 120, wherein the first and second heat exchanger plates are arrangedaltematingly to form an asymmetric heat exchanger 100, wherein the interplate ﬂowchannels are formed with different volumes. Altematively, the different volumes of theinterplate ﬂow channels are formed by an extended profile on the same press depth orcorrugation depth. For example, the first and second heat exchanger plates are providedwith different corrugation depths. For example, the first and/or second heat exchangerplates is/ are asymmetric heat exchanger plates. Altematively, the first and/or second heat exchanger plates is/are symmetric heat exchanger plates.

With reference to Fig. 6a the first pattem of ridges R1 and grooves G1 of thefirst heat exchanger plate 110 is illustrated schematically. Said pattem is a pressedherringbone pattem, wherein the ridges R1 and grooves G1 are arranged with two inclined legs meeting in an apex, such as a centrally arranged apex, forrning an arrow pattern. For example, the apices are distributed along an imaginary centre line, such as alongitudinal centre line of a rectangular heat exchanger plate. The pattern of the firstheat exchanger plate 110, i.e. the first pattern of ridges R1 and grooves G1, exhibits afirst chevron angle ßl. The chevron angle is the angle between the ridge and animaginary line across the plate, perpendicular to the long sides of a rectangular plate,which is illustrated schematically by means of the dashed line C. For example, thechevron angle is the same on both sides of the apex. For example, the entire orsubstantially entire first pattem of ridges and grooves is formed with the first chevronangle ßl throughout the heat exchanging surface 130 of the plate. For example, the firstchevron angle ßl is between 0° and 90°, 25° and 70° or 40° and 65°.

With reference to Fig. 6b the first pattem of ridges R1 and grooves G1 of thefirst heat exchanger plate 110 is illustrated schematically according to an altemativeembodiment, wherein the pressed pattem is in the form of obliquely extending straightlines. Hence, the pressed pattem of ridges and grooves is a corrugated pattem ofobliquely extending straight lines. The obliquely extending straight lines of the first heat exchanger plates 110 are arranged in the angle ßl.

With reference to Fig. 7a the second pattem of ridges R2a, R2b and groovesG2a, G2b of the second heat exchanger plate 120 is illustrated schematically. Saidsecond pattem is a pressed herringbone pattem as described above with reference to thefirst heat exchanger plate 110 but with a second chevron angle ß2 different from thefirst chevron angle ßl. Hence, the second heat exchanger plate 120 is arranged with aherringbone pattem having a different angle than the first heat exchanger plate. Forexample, the second chevron angle ß2 is between 0° and 90°, 25° and 70° or 40° and65°. For example, the entire or substantially entire pattem of ridges and grooves of thesecond heat exchanger plates 120 is formed with the second chevron angle [32 throughout the heat exchanging surface 140 of the plate.

With reference to Fig. 7b the second pattem of ridges R1 and grooves G1 ofthe second heat exchanger plate 120 is illustrated schematically according to analtemative embodiment, wherein the pressed pattem is in the form of obliquely extending straight lines. Hence, the pressed pattem of ridges and grooves is a corrugated pattern of obliquely extending straight lines. The obliquely extending straight lines of the second heat exchanger plates 120 are arranged in the angle ß2.

Hence, the first and second heat exchanger plates 110, 120 are forrned withdifferent chevron angles ßl, ß2 and different pressed patterns resulting in differentinterplate volumes. For example, the first and second heat exchanger plates 110, 120 areprovided with different corrugation depths. Altematively or in addition, the first andsecond heat exchanger plates 110, 120 are provided with different corrugationfrequencies. For example, the first and second heat exchanger plates 110, 120 areprovided with the same corrugation depth but different corrugation frequencies. Hence,the first and second heat exchanger plates 110, 120 are provided with differentcorrugation depths and/or different corrugation frequencies. For example, one of thefirst and second heat exchanger plates 110, 120 is a symmetric heat exchanger plate,wherein the other is asymmetric. Altematively, both the first and second heat exchangerplates 110, 120 are asymmetric. Altematively, both the first and second heat exchanger plates 110, 120 are symmetric.

In Figs. 8 and 9 contact points between the first and second plates 110, 120 areillustrated schematically using the example of Fig. 5. In and/or around the contact points170 between crossing ridges and grooves brazing joints 170 are formed. In theembodiment of Figs. 8 and 9 brazing joints 170 are formed in all contact points.Altematively, brazing j oints 170 are formed in only some of the contact points. In Fig. 8the first heat exchanger plate 110 is arranged on the second heat exchanger plate 120,wherein contact points are formed in a first pattem. In Fig. 8 all crossings between theridges R1 of the first heat exchanger plate 110 and ridges or grooves of the second heatexchanger plate 120 result in a contact point.

Fig. 9 is a schematic view of the second heat exchanger plate 120 arranged onthe first heat exchanger plate 110, wherein contact points are formed in a secondpattem. In Fig. 9 only crossings between the first ridges R2a of the second heatexchanger plate 120 result in a contact point, which may form a brazing joint 170,wherein the second ridges R2b are arranged with a gap to the crossing ridges or grooves of the first heat exchanger plate 110. Hence, and no contact points are formed, and no brazing joint is formed, between the second ridges R2b of the second heat exchanger plate 120 and the first heat exchanger plate 110. In Fig. 9 all contact points are showedwith a brazing joint 170.

According to one embodiment, the brazing j oints 170 between the first andsecond heat exchanger plates 110, 120 are elongated, such as oval, wherein the brazingjoints 170 are arranged in a first orientation in the interplate ﬂow channels havingbigger volume and in a second orientation in the interplate flow channels having smallervolume to provide a favourable pressure drop in the desired interplate ﬂow channels.For example, the brazing joints 170 are arranged in a first angle in relation to alongitudinal direction of the plates 110, 120 in the interplate ﬂow channels havingbigger volume and in a second angle in the remaining interplate ﬂow channels.

According to one embodiment, the first angle is bigger than the second angle.

With reference to Fig. 10 a cross section of a part of a heat exchangercomprising first and second heat exchanger plates 110, 120 according to anotherembodiment is illustrated schematically. In the embodiment of Fig. 10 the first heatexchanger plate 110 is a symmetric heat exchanger plate, wherein the second heatexchanger plate 120 is an asymmetric heat exchanger plate as described above. Hence,the corrugation depth of the first heat exchanger plate 110 is constant, wherein thecorrugation depth of the second heat exchanger plate 120 is varying. The second heatexchanger plate 120 is formed with at least two different corrugation depths. Also, thefirst and second heat exchanger plates 110, 120 are formed with corrugated pattemsdifferent angles, such as chevron angles, as described above. In the embodiment of Fig.10 the chevron angle of the first heat exchanger plate 110 is 54 degrees, wherein thechevron angle of the second heat exchanger plate 120 is 61 degrees. For example,neighbouring interplate volumes are different, so that the interplate volume on one sideof the first heat exchanger plates 110 is different from the interplate volume on theopposite side of the first heat exchanger plates 110. Of course, this also apply for thesecond heat exchanger plates 120. Hence, the interplate volume between the first andsecond heat exchanger plates is different from the interplate volume between the secondand first heat exchanger plates. Similarly, a cross section area on one side of the firstheat exchanger plates 110 is different from the cross section area on the opposite side ofthe first heat exchanger plates 110.

With reference to Fig. 11 a cross section of a part of a heat exchanger comprising first and second heat exchanger plates 110, 120 according to yet another embodiment is illustrated schematically. In the embodiment of Fig. 11 the first heatexchanger plate 110 is a symmetric heat exchanger plate, Wherein the second heatexchanger plate 120 is an asymmetric heat exchanger plate as described above. In theembodiment of Fig. 11 the chevron angle of the first heat exchanger plate 110 is 45degrees, Wherein the chevron angle of the second heat exchanger plate 120 is 61 degrees.

With reference to Fig. 12 a cross section of a part of a heat exchangercomprising first and second heat exchanger plates 110, 120 according to yet anotherembodiment is illustrated schematically. In the embodiment of Fig. 12 the first heatexchanger plate 110 is an asymmetric heat exchanger plate, Wherein the second heatexchanger plate 120 is also an asymmetric heat exchanger plate. In the embodiment ofFig. 12 the chevron angle of the first heat exchanger plate 110 is different from thechevron angle of the second heat exchanger plate 120 as described above. Also, theinterplate ﬂow channels have different volumes as described above. For example, thebrazing joints are elongated, such as oval, and arranged in a first orientation in theinterplate ﬂoW channels having bigger volume and in a different, second orientation in the interplate ﬂoW channels having smaller volume.

With reference to Fig. 13 a cross section of a part of a stack of first and secondheat exchanger plates 110, 120 according to yet another embodiment is illustratedschematically. In the embodiment of Fig. 13 the first and second heat exchanger plates110, 120 are provided With different corrugation depths. The first heat exchanger plate110 is a symmetric heat exchanger plate, Wherein the second heat exchanger plate 120 isan asymmetric heat exchanger plate. Altematively, both the first and second heatexchanger plates 110, 120 are symmetric or asymmetric. The chevron angle of the firstheat exchanger plate 110 is different from the chevron angle of the second heatexchanger plate 120 and the interplate ﬂoW channel volumes formed by the first andsecond heat exchanger plates 110, 120 When brazed together in brazing j oints aredifferent.

