WO2001025698A1

WO2001025698A1 - Heat-exchanger unit and method for producing the same

Info

Publication number: WO2001025698A1
Application number: PCT/EP2000/007777
Authority: WO
Inventors: Konrad Lustig
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 1999-10-05
Filing date: 2000-08-10
Publication date: 2001-04-12
Also published as: DE19947730C1

Abstract

The invention relates to a heat-exchanger unit, comprising at least one surface which absorbs or radiates thermal energy and a system of chambers which is thermally coupled to said surface and through which a fluid that absorbs or radiates the thermal energy can flow. The invention is characterised in that the surface (2) and the system of chambers (4) are formed by a support structure, containing cellulose material and that the surface of this support structure is coated with a layer impermeable to fluid (5), at least on the support structure surface which can be wetted by the fluid that absorbs or radiates the thermal energy.

Description

Heat exchanger unit and method for producing a heat exchanger unit

Technical field

The invention relates to a heat exchanger unit with at least one surface that absorbs or releases heat energy and a chamber system that is thermally coupled to the surface, through which a flood that absorbs or releases the heat energy is downstream.

State of the art

Heat exchanger units are used for the thermal transfer of energy between two material flows or between a material flow and a body thermally coupled to the material flow, heat transfer only taking place if there is a temperature difference between the thermally coupled material flows or the body and the material flow. The material flows themselves can be of a gaseous or liquid nature, the individual material flows being carried separately in each heat exchanger without mixing with one another.

A typical example of a heat exchanger unit in which heat transfer takes place between a gas stream and any, preferably liquid, material stream which is at a lower temperature level than the gas stream is described in US Pat. No. 4,776,391. Here, the gas flow, which is guided in a line housing enclosing the gas flow, flows over a cooling line system through which a coolant flows and which, due to a large heat-transferring surface, has an effective heat transfer. Alternative heat exchanger units in which a targeted heat transfer between two gas flows can be found in the American publications US 5,697,435 and US 4,729,428.

Heat exchangers of another type relate to chamber systems through which a cooling or heating material flow flows and which are thermally coupled to a body to be cooled or heated. The best known arrangements are ceiling or floor heating systems, in which a liquid material flow is led through a pipe system which is integrated in a wall or in the floor. Direct thermal contact between the wall or floor and the pipe system results in heat transfer between the mostly warm material flow and the cold wall or floor body.

Finally, heat exchanger units can also enable heat transfer between the thermal energy in the solar radiation flow and a gaseous or liquid material flow. Such heat exchangers, referred to as solar absorbers, have a surface that absorbs the solar radiation flow, under which a line system is arranged directly, through which the material flow to be heated, in most cases water is used, is heated.

Heat transfer systems, regardless of which category, are increasingly becoming the focus of general interest, especially since they help to optimize energy use, especially against the background of rising energy prices. In addition to their functionality and performance, the acquisition costs associated with their manufacture play an important role in the use of heat exchanger units. Especially for the use of heat exchanger units in countries where the energy supply is mostly critical and the economic potential is poorly developed, heat exchanger units offer possible alternatives and possibilities to better use existing energy resources and to develop new energy sources.

All known heat exchanger units use more or less complex pipe constructions for targeted material flow management, which are in mutual thermal Stand in contact and are mainly made of metallic materials and thus have very good thermal conductivity. In this connection, reference is again made to the sometimes very complex and filigree designs of the prior art specified above.

Presentation of the invention

The invention is based on the object of developing a heat exchanger unit with at least one heat energy absorbing or emitting surface and a chamber system thermally coupled to the surface through which a medium absorbing or emitting the heat energy can flow in such a way that those used for the production of the heat exchanger unit Materials are as inexpensive as possible and that, in addition, the efficiency of the heat exchanger unit should be compared or even improved compared to the performance features of known heat exchanger units. An essential aspect of the invention is to be a cost-effective production of heat exchanger units, so that use of these systems is not only used in economically highly developed countries, but is also particularly widespread in third world countries.

Furthermore, a method for producing a heat exchanger unit is specified which requires the simplest possible manufacturing steps, so that simple reworking of the technical teaching is possible without the need for expensive systems.

The solution to the problem on which the invention is based is specified in claim 1. The subject of claim 9 is a method for producing a heat exchanger unit. Claims 15 and 19 are directed to certain uses of the heat exchanger unit designed according to the invention.

According to the invention, a heat exchanger unit is designed in such a way that the surface and the chamber system are made of a support structure is formed, which has CeUulosematerial, preferably are made entirely of CeUulosematerial and the entire surface of the support structure is covered or sealed with a liquid-impermeable layer.

Cellulose materials are used in a variety of applications today. Cellulose in the form of cardboard or corrugated cardboard is often used, in particular, in the packaging and transport industry of commercial goods. In the meantime, due to their high stability and low weight, these materials are increasingly being used as construction materials for furniture or the like. The heat exchanger designed according to the invention is based on CeUulosematerial in the form of corrugated cardboard.

Corrugated cardboard in its simplest form has a flat layer made of CeUulosematerial or cardboard paper, on one side of which a corrugated cellulose layer is applied, which, with the flat cardboard layer, includes a multiplicity of parallel, mutually open channels. If such a corrugated cardboard were brought into contact with a liquid, such as water, the CeUulosematerial would dissolve for a short time, whereby the corrugated cardboard structure would be destroyed. However, if the surface is sealed, that is, preferably both the upper sides and in particular the inner walls of the corrugated cardboard channels, with a water-impermeable layer, a chamber system is obtained in a simple and inexpensive manner through which a liquid can be passed in a targeted manner. At least it is necessary to provide all those surface areas of the corrugated cardboard structure with a liquid-impermeable layer that come into contact with the liquid, i.e. especially the inside of the channels.

In order to keep the process of sealing or coating the surface of the corrugated cardboard as inexpensive as possible, both the work steps for producing such a seal and the materials to be used for this purpose should be selected as simply and inexpensively as possible. As a particularly suitable Coating material is suitable for epoxy resins that are to be applied to the surface of the corrugated cardboard. A suitable procedure is to simply immerse the cardboard structure in the resin, which is in the liquid phase, so that the cardboard is completely saturated with resin, that is to say in the wall and also on the outside. Depending on the flow behavior of the liquid resin, it is sufficient to let the cardboard soaked in resin with its parallel channel structure drain in a vertical orientation so that the resin that is not directly wetted with the surface of the corrugated cardboard can drip off. The draining process itself can optionally be supported by blowing it out with compressed air or similar gas flows in order to avoid clogging of the individual channels.

In order to accelerate the drying process, the corrugated cardboard wetted with the resin can be exposed to a flow of heat or heat, for example by means of warm air or radiant heaters. Depending on the structure size and the further use of the resin-coated corrugated cardboard, the coating thickness can be optimized by the duration and in particular by the number of coating processes to be carried out in succession.

Since the cost of commercially available corrugated cardboard is negligible compared to the cost of polymer resins, the main cost factor for the heat exchanger according to the invention is determined by the price of the polymer resin and the work. An assessment of the savings potential that is associated with the heat exchanger unit designed according to the invention, compared to the metallic flow-guiding heat exchanger constructions, is approximately one third.

The heat exchanger unit designed according to the invention is completely water-resistant due to the surface sealing by means of epoxy resin, so that a material flow, such as water, can be passed through the large number of channels running parallel on the corrugated cardboard. The possible operational or possible uses should be made with reference to the figure attached to the description.

Brief description of the invention

The invention is described below by way of example without limitation of the general inventive concept using an exemplary embodiment with reference to the drawing. It shows:

Fig. 1 Corrugated cardboard designed according to the invention in one embodiment for use as a solar absorber

WAYS OF CARRYING OUT THE INVENTION, INDUSTRIAL APPLICABILITY

The combination according to the invention of a corrugated cardboard known per se with an epoxy resin layer applied to the surface of the corrugated cardