DK180373B1

DK180373B1 - Heat exchange unit and assembly

Info

Publication number: DK180373B1
Application number: DKPA201770808A
Authority: DK
Inventors: Hjelmsmark Henrik
Original assignee: Sani Membranes Aps
Priority date: 2017-10-26
Filing date: 2017-10-26
Publication date: 2021-02-12
Also published as: DK201770808A1; WO2019081769A1

Abstract

The invention relates to a liquid‐to‐liquid heat exchange unit, which provides a planar, rigid heat exchange plate for cooling or heating of liquid media, said plate having a planar thermo‐conducting sheet, which is fluid tight bonded at its edges to the surface of a hollow supporting plate comprising exit openings, internal flow channels, and a flow area for a first liquid medium, and the thermo‐conducting sheet being in fluid contact with said first liquid medium at its internal surface and being in fluid contact with a second liquid medium at its external surface.

Description

DK 180373 B1 1

HEAT EXCHANGE UNIT AND ASSEMBLY Field of the Invention The present invention relates to a planar, heat exchange unit for heat exchange between two liquid media, said unit having a thermo-conducting sheet or thin foil that is suitable for heat transfer bonded onto at least one outer surface of a supporting plate with integrated flow paths for a first liquid media inside the plate and the thermo- conducting sheet being in fluid contact with an outer second liguid media. The heat exchange unit comprises a supporting plate having a first and a second planar, preferably rectangular, surface enclosing at least two connected exit openings, internal flow channels, and at least one flow area for a first liquid media, said area being formed to enable fluid contact between said first liquid and the internal surface of a thermo- conducting sheet bonded at the perimeter onto the planar outer surface, said flow channels or flow area being provided with perforations forming a fluid connection between flow area and internal channels, and said flow area being sealed at its periphery with the periphery of the thermo-conducting sheet, the external surface of which is in fluid contact with a second liquid media, thus enabling heat exchange. in addition, the present invention relates to an assembly of at least one planar, rigid, heat exchange unit into a heat exchange module for heat exchange between two liquid media streams. The heat exchange module may, e.g. be configured for counter flow or mixed flow liquid-to-liquid heat exchange. The modules may be connected in series to serve any larger needs for heat exchange between liquid media. The invention further relates to the use of the heat exchange unit and module for heat exchange of liquid media having sanitary requirements, e.g. heat exchange, including pasteurization, of liquid dairy products, and of highly viscous media, as well as liquid media having a content of suspended solids. Description of the Prior Art Apparatuses for heat exchange between two liquid media are generally composed of a thermo-conducting material, typically plates arranged in stacks of plates, and the apparatus is subjected to a liquid flow on both sides of the thermo-conducting plates, such as stainless steel plates. The heat exchange plates of the prior art are typically pressed plates of sufficient thickness, such as 0.8 mm to 2 mm being able to withstand relatively high pressures without being deformed during manufacturing and operation. The high plate thickness leads to decreased heat conduction and a large material consumption in the final product, which typically is very heavy and requiring considerable mechanical assembly and fastenings means.

DK 180373 B1 2 There are three typical configurations of plate heat exchangers: gasket, fused and welded. The gasketed units are plate and frame types, where a very thick frame plate is used to squeeze a large number of gaskets positioned between plates. This configuration may be disassembled and cleaned, however the gaskets often leak. The fused or solded units, as well as the welded units cannot be cleaned, so if the heat surface becomes dysfunctional or the flow path is blocked, the unit has to be scrapped. US 2017/182463 Al describes a filter plate module comprising a plurality of planar filter units wherein a single unit comprises a supporting plate which comprises a flow area on at least one of a first or a second rigid outer surface of the supporting plate and a thermo- conducting sheet which is fluid tight bonded to the perimeter of the least one flow area, two fluidly connected exit openings for a first liquid medium, internal flow channels for the first liquid medium and perforations for fluid connection between the flow area and the internal channels. US2001/016985 Al discloses a heat exchanger utilizing active fluid transport of a heat transfer fluid is manufactured with multiple discrete flow passages provided by a simple but versatile construction. The microstructured channels are replicated onto a film layer which is utilized in the fluid transfer heat exchanger. The surface structure defines the flow channels which are generally uninterrupted and highly ordered. A cover layer having thermal conductive properties is provided on the structured bearing film surface.

A disadvantage of thermo-conducting metal sheets is that they are easily corrodible when in contact with, e.g. even slightly acidic media. It is a purpose of the present invention to provide a heat exchange unit which is lighter than the prior art heat exchange units; which has improved flow turbulence for increased heat exchange; which allows for simple cleaning operation; and, among other advantages, is easily scalable. In addition, it is an object of the present invention to provide a planar heat exchange unit having a simple plate-like construction, with optimized internal flow path in a supporting plate for a first liquid medium to be cooled or heated, where the medium is in fluid contact with the internal surface of a thermo- conducting sheet being bonded to at least one surface of the supporting plate, and being optimized for reduced pressure loss of a second medium to be cooled or heated while flowing past the external surface of the thermo-conducting sheet. Summary of the invention This is achieved with a heat exchange unit, which provides a planar, rigid heat exchange unit for cooling or heating of liquid media, wherein a planar thermo-conducting sheet, which is fluid tight bonded at its edges to the surface of a hollow supporting plate comprising a flow area for a first liquid medium, the thermo-conducting sheet being in fluid contact with said first liquid medium at its internal surface and being in fluid contact with a second liquid medium at its external surface. The flow area is connected

DK 180373 B1 3 through a flow path to at least two exit openings for the first liquid medium, and the flow path comprising internal flow channels and holes or perforations leading to the flow area for liquid contact of the first medium with the internal surface of the thermo- conducting sheet, thus providing heat exchange between the two liquid media.

In addition, the thermo-conducting sheet may be liquid tight bonded to the supporting plate at one or more additional points or lines. The supporting plate is typically formed by liquid tight bonding, such as edgewise bonding or heat-fusion of two fitting half-plates made of a light material, such as plastics which allows for the half-plates to be formed by molding.

The thermo-conducting sheet can be a thin foil of a thermo-conducting material, such as a metal, such as stainless steel, aluminium or die cast aluminium alloys; or of heat conducting plastics or a hybrid material, such as polysulfone or nylon having heat- conductive additives including graphite, carbon fibers, and ceramics such as aluminum nitride and boron nitride. The thermo-conducting sheet used for heat exchange is preferably impermeable to the type of liquid media to be cooled or heated.

A useful thin foil of a thermo-conducting material is based on PP, Polypropylene, with an added thermal conductivity component is, e.g. TECACOMP® TC (Ensinger, Ensinger Platz, Seewalchen am Attersee, Austria) whereby thermal conductivity can be up to 25 W/(m-K) depending on the filler used, and as thermoconducting sheet can be, e.g., only of 0.1 mm thickness for efficient heat exchange in a unit or module of the invention.

An alternative thin foil of a thermo-conducting material is based high alloy stainless steel whereby thermal conductivity can be very high, and as thermo-conducting sheet can be as example only 0.05 mm of thickness, a very efficient heat exchange can be obtained, and at the same time consumption of high value material is minimal. In some executions of the foil, a preforming of the sheet may be used to secure improved bonding to the plastic base plate and at the same time this preforming can counteract problems caused by differences in thermal expansion between plastic and metal. In certain embodiments of the units and modules of the invention the thermo-conducting sheet is made from a woven or non-woven polypropylene sheet having a filler of thermo-conducting plastic material molded into and on top of the woven or non-woven sheet. Types of useful polymeric mixed plastics materials may be formed into suitable liquid and/or gas impermeable, heat conducting thin sheets using the methods and combinations of materials, and methods for making membranes by forming a nanofibrous layer on a macroporous support layer and applying polymer to the nanofibrous layer. disclosed in US Pub. No.: US 2015/0059578 Al (Huizing et al.) the contents of which are hereby incorporated by reference. For use in embodiments of the present invention the composite membranes taught by Huizing et al. may advantageously be given a final coating with an impermeable polymer.

In an embodiment of the heat exchange module of the invention one first liquid medium to be heat exchanged can flow in the channels and flow distribution areas formed inside the supporting plates having one or more thermo-conducting sheets bonded to their planar outer surfaces, while a free flow of a second liquid medium is maintained on the outside and flowing through gaps between the stacked plates of the module.

The heat exchange second liquid media can be highly viscous and even contain larger particulate impurities, as long as the media does not block the free flow passage outside or between the heat exchange plates.

Surprisingly, the present invention enables cleaning at both external surfaces of the heat exchange unit and in modular unit assemblies as well as at the internal surfaces inside the supporting plate(s) (1) at the flow path for the first liquid medium in the heat exchange unit.

The heat exchange module of the invention is suitable for applications, such as milk pasteurization, where sanitary requirements can be fulfilled with external flushing between module plates as well as with internal cleaning flushing of the flow paths of the supporting plate.

In addition, the heat exchange module is highly resistant to corrosion when having a polymer based thermo-conducting sheet.

Furthermore, the heat exchange modules of the invention may be used for energy exchange of hot and cool flows in large scale district heating system based on hot or warm water.

Definitions The term “thermo-conducting sheet” as used herein shall mean a thin thermo- conducting foil or membrane capable of being bonded or sealed liquid tight to a supporting plate, typically a plastics plate.

A “thermo-conducting sheet” as used herein is relatively thin and can be flexible, typically made by rolling a metal or plastic sheet into thin foil or by casting of a hybrid polymeric or plastics material, e.g. such as highly rigid polypropylene having suitable thermo-conduction enhancing additives.

The term “flow area” as used herein shall mean a confined and optionally corrugated or mesh like surface area of a supporting plate.

The flow area may serve as a flow distribution area for a first liquid medium in fluid contact with a thermo-conducting sheet.

The flow area defines the area available for heat exchange at the internal surface of the thermo-conducting sheet.

The term “exit opening” as used herein shall mean an opening for a flow of liquid media into and/or out of the support plate(s) of the planar heat exchange unit and heat exchange module of the invention.

Each exit opening is thus opening up to both sides of the unit or the module, and one or both sides can be connected to the flow of the first media. Atleast two connected exits provide for functional flow operation of the unit.

The exit openings are connected through various flow channels and flow areas in the supporting plate, thus allowing flow of liquid media from one exit opening to the other. 5 In certain embodiments the connected exits are located at opposite ends of the planar unit.

The terms “heat exchange module” and “heat exchange unit assembly” are used interchangeably herein and are used for the subject matter of Figure 5 as well as for modules and unit assemblies when integrated with various connecting parts in housings and systems for heat exchange.

The terms “first liquid medium” and “first liquid media” (to be cooled or heated) are interchangeably used herein and are used for the media flowing internally in the hollow supporting plate and being in fluid contact with the internal surface of the heat exchange thermo-conducting sheet.

The terms “second liquid medium” and “second liquid media” (to be cooled or heated) are interchangeably used herein and are used for the media flowing externally on the heat exchange unit and being in fluid contact with the external surface of the heat exchange thermo-conducting sheet.

The terms “to be cooled or heated” and “to be heat exchanged” are used interchangeably herein and used to characterize a liquid medium or media flowing internally in a hollow supporting plate of the heat exchange unit of the invention or externally in fluid contact with the heat exchange unit.

“Internal surface” of the heat exchange thermo-conducting sheet shall herein mean the thermo-conducting sheet surface facing the outer surface of the supporting hollow plate and being in fluid contact with the first liquid medium.

“External surface” of the heat exchange thermo-conducting sheet shall herein mean the thermo-conducting sheet surface facing the external or second liquid cooling or heating medium.

The terms “liquid tight sealing”, “fluid tight sealing”, and “liquid tight bonding” etc. are used interchangeably herein and may also specify gas tight sealing when the heat exchange unit of the invention is suitable for heat exchange of gas-to-gas (air-to-air) or gas-to-liquid.

The term “viscous media or media having suspended solids” as used herein shall mean liquid media, such as dairy products, fruit and vegetable juice, mineral and vegetable oil, waste water of many kinds, media streams having a corrosive effect and the like.

Brief description of the drawings Fig. 1 is a perspective view of a heat exchange unit comprising the supporting plate (1) comprising two half-plates (2, 3), exit openings with cylindrical rims (4, 5), flow area (6), thermoconducting sheet (7), bonding points (8), internal flow channels (9A, 9B), perforations (10A, 10B) leading to the flow area (6). Fig. 2 is an exploded perspective view of a heat exchange unit showing the various parts forming the unit as shown in Figure 1, and showing in detail an embodiment of internal features, such as a guided flow distribution with two opposite exit openings (4, 5) having fluid connection to five channels (9A and 9B) with manifolding to/from multiple (twentyfive) perforations (10A, 10B) arranged in a line and leading flow to the flow area (6)of the two half-plates forming the supporting plate.

Fig. 3 is a cross-sectional view perpendicular to the longitudinal extension of a heat exchange unit, showing the two half-plates (2, 3), an exemplary liquid media flow channel (9A, 9B), perforations (10A, 10B), grid structure or mesh with groove (12) and ridge (13), thermo-conducting sheet (7) and inlet and outlet to and from the flow area, Fig. 4 is a top view of the grid or mesh with groove (12) and ridge (13) forming the flow area (6) available for heat exchange in fluid contact with the internal surface of the heat exchange thermo-conducting sheet.

Fig. 5 is a perspective view of a heat exchange unit assembly (20) built up as a heat exchange module with exit openings for flow of first liquid media (C, D) and gaps between plates for flow of second liquid media (A, B). Detailed description of the invention Certain embodiments of the present invention relates to a rigid, planar heat exchange unit assembly, wherein said heat exchange plate comprises at least a first and a second exit (4, 5) opening for a liquid medium, and where internal channels extend from said first exit opening (4) to said second exit opening (5) and in between enters and exits through perforations (10A, 10B) to at least one flow area (6) sealingly covered by a thermo-conducting sheet (7), where said perforations may comprise slits or holes making fluid connection between the flow area and the internal channels (9A, 9B), said flow and flow area being formed as mesh like channels (12, 13) on and as a part of the outside of the supporting plate (1), said mesh formed to ensure a flow area between a covering thermo-conducting sheet and the heat exchange plate surface, said thermo- conducting sheet being bonded at the perimeter of the flow area.

Hereby is achieved the possibility, with very minute pressure loss, to flush or create a cross flow over all areas of the inside of the supporting plate with a turbulent stream from one exit opening being in fluid connection to another exit opening, or the

DK 180373 B1 7 possibility to flow from one or both exit openings while at the same time having the possibility of applying a hydraulic pressure on the external surface of the thermo- conducting sheet from an unimpeded cross flow of cooling or heating liquid media outside the heat exchange unit.

An applied pressure on the external surface of the thermo-conducting sheet may be needed to drive the flow and to keep the thermo- conducting sheet fixed during operation.

The supporting plate comprises at least one flow distribution area of the outer surface of the supporting plate, said area being available for heat exchange and being overlaid with and sealed at the perimeter by a thermo-conducting sheet, thus being positioned adjacent to said flow distribution area.

The thermo-conducting sheet is bonded along the perimeter of said flow area, which is available for heat exchange.

The bonding provides liquid tight sealing of the internal surface of the heat exchange sheet from the outside of the heat exchange unit or module.

Said flow area (6) is formed as an integral part of the supporting plate (1) and comprises indents or channels (12, 13) forming a mesh like flow area that can lift up the thermo- conducting sheet to withstand a hydraulic pressure, while allowing a substantial flow between said internal surface of the thermo-conducting sheet and the supporting plate, even when a pressure being applied from the outside on the heat exchange unit compresses the thermo-conducting sheet towards the surface of the supporting plate.

The thermo-conducting sheet may partly take form from the supporting flow area due to the outside pressure, hereby forming a corrugated surface increasing heat exchange efficiency.

The flow area on the support plate is formed with at least one entry and at least one outlet and with the flow area between said entry and exit being formed by perforations leading to internal channels, said channels leading to the exit openings, such as by connecting to the exit opening through a manifold.

Said entry and outlet may be formed by a number of perforations in either side of the flow area, hereby ensuring a uniform flow over the entire flow area available for heat exchange, and ensuring minimal pressure loss through an adequate number of perforations, said perforations still small enough to ensure the lifting function for the applied pressure on the thermo-conducting sheet on said mesh.

Said flow distribution area together with said channels and connected exit openings allow for unimpeded and controlled flow of the first liquid medium through the supporting plate leading to enhanced turbulence conditions at the internal surface of the thermo-conducting sheet.

The unimpeded flow of the first and the second liquid media allows for a very homogenous pressure gradient over the thermo-conducting sheet, thus improving operational lifetime and making it possible to create a turbulence optimized over the entire sheet surface leading to a substantial turbulence and heat exchange improvement of the thermo-conducting sheet area.

DK 180373 B1 8 In an embodiment, said supporting plate of the heat exchange unit comprises two half- plates which are bonded together at the periphery, where the two half-plates are identical in shape keeping the number of different parts of the unit/module at a minimum.

The bonding at the perimeter of the plates seals the internal surface of the thermo-conducting sheet from the cooling or heating first liquid medium flowing past the external surface of the thermo-conducting sheet without any further need for a gasket.

More bonding areas may be added inside the supporting plate edge or perimeter to make the planar unit more rigid.

In an embodiment, the assembly of the heat exchange unit is comprised by fusing of a thermo-conducting sheet onto the outer surface of the supporting plate, which in turn is formed by bonding, such as by fusion or in molding, of two identically shaped half- plates, and where the exit openings are formed by integrated parts of the two half- plates.

In an embodiment, said at least two exit openings for the first liquid medium are positioned at a distance from each other, whereby it is possible to clean the flow channels and area of the heat exchange unit effectively by flushing from one exit to the other exit by flushing with a cleaning liquid.

In an embodiment, the external surface of the thermo-conducting sheet has a mesh structure, such as an overlaying fishbone like curve-shape similar to that seen in conventional plate heat exchangers.

This overlaying shape is dimensioned to increase turbulence of the external flow of the second liquid medium, hereby optimizing heat exchange capacity at comparably lower external flow volumes.

In an embodiment, said at least two exit openings extend transversely to the planar surface of the supporting plate.

The perpendicular exits allow for a large access area to the internal flow channels and flow distribution areas forming the heat exchange area, and, at the same time, the relatively large channels reduce counter pressure of flow to the exits.

Thus, high flow speeds between the two exit openings during heat exchange flows or during cleaning operation are possible.

In an embodiment, said supporting plate comprises on its planar sides two or more cylindrical rims or studs or protrusions surrounding the exit openings.

The combined or stacked cylindrical protrusions, when the heat exchange plates are stacked together, form the exit path for the first liquid medium while keeping the number of assembly parts to a minimum.

Said connected exits forming the exit manifold can be fused together at contact areas, hereby forming a manifold sealing the first internal media from the second external media.

In an embodiment, said heat exchange unit or heat exchange modular assembly comprises at least one heat exchange thermo-conducting sheet in fluid tight bonding or

DK 180373 B1 9 sealing onto a supporting hollow plate.

Hereby, each heat exchange unit may comprise two layers of thermo-conducting sheets, i.e. provided on both sides of the supporting plate, such as where the internal surface is protected against the pressure exerted against the lifting points formed by the corrugated or fishbone-like contact points of the mesh like structure.

In an embodiment, said supporting plate comprises, e.g. at its edge or perimeter, one or more bonding points for bonding two adjacent planar heat exchange units or bonding of a heat exchange unit to an overlaying unit in a stack of heat exchange units forming a module.

The bonding points together with the protruding exit opening rims define the distance between two planar heat exchange units in a stack or module.

Said protruding exits of adjacent heat exchange units are bonded, such as by heat fusion, to achieve sealing between exit openings to provide an integrated flow path to the outside and external flow connections for liquid heat exchange media or for connections to a flow of cleaning liquid through the bonded plurality of planar heat exchange units forming the module.

The heat exchange units are planar and can be stacked together using a few plates to many dozens of plates forming one bonded rigid heat exchange module.

The heat exchange units are stacked with spacing for the external or second media to be heat exchanged, offering a gap outside for access or flow of media between the units and in contact with the external surface of the thermo-conducting sheets.

The gap between plates, e.g. as illustrated in Fig. 5, can be dimensioned to secure a free and unimpeded flow of media (A, B) to be heat exchanged and allows for flow of viscous media or media having suspended solids.

The free gaps between heat exchange plates or planar heat exchange units allow for inspection of the thermo-conducting sheet and other parts being in touch with the liquid media thus making visual inspection of cleaning operation and heat exchange process possible.

In one embodiment, an assembly of the heat exchange units of the invention comprises a plurality of planar heat exchange units, forming a rigid heat exchange module, said heat exchange plates are situated parallel juxtaposed having the heat exchange area facing the heat exchange area of an adjacent heat exchange plate.

Said plurality of heat exchange plates forming a square or rectangular entry for the second liquid media, such that said media is able to pass between the planar heat exchange units allowing for a large thermo-conducting sheet area (heat exchange area) on a small foot print.

The protruding exits of each supporting plate of the heat exchange unit combined, such as bonded together by, e.g., welding or melting, form two or more combined exits extending transversely to the surface of said heat exchange module.

DK 180373 B1 10 In one embodiment of said plurality of heat exchange units forming a heat exchange module, the gap between the planar heat exchange units is filled with a spacer netting or mesh that creates turbulent flow over the heat exchange area even at low cross flow volumes of the liquid media and at the same time keeping the thermo-conducting sheet in place at low or negative pressures applied to the thermo-conducting sheet. In one embodiment of said plurality of planar heat exchange units forming a heat exchange module, said plurality of units is placed in a housing, said housing forming a square or rectangular inlet and outlet for the liquid media to be heat exchanged, thus guiding the external second liquid flow and the internal first liquid flow at inlets and outlets that in exemplary embodiments are provided transversely from the housing. The bonded supporting plates with the attached thermo-conducting sheets each form a pressure vessel so that when a flow and a pressure are applied through an exit opening, a flushing of the plate may take place, between two exits, thereby cleaning, i.a. the internal surface of the bonded thermo-conducting sheet.

The invention provides a heat exchange plate unit which has, with respect to known liquid-to-liquid heat exchangers, such as plate heat exchangers, the advantages of having at the same time: 1) a flushable interior side, such as for turbulent flow of a heat conducting media or for flushing with a cleaning liquid, 2) an external free flow of a second liquid stream to be heat exchanged, 3) a varied free-flow gap being defined by the possibility for variation of gap distance between heat exchange plates (1 to 6 mm) when stacked, 4) a possibility to use a very thin thermal conducting sheet improving heat transfer through short thermal path, 5) a possibility to use a very thin thermal conducting sheet reducing the need for thermal conductive material to an absolute minimum, while having the individual planar heat exchange units manufactured of relatively small thickness, however still rigid (3-8 mm thick supporting plate consisting of 2 bonded half- plates), all of which making a very compact and light heat exchange unit possible.

The heat exchange modular assembly has a shortened length of the paths of the liquids to be heat exchanged (10 to 100 cm) and a non-impeding (5 to 100 cm long) but relatively large inside flow area available for heat exchange, combined with a large active area (up to about half of heat exchange plate thickness), a plurality of flow leading channels for the first liquid stream or discharge leading to at least two larger perpendicular exit openings, and an overall structure with sufficient mechanical strength for it to keep a constant geometry at high cross flow rates and pressure gradients, guaranteeing the stability of the hydrodynamic conditions, under pressure, media and temperature constraints and at a satisfactory constructional cost.

DK 180373 B1 11 The flow area used for heat exchange between the two liquid media may be in one embodiment formed with a mesh like channel structure where channels are 0.2-2.0 mm wide giving similar space between ridges (13) for lifting the thermo-conducting sheet, the ridge or lifting area formed without sharp points or ridges securing a sufficiently gentle carrier surface against outside pressure on the thermo-conducting sheet. The heat exchange area flow channels, perforations (slits and holes) as well as internal channels are formed hydrodynamically, securing that minimal blocking and pressure loss will take place in the internal liquid flow path from and through the exit openings. The slits or holes connecting the inside channels with flow area on the outer surface of the supporting plate are dimensioned to the needed flow and to physical size to needed lifting of thermo-conducting sheet, typically 0.2-2.0 mm wide.

The heat exchange units can be sized according to need for heat exchange area as well as to cost optimized production and are typically from 10 cm by 10 cm of heat exchange area up to 50 cm by 100 cm heat exchange area. The typical size for industrial applications is 20 cm by 20 cm up to 20 by 100 cm heat exchange area.

The planar heat exchange units are typically made of 3-8 mm thick supporting plates made up by two half-plates. The plate design, material and thickness are dimensioned to ensure a rigid construction of the unit and assembled modules under turbulent external and internal flow.

The inside channels formed by the two half-plates can be of rounded cross section, and typically around half of the plate thickness in diameter as individual channels or be made up by mesh type volumes. However, in either case, the design must consider flow and pressure losses, avoiding very low or very high flow speed areas. For example, a mesh-like flow area may be formed as a fishbone structure that allows flow distribution while keeping distance to the internal surface of the thermo-conducting sheet at contact points.

The inside channels lead to plate exit openings that can be designed to lead specific types of liquids from the stacked assembly of heat exchange units to the exit with negligible pressure loss. Typically, the plate exits are 10-50 mm in diameter.

Materials used for the heat exchange unit plate parts are typically plastics, such as polymeric or co-polymeric thermoplastics, but can be of hybrid material or metallic origin or any other suitable material that can be bonded and withstand the liquid media to be heat exchanged, the temperature span needed, typically 5-95 degrees Celsius as well as the medias used for cleaning the units and modular assemblies. The choice of material must foresee thermal expansion and rigidity of the heat exchange unit/module. Preferred execution is heat exchange plates in molded plastic material, such as polypropylene, and with, e.g., a polymeric based hybrid thermo-conducting sheet used

DK 180373 B1 12 for heat exchange. Other executions can be as sintered parts or 3D printed versions in various materials. Bonding of the various parts into one unit including half-plate to half-plate liquid tight bonding, thermo-conducting sheet to supporting plate liquid tight bonding and heat exchange units into stack bonding may be by laser welding, direct or indirect heat welding, in mold fabrication, ultrasonic welding, use of glue or hot-melt or solvents, or mechanically bonding with mechanical elements or connections designed into the parts. In the preferred execution, plastic parts are welded together through heat applied melting of very specific areas of the designed parts, said heat exchange plate parts being molded by injection molding of polymer thermoplastic. The thermo-conducting sheet may be bonded to the plate using a combination of hot-melt, in molding and welding to achieve liquid tight sealing.

By using thermoplastics such as polypropylene or polyethylene, the material of the supporting plate (or half-plates) can be recycled through re-melting of the plastic.

In an embodiment of the heat exchange assembly of the invention, the second liquid medium is pumped at a speed of typically 1 to 5 meters per second across the external surface of the thermo-conducting sheet to keep a high heat conducting efficiency and to keep possible suspended solids from building up and depositing on the thermo- conducting sheet. The first liquid medium is pumped at a speed of typically 0.5 to 2.5 meters per second through the flow channels and flow distribution areas and heat exchange area in the supporting plate and across the internal surface of the thermo- conducting sheet to keep a high heat conducting efficiency and to keep the boundary layer on the internal thermo-conducting sheet surface as small as possible, hereby keeping the heat exchange efficiency high and functional in operation for a longer time.

An embodiment of the invention is a heat exchange unit, which provides a planar, rigid heat exchange unit for cooling or heating of liquid media, wherein a planar thermo- conducting sheet, which is fluid tight bonded at its edges to the surface of a hollow supporting plate comprising a flow area for a first liquid medium, the thermo- conducting sheet being in fluid contact with said first liquid medium at its internal surface and being in fluid contact with a second liquid medium at its external surface. And in this embodiment the flow area is connected through a flow path to at least two exit openings for the first liquid medium, and the flow path comprising internal flow channels and holes or perforations leading to the flow area for liquid contact of the first medium with the internal surface of the thermo-conducting sheet, thus providing heat exchange between the two liquid media.

A heat exchange module (20) according to any one of claims 2 to 10, wherein the supporting plate (1) comprises at least two exit openings (4, 5) and at least two internal flow channels (9A, 9B), defining at least two independent sets of flow paths through said

DK 180373 B1 13 supporting plate which are in fluid connection with the at least one flow area (6), each set of flow paths comprising at least two exit openings (4, 5) being in fluid connection, and at least one internal flow channel (9A,9B), such that said heat exchange module (20) is configured for allowing liquid media (C, D) to pass from a first exit opening (4) through one or more internal flow channels to said at least one flow area (6) and through one or more internal flow channels to a second exit opening (5).

Detailed description of the drawings Other features and advantages of the invention are disclosed in the following description and examples of drawings, embodiments, working examples, and applications within cooling and heating of liquid media, with reference to the accompanying drawings and reference numbers therein.

Figure 1 Illustrates one embodiment of the heat exchange unit which may be formed by a) bonding at least one thermo-conducting sheet (7) onto a supporting plate (1) having internal preformed flow channels (94, 9B) in fluid connection (not shown) with a plurality of perforations (10A, 10B) opening onto a flow area (6) on at least one outer side, where the bonding provides liquid tight sealing along the edges or periphery of the flow area (6); and b) the supporting plate being formed by bonding of two equal-size half-plates (2, 3) along their edges, where the bonding provides liquid tight sealing, and the supporting plate (1) being provided with two exit openings (4, 5) are provided with a cylindrical rim and internal fluid connection with the flow channels (9A, 9B).

In addition, the supporting plate (1) may be provided with protrusions (8) distributed spaced apart along the edges of both sides of the plate. The protrusions (8) function as bonding points when two or more heat exchange units are stacked into a heat exchange module.

In the illustrated embodiment, the exit openings (4, 5) of the heat exchange unit is on opposite ends of the heat exchange area (6) and the heat exchange area is covered with an adjacent thermo-conducting sheet with a cut out showing the corrugated or mesh like flow area (6) below the thermo-conducting sheet. As indicated, a number of internal channels (9A and 9B) connect the two exit openings on the plate (1) to the flow area via the perforations (10A, 10B) in either end of the flow area hereby forming a flow path under the thermo-conducting sheet from exit (4) to exit (5). Bonding points (8) used when staking the plates into a module are also indicated. Said bonding points (8) together with the cylindrical, protruding exit openings (4, 5) define the distance between two plates (1). In the shown embodiment, the two half-plates (2, 3) are identical or laterally reversed. In some embodiments, the perforations (10A, 10B) constitutes of slits and/or holes.

DK 180373 B1 14 An embodiment of the invention provides a rigid, planar heat exchange unit, comprising an internally channeled planar supporting plate (1) formed by liquid tight bonding of two planar, typically identical, half-plates (2, 3), the heat exchange effect obtained through a thermo-conducting sheet (7) in fluid contact with a first and a second liquid media having different temperatures, and where the thermo-conducting sheet (7) is peripherally bonded to and covering a flow area (6) for the first liquid medium on the supporting plate (1), where the area (6) is formed as a grid having raised contact points (13) supporting the internal surface of the thermo-conducting sheet (7); while at the same time having the second liquid media in fluid contact with the external thermo- conducting sheet surface; the supporting plate (1) having perforation slits or holes (10A, 10B) connecting the distribution area (6) and the at least one channel (9A, 9B).

The channels inside the plates are for leading the first liquid media to at least two or more paired exit openings (4, 5) being perpendicular to the supporting plate, the exit openings forming integral exit channels in an assembly of heat exchange units.

In a configuration of the invention with at least two exit openings in fluid connection, it is possible to lead a media stream contacting the internal surface of the thermo- conducting sheet to ensure optimal heat exchange or optimal flushing with liquid cleaning media from one exit (4 or 5) to the other exit (4 or 5).

The flow area surface (6) is covered by liquid tight bonding of a flat thermo-conducting sheet (7) along its perimeter whereby heat exchange can be achieved.

Figure 2 Illustrates an exploded perspective view of a heat exchange unit assembly with two half-plates (2, 3) and two thermo-conducting sheets (7). The upper half-plate (2) shows the outside surface (2s) of the supporting plate (1) with the flow area (6), in either end perforated with holes (10A, 10B), bonding points (8) and protruding exit openings (4, 5). The lower half-plate (3) shows the half inside flow channels (9A, 9B) forming full channels when half-plates (2, 3) are bonded together, these are connecting the plate exit openings (4, 5) with the perforations (10A, 10B).

The embodiment shows a variation in layout of the inside channels (9A, 9B) forming a manifold for the flow channels (9A, 9B). The shown manifold may in another embodiment be replaced with an internal flow volume, for example being fish-bone shaped, to keep spacing between the half-plates (2, 3).

The exit openings (4, 5) can be placed as convenient, for example in opposite plate ends or corners or side by side, considering efficient flow or flow distribution of the channels (9A, 9B) as well as uniform flow distribution over the flow and heat exchange area (6).

In a larger plate, more fluidly connected exit openings may be needed to secure flow and distribution of the first liquid medium.

DK 180373 B1 15 The supporting plate comprises bonding points (8), the bonding points also functioning as distance points together with the protruding exit rims (4, 5) such that the second liquid medium can pass through the gap thus formed between the thermo-conducting sheet(s) in-between two adjacent heat exchange units in a module.

The bonding points (8) are here illustrated as a solid cylinder shaped protrusion extending transversely to the surface of the supporting plates (1). Alternatively, the distance between the plates can be supported by a mechanical member or bar positioned at the edge of the heat exchange unit.

Figure 3 Illustrates a cross-sectional view of a detail of a heat exchange plate unit, showing an example of a flow channel (9A/9B), perforations (10A/10B), the grid structure of the flow area (6) and the adjacent thermo-conducting sheet (7). The grid or mesh like structure of the flow area (6) is formed as an integral part of the half-plates (2, 3) and may be formed with indentions, protrusions (13) and grooves (12), the grooves forming channels for flow and the protrusions forming support areas for the thermo- conducting sheet (7). The heat exchange area grooves or channels are connected to the internal channels via the perforations (10A, 10B). The openness of the flow area (6) is designed to support the thermo-conducting sheet, which again depends on the applied pressure on the thermo-conducting sheet during various operation types and the type of thermo-conducting sheet, as may be needed during operations using a relatively high pressure across the thermo-conducting sheet and a relatively thin or brittle thermo- conducting sheet may need several support points, protrusions or ridges (13), to ensure a free flow area in the grooves (12) facing the internal surface of the thermo-conducting sheet.

Figure 4 Illustrates a top view of an example of the grid forming the corrugated flow or heat exchange area (6) below the thermo-conducting sheet or facing the internal surface of the thermo-conducting sheet. The grooves (12) form a grid of flow channels and the protrusions or ridges (13) can be formed in a symmetrical mesh as shown. The groove (12) and protrusion (13) construction can be prepared to direct the liquid flow with more open groove areas and/or be made with narrow grooves forming a relatively more flow impeding area in order to secure a uniform turbulent flow speed in fluid contact with the internal surface of the thermo-conducting sheet.

Figure 5 shows a stack of heat exchange units forming a heat exchange module. This example shows a heat exchange module (20) built up by a plurality of planar heat exchange units and also shown are the flows of first liquid media (C, D) and second liquid media (A, B) providing counter flow like heat exchange operation. When the heat exchange module is in use, a first liquid flow enters at (A) and leaves at (B) and a second liquid flow enters at (C) and exits at (D).

DK 180373 B1 16 During CIP cleaning — Cleaning In Place — liquid cleaning media are most often only used on the external or outer surface of the heat exchange units in a modular assembly, the cleaning liquid entering at (A) and leaving at (B), and often at high flow rates to ensure cleaning of all surfaces. The embodiment shown enables cleaning at the internal surfaces inside the supporting plates (1) at the flow path for the first liquid medium in a heat exchange unit and in modular unit assemblies. When this is needed, a cleaning flow may enter at (C) and leave at (D) (or vice versa), and at the same time a cleaning flow can enter at (A) and exit at (B) to ensure a sufficient pressure to keep the thermo- conducting sheet in place.

In addition, a heat exchange unit with more than one flow area section or heat exchange area is possible, where each flow area is in fluid connection and edgewise liquid tight sealed by bonding of a thermo-conducting sheet. This embodiment might provide multiple, such as 4, 5, 6 or more separate flow areas (6) on either side of the supporting plate, each area being fluidly connected consecutively to the next, so that a flow path from exit (5) to exit (4) is formed. Heat exchange areas may be connected with a number of separate internal flow channels (9A/9B) and fluid connecting perforations (10A, 10B) in either end of the channels, forming an outlet from one flow area and an inlet to the next flow area. Perforations and internal channels are positioned to give a uniform flow over the flow area (6) below the thermo-conducting sheet(s) (7, not shown here).

Reasons for selecting a number of heat exchange areas can be many, such as directing the flow or cleaning media flow path, bonding method for thermo-conducting sheet, size of thermo-conducting sheet area, stiffness of supporting plate and fabrication method of supporting plate.

Not shown in the presented illustrations are examples of internal channels (9A, 9B) formed as individual flow volumes instead of separate channels in a manifold. Also not shown are examples of a separate mesh positioned in between the planar heat exchange units when assembled into a heat exchange module. An open structured mesh squeezed in between heat exchange plates will further increase turbulence of the flow of the second liquid medium and protect the thermo-conducting sheet from hydraulic pressure differences.

The bonded assembly of a plurality of heat exchange units shall have a sufficiently rigid structure to provide good dimensional stability under mechanical, thermal and chemical stress.

All unit parts can be of food and pharmaceutical grade material with traceable origins, making the heat exchange unit and modular assembly suitable for heat exchange operations of liquid human food, consumables, pharmaceuticals, and the likes. The plate materials used are preferably of a plastics material that can be reused by re-melting, or be burned as a clean fossil-like fuel.

DK 180373 B1 17 All plastics parts of the unit can be produced by 3D printing or sintering of other means. The skilled person in thermal process will know that the heat exchangers described herein can also be used in heat exchange for gas-to-gas as well as for gas-to-liquid media, where gas tight conditions are required, such as for evaporation and or condensation on either one or both sides of the thermo-conducting sheet.

Additional embodiments of the invention are described below: A heat exchange module (20), wherein said heat exchange unit assembly (20) comprises a plurality of planar heat exchange units, said units being situated parallel juxtaposed having the external surface of the thermo-conducting sheet on one unit facing the external surface of the thermo-conducting sheet of an adjacent heat exchange unit, said plurality of heat exchange plates forming a square or rectangular entry for a liquid media (A) such that said media is able to pass between the planar heat exchange units, and where the at least two perpendicular exit openings (4, 5) are formed by integrated parts of said half-plates (2, 3), and where the distance between the planar units is defined by the height of the rims of the exit openings (4, 5) and of the bonding points (8). A heat exchange module (20), wherein the supporting plate (1) comprises at least two exit openings (4, 5) and at least two internal flow channels (9A, 9B), defining at least two independent sets of flow paths through said supporting plate which are in fluid connection with the at least one flow area (6), each set of flow paths comprising at least two exit openings (4, 5) being in fluid connection, and at least one internal flow channel (9A,9B), such that said heat exchange module (20) is configured for allowing liquid media (C, D) to pass from a first exit opening (4) through one or more internal flow channels to said at least one flow area (6) and through one or more internal flow channels to a second exit opening (5). A heat exchange unit module (20), wherein said heat exchange unit assembly (20) comprises an additional open mesh between opposite juxtaposed heat exchange units (7), said additional open mesh being configured for flow of second liquid media and creating a turbulent flow between said planar heat exchange units at low flow volume, while also keeping the thermo-conducting sheets (7) fixed, hereby allowing for flush of the thermo-conducting sheets with a negative pressure across the thermo-conducting sheet. The skilled person of the art will be aware that different modifications can be made to the embodiments described above as well as the working example described below, without departing from the scope and spirit of the invention Working examples

DK 180373 B1 18 Example 1. Manufacture of a heat exchange unit and module prototypes. The manufacture of a heat exchange unit of the invention having five flow areas in fluid connection on both sides of the supporting plate follows the steps below. Injection molding of half-plates using a semi-crystalline homopolymer of polypropylene, to outer dimensions of these being 240 x 200 x 2 mm, making the bonded supporting plate 4 mm thick. These dimensions lead to a very rigid base plate with two protruding exits, connected to the internal manifold channels, that lead to five individual, but successively interconnected flow areas on the outside of the plate. The flow areas together cover approximately 190 x 190 mm on both side of the supporting plate, and a

0.2 mm thermo-conducting polypropylene based completely tight membrane on a non- woven mesh covers the five flow areas and is sealingly heat-bonded around each flow area. Hereby an effective, rigid heat exchanger plate, with high chemical and thermal span of operation, is made out of plastics only.

The planar heat exchange units are build up into a rigid stack of 33 plates forming a heat exchange module of 2.5 square meter of heat exchange surface. In building up the stack of plates, each protruding exit is heat-bonded to the exit of the juxtaposed plates, and the bonding points on the perimeter are also heat-bonded together so that these together with the exits secure a uniform distance of 1.6 mm of free gap between the plates.

The protruding exits have an internal diameter of 16 mm, and in the built up module there are 4 exits where in operation 2 of these are entries for the first media and 2 are exits for said first media. The exits each connect to the internal manifold in the plates and said manifold is formed by 2 mm channels in the plate formed when the 2 half plates are connected. The internal channels lead to the first flow area connecting to this through slits in the plate and same design | used between consecutive flow areas, and from last flow area to the other protruding exit.

The heat exchanger module is then positioned into a pressure withstanding molded polypropylene flow housing where there are four 16 mm exit openings for the first media: 2 openings for inlet and 2 openings for outlet, where said exits are sealingly connected to the heat exchanger module as well as sealed in towards the flow housing. The second media can enter the heat exchanger module through a 200 mm x 200 mm opening in each end of the housing giving access to the gaps between the stacked heat exchanger plates. The flow housing allows for several heat exchange modules in flow housings to be stacked forming large, longer heat exchangers. In given example 4 housings are stacked making an assembled unit with 10 sqm heat exchange surface. Results achieved.

By leading a fairly large flow of 600 L/min of a second media through the flow channel and a flow of 60 L/min of a first media through the heat exchanger module and through the 2.5 m' flow areas, we measured a resulting heat exchange similar to that of similar size traditional heat exchanges.

Claims

DK 180373 B1 Requirements

A planar, rigid heat exchanger unit for liquid-to-liquid heat exchange, wherein a heat-conducting foil (7) is attached to a support plate (1) and liquid-tight sealed to the circumference of a flow area (6) on at least one of a first or a second rigid outer surface (2s, 3s) of the support plate (1) having at least two fluidly connected outlet openings (4, 5) for a first liquid medium, inner flow channels (9A, 9B) for the first liquid medium, perforations (10A , 10B) for fluid communication of the inner flow channels (9A, 9B) to the flow area (6) for fluid contact with an inner surface of the heat-conducting foil (7), and an outer surface of the heat-conducting foil which is in fluid contact with a flow of a second liquid medium, whereby heat exchange is provided between the two liquid media, wherein the at least one flow area (6) is formed by a grooved or corrugated surface, and wherein said outlet openings (4, 5) are perpendicular to the support plate (1).

The heat exchanger unit according to claim 1, characterized in that the support plate (1) comprises two half-plates attached to each other and in which a flow area (6) is formed in each of the first and second rigid outer surface (2s, 3s) of the support plate (1).

A single heat exchange module (20) comprising a plurality of planar rigid heat exchanger units according to claim 1 or 2.

A heat exchange module (20) according to claim 3, wherein the first and a second rigid outer surface (2s, 3s) are provided on the first and the second half plate in each support plate (1) on each heat exchanger unit, and wherein the first and the second rigid outer surface (2s, 3s) encloses the inner flow channels (9A, 9B) and the perforations (10A, 10B) located on one or both rigid outer surfaces (2s), 3s) of the support plate (1), the at least one heat conducting foil (7) is placed liquid-tight bonded next to and covering the flow area (6) on the surface of the support plate (1), where the fluidly connected outlet openings (4, 5) have projecting edges, and where the inner flow channels (9A, 9B) extend from the outlets (4, 5) to the perforations (10A, 10B), and wherein the support plate comprises attachment points (8) which act as spacing points together with the projecting exit edges (4, 5) to form a space between the planar rigid heat exchange units for passage of e t other liquid medium between two adjacent heat exchanger units in the module.

DK 180373 B1

A heat exchange module (20) according to claim 3 or 4, wherein the at least one flow or flow distribution area or heat exchange area (6) is formed by grooves (12) and projections (13), these projections being configured to support the overlying heat conducting foil (7), and the grooves (12) define a flow path configured for flow distribution in the flow area (6) between the inner surface of the thermally conductive foil (7) and an outer surface (2s, 3s) of the support plate (1).

A heat exchanger module (20) according to any one of claims 3 to 5, wherein the at least one flow area (6) is an integral part of the rigid outer surface (2s, 3s) of the support plate (1).

A heat exchanger module (20) according to claim 6, wherein the at least one flow area (6) forms a corrugated top and groove structure or net-like structure on the surface (2s, 3s), the structure creating a corrugated surface in fluid contact with the covering interior side of the heat conducting surface, and where the curved surface is configured to create a turbulent flow inside and outside the support plate (1) at low flow rates for liquid media.

A heat exchanger module (20) according to any one of claims 3 to 7, wherein the support plate (1) has an outer circumference that is square or rectangular.

A heat exchanger module (20) according to any one of claims 3 to 8, wherein the support plate is formed by liquid tight fastening such as edge welding or heat melting of two suitable half-plates made of a light material, such as plastic.

A heat exchanger module (20) according to claim 9, wherein the two half-plates (2, 3) are fixed at the periphery, and the two half-plates (2,3) are symmetrical or identical in shape.

A heat exchanger module according to claim 9 or 10, wherein the half-plates are formed by molding.

A heat exchanger module (20) according to any one of claims 3 to 11, wherein the thermally conductive film is selected as a thin film of a thermally conductive material, such as metal, such as stainless steel, aluminum or molded aluminum alloys; or of heat-conducting plastic material or a hybrid material such as polypropylene, polysulfone or nylon having heat-conducting additives including graphite-carbon fibers and ceramics such as aluminum nitride and boron nitride; wherein the thermally conductive film is impermeable to the liquid media to be cooled or heated.

A heat exchanger module (20) according to any one of claims 3 to 12, wherein the outer surface of the heat conductive film (7) has a net-like structure, such as a superimposed herringbone-like curve shape.

DK 180373 B1

A heat exchanger module (20) according to any one of claims 3 to 13, wherein the at least two outlet openings (4, 5) and their projecting edges extend transversely from the planar surface of the first and second rigid outer surfaces (2s, 3s) of the support plate.

A heat exchanger module (20) according to any one of claims 3 to 14, wherein the internal flow channels (9A, 9B) comprise a number of separate channels or flow volumes formed by the inside of the half-plates (2, 3) and wherein the separate channels form a manifold leading to the outlet openings (4, 5).