EP4303519A1

EP4303519A1 - A gas-liquid plate heat exchanger and method of assembling same

Info

Publication number: EP4303519A1
Application number: EP23183753.5A
Authority: EP
Inventors: Stig Gregersen
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-07-08
Filing date: 2023-07-06
Publication date: 2024-01-10

Abstract

A gas-liquid plate heat exchanger (1) comprises a stack of alternating first heat transfer plates (2) and second heat transfer plates (3) interposed between opposite exterior panels (4,5). The first heat transfer plates (2) and the second heat transfer plates (3) have respective aligned first liquid inlet openings (17) and second liquid inlet openings (19) and aligned first liquid outlet openings (18) and second liquid outlet openings (20). The first heat transfer plate (2) has a first surface pattern (44) on a first face (6), and a first opposite face (7), and an adjacent second heat transfer plate (3) has a second surface pattern (45) on a second face (9), and a second opposite face (10). The second face (9) faces the first opposite face (7) and the second surface pattern (44) is different from the first surface pattern (45). A liquid flow space (12) is delimited between the first face (6) and the second opposite face (10) by the first surface pattern (44). A gas flow space (13) is delimited between the second face (9) and the first opposite face (7) by the second surface pattern (45). The liquid flow space (12) and the gas flow space (13) are kept sealed from each other by forcing the opposite exterior panels (4,5) towards each other by means of clamping means (46,47) .

Description

The present invention relates to a gas-liquid plate heat exchanger.
In particular the present invention relates to a gas-liquid plate heat exchanger comprising a stack of alternating first heat transfer plates and second heat transfer plates interposed between opposite exterior panels of the kind wherein the first heat transfer plates and the second heat transfer plates have respective aligned first liquid inlet openings and second liquid inlet openings and aligned first liquid outlet openings and second liquid outlet openings.
For environmental reasons there is huge desire for energy recovery from hot waste gasses, such as the hot gas used in industrial drying plants.
In a traditional plate heat exchanger the flow cross sectional areas for the two fluids exchanging heat are of similar size. This is suitable for exchange of heat between two fluids with densities and heat capacities of similar magnitude. Due to this relationship, and due to the fact that flow channels are narrow, traditional plate heat exchangers are not suitable for exchange of heat between a gas and a liquid, and are almost exclusively used for heat exchange between two liquids or heat exchange between a liquid and condensing steam.
In existing gas-liquid plate heat exchangers corrugated heat transfer plates are most often assembled in pairs by welding or brazing. The space between two heat transfer plates, which make up a pair, constitutes the liquid flow channels. The space between different pairs constitutes the gas flow channel.
An example of plate heat exchanger is disclosed in European patent application no. EP1203193A1 . Said known gas-liquid plate heat exchanger is composed of heat transfer plates permanently joined and held together by means of weldings and brazings, and has pressure drop promoting means.
It is a first aspect of the present invention to provide a gas-liquid plate heat exchanger having a high ratio between the gas flow cross sectional area and the liquid flow cross sectional area.
It is a second aspect of the present invention to provide a gas-liquid plate heat exchanger where the stacked heat transfer plates are easy to assemble.
It is a third aspect of the present invention to provide a gas-liquid plate heat exchanger wherein the heat transfer plates are assembled without weldings and/or brazings.
It is a fourth aspect of the present invention to provide a gas-liquid plate heat exchanger wherein gas and liquid can flow in counter-current flow mode or in cross-current flow mode or in co-current flow mode depending on which is preferred for a specific application.
These and further aspects are achieved according to the present invention by providing a gas-liquid plate heat exchanger comprising that:

the first heat transfer plate has a first surface pattern on a first face, and a first opposite face,
an adjacent second heat transfer plate has a second surface pattern on a second face, and a second opposite face, wherein the second face faces the first opposite face,
and wherein the second surface pattern is different from the first surface pattern,
a liquid flow space is delimited between the first face and the second opposite face, and is further defined by at least the first surface pattern,
a gas flow space is delimited between the second face and the first opposite face, and is further defined by at least the second surface pattern, and
the liquid flow space and the gas flow space are kept sealed from each other by forcing the opposite exterior panels towards each other by means of clamping means.

Within the context of the present invention the term "surface pattern" means a 3-dimensional physical structure that serves to obtain a distance between adjacent first and second heat transfer plates. Thus a surface pattern defines structures raised from the above-mentioned first and second faces of said heat transfer plates. In the assembled state the flow spaces between the first heat transfer plates and the second heat transfer plates are thus obtained by virtue of clamping said heat transfer plates together by a clamping force whereby the surface patterns create flow paths for the gas and liquid, respectively. A "surface pattern" is thus a topographic pattern.
Due to being held together by a clamping force the heat transfer plates are both easy to assemble and disassemble, e.g. to separate from each other in order to e.g. clean or replace any of the individual heat transfer plates, or other component arranged between adjacent heat transfer plates.
The first surface pattern and/or second surface pattern is/are preferably provided over at least the main central part of the respective heat transfer plates for promoting turbulent flow through the first flow space and the second flow space, respectively, and for supporting the stacked heat transfer plates by providing many contact points between alternating adjacent first heat transfer plates and second heat transfer plates, which allows the heat transfer plates to be thin to reduce production costs. The first surface pattern and/or second surface pattern may also be provided at the periphery and/or around the liquid inlet opening and liquid outlet opening of the first heat transfer plates and/or second heat transfer plates, respectively, for providing support at these locations.
A liquid inlet opening and a liquid outlet opening advantageously extend through a heat transfer plate in a direction perpendicular to the general plane of the stacked heat transfer plates, thus said openings can advantageously be used for aligning the heat transfer plates properly to desired height of the stack of heat transfer plates of the gas-liquid plate heat exchanger of the present invention. By e.g. placing the liquid inlet openings on a mandrel and the liquid outlet opening on another mandrel, a perfectly aligned stack of heat transfer plates is automatically obtained and arranged for being clamped together.
The aligned liquid inlet openings define a liquid inlet passage perpendicular to the stack of heat transfer plates at one side of the gas-liquid plate heat exchanger, and the aligned liquid outlet openings define a corresponding liquid outlet passage perpendicular to the stack of heat transfer plates at the opposite side, or on the same side, of the gas-liquid plate heat exchanger.
The first heat transfer plates and/or second heat transfer plates can be designed so that the periphery of the liquid flow spaces are fluid-tightly sealed when the stacked heat transfer plates are clamped together, e.g. by providing the first heat transfer plate and/or the second heat transfer plate with an appropriate peripheral flange portion configured for sealing off the periphery of the liquid flow spaces. Preferably said flange portion comprises a groove, or is constituted by a groove.
The first heat transfer plates and the second heat transfer plates can have any desired shape, including but not limited to square, rectangular, polygonal or even circular or oval. The intended use of the gas-liquid plate heat exchanger may be decisive of the kind of shape of the heat transfer plates. The heat transfer plates may be elongate to fit into a suction channel.
The exterior panels may be provided with an inlet neck flange at the liquid inlet passage and an outlet neck flange at the liquid outlet passage to facilitate coupling the gas-liquid plate heat exchanger to the source of liquid and to a discharge, respectively. The gas can be connected to the gas flow space by means of transition pieces.
The heat transfer plates of the gas-liquid plate heat exchanger according to the present invention may be made so that the first opposite face has a third surface pattern and/or the second opposite face has a fourth surface pattern. Optionally the third surface pattern may be created as an inherent result of a manufacturing step of the first surface pattern of the first heat transfer plate. Optionally the fourth surface pattern may be created as an inherent result of a manufacturing step of the second surface pattern of the second heat transfer plate. If e.g. the first surface pattern and the second surface pattern are made by pressing from the respective opposite faces the indentations arising from the pressing process on said opposite faces represent the respective third surface pattern and fourth surface patterns. Thus the first surface pattern may be a male pattern and the third surface pattern may be a complementary female pattern. Similarly the second surface pattern may be a male pattern and the fourth surface pattern may be a complementary female pattern.
It may be preferred that said gas-liquid plate heat exchanger comprises gasket means between the stacked heat transfer plates for assisting in defining and/or keeping the liquid flow space and the gas flow space fluid-tightly sealed from each other. The gasket means may be applied simultaneously with stacking the heat transfer plates.
The aligned liquid inlet openings and the aligned liquid outlet openings are in liquid communication with the liquid flow spaces between adjacent heat transfer plates, and not with the gas flow spaces. Thus the gas-liquid plate heat exchanger may preferably be configured so that the only way in and out of the liquid flow spaces is at the liquid inlet opening and at the liquid outlet opening, respectively.
A first gasket may be provided in one or more of the liquid flow spaces, preferably all liquid flow spaces, between adjacent first heat transfer plates and second heat transfer plates along their periphery. Such a first gasket may extends between the stacked heat transfer plates along the periphery of the first face of the first heat transfer plate and the opposite second face of the second heat transfer plate of said stacked heat transfer plates to serve to further ensure liquid-tight liquid flow spaces, thus sealed assembling of said adjacent heat transfer plates and distinct separation of the liquid flow space (s) from the gas flow space (s). The first gaskets may thus define the border of the liquid flow spaces.
A second gasket may be provided in one or more of the gas flow spaces between adjacent heat transfer plates around the liquid inlet opening(s). Correspondingly a third gasket may be provided in one or more of the gas flow spaces, preferably all gas flow spaces, around the liquid outlet opening(s), so that liquid does not enter the gas flow spaces from the liquid flow spaces.
By providing a second gasket and/or a third gasket, preferably in each of the gas flow spaces around the liquid inlet opening and the liquid outlet opening, respectively, a fluid-tight seal between the opposite first face of the first heat transfer plate and the second face of the second heat transfer plate can easily be obtained.
In a preferred embodiment, the first gasket, second gasket and third gasket ensure that the only way from the aligned liquid inlet openings to the aligned liquid outlet openings is via the liquid flow spaces, which means that when the liquid is lead to the liquid inlet openings, it will flow into and across the respective liquid flow spaces out of the liquid flow openings.
The liquid inlet opening and the liquid outlet opening are preferably circular, in which case the second gasket and the third gasket preferably are simple O-rings.
The gas flow spaces may be open along at least some of their periphery so that the gas can be lead across the gas flow spaces in any direction.
The gas-liquid plate heat exchanger can e.g. be arranged inside or be connected to an outflow pipe, a ventilation, or a vent duct pipe in which the gas flows, e.g. as a waste gas in relation to a production facility. The gas flowing through the liquid-gas heat exchanger may also be a gas product stream used to produce a heated liquid for heating up another facility. The gas enters the gas flow spaces at the end of the gas-liquid plate heat exchanger opposite the liquid entry end, thus at the end with the aligned liquid outlet openings.
It may be preferred that each of the first heat transfer plates and the second heat transfer plates has a first edge part and an opposite second edge part, and a third edge part and an opposite fourth edge part that extend between the first and second edge part, and preferably that the gas-liquid plate heat exchanger comprises at least one fourth gasket and at least one fifth gasket provided at the third and fourth edge part of the adjacent stacked heat transfer plates, respectively, for fluid-tightly sealing off the gas flow spaces at the third edge part and the fourth edge part of the stacked heat transfer plates, respectively.
In a preferred embodiment, the second gasket and the third gasket in combination with the at least one fourth gasket and at least one fifth gasket ensure that the only way into and out of the gas flow spaces is at the first edge part and opposite second edge part of the stacked heat transfer plates. Thus the first edge part may provide the gas entry and the second edge part may provide the gas exit.
The first surface pattern may advantageously define a liquid flow channel through each of the liquid flow spaces, and the second surface pattern may define a gas flow path through each of the gas flow spaces. Due to the configuration of the heat transfer plates of the gas-liquid plate heat exchanger of the present invention there is substantial no, or only a minimal, loss of gas pressure during passage of the gas flow spaces.
The liquid flow from the liquid inlet openings to the liquid outlet openings through the liquid flow space, and the gas flow from the first edge part through the gas flow space and out at the second edge part, may be selected to be in counter-current or co-current as desired. In a particular preferred embodiment the flow path of the liquid may also be cross-current the flow path of the gas.
The clamping means can e.g. threaded rods extending through aligned holes along the periphery of the opposite exterior panels. When the threaded rod is tightened the opposite exterior panels can easily be forced towards each other to close the liquid flow spaces and the gas flow spaces.
The first pattern may comprise at least one first spacer that serves for defining a height of the liquid flow spaces. Correspondingly the second pattern may comprise at least one second spacer or plate support means that serve for defining a height of the gas flow spaces.
Preferably the cross-sectional area of the gas flow path, as primarily defined by at least the second pattern, thus at an edge part of the heat transfer plates where the gas enters, is several times larger than the cross-sectional area of the liquid flow channel of the liquid flow space, as primarily defined by at least the first flow pattern.
Preferably the ratio between the above-defined cross-sectional area of the gas flow path and the above-defined cross-sectional area of the liquid flow channel of the liquid flow space is at least 2, more preferred at least 20, more preferred at least 40, and most preferred at least 50.
The volumetric flow rate of the liquid may be calculated as the cross-sectional area of the liquid flow channel times the flow rate of the liquid, and the volumetric flow rate of the gas may correspondingly be calculated as the cross-sectional area of the gas flow path times the flow rate of the gas.
The gaskets can be made of a variety of materials, and should be strong enough to withstand the clamping force without crushing or displacing. The gaskets can e.g. be made of nitrile rubber or fluorocarbon rubber to withstand a high-temperature gas.
For embodiments with the first gaskets, the second gaskets and the third gaskets (and optionally the at least one fourth and the at least one fifth gasket), it is preferred that the gaskets are unattached to the stacked heat transfer plates and thus secured between the stacked heat transfer plates in the assembled state only by the clamping force, which means that not only the stacked heat transfer plates but also the gaskets are very easy to separate from the assembled gas-liquid plate heat exchanger in order to e.g. clean or replace any thereof.
Alternatively, the different gaskets may be attached (e.g. by gluing) to either the first heat transfer plates or second heat transfer plates. The first gaskets may e.g. be attached to the first face of the first heat transfer plates, and the second gaskets and third gaskets may be attached to the second face of the second heat transfer plates, in which case the stacked heat transfer plates with the gasket(s) attached thereto are easy to separate from each other in order as a common unit to be cleaned or replaced. Normally all gaskets will be replaced if one of the gaskets is damaged to avoid unnecessary assemblings and disassemblings of the gas-liquid plate heat exchanger, but the present invention does offer the possibility of changing fewer gaskets, e.g. only any damaged gaskets if desired.
As liquids generally have higher volumetric heat capacity (in terms of kJ/m³*°C)than gasses, it is preferred that the gas-liquid plate heat exchanger is configured to allow the volumetric flow rate of the gas to be higher than the volumetric flow rate of the liquid to obtain an effective heat exchange between the liquid and gas.
In a preferred embodiment, the first surface pattern comprises several elongated first spacers arranged substantially transverse to the direction between the liquid inlet opening and the liquid outlet opening. The liquid flow channel may be defined by several transverse flow sections, separated by the elongated first spacers, and interconnected via opposite U-shaped flow sections defined at opposite ends of the elongated first spacers. A liquid flow channel is thus a chicane of tight turns for achieving sufficient flow rate for high heat transfer of the liquid inside a liquid flow space.
In a preferred embodiment, the second surface pattern comprises a plurality of individual second spacers arranged spaced apart from each other. The second spacers may be formed as identical or different distinct small protruding objects, be substantially evenly or unevenly distributed over the main part of the second heat transfer plate, and have any suitable configuration, including but not limited to frustum-conical or cylindrical. It may be preferred that the distinct small protruding objects are arranged in a matrix pattern of n x m such objects. If the heat transfer plates are rectangular the number of such objects along the short edge may be n and the number of such objects along the long side may be m, wherein m > n. Optionally the distance between all such objects are the same in any of the n-direction and the m-direction. In yet a modified embodiment the second spacers in a row of a matrix may be offset the second spacer in an adjacent row of the matrix, and the second spacers in a column of the matrix may be offset the second spacer in an adjacent column of the matrix.
The elongated first spacers and the distinct individual second spacers provide a third dimension to the respective first heat transfer plates and second heat transfer plates that creates the respective flow spaces.
Said spacers of the respective patterns may be created by pressing, e.g. embossing, or in the alternative be adhered by gluing or welding to the heat transfer plates, or be added in any imaginable way. The heat transfer plates may even be 3D-printet. If the second spacers are a plurality of small individual protruding elements the gas can be forced to zig-zag between said second spacers. So contrary to the liquid, the flow path of which is kept under directional control, the gas can finds its own way from where the gas enters the gas-liquid plate heat exchanger to where the gas exits the gas-liquid plate heat exchanger.
It is further preferred that one or both of the first heat transfer plate and the second heat transfer plates additionally comprises a peripheral spacer that protrudes inside the liquid flow spaces, and having the same height as the height of the aforementioned first spacers. The peripheral spacers advantageously serve to support the stacked heat transfer plates at their periphery, and assists in avoiding that any of the first gaskets displace, which is especially important when the pressure of the liquid is relatively high, e.g. above 2 bar.
The stacked heat transfer plates may further be supported at their periphery by a combination of any of the peripheral spacers, the first surface pattern and/or the second surface pattern of the stacked heat transfer plates, and the at least one fourth gasket and the at least one fifth gasket.
The gas-liquid plate heat exchanger may have a single peripheral spacer in each of the liquid flow spaces that extend along the entire periphery of the stacked heat transfer plates, although in the alternative it might have two or more peripheral spacers to maintain a desired fluid-tight seal along the periphery of the stacked heat transfer plates during use of the gas-liquid plate heat exchanger.
For embodiments where the stacked heat transfer plates are substantially rectangular with a first edge and an opposite second edge, and a third edge and an opposite fourth edge, it is preferred that the gas-liquid plate heat exchanger comprises four first peripheral spacers extending along the first, second, third and fourth edge of the first heat transfer plate, respectively, and four second peripheral spacers extending along the first, second, third and fourth edge of the second heat transfer plate, respectively, where the ends of the respective peripheral spacers are spaced apart by a small gap for allow a controlled expansion of the first gasket into such gaps. In the alternative a single circumferential first peripheral spacer can be provided.
However, the pressure of the liquid at, or in, the liquid inlet openings and the liquid outlet openings may be considerable different from the pressure of the gas in the area around the liquid inlet openings and the liquid outlet openings, in which case it is desirable to prevent that the pressure difference causes undesirable deformation or even displacement of the second gasket(s) and the third gasket(s). This can be achieved by providing a first retaining element and a second retaining element in each of the gas flow spaces, where the first retaining element and the second retaining element surround, and optionally abut, the second gasket and the third gasket, respectively, and are clamped between the opposite first face of the first heat transfer plate and the second face of the second heat transfer plate.
As the first retaining element and the second retaining element are clamped between the stacked heat transfer plates, they on one hand prevent deformation of the second gasket and the third gasket in the direction away from the liquid inlet openings and the liquid outlet openings, respectively, and on the other hand support the stacked heat transfer plates at the liquid inlet openings and the liquid outlet openings, respectively.
The second gasket, the third gasket, and the first and second retaining element are preferably positioned so that the face of the second gasket and of the third gasket facing the liquid inlet openings and the liquid outlet openings, respectively, is substantially flush with the edge of said liquid inlet openings and said liquid outlet openings, respectively, during use of the gas-liquid plate heat exchanger, as this reduces the amount of turbulent flow inside said liquid inlet openings and said liquid outlet openings.
It may be preferred that each of the first heat transfer plates are provided with at least one third spacer and at least one fourth spacer that protrude from the first face of a first heat transfer plate, and/or that each of the second heat transfer plates is provided with at least one fifth spacer and at least one sixth spacer that protrude from the second opposite face of a second heat transfer plate. The at least one third spacer and the at least one fourth spacer may conveniently serve to prevent deformation of the heat transfer plates around the liquid inlet openings and the liquid outlet openings when the clamping force is applied and maintained to obtain a fluid-tight joining of adjacent heat transfer plates. Preferably the at least one third spacer and the at least one fourth spacer is arranged above the first retaining element and the second retaining element. Thus the at least one third spacer and the at least one fourth spacer may be arranged at substantially same radius from the central axis of the respective liquid inlet opening and liquid outlet opening as the first retaining element and the second retaining element. The at least one third spacer and the at least one fourth spacer may be plural spaced apart dimples made inside an opposite face of a heat transfer plate.
The purpose of the at least one third spacer and at least one fourth spacer, and/or the at least one fifth spacer and the at least one sixth spacer, is to keep the position of the heat transfer plates in fixed position in relation to each other.
The first heat transfer plates and the second heat transfer plates can preferably be made from sheet metal, which can be formed into the final form using a conventional sheet metal forming techniques, where the liquid inlet opening and the liquid outlet opening e.g. can be made by punching, and where any of the spacers and surface patterns e.g. can be made by press braking.
It is preferred that a plate support means may be provided in each of the gas flow spaces along the periphery of the stacked heat transfer plates, where the plate support means extends between the first opposite face of the first heat transfer plate and the second face of the second heat transfer plate to support the stacked heat transfer plates, thereby further preventing deformation at the periphery of the stacked heat transfer plates. The plate support means may conveniently be configured for allowing gas to flow in and out of the gas flow spaces. A further advantage of the plate support means is the freedom to choose at which section(s) of the perimeter of the gas-liquid plate heat exchanger gas inflow may be permitted, and/or gas outflow may be prevented. The plate support means may be constructed in different ways, and may be manufactured by moulding or extrusion, or from sheet metal. In one embodiment a plate support means may be provided simply by bending a free edge of any of the heat transfer plates, to thereby obtain increased height at such free edges. In case the heat transfer plates are substantially rectangular e.g. the parallel long edges may be subjected to a bending, or similar mechanical processing, to obtain the plate support means.
The first heat transfer plates, the second heat transfer plates, the plate support means, and/or the first retaining element(s) and the second retaining element(s) may preferably be made of metal (e.g. steel, preferably stainless steel), although alloys, composite materials, or plastics may also be used e.g. in order to meet corrosive and erosive requirements, as well at having sufficient rigidity.
The plate support means in each of the gas flow spaces may comprise a first, second, third and fourth support part provided at the first, second, third and fourth edge part of the stacked heat transfer plates, respectively, where the first support part and the second support part are adapted for allowing the gas to flow in and out of the gas flow space at the first edge part and the second edge part of the stacked plates, respectively. The first, second, third and fourth support part in each of the gas flow spaces may in combination extend along the entire periphery of the stacked heat transfer plates in order to further support said stacked heat transfer plates along their entire periphery.
For embodiments where the first heat transfer plates and the second heat transfer plates are substantial rectangular, it may be preferred that the first, second, third and fourth support part have a cross-sectional profile extending in the direction between the first edge and the second edge of the stacked heat transfer plates, i.e. in the main flow direction of the gas, and/or that the first and second support part as well as the third support part and the fourth support part are identical. Such embodiments may be especially preferred to reduce production costs.
The first support part and the second support part may have cross-sectional profiles having a square wave form extending in the main flow direction of the gas. The square wave form reduces the pressure exerted by the gas on the first support part and on the second support part, and allows the first support part and the second support part to be manufactured with low material costs while providing sufficient support for the stacked heat transfer plates, as well as sufficient space for the gas to flow in and out of the gas flow spaces.
For embodiments where the stacked heat transfer plates are substantially rectangular, the plate support means in each of the gas flow spaces may comprise a first, second, third and fourth support part provided at the first, second, third and fourth edge of the stacked heat transfer plates, respectively, where the first support part and the second support part are adapted for allowing the gas to flow in and out of the gas flow space at the first edge and the second edge of the stacked heat transfer plates, respectively.
Each of the third support part and the fourth support part may comprise a first portion extending along the opposite first face of the first heat transfer plate, a second portion extending along the second face of the second heat transfer plate and a third portion extending between the first portion and the second portion. One or more of said portions may have a Z-shaped or an H-shaped cross-sectional profile.
It may be preferred that the first, second, third and fourth support part are formed as separate components, although they could be formed integrally as a one-piece component with the cross-sectional profile extending in the main flow direction of the gas, thus in the direction between the first edge and the second edge of the stacked heat transfer plates.
The at least one fourth gasket may be a single fourth gasket extending along the entire length of the third edge of the stacked heat transfer plates and across the entire height of the stacked heat transfer plates, wherein the gas-liquid plate heat exchanger comprises appropriate means for forcing the fourth gasket towards the third edge of the stacked heat transfer plates for fluid-tightly sealing off the gas flow spaces at the third edge of the stacked heat transfer plates.
The at least one fifth gasket may correspondingly be a single fifth gasket extending along the entire length of the fourth edge of the stacked heat transfer plates and across the entire height of the stacked heat transfer plates, wherein the gas-liquid plate heat exchanger comprises appropriate means for forcing the fifth gasket towards the fourth edge of the stacked heat transfer plates for fluid-tightly sealing off the gas flow spaces at the fourth edge of the stacked heat transfer plates.
Such a single fourth gasket and/or fifth gasket is quick and easy to replace.
Alternatively, the at least one fourth gasket and at least one fifth gasket may comprise a fourth gasket and a fifth gasket, respectively, in each of the gas flow spaces, wherein such fourth gasket and such fifth gasket may be attached, e.g. by gluing, to the inner face of the plate support means at the third and fourth edge, respectively, of the stacked heat transfer plates for fluid-tightly sealing off the gas flow space at the respective third edge and fourth edge of the stacked heat transfer plates.
It may however be preferred that the at least one fourth gasket and the at least one fifth gasket comprises two fourth gaskets and two fifth gaskets, respectively, in each of the gas flow spaces, wherein the two fourth gaskets extend along the entire length of the third edge of the stacked heat transfer plates and are provided efficiently fluid-tightly between the plate support means and the first heat transfer plate and the second heat transfer plate, respectively, and wherein the two fifth gaskets extend along the entire length of the fourth edge of the stacked heat transfer plates and are provided fluid-tightly between the plate support means and the first heat transfer plate and the second heat transfer plate, respectively, so that the gas flow spaces are efficiently fluid-tightly sealed off at the third edge and fourth edge of the stacked heat transfer plates, respectively.
The two fourth gaskets and the two fifth gaskets also assist in maintaining the intended position of the plate support means during use of the plate heat exchanger, because they provide friction between the plate support means and the first heat transfer plates and the second heat transfer plates.
The plate support means may comprise grooves for receiving the gaskets, e.g. for receiving the at least one fourth gasket and/or the at least one fifth gasket. In the alternative the plate support means does not have any grooves, which reduces the production costs.
The present inventions further relates to a method of assembling a gas-liquid plate heat exchanger as described above.
The method comprises the steps of:

a) arranging the first heat transfer plates and the second heat transfer plates alternating in a stack between the exterior panels with aligned first liquid inlet openings and aligned second liquid inlet openings, and aligned first liquid outlet openings and aligned second liquid outlet openings to define liquid flow spaces alternating with and gas flow spaces, and
b) applying a clamping force to the opposite exterior panels to seal the liquid flow spaces from the gas flow spaces.

The method according to the present invention may further comprise providing a first guide member and a second guide member, such a mandrel, with a fixed structure and a height being at least, or substantially, the same as the height of the stacked heat transfer plates and a shape that matches the shape of the aligned liquid inlet openings and the aligned liquid outlet openings, respectively.
The guide members may preferably be configured so that they allow fluid communication between the liquid flow spaces and the respective liquid inlet openings and the liquid outlet openings, whereby the guide members can be left inside the stacked heat transfer plates during use of the gas-liquid plate heat exchanger. The guide members may additionally be utilized to keep the first retaining member and the second retaining member centred around the central axes of the respective liquid inlet opening and liquid outlet opening, and to ensure centring of the second gasket and the third gasket.
In a preferred embodiment the guide members may comprise a number of exterior rods with the same length as the height of the stacked heat transfer plates, and a number of interior connection members for interconnecting the exterior rods, where the rods are arranged so that they abut the liquid inlet openings and liquid outlet openings of the stacked heat transfer plates, respectively, during assembly of the gas-liquid plate heat exchanger.
The assembling method may thus comprise in step a) fitting the liquid inlet openings and the liquid outlet opening of the respective first heat transfer plates and second heat transfer plates around the first guide member and the second guide member, respectively, to ensure that the first heat transfer plates and the second heat transfer plates are correctly aligned the liquid inlet opening(s) and liquid outlet openings, and for the embodiments with the second gasket and the third gasket, to ensure that the second gasket and the third gasket are also aligned with the liquid inlet openings and the liquid outlet openings, respectively.
When the first heat transfer plates, the second heat transfer plates, the first, the second, the third and the fourth gaskets and the plate support means of the present invention are referred to in the singular, it is to be understood that the assembled gas-liquid plate heat exchanger may comprise a plurality of each of these components.
Optionally the assembling method may comprise removing the first guide member and the second guide member after step b).
In some embodiments the method may further comprise