The heat exchanger according to the present invention is, e.g. used forcondensation or evaporation, Wherein at least one media at some point is in gaseousphase. For example, the heat exchanger is used for heat exchange, Wherein condensationor evaporation takes place in the interplate ﬂoW channels of bigger volume. Forexample, a liquid media, such as Water or brine, is conducted through the interplate ﬂoW channels having smaller volume.

Claims

1. A brazed plate heat exchanger (100) comprising a plurality of first andsecond heat exchanger plates (110, 120), Wherein the first heat exchanger plates (110)are formed With a first pattern of ridges and grooves, and the second heat exchangerplates (120) are forrned With a second pattern of ridges and grooves providing contactpoints between at least some crossing ridges and grooves of neighbouring plates underforrnation of interplate ﬂoW channels for ﬂuids to exchange heat, said interplate ﬂoWchannels being in selective ﬂuid communication through port openings, characterisedin thatthe first pattem of ridges and grooves is different from the second pattem of ridges andgrooVes, so that an interplate ﬂoW channel Volume on one side of the first heatexchanger plates (110) is different from the interplate ﬂoW channel Volume on theopposite side of the first heat exchanger plates (110), andthe first pattern of ridges and grooves exhibits a first angle (ßl) and the second patternof ridges and grooves exhibits a second angle (ß2) different from the first angle (ßl).

2. The brazed plate heat exchanger of claim 1, Wherein the interplate ﬂoWchannels on one side of the first heat exchanger plates (110) have a different cross section area than on the opposite side.

3. The brazed plate heat exchanger of claim 1 or 2, Wherein at least the second heat exchanger plates (110, 120) are asymmetric.

4. The brazed plate heat exchanger of any of the preceding claims, Wherein the first heat exchanger plates (110) are symmetric.

5. The brazed plate heat exchanger of claim 4, Wherein the grooves (G1) ofthe first heat exchanger plates (110) are forrned With identical corrugation depth (Dl), Wherein first grooves (G2a) of the second heat exchanger plates (120) are forrned With a first depth (D2a), and second grooves (G2b) of the second heat exchanger plates (120)are formed With a second depth (D2b) different from the first depth (D2a).

6. The brazed plate heat exchanger of any of the preceding clainis, Whereina depth (D1) of the grooves (G1) of the first heat exchanger plate (110) is in the range of05-5 nini, preferably in the range of 0.6-2 nini.

7. The brazed plate heat exchanger of any of the preceding clainis, Whereina first depth (D2a) of the second heat exchanger plate (120) is in the range of 0.5-5 nini,preferably in the range of 06-3 nini, and a second depth (D2b) of the second heatexchanger plate (120) is in the range of 30-80% of the first depth (D2a).

8. The brazed plate heat exchanger of any of the preceding clainis, Wherein the first angle (ßl) of the first pattern of ridges and grooves is in the range of 25-70°.

9. The brazed plate heat exchanger of any of the preceding clainis, Whereinthe second angle (ß2) of the second pattern of ridges and grooves is in the range of 25-70°.

10. The brazed plate heat exchanger of any of the preceding clainis, Whereina difference between the first angle (ßl) of the first pattern of ridges and grooves andthe second angle (ß2) of the second pattern of ridges and grooves is in the range of 2-35°.

11. The brazed plate heat exchanger of any of the preceding clainis, Whereinthe first and second heat exchanger plates (110, 120) are provided With different corrugation depths.

12. The brazed plate heat exchanger of any of the preceding clainis, Wherein the heat exchanger plates (110, 120) are provided With different corrugation Widths.

13. The brazed plate heat exchanger of any of the preceding claims, whereinthe ridges and grooves are arranged in a herringbone pattern, wherein the first and second angles (ßl, ß2) are first and second chevron angles.

14. The brazed plate heat exchanger of any of the preceding claims, whereinbrazing points (170) between the first and second heat exchanger plates (110, 120) areelongated and arranged in a first orientation in the interplate flow channels havingbigger Volume and in a second orientation in the interplate ﬂow channels having smallerVolume.

15. Use of a brazed plate heat exchanger according to any of claims 1-14 foreVaporation or condensation of media.

16. Use of a brazed heat exchanger according to claim 15, wherein media isevaporated or condensed in the interplate ﬂow channels of smaller volume, wherein liquid media is conducted to the interplate ﬂow channels of bigger Volume.