NL1022796C2 - Heat exchanger, has heat conducting fins arranged on both sides of each wall such that fins are in thermal contact with each other and have contact surface joined to wall - Google Patents

Abstract

The exchanger has two sets of medium through-flow channels (P, S) divided by walls (2) through which two media flow in a heat- exchanging contact. Heat conducting fins (3-8) are arranged on both sides of each wall such that they are in thermal contact with each other. The wall and the fins act as membrane and heat transferring strips, respectively. The fins have contact surfaces joined to the wall. An independent claim is also included for a method of manufacturing a heat exchanger.

Description

Heat exchanger and method for manufacturing thereof

The invention relates to a heat exchanger, comprising two sets of interwoven placed medium flow channels through which two media can physically separate from each other in a primary circuit (P) and a secondary circuit (S) respectively and can only flow in heat exchanging contact; walls separating said channels; thermally conductive fins arranged on both sides of each wall, which fins extend with their major planes in the respective flow directions of said media, a fin on one side of a wall having a contact surface forming part of the fin in the major plane the respective wall 15 is in thermal contact with a similar contact surface of a fin on the other side of that wall; a housing in which the walls defining the channels with the fins are received, to which housing two inlets and two outlets connect for the two sets of channels, either individually per channel, or via respective manifolds common to the sets of channels.

Such a heat exchanger is known in many embodiments. It is an object of the invention to design a heat exchanger such that it is very light and can be manufactured cheaply, while nevertheless having an excellent efficiency.

In connection with this, the heat exchanger 30 according to the invention is characterized in that the walls are designed as membranes, and the fins are designed as H heat transferring, for example, metal strips with H a general wave form, which fins are provided with H walls connected contact surfaces and main surfaces extending between two H 5 walls, such that H, in addition to a thermal function, the fins also have an H constructive function, the H heat transfer coefficient of the entire partition wall H being at least 1 W / m 2 K.

The heat exchanger according to the invention thus derives its mechanical strength and rigidity mainly from the fins. According to the state of the art, the mechanical strength and rigidity of H heat exchangers are generally determined not by fins but by the heat-exchanging walls. This requires the use of mechanically strong and therefore thick walls, which therefore have the inherent disadvantage of a higher heat resistance, in so far as it concerns the same materials.

The heat exchanger according to the invention can combine a high efficiency with a very compact construction.

It should be understood that a membrane I is, at least in theoretical sense, an "infinitely thin" sheet-like element, which has a negligible bending stiffness and can therefore derive its stiffness solely from B being clamped at its ends, whether or not in combination with a certain tensile stress in the form B of a bias. When a B pressure difference occurs between the primary circuit and the B secondary circuit, a certain deflection of a practical membrane cannot be completely prevented. This means that the pressure resistance of a heat exchanger according to the invention is limited to a value which is determined by the mechanical properties, such as the thickness of the film used, the tensile strength, the stretchability, the yield strength, the pretension, the mutual distance between the film layers. En Λ Λ Λ Λ 3 and the like. When a pre-stress is used, this forms an additional load on the film material. The maximum tensile stress in the film is therefore equal to the total maximum tensile stress, reduced by the pre-stress.

In order to make the heat transfer between the layers of fins as large as possible, that embodiment is preferred in which corresponding contact surfaces are in thermal contact via the wall. In a practical embodiment, the heat exchanger is characterized in that the contact surfaces are adhered to the wall by means of an adhesive layer applied to at least one contact surface.

An alternative is characterized in that corresponding contact surfaces are directly connected to each other via a perforation in the wall by means of an adhesive layer applied to at least one contact surface.

It will be clear that it is essential that the heat resistance formed by the foil wall and the adhesive layer should be as small as possible. In connection with this, these layers must be thin.

With regard to the heat contact between neighboring layers of fins, that embodiment is preferred in which the walls consist of PVC and that the fins are connected to the walls by an ultrasonic treatment or a thermal treatment, in combination with pressure.

The connection can for instance take place by welding, soldering or the like, at least such that the heat resistance formed by the foil is lacking.

A preferred embodiment has the special feature that the housing is dimensionally stable and the walls are connected to the housing so that the tensile stresses occurring in the walls can be absorbed by the housing due to a pressure difference between the two sets of channels.

Another exemplary embodiment is characterized in that the walls are pre-stressed such that, with a preselected maximum permissible pressure difference between the two sets of medium flow channels, the H sag of the wall between two free spaces defined by the contact surfaces H of the fins, that that is, the deflection of the H membrane occurring at the respective pressure, divided by the respective mutual distance H between the respective contact surfaces, amounts to a maximum of 2.5% H.

H In the embodiment in which corresponding H 10 contact surfaces are in thermal contact via the film wall, the heat exchanger preferably has the feature that the heat resistance of the film transversely of its main surface is at most 0.1 of the H heat resistance in the case of direct contact between contact surfaces facing each other, and therefore H is negligible.

The heat exchanger is preferably characterized in that the heat resistance of the film in its main surface over the mutual distance between two fins adjoining in the direction of flow is at least 10 times as large as in the case of fins directly thermally coupled to each other.

A practical embodiment has the special feature that the walls consist of PET, for example stretched PET, have been treated with a corona discharge, are subsequently provided with a primer, followed by an adhesive layer for connection to the contact surfaces of the fins.

An alternative embodiment has the feature that the walls consist of PVC and that the fins are connected to the walls by an ultrasonic treatment or a thermal treatment, in combination H with pressure.

A substantial improvement of the tensile strength I relative to the usual film materials is obtained with a heat exchanger, which has the feature I that the film consists of a fiber-reinforced material, which fibers consist, for example, of glass, boron, carbon. The fibers may, for example, be designed as a fabric or as a non-woven.

A great improvement of the thermal conductivity of the film is realized with a heat exchanger which has the feature that the walls consist of a plastic in which aluminum powder is embedded.

In order to be able to make the heat exchanger maintenance-free and to be able to make it suitable for the most diverse applications, the heat exchanger can have the feature that the walls consist of PET, for example stretched PET, have been treated with a corona discharge, then are provided with a primer followed by an adhesive layer for connection to the contact surfaces of the fins.

A very practical embodiment has the special feature that the walls protrude outside the fins, such that they can be connected to a frame, for instance in order to bias them, or in such a way that the projecting wall parts can be thermally formed into weaving. and manifolds for joining and separating the sets of channels, respectively. With this embodiment, the problem of executing a weaving and manifold on both sides of the heat exchanger is reduced.

A particular embodiment has the feature that the heat exchanger is constructed in a modular manner from blocks that can be releasably coupled together. In this way it is achieved that the heat exchanger can be manufactured by using blocks in different dimensions, without the need for substantial conversion of a production line.

A particular embodiment has the feature that the layers are arranged in the order P, S, P, S, P, S and so on.

Another embodiment has the feature that the layers are arranged in the order P, P, S, S, P, P, and so on.

1 022796

In order to limit the mechanical load on the film layers as much as possible during production of the heat exchanger, a preferred embodiment has the special feature that the contact surfaces of the fins 5 have rounded peripheral edges.

H In an embodiment in which the film consists of H a fiber-reinforced material, the heat exchanger H can have the special feature that the fibers have an anisotropic H heat conduction, such as carbon fibers, wherein H the heat conduction in the main surface of the film is smaller than H in the transverse direction thereto. Hereby an H substantial improvement of both the tensile strength of the H film webs and hence the pressure resistance of the H heat exchanger is substantially improved and it is also achieved that the heat contact between adjacent fins is very good.

H The film materials can be suitably selected with regard to operating conditions and applications. Both thermoplastic plastics and thermosets, such as polyetherimide, are suitable.

The foil materials can also be provided with a cover layer, for example with another plastic, a silicone material or the like. In the case of fiber reinforcement, the fibers may have diameters of a few .mu.m.

Another choice for the material of the membranes is metal, in particular a plastic film with a metal covering layer on at least one of both sides.

A very simple solution of a possibly occurring corrosion problem consists in that the adhesion has taken place with an anticorrosive coating applied to at least one of the two contact surfaces, for example comprising a primer layer and / or an adhesive layer which extends over the entire surface. of the I fins and possibly the wall.

A specific embodiment has the special feature that the adhesive layer is of the thermally activatable type and that the fins are attached to the respective wall and / or to an adjacent pair of fins by heating and pressure by means of a heated pressure stamp at the area of the contact surfaces. to be.

In yet another variant, the heat exchanger is characterized in that the fins on the side remote from the said cover layer are provided with a second cover layer which is resistant to the said heating and pressure.

The invention will now be explained with reference to the accompanying drawings. Show here:

FIG. 1 is a perspective partial view of a heat exchanger according to the invention, wherein the housing is not drawn for the sake of clarity; FIG. 2a shows a schematic perspective view on a small scale of a heat exchanger according to the invention with a housing and weaving and manifolds;

FIG. 2b the detail II from FIG. 2a on a larger scale; FIG. 3 a schematic representation of an alternative, staggered arrangement of the fins;

FIG. 4 a schematic representation of one. unreinforced membrane;

FIG. 5 is a partly broken away perspective view of a membrane reinforced with a fiber fabric;

FIG. 6 one with FIG. 5 is a view corresponding with a non-woven membrane;

FIG. 7a and 7b show respective phases of attaching the contact surfaces of fins to a membrane;

FIG. 8 an alternative method of attachment;

FIG. 9a a with FIG. 8 corresponding cross section of an alternative form;

FIG. 9b is a perspective view of the preliminary phase of the structure according to FIG. 9a;

FIG. 10a and 10b with Figs. 7a and 7b correspond to views of an embodiment in which the fins are directly coupled to each other via holes in the membrane.

H FIG. 10c is a perspective view of the device shown in H FIG. 10a, corresponding to FIG. 9b; H FIG. 11 shows the preliminary phase of an embodiment in which H 5 is provided with an adhesive layer on both sides of the membrane.

FIG. 12 one with FIG. 11 shows a corresponding view of an embodiment in which the contact surfaces of the fins are coated; FIG. 13a shows a highly schematic view of H an apparatus for manufacturing a heat exchanger according to the invention in an industrial manner;

FIG. 13b the detail XIII from FIG. 13a on an enlarged scale; FIG. 13c shows a slightly further elaborated and detailed perspective view of the device according to FIG. 13a;

FIG. 14 is a cross-sectional view of a part of a heat exchanger according to the invention during the production phase, in which the membranes are clamped by tensioning means; FIG. 15 is a front view of a heat exchanger with the fins and the medium circuits arranged in a first arrangement; FIG. 16 one with FIG. Corresponding view, in which the fins and the medium circuits are arranged in a second arrangement; and

FIG. 17 is a cross-sectional view of H alternative tensioning means.

FIG. 1 shows a heat exchanger 1, comprising a number of layers of foil 2, between which strips 3, 4, 5, 6, 7, 8, etc. extend. These strips I 3-8 form heat-conducting fins and for this purpose are made, for example, of copper. By means of means to be described below, the fins are adhered to said sheets with their contact surfaces facing each other on either side of the sheet 2. In this embodiment, the successive film layers alternately define a λ Λ Λ A: - ¾ r ** 9 primary and a secondary circuit, indicated by arrows P and S in the figure. These medium circuits concern the flow in heat-exchanging contact with each other media, for example gaseous media, liquid media or gas and liquid or two-phase media respectively.

It is further apparent from the drawing that the strips 3, 4, 5 have a limited length in the medium flow direction and that the following fins 10 strips 6, 7, 8 are placed at some distance. This benefits the effective heat transfer. The gap 9, which is not provided with fins, effectively acts as heat separation in the conveying direction. For this it is required that the foil material has a limited thermal conductivity and, for example, is not made of a good heat-conducting material such as copper. Plastic, for example, is a very suitable choice. Because the films are designed as membranes and are therefore very thin, they present only a negligible heat resistance at the location of the heat transferring contact surfaces of the fins facing each other.

FIG. 2 shows a heat exchanger 10 that is built up on the basis of the aforementioned membrane fin heat exchanger, wherein use is made of a housing. At the free ends, respective weaving and manifolds include 12 for P in, 13 for P out, 14 for S in and 15 for S out.

FIG. 2b shows the interior of the heat exchanger 10. This is essentially the same unit as 30 in FIG. 1 and is therefore also designated by reference numeral 1.

FIG. 3 shows very schematically an alternative arrangement of fins in strips 16, 17, 18, 19, 20, 16, respectively. It should be clear that the fins are shifted in the transverse direction relative to the flow direction 21 by 1/5 pitch. As a result, the leading edge of each fin is always in a practically undisturbed flow. This is the ίΠηοτηΛ.

Η Η heat transfer for good.

H FIG. 4 schematically shows a membrane 22.

H FIG. 5 shows a membrane 23 which is reinforced with a fabric 24, for example consisting of glass fiber, H 5 carbon fiber or the like. It is noted that the H drawing is not to scale, and that a mat 24 of this H type can also be impregnated with a plastic, as a result of which the fabric is medium-tight and moreover can for instance melt by heat to secure the contact surfaces of the fins .

FIG. 6 shows a membrane 25 with a non-woven reinforcement 26.

FIG. 7a shows a membrane 28 with layers of glue 29 at the area of contact surfaces 30 of fins 31. By pressing H 15, the area shown in FIG. 7b, structure H is obtained, wherein the glue is slightly squeezed into H side zones 32. The glue 29 can be preheated or be of pressure-sensitive type.

FIG. 8 shows an embodiment in which the fins 31 are pressed into the film 28 under heating and pressure.

As a result, the film material in the intermediate zone 33 is thinned and the material is pressed slightly outwards in the zones 34 to the side. This embodiment is favorable in the sense that a good seal is always guaranteed, while the already thin foil material is additionally diluted.

FIG. 9a shows a variant in which fins 35, 36 are provided with complementary ridges and 37, 38, respectively. As a result, a good positioning of the contact surfaces is always guaranteed. The ridges 37, 38 also extend transversely. This aspect is clearly visible in FIG. 9b. The arrows 39 indicate that the fins 35, 36 are forced towards each other under heating and pressure I under compression of the foil 28. In the embodiment according to FIG. 10, the foil 40 I is provided with openings 41, through which the contact surfaces I of the fins 31 can come into contact with each other. The contact surfaces are provided with adhesive layers 42, whereby; 11 through these very thin adhesive layers, the fins can be brought into direct contact with each other, as shown in FIG. 10b. FIG. 10a also shows that the peripheral edge of opening 40 is provided with a mass 43 forming a sealing ring to ensure a medium-tight connection.

FIG. 11 shows an embodiment in which a foil 44 is provided on both sides with an adhesive layer 45 for coupling to the contact surfaces of the fins 31.

In FIG. 12, the contact surfaces of the fins 31 are provided with adhesive layers 46.

FIG. 13 shows the manner in which the film webs 48 and the fin strips 49 adhered thereto can be assembled into a package as drawn for example in FIG. 1.

As shown in FIG. 13c, a storage container 50 contains ten storage rolls 51, to which foil webs with strips of fins are glued thereon. One of the rollers, designated by reference numeral 52, contains only film material 48 without fins. The various webs are guided together by the nip of two guide and pressure rollers 53, 54 and introduced into an electromagnetic heating device 55, so that the respective surfaces of the films (Fig. 11) or the contact surfaces of the fins (Fig. 12) hot melt present melts, so that the desired adhesion can be achieved. The input pressure rollers 56, 57 and 58, 59 contribute to this.

FIG. 13b, corresponding to FIG. 8 shows an embodiment in which the desired adhesion has been achieved by pressure and temperature increase in the device 55, 56, 57, 58, 59.

FIG. 14 shows film 60 on which fins 61 are adhered. The films can be positioned by means of snap profiles 62, it being noted that an extension of the film is realized through the respective recess 63 and the projection 64 cooperating therewith, which together with the stretchability of the film leads to a certain prestress. By stacking the profiles 62, a modular way a heat exchanger 1 of the type according to FIG. 1 or other H type. The direction of pressing is symbolically indicated with an arrow 65. Arrow 66 symbolically indicates the mobility of the film, it being understood that during the pressing according to arrow 65 a film is stretched and thus placed under bias.

FIG. 15 shows, inter alia, FIG. 1, the primary and secondary circuits 10 following each other.

FIG. 16 shows a variant in which two primary I circuits are adjacent to each other, followed by two I secondary, followed by two primary I, etc.

FIG. 17 finally shows an alternative to the method of clamping in accordance with FIG. 14. In the embodiment according to FIG. 17, each of the clamping blocks 62 is designed as a generally U-shaped profile 67 with an outwardly narrowing opening 68, in which a roller 70 loaded by a compression spring 69 is located. A film web 60 can be inserted in the nip between the bottom surface 71 of the opening 68 and the roller 70 as according to arrow 71. This allows a slight pressure against the spring pressure of spring 69 in the front edge of film 60 to exert it. pass contact surface between surface 71 and roller 70. This H application is done with some force, whereby the film H is lightly stretched until the required prestressing is achieved. Then the film is released and held in the said nip. This guarantees a permanent I bias.

30 * * * * * I 1022796

Claims (23)

A heat exchanger, comprising two sets of interwoven placed medium flow channels through which two media can physically separate from each other in a primary circuit (P) and a secondary circuit (S) and in exclusively heat-exchanging contact; walls, heat-conducting fins arranged on both sides of each wall, said fins extending with their main surfaces in the respective flow directions of said media, a fin on one side of a wall having one of the the contact surface forming part of the main surface of the wall in question is in thermal contact with a similar contact surface of a fin on the other side of that wall; a housing in which the walls defining the channels with the fins are accommodated, to which housing two inlets and two outlets connect for the two sets of channels, either individually per channel, or via respective manifolds common to the sets of channels, characterized in that the walls are in the form of membranes, and the fins are in the form of heat-transferring, for example, metal strips with a general wave shape, which fins are provided with contact surfaces connected to the walls and main surfaces extending between two walls, all such, in addition to a thermal function, the fins also have a structural function 1022796 H, H where the heat transfer coefficient of the entire H partition wall is at least 1 W / m2K. 2. A heat exchanger according to claim 1, characterized in that corresponding contact surfaces are in thermal contact via the wall. 3. A heat exchanger as claimed in claim 2, characterized in that the contact surfaces are adhered to the wall by means of an adhesive layer applied to at least one contact surface. 4. A heat exchanger according to claim 2, characterized in that corresponding contact surfaces I are directly connected to each other via a perforation in the wall by means of an adhesive layer applied to at least one contact surface. 5. A heat exchanger as claimed in claim 1, characterized in that the housing is dimensionally stable and the walls are connected to the housing so as to be tensile, such that the tensile stresses occurring in the walls can be caused by a pressure difference between the two sets of channels through the housing. be included. 6. A heat exchanger according to claim 1, characterized in that the walls are pre-stressed such that with a preselected maximum permissible pressure difference H 30 between the two sets of medium flow channels, the sag of the wall between two through the contact surfaces I of the fins determined free space, that is to say that the deflection of the membrane occurring at the respective pressure divided by the respective mutual distance between the respective contact surfaces, amounts to a maximum of 2.5% I. A heat exchanger according to claim 2, characterized in that the heat resistance of the film transversely to its main surface is at most 0.1 of the heat resistance in the case of direct contact between contact surfaces facing each other, and so 5 is negligible. 8. A heat exchanger according to claim 1, characterized in that the heat resistance of the film in its main surface over the mutual distance between two fins adjoining in the direction of flow is at least 10 times as large as in the case of thermally directly coupled to each other. 9. A heat exchanger as claimed in claim 1, characterized in that the walls consist of PET, for example stretched PET, are treated with a corona discharge, subsequently provided with a primer, followed by an adhesive layer for connection to the contact surfaces of the fins. . 10. A heat exchanger according to claim 1, characterized in that the walls consist of PVC and that the fins are connected to the walls by an ultrasonic treatment or a thermal treatment, in combination with pressure. 11. A heat exchanger according to claim 1, characterized in that the foil consists of a fiber-reinforced material, which fibers consist, for example, of glass, boron, carbon. A heat exchanger according to claim 1, characterized in that the walls consist of a plastic, in which aluminum powder is embedded. A heat exchanger according to claim 1, characterized in that the wall or any glue layer applied thereon according to claim 9 is conditioned 4 to 9 9 7 Q 8 to obtain a property from the group to which belong: H - anti-bacterial properties H - anti-adhesion property to repel dirt and H other fouling H - anti-static properties H - surface tension changing, which conditioning H can be applied, for example, by dipping or spraying with a suitable agent. H 10 14. A heat exchanger according to claim 1, characterized in that the walls protrude outside the fins, such that they can be connected to a frame, for example in order to bias them or in such a way that the projecting wall parts can be thermally are formed into weaving and manifolds for joining and separating the sets of channels respectively. 15. A heat exchanger according to claim 1, characterized in that the heat exchanger is constructed in a modular manner from blocks that can be detachably connected to each other. 16. A heat exchanger according to claim 1, characterized in that the layers are arranged in the order P, S, P, S, P, S and so on. 17. A heat exchanger according to claim 1, characterized in that the layers are arranged in the order P, P, I, S, S, P, P, and so on. A heat exchanger according to claim 1, characterized in that the contact surfaces of the fins have rounded peripheral edges. A heat exchanger according to claim 11, characterized in that the fibers have an anisotropic heat conduction, such as carbon fibers, wherein the heat conduction in the main surface of the film is smaller than in the transverse direction thereto. 20. A heat exchanger according to claim 3 or 4, characterized in that the adhesion has been effected with a corrosion-resistant cover layer applied to at least one of the two contact surfaces, for example comprising a primer layer and / or an adhesive layer which extends over the entire surface of the fins. and optionally extending the wall. 21. A heat exchanger according to claim 3 or 4, characterized in that the adhesive layer is of the thermally activatable type and that the fins are heated and pressurized by means of a heated pressure stamp at the area of the contact surfaces on the relevant wall and / or on fins located opposite are attached. A heat exchanger according to claims 20 and 21, characterized in that the fins on the side remote from said cover layer are provided with a second cover layer which is resistant to said heating and pressure. 23. Method for manufacturing a heat exchanger according to claim 1, comprising two sets of interwoven placed medium flow channels through which two media can physically separate from each other in a primary circuit (P) and a secondary circuit (S) and in heat-exchanging contact; Walls separating said channels; thermally conductive fins arranged on both sides of each wall, which fins extend with their major faces in the respective flow directions of said media, with a fin on one side of a wall through a contact surface in the major plane of the wall in question is in thermal contact with a similar contact surface of a fin on the other side of that wall; 1022736 H a housing in which the channels defining walls I with the fins are accommodated, to which housing two inputs H and tweq outlets connect for the two sets of channels, H either individually per channel, or via respective H 5 manifolds common to the sets of channels, wherein the walls are designed as membranes, the fins are designed as metal strips of a general wave shape with contact surfaces connected to the walls and main surfaces extending between two walls, H such that the fins, except H, have a thermal function, also have a constructive function; Comprising the steps of (a) providing a plurality of metal strips with a general wave shape; (b) providing a plurality of webs of membrane material; and (c) introducing said strips and tracks in register in an intermittent relationship into a connecting device and interconnecting them through a device into a package. H 25 ***** I 1022796