providing one or more of first gaskets, second and third gaskets,
wherein step a) further may comprise one or more of
- arranging a first gasket in each of the liquid flow spaces along the periphery of the stacked heat transfer plates during stacking of the heat transfer plates,
- arranging a second gasket and a third gasket in each of the gas flow spaces around the liquid inlet openings and the liquid outlet openings, respectively, during stacking of the heat transfer plates
- arranging a first retaining element and a second retaining element around the second gasket and the third gasket, respectively, during stacking of the heat transfer plates.

In a preferred embodiment of said method welding and/or brazing steps are not used when joining the heat transfer plates fluid-tight. Adjacent heat transfer plate are stacked with gasket means and any other of the above described means in-between those adjacent heat transfer plate, and simply clamped together, e.g. by means of screw rods, to sealingly obtain and delimit the gas flow spaces and the liquid flow spaces through the gas-liquid plate heat exchanger. Due to lacking weldings and/or brazings the gas-liquid plate heat exchanger of the present invention can quickly be taken apart again, and all individual parts can either be reused, if in good standing, or be recycled.
Further details and advantages of the present invention are described below with reference to the drawing, which show an exemplary embodiment of a gas-liquid plate heat exchanger according to the present invention.
In the figures the gas-liquid plate heat exchanger is seen with the opposite short edges open. It should be emphasized that this is only for illustrative purposes and overview.
Appropriately configured gas end parts are, within the scope of the present invention, intended provided at the gas entry end and the gas exit end. The gas end parts may e.g. be secured to the exterior panels, and to the stack of heat transfer plates by means of opposite further special flange parts provided in extension of said stack. A gas inlet end part may be configured internally to guide the incoming gas into the individual gas flow spaces, and a gas outlet end part may be configured internally to guide the outgoing gas further on to a discharge. The gas inlet part may have suitable inlet connection (s) and inlet aperture(s) for coupling the gas-liquid plate heat exchanger to a source of gas, and the gas outlet part may similarly have suitable outlet connection(s) and outlet aperture(s) for coupling the gas-liquid plate heat exchanger to the discharge.
The gas-liquid plate heat exchanger may not need weldings and/or brazings to delimit the liquid flow space and the gas flow spaces.

Fig. 1 is a perspective view of the gas-liquid plate heat exchanger in assembled state,
Fig. 2 is a side view of the gas-liquid plate heat exchanger seen in fig. 1,
Figs. 3 and 4 show a first heat transfer plate of the gas-liquid plate heat exchanger of fig. 1, seen from the first face,
Figs. 5 and 6 show a second heat transfer plate of the gas-liquid plate heat exchanger of fig. 1, seen from the second face,
Fig. 7 is an enlarged scale view of a corner fragment of the second heat transfer plate seen in fig. 5,
Fig. 8 is a cross-sectional view taken along line VIII-VIII of fig. 2, where the inlet neck flange have been removed,
Fig. 9 is an enlarged scale view of a corner fragment of fig. 8,
Fig. 10 is a perspective view of a plate support means of the gas-liquid plate heat exchanger seen in fig. 1,
Fig. 11 is a cross-sectional view taken along line XI-XI of fig. 10,
Fig. 12 is an enlarged scale view of a fragment of fig. 11,
Fig. 13 is a partial perspective view taken along line XIII-XIII of fig. 2, where the exterior panels, inlet neck flange and the topmost heat transfer plate have been removed,
Fig. 14 is an enlarged scale partial view of fig. 13 showing the liquid inlet openings surrounded by gaskets,
Fig. 15 is a partial perspective view from below the gas-liquid plate heat exchanger seen in fig. 1, and taken along line XV-XV of fig. 2, where the exterior panels and outlet neck flange have been removed, and
Fig. 16 is a perspective view of a guide member.

The gas-liquid plate heat exchanger 1 has several first heat transfer plates 2 and several second heat transfer plates 3, which are arranged parallel and alternating, and, as shown in figs. 1 and 2, are clamped together in a stack between a first exterior panel 4 and a second exterior panel 5. The heat transfer plates 2,3 can be made from steel or titanium sheet metal, which may be formed into the shown form by means of e.g. press braking.
As shown in fig. 3, a first heat transfer plates 2 has a first face 6 and an opposite first face 7, and a first 8a, second 8b, third 8c and fourth edge 8d. As shown in fig. 5, a second heat transfer plate 3 has a second face 9 and an opposite second face 10, and a first 11a, second 11b, third 11c and fourth edge 11d.
The stacked heat transfer plates 2,3 define several alternating liquid flow spaces 12 and gas flow spaces 13, where each of the liquid flow spaces 12 is defined between the first face 6 of a first heat transfer plate 2 facing towards the opposite second face 10 of a second heat transfer plate 3, and each of the gas flow spaces 13 are defined between the opposite first face 7 of a first heat transfer plate 2 facing towards the second face 9 of an adjacent second heat transfer plate 3.
The liquid flow spaces 12 comprises a liquid flow channel along the stacked heat transfer plates 2,3, and the gas flow spaces 13 form a gas flow path along the stacked heat transfer plates 2,3.
As shown in figs. 3 and 8, a first heat transfer plate 2 has four separate first peripheral spacers 14a,14b,14c,14d, which extend along and are spaced apart (by a distance A) from the first 8a, second 8b, third 8c and fourth edge 8d of the first heat transfer plate 2, respectively. The four first peripheral spacers 14a,14b,14c,14d protrude from the first face 6 of the first heat transfer plate 2 towards, and being in contact with, the opposite second face 10 of the second heat transfer plate 3.
As shown in figs. 5 and 8, a second heat transfer plate 3 has four separate second peripheral spacers 15a,15b,15c,15d, which extend along and are spaced apart (by a distance B) from the first 11a, second 11b, third 11c and fourth edge 11d of the second heat transfer plate 3, respectively. The four second peripheral spacers 15a,15b,15c,15d protrude from the opposite second face 10 of the second heat transfer plate 3 towards, and being in contact with, the first face 6 of the first heat transfer plate 2. The peripheral spacers 15c,15d extend along the entire length of the third edge 11c and the fourth edge 11d, respectively.
Within each of the liquid flow spaces 12, the first peripheral spacers 14a,14b,14c,14d and the second peripheral spacers 15a,15b,15c,15d are pairwise spaced apart (the distance A is larger than the distance B) in the direction parallel with the general plane of the heat transfer plates 2,3, and thus define an interspace there between for tightly housing a first gasket 16, which extends along the entire periphery of the stacked heat transfer plates 2,3. The size of the first gasket 16 is slightly larger than the size of the interspace so that the first peripheral gasket is slightly compressed in the interspace when the heat transfer plates 2,3 are clamped together to provide a fluid-tight seal between the first face 6 of the first heat transfer plate 2 and the opposite second face 10 of the second heat transfer plate 3 along the entire periphery of the liquid flow space 12.
As seen in figs. 3 and 4 the first heat transfer plates 2 have a first liquid inlet opening 17 near its first edge 8a and a first liquid outlet opening 18 near its second edge 8b, and as seen in figs. 5 and 6 the second heat transfer plates 3 have a second liquid inlet opening 19 near its first edge 11a and a second liquid outlet opening 20 near its second edge 11b. The liquid inlet openings 17,19 are aligned and define a liquid inlet passage 21, as illustrated by arrow L1 in fig. 1, that extends through the stacked heat transfer plates 2,3, and the liquid outlet openings 14,15 are aligned and define a liquid outlet passage 22, as illustrated by arrow L2 in fig. 1, that extends through the stack of alternating heat transfer plates 2,3. As further shown in fig. 1 the gas flow is counter current to the liquid flow, as illustrated by arrows G1,G2.
Within each of the gas flow spaces 13, a plate support means 23 is provided in the form of a first 23a, second 23b, third 23c and fourth support part 23d, which are located at the first 8a,11a, second 8b,11b, third 8c,11c and fourth edge 8d,11d of the stacked heat transfer plates 2,3, respectively. The third support part 23c and the fourth support part 23d are identical, and extend along the entire length of the respective third edge 8c,11c and fourth edge 8d,11d of the stacked heat transfer plates 2,3. The first support part 23a and the second support part 23b are identical, and extend along the first edge 8a,11a and the second edge 8b,11b of the stacked heat transfer plates 2,3. In the shown embodiment, these four support parts 23a,23b,23c,23d are separate components, but they could quite as well have been a one-piece component. The third support part 23c and the fourth support part 23d may conveniently be made as integral parts of the heat transfer plates 2,3 during pressing of those.
Within each of the gas flow spaces 13, a second gasket 24 and a third gasket 25 are provided between the opposite face 7 of the first heat transfer plate 2 and the second face 9 of the adjacent second heat transfer plate 3, and around the liquid inlet openings 17,19 and around the liquid outlet openings 18,20, respectively. The second gasket 24 and the third gasket 25 have same overall outline to match the liquid inlet openings 17,19 and the liquid outlet openings 18,20. In the present embodiment they are circular, and are preferably shaped as a ring torus when uncompressed. The uncompressed height of the second gasket 24 and of the third gasket 25 is slightly larger than the height of the gas flow spaces 13 to provide a fluid-tight sealing in the assembled state of the gas-liquid plate heat exchanger 1.
Within each of the gas flow spaces 13, a first retaining element 26 and a second retaining element 27 are located around and in abutment with the second gasket 24 and the third gasket 25, respectively. The first retaining element 26 and the second retaining element 27 extend between the opposite first face 7 of the first heat transfer plate 2 and the second face 9 of the second heat transfer plate 3, and are fixed at their respective positions due to the clamping force exerted on the stacked heat transfer plates 2,3, thereby preventing the second gasket 24 and the third gasket 25 from moving radially away from the liquid inlet passage 21 and the liquid outlet passage 22, respectively. The first retaining element 26 and the second retaining element 27 may conveniently be made as integral parts of the heat transfer plates during pressing of those.
The first heat transfer plates 2 has six third spacers 28 and six fourth spacers 29 located around the first retaining element 26 and the second retaining element 27, respectively, and protruding from the first face 6 of the first heat transfer plate 2. The third spacers 28 and the fourth spacers 29 assist in preventing deformation of the heat transfer plates 23 around the liquid inlet openings 17,19 and the liquid outlet openings 18,20.
The uncompressed height of the second gasket 24 and the third gasket 25 is slightly larger than the height of the gas flow spaces 13 so that the second gasket 24 and the third gasket 25 in each gas flow space 13 are compressed fluid-tightly between the opposite first face 7 of the first heat transfer plate 2 and the second face 9 of the second heat transfer plate 3 by the clamping force exerted on the stacked heat transfer plates 2,3 by the clamping means, so that each second gasket 24 and third gasket 25 provides a fluid-tight seal between the gas flow space 13, in which they are located, and the liquid inlet passage 21 and the liquid outlet passage 22, respectively. The second gasket 24 and the third gasket 25 are arranged so that the face of the second gasket 24 facing the inlet passage 21 and the face of the third gasket 25 facing the outlet passage 22 are substantially flush with the edge of the liquid inlet openings 17,19 and the outlet openings 18,20, respectively, in order to reduce the degree of turbulence of the liquid inside said liquid inlet passage 21 and said liquid outlet passage 22, respectively.
Each of the alternating liquid flow spaces 12 is delimited by the first face 6 of the first heat transfer plate 2, the opposite second face 10 of the second heat transfer plate 3, and the first gasket 16, which together ensure that the only way in and out of the each of the liquid flow spaces 12 is from the liquid inlet passage 21 and the liquid outlet passage 22, respectively.
As seen in fig. 1 the liquid enters and exits the stacked heat transfer plates 2,3 via an inlet neck flange 30 on the first exterior panel 4 and an outlet neck flange 31 on the second exterior panel 5, respectively. The liquid flows from the inlet neck flange 30 into the liquid inlet passage 21 and then into the individual liquid flow spaces 12. The second gasket 24 and the third gasket 25 in each of the gas flow spaces 13 ensure that the liquid is prevented from flowing from the liquid inlet passage 21 to the gas flow spaces 13, which means that the only flow path from the liquid inlet passage 21 across the stacked heat transfer plates 2,3 to the liquid outlet passage 22 is through the liquid flow spaces 12. The liquid flows out of the liquid flow spaces 12 into the liquid outlet passage 22, and then into the outlet neck flange 31.
Each of the first support part 23a and the second support part 23b within each of the gas flow spaces 13 has a square wave shape with a number of first portion 32 extending in the direction perpendicular to the general plane of the stacked heat transfer plates 2,3, and a number of second portions 33 extending between adjacent first portions 32, where the second portions 33 alternatingly extend along the opposite first face 7 of the first heat transfer plate 2 and along the second face 9 of the second heat transfer plate 3.
Each of the third support part 23c and the fourth support part 23d within each gas flow space 13 has a cross-sectional profile with a first portion 34 extending along the opposite first face 7 of the first heat transfer plate 2, a second portion 35 extending along the second face 9 of the second heat transfer plate 3, and a third portion 36 extending between the first portion 34 and the second portion 35, i.e. as a Z-shaped cross-sectional profile.
The four support parts 23a,23b,23c,23d as well as the second retaining element 26 and the third retaining element 27 are rigid (e.g. made of steel) and clamped between the stacked heat transfer plates 2,3 for supporting the stacked heat transfer plates 2,3 at their respective positions.
The second spacer 15c at the third edge 11c and the second spacer 15d at the fourth edge 11d of the second heat transfer plates 3 are formed so that they at the same time provide a third groove 39 and a fourth groove 43, respectively, on the second face 9 of the second heat transfer plates 3.
Each of the gas flow spaces 13 are fluid-tightly sealed at the third edge 8c,11c of the stacked heat transfer plates 2,3 by means of two fourth gaskets 36,37, where one fourth gasket 36 is located in a first groove 38 provided in the third support part 23c and the other fourth gasket 37 in the third groove 39.
Correspondingly the gas flow spaces 13 are fluid-tightly sealed at the fourth edge 8d,11d of the stacked heat transfer plates 2,3 by two fifth gaskets 40,41, where one fifth gasket 40 is located in a second groove 42 provided in the third support part 23d, and the other fifth gasket 41 in the fourth groove 43, which ensures that the gas flowing through the gas flow spaces 13 flows between the first edge 8a,11a and the second edge 8b,11b of the stacked heat transfer plates 2,3.
Each of the alternating gas flow spaces 13 is delimited by the opposite first face 7 of the first heat transfer plate 2, the second face 9 of the second heat transfer plate 3, the second gasket 24 and the third gasket 25, and the two fourth gaskets 36,37 and the two fifth gaskets 40,41, which together ensure that the only way in and out of the each of the gas flow spaces 13 is at the first edge 8a,11a and at the second edge 8b,11b of the stacked heat transfer plates 2,3.
The main central part of each of the first heat transfer plates 2 is provided with a first surface pattern in the form of a number of elongated and transverse spaced apart first spacers 44, which protrude from the first face 6 of the first heat transfer plate 3 and are in contact with the opposite second face of the adjacent second heat transfer plate 3. The main flow direction of the liquid is in the direction from the liquid inlet opening 17 to the liquid outlet opening 18. The first spacers 44 are configured to define a liquid flow channel across the liquid flow spaces 12 with alternating transverse straight flow sections, thus substantially parallel flow legs, and U-shaped flow sections that fluidly connect said parallel flow legs, as indicated by arrow C. The liquid is thus channelled and controlled directionally through the liquid flow channel. As the flow legs extends between the short edges of the adjacent heat transfer plates 2,3 the cross sectional flow area for the liquid flow is reduced to the distance between two groves 42 multiplied by the height of liquid flow space 12, by means of which the liquid flow velocity is increased, which in turn increases heat transfer.
The main central part of each of the second heat transfer plates 3, except for the second heat transfer plate closest to the first exterior panel, is provided with a second surface pattern in the form of several small distinct spaced apart frustum-conical second spacers 45 that protrude from the second face 9 of the second heat transfer plate 3 and are in contact with the opposite first face 7 of the adjacent first heat transfer plate 2. The main flow direction of the gas is in the direction between the second edge 8b,11b and the first edge 8a,11a of the stacked heat transfer plates 2,3. The frustum-conical spacers 45 are small spaced apart protruding objects that define a gas flow path across the gas flow spaces 13 where the gas is forced to zig-zag between the second spacers 45, as indicated by the arrows D. The second spacers 45 are shown shaped as a conical frustum, but any appropriate shape may be used.
The first and second surface pattern support the stacked heat transfer plates 2,3 over the main central part of the heat transfer plates 2,3, and increase the turbulence of the liquid and gas when passing through the respective liquid flow spaces 12 and the respective gas flow spaces 13. The increased turbulence of the liquid and gas increases the heat transfer on the liquid face and on the gas face of the respective eat transfer plates 2,3,
In the shown embodiment, the cross-sectional area of the gas flow path is about 35 times higher than that of the liquid flow channel.
All first heat transfer plates 2 are identical, although the first liquid inlet opening 17 of the first heat transfer plate 2 closest to the second exterior panel 5 is unnecessary and could be removed, in which case however the production costs would increase due to having to produce a different version of the first heat transfer plate 2. The second heat transfer plate closest to the first exterior panel 4 differs from the other second heat transfer plates 3 in that it does not have an embossed pattern and does not have a second liquid outlet opening. The exterior panels 4,5 are forced towards each other by means of e.g. threaded rods or bolts 46 and nuts 47 (only one pair is shown although plural is intended) extending through openings 48 in the exterior panels 4,5.
Figs. 15 and 16 show a guide member 49 that can be used for facilitating assembling of the gas-liquid plate heat exchanger. Fig. 15 illustrates the position of one of such two guide members 49. It is to be understood that the two guide members 49 may be removed after assembly.
The guide member 49 has six exterior rods 50 with the same length as the height of the stacked heat transfer plates 2,3, and three interior connection members 51 interconnecting the rods 50. As shown in fig. 15, the rods 50 are arranged so that they abut the liquid outlet openings 18,20 of the stacked heat transfer plates 2,3, and the connection members 51 are arranged so that they do not block the liquid flow channel between the liquid flow spaces 12 and the liquid outlet passage 18,20.
The present invention provide gas-liquid plate heat exchangers having much higher ratio between the cross-sectional areas of the gas flow spaces and the cross-sectional area of the liquid flow channel than for known gas-liquid plate heat exchangers. The heat transfer plates do not need to be welded or braced together due to the assembling, as the heat transfer plates can be held together only by clamping means and the resulting clamping force. Gasket means may be preferred to optimize sealing between adjacent heat transfer plates, thus to ensure fluid-tight sealing at joints. Due to these advantageous innovative features production costs are substantial reduced compared to productions costs for manufacturing known gas-liquid plate heat exchangers, as well as the manufacturing costs are much more environmentally friendly.

Claims

A gas-liquid plate heat exchanger (1) comprising a stack of alternating first heat transfer plates (2) and second heat transfer plates (3) interposed between opposite exterior panels (4,5),
the first heat transfer plates (2) and the second heat transfer plates (3) have respective aligned first liquid inlet openings (17) and second liquid inlet openings (19) and aligned first liquid outlet openings (18) and second liquid outlet openings (20),

characterised in that
- the first heat transfer plate (2) has a first surface pattern (44) on a first face (6), and a first opposite face (7),

- an adjacent second heat transfer plate (3) has a second surface pattern (45) on a second face (9), and a second opposite face (10), wherein the second face (9) faces the first opposite face (7),

- the second surface pattern (44) is different from the first surface pattern (45),

- a liquid flow space (12) is delimited between the first face (6) and the second opposite face (10), and is further defined by at least the first surface pattern (44),

- a gas flow space (13) is delimited between the second face (9) and the first opposite face (7), and is further defined by at least the second surface pattern (45), and

- the liquid flow space (12) and the gas flow space (13) are kept sealed from each other by forcing the opposite exterior panels (4,5) towards each other by means of clamping means (46,47).
A gas-liquid plate heat exchanger (1) according to claim 1, characterised in that the first opposite face (7) has a third surface pattern and/or the second opposite face (10) has a fourth surface pattern,
- optionally the third surface pattern is created as an inherent result of a manufacturing step of the first surface pattern of the first heat transfer plate (2),

- optionally the fourth surface pattern is created as an inherent result of a manufacturing step of the second surface pattern of the second heat transfer plate (3).
A gas-liquid plate heat exchanger (1) according to claim 1 or 2, characterised in that the gas-liquid plate heat exchanger (1) comprises gasket means between said heat transfer plates (2,3).
A gas-liquid plate heat exchanger (1) according to any of claims 1, 2 or 3, characterised in comprising one or more of
- a first gasket (16) provided in one or more of the liquid flow spaces (12) between adjacent first heat transfer plates (2) and second heat transfer plates (3) along their periphery,

- a second gasket (24) provided in one or more of the gas flow spaces (13) around the liquid inlet opening(s) (17,19), and

- a third gasket (25) provided in one or more of the gas flow spaces (13) around the liquid outlet opening(s) (18,20).
A gas-liquid plate heat exchanger (1) according to any of the preceding claims 1 - 4, characterised in that
- each of the first heat transfer plates (2) and second heat transfer plates (3) has a first edge part (8a,11a) and an opposite second edge part (8b,11b), and a third edge part (8c,11c) and an opposite fourth edge part (8d,11d) that extend between the first (8a,11a) and second edge part (8b,11b), and

- preferably the gas-liquid plate heat exchanger (1) comprises at least one fourth gasket (36,37) and at least one fifth gasket (40,41) provided at the third edge part (8c,11c) and the fourth edge part (8d,11d) of the stacked heat transfer plates (2,3), respectively.
A gas-liquid plate heat exchanger (1) according to any of the preceding claims 1 - 5, characterised in that the first surface pattern (44) defines a flow channel through each of the first flow spaces (12), and the second surface pattern (45) defines a flow pathway through each of the second flow spaces (13), and the ratio r_c between the flow cross-section of the flow pathway and the flow channel is at least 2, more preferably at least 20, more preferably at least 40, and most preferably at least 50.
A gas-liquid plate heat exchanger(1) according to any of the preceding claims 1 - 6, characterised in that
- the first pattern comprises at least one first peripheral spacer (14a,14b,14c,14d) defining a height of the liquid flow spaces (12), and

- the second pattern comprises at least one peripheral plate support means (23a,23b,23c,23d) defining a height of the gas flow spaces (13),
preferably the first surface pattern comprises several elongated first spacers (44) arranged substantially transverse to the direction between the liquid inlet openings (17,19) and the liquid outlet openings (18,20), preferably the second surface pattern comprises a plurality of individual second spacers (45) arranged spaced apart from each other.
A gas-liquid plate heat exchanger (1) of any of the preceding claims 4 - 7, characterised in that a first retaining element (26) and a second retaining element (27) are provided in each of the gas flow spaces (13) surrounding and abutting the second gasket (24) and the third gasket (25), respectively, and being clamped between the opposite first face (7) of the first heat transfer plate (2) and the second face (9) of the second heat transfer plate (3).
A gas-liquid plate heat exchanger(1) of claim 8, characterised in that each of the first heat transfer plates (2) is provided with at least one third spacer (28) and at least one fourth spacer (29) that protrude from the first face (7) of the first heat transfer plate (2), and/or that each of the second heat transfer plates (3) is provided with at least one fifth spacer and at least one sixth spacer that protrude from the second face (9) of the second heat transfer plate (3).
A gas-liquid plate heat exchanger (1) according to any pf the preceding claims 1 - 9, characterised in that the ratio (r_v) between the volume of the liquid flow spaces (12) and the volume of the gas flow spaces (13) is at least 2, and/or the ratio (r_H) between the height of the liquid flow spaces (12) and the height of the gas flow spaces (13) is at least 2.
A gas-liquid plate heat exchanger(1) according to any of the preceding claims 1 - 10, characterised in that a plate support means (23) is provided in each of the gas flow spaces (13) along the periphery of the stacked heat transfer plates (2,3), where the plate support means (23) extends between the opposite face (7) of the first heat transfer plate (2) and the second face (9) of the second heat transfer plate (3), and wherein said plate support means (23) is adapted for allowing gas to flow in and out of the gas flow spaces (13).
A gas-liquid plate heat exchanger (1) according to claim 11, characterised in comprising
- the plate support means (23),

- two fourth gaskets (36,37) and two fifth gaskets (30,41), respectively, in each of the gas flow spaces (13),
wherein
- the two fourth gaskets (36,37) extend along the entire length of the third edge (8c,11c) of the stacked heat transfer plates (2,3) and are provided fluid-tightly between the plate support means (23) and the first heat transfer plate (2) and the second heat transfer plate (3), respectively, and
wherein

- the two fifth gaskets (40,41) extend along the entire length of the fourth edge (8d,11d) of the stacked heat transfer plates (2,3) and are provided fluid-tightly between the plate support means (23) and the first heat transfer plate (2) and the second heat transfer plate (3), respectively.
A gas-liquid plate heat exchanger (1) according to any of the preceding claims 1 - 12, characterised in that the liquid flow spaces (12) and the gas flow spaces (13) is/are fluid-tight delimited between adjacent heat transfer plates without the use of weldings and/or brazings.
A method of assembling a gas-liquid plate heat exchanger (1) according to any of claims 1 - 13, characterised in that the method comprises the steps of:
a) arranging the first heat transfer plates (2) and the second heat transfer plates (3) alternating in a stack between the exterior panels (4,5) with aligned first liquid inlet openings and aligned second liquid inlet openings, and aligned first liquid outlet openings and aligned second liquid outlet openings, to define liquid flow spaces (12) alternating with gas flow spaces (13), and

b) applying a clamping force to the opposite exterior panels (4,5) to seal the liquid flow spaces (12) from the gas flow spaces (13).
A method according to claim 14, characterised in comprising:
- in step a) providing a first guide member and a second guide member with a fixed structure and a height being at least the same as the height of the stacked heat transfer plates (2,3), and a shape that matches the shape of the aligned liquid inlet openings (17,19) and the aligned liquid outlet openings (18,20), respectively,

- wherein step a) comprises aligning the first heat transfer plates (2) and the second heat transfer plates (3) by fitting their liquid inlet openings (17,19) and their liquid outlet openings (18,20) around the first guide member and the second guide member, respectively, and

- optionally removing the first guide member and the second guide member after step b).
A method according to any of claims 14 and 15, characterised in comprising providing one or more of first gaskets (16), second gasket (24) and third gaskets (25), wherein step a) further comprises one or more of
- arranging a first gasket (16) in each of the liquid flow spaces (12) along the periphery of the stacked heat transfer plates (2,3) during stacking of the heat transfer plates (2,3),

- arranging a second gasket (24) and a third gasket (25) in each of the gas flow spaces (13) around the liquid inlet openings (17,19) and the liquid outlet openings (18,20), respectively, during stacking of the heat transfer plates (2,3),

- arranging a first retaining element (26) and a second retaining element (27) around the second gasket (24) and the third gasket (25), respectively, during stacking of the heat transfer plates (2,3).
A method according to any of claims 14, 15 and 16, characterised in that the method does not include welding and/or brazing steps to fluid-tight delimit and define the liquid flow space and the gas flow spaces between adjacent heat transfer plates (2,3).