WO2001057461A1

WO2001057461A1 - Heat exchanger and foil laminate therefor

Info

Publication number: WO2001057461A1
Application number: PCT/NL2001/000095
Authority: WO
Inventors: Air B.V. Comfort
Original assignee: Reinders, Johannes, Antonius, Maria; Berben, Ernest, Jozef, Elias; Eichweber, Heinz, Gerhard, Kurt
Priority date: 2000-02-04
Filing date: 2001-02-05
Publication date: 2001-08-09
Also published as: AU3780301A

Abstract

The invention relates to a heat exchanger, comprising at least one first conduit and at least one second conduit, the first and second conduit being separated by at least one closed heat exchanging wall such that heat may be exchanged between the first and second conduit, wherein the at least one heat exchanging wall comprises a foil laminate, said foil laminate consisting of at least one carrier layer and at least one heat conducting layer arranged thereon, the at least one heat comducting layer being composed of a plurality of spaced apart layer parts.

Description

HEAT EXCHANGER AND FOIL LAMINATE THEREFOR

The invention relates to a heat exchanger, comprising at least one first conduit and at least one second conduit, the first and second conduit being separated by at least one closed heat exchanging wall such that heat may be exchanged between the first and second conduit. Such a heat exchanger is generally known.

In certain applications, for instance heat exchangers, it may be desirable to promote conduction of heat in one direction and to reduce conduction of heat perpendicular to this direction as much as possible. Furthermore the design of a heat exchanger should be economically feasible.

The present invention therefore has for its object to provide a heat exchanger combining the above features.

This object is accomplished in accordance with the invention, in that the at least one heat exchanging wall comprises a foil laminate, said foil laminate consisting of at least one carrier layer and at least one heat conducting layer arranged thereon, the at least one heat conducting layer being composed of a plurality of spaced apart layer parts . These layer parts may have any- desired shape. Since the heat conducting layer comprises spaced apart layer parts, the conduction of heat within the layer will be reduced. There will thus only be transport of heat within a layer part, and not from one layer part to another. The heat conducting material may for instance be copper, aluminum or graphite.

In order to obtain a uniform transport of heat through the wall', the layer parts are preferably arranged on the at least one carrier layer in a regular pattern.

In one embodiment the layer parts comprise parallel first strips. In a preferred embodiment the layer parts are made by spraying. By this method of production the layer parts of a heat conducting material may be arranged in the laminate according to the invention in relatively simple manner.

In another embodiment of the invention the at least one carrier layer has an open structure. In this way the local properties differ in the direction of thickness of the laminate. Especially when the foil laminate in used for a heat exchanger wall, the heat resistance will be lower in places where the openings are arranged than in places where the carrier layer is present. The carrier layer however, cannot be eliminated, as the structural integrity of the laminate would then be lost.

The open structure is preferably achieved in that the at least one carrier layer comprises a plurality of openings distributed over its surface area.

In yet another embodiment the carrier layer is composed of at least two substantially parallel spaced apart second strips, said second strips being arranged overlapping the first strips. Due to the second strips overlapping the first strips, the carrier layer may be connected to the heat conducting layer through the adhesive layer, resulting in a strong laminate. As the second strips are spaced apart, parts of the first strips on both sides will be exposed. When the first strips are made of an heat conducting material, the heat resistance will be minimum at these locations. In a preferred embodiment of the invention an adhesive layer is arranged on both sides of the at least one carrier layer, and the first and second strips are arranged mutually parallel, the second strips being connected to opposite sides of the adjacent first strips. This results in second strips having a substantially S- shaped cross section, which mechanically connect the first strips. In yet another embodiment of the invention the foil laminate comprises a coating layer including a hydrophilic material. In heat exchangers that are used for so called dew point cooling devices it is necessary that one side of the heat exchanging walls is moistened, so that an airflow on the other side of the heat exchanging wall may be cooled by evaporation of the moisture .

In yet another embodiment of the invention the coating layer is connected with the adhesive layer through the openings between the first strips such that the heat conducting layer is arranged between the coating layer and the carrier layer. This leads to a very strong laminate, in which the first strips are firmly held. The coating layer may preferably comprise a wetting material, whereby moisture may be distributed uniformly over the laminate. Materials are being marketed which may be applied to for instance the heat conducting layer in liquid form and then form a thin film which leads to a reduction of the surface tension of the layer, so that moisture may uniformly be distributed on the surface. Such a material further has for its result that water does not directly contact the heat conducting layer, so that corrosion is prevented. The coating layer can further comprise a hygroscopic material, which attracts moisture and forms a buffer for moisture, so that there will always be sufficient moisture for evaporation.

In yet another embodiment the foil laminate may comprise a water repellent layer. When moist air is cooled in such a heat exchanger, there is a chance that this air will condense on the foil laminate. Due to the water repellent layer the moisture may easily be discharged from the heat exchanger and may possibly be used for wetting the hygroscopic layer. The water repellent layer may for instance comprise silicone or teflon. These and other features of the invention will be further illustrated by reference to the accompanying drawing:

Fig. 1 shows a first embodiment of the laminate in accordance with the invention;

Fig. 2 shows a second embodiment of the laminate in accordance with the invention;

Fig. 3 shows a third embodiment of the laminate in accordance with the invention; Fig. 4 shows a fourth embodiment of the laminate in accordance with the invention;

Fig. 5 shows a fifth embodiment of the laminate in accordance with the invention;

Fig. 6 shows a sixth embodiment of the laminate in accordance with the invention;

Fig. 7 shows a heat exchanger plate in accordance with the invention;

Fig. 8 shows a detail of fig. 7 on an enlarged scale; and Fig. 9 shows a seventh embodiment of the laminate in accordance with the invention, which is suitable for exchanging heat between two air flows .

Fig. 1 shows a first embodiment of the laminate 1. The laminate comprises a first layer that is composed of first strips 2 made of a material having good heat conducting properties, e.g. a metal like copper, aluminum and the like. At the bottom a second layer or carrier layer 3 is arranged, which is connected to the first layer composed of the first strips 2 by means of an adhesive layer 4. This carrier layer is made of a material which conducts heat less well than the material of the first strips 2, for instance a synthetic foil.

The choice of the adhesive layer is governed i.a. by the intended use of the laminate. If the laminate has to be used at higher temperatures, it is necessary to choose an adhesive layer that can withstand such high temperatures . Instead of a carrier layer 3 and a separate adhesive layer 4, an adhesive layer could also be used as carrier layer.

Fig. 2 shows a second embodiment of the laminate 10 in accordance with the invention. Here also the first layer is composed of heat conducting strips 2. These strips are arranged mutually parallel and spaced apart. In the interspace between two adjacent first strips 2 second strips 11 are arranged, which form the carrier layer of the laminate. These second strips are arranged overlapping the first strips 2. The first strips are connected to the second strips by means of adhesive layers (not shown here) , that are arranged on both sides of the second strips. Fig. 3 shows a third embodiment of the laminate

15 in accordance with the invention. Here also a first layer is formed by heat conducting strips 2 on which a carrier layer 16 is arranged, which has an open structure. This open structure is formed by openings 17 arranged in the carrier layer 16. The openings 17 are distributed over the surface such that an impermeable laminate is formed, allowing a closed wall to be made. The heat conducting elements 2 comprise exposed parts on both sides, which allow an improved heat exchange. In fig. 4 a fourth embodiment of a laminate 20 in accordance with the invention is shown. This laminate 20 mainly corresponds with the embodiment as shown in fig. 1. Here also the first layer is formed by heat conducting strips 2. Under this heat conducting layer a carrying layer 3 is arranged, that is fastened to the heat conducting strips 2 by means of an adhesive layer 4. On the other side of the heat conducting strips 2 a layer of hygroscopic material 21 is arranged. This material is porous and can therefore easily absorb moisture. This layer 21 may for instance be arranged on the heat conducting elements 2 by means of a dot-coated adhesive layer. In this way the transport of heat perpendicular to the plain of the laminate is not obstructed by the adhesive layer.

Fig. 5 shows a fifth embodiment 30, comprising a carrier layer 31 and a plurality of heat conducting layer parts 32 arranged thereon. The layer parts 32 are spaced apart, so that there is no possibility of heat transfer between the layer parts 32.

Fig. 6 shows a cross-section of a foil laminate 40 in accordance with the invention. This laminate 40 comprises a carrier layer 41 having heat conducting layer parts 42 on both sides. At the bottom a water repellent layer 43 is arranged over the heat conducting layer parts 42, so that condensed water may easily be discharged. At the top a hydrophilic layer 44 is arranged, whereby water is attracted. On this hydrophilic layer 44 a hydroscopic layer 45 is arranged, so that a certain amount of water may be stored. The hydrophilic layer 44 and the water repellent layer 43 further serve as corrosion resistance for the heat conducting layer parts 42. Fig. 7 shows a cross-section through a laminate

51 folded into a heat exchanger plate 50. Fins 52 have been formed, resulting in channels being formed in the plate 50.

Fig. 8 shows a detail of the heat exchanger plate 50. The fins 52 have been formed by folding together the laminate. In this embodiment the laminate consists of a carrier layer 53, heat conducting layer parts 54 arranged thereon, and a protective film 55 arranged thereover. This film 55 may for instance be a water repellent layer.

It should be noted that the embodiments shown in the figures are not represented at true scale.

Fig. 9 shows a cross-section of a laminate formed in accordance with the invention that is suitable for heat exchange between two airflows. The laminate 60 has been shaped such that two fins 61 are formed on both sides, so that the area of contact is enlarged. The laminate itself consists of a carrier layer 62 and heat conducting parts 63 arranged thereon. If the exchange of heat involves two non-aggressive airflows, no protective layer is necessary. Such a protective layer may however be provided as a thin coating at the side of the heat exchanging parts 63.

Although the invention has been described above by way of a number of examples, it is not limited thereto. Instead of or in addition to the interruptions in longitudinal direction of the laminate, interruptions could also be formed in the lateral direction, for instance when the heat exchanger functions in cross-flow. Furthermore other configurations of the heat conducting layer and the carrier layer are conceivable, whereas there are also many alternatives in the choice of materials. Consequently, the scope of the invention is solely determined by the appended claims .

Claims

1. Heat exchanger, comprising at least one first conduit and at least one second conduit, the first and second conduit being separated by at least one closed heat exchanging wall such that heat may be exchanged between the first and second conduit, characterized in that the at least one heat exchanging wall comprises a foil laminate, said foil laminate consisting of at least one carrier layer and at least one heat conducting layer arranged thereon, the at least one heat conducting layer being composed of a plurality of spaced apart layer parts .

2. Heat exchanger as claimed in claim 1, characterized in that the layer parts are arranged on the at least one carrier layer in a regular pattern.

3. Heat exchanger as claimed in claim 2 , characterized in that the layer parts comprise parallel first strips .

4. Heat exchanger as claimed in any one of the preceding claims, characterized in that the layer parts are made by spraying a material like e.g. copper.

5. Heat exchanger as claimed in any one of the preceding claims, characterized in that the at least one carrier layer has an open structure.

6. Heat exchanger as claimed in claim 5, characterized in that the at least one carrier layer comprises a plurality of openings distributed over its surface .

7. Heat exchanger as claimed in claim 3 , characterized in that the carrier layer is composed of at least two substantially parallel spaced apart second strips, said second strips being arranged overlapping the first strips.

8. Heat exchanger as claimed in claim 7, characterized in that on both sides of the at least one carrier layer an adhesive layer is arranged, and in that the first and second strips are arranged mutually parallel, the second strips being connected to opposite sides of adjacent first strips.

9. Heat exchanger as claimed in any one of the preceding claims, characterized by at least one coating layer comprising a hydrophilic material .

10. Heat exchanger as claimed in claim 9, characterized in that the coating layer is connected to the adhesive layer through the openings between the first strips such that the heat conducting layer is arranged between the coating layer and the carrier layer.

11. Heat exchanger as claimed in claim 9 or 10, characterized in that the coating layer comprises a wetting material.

12. Heat exchanger as claimed in claim 9, 10 or 11, characterized in that the coating layer comprises a hygroscopic material.

13. Heat exchanger as claimed in any one of the preceding claims, characterized by a water repellent layer .

14. Heat exchanger as claimed in claim 13, characterized in that the water repellant layer comprises silicone and/or polytetrafluoroethene.

15. Foil laminate for use in a heat exchanger as claimed in any one of the preceding claims .

16. Use of a foil laminate as claimed in claim

15 in a heat exchanging wall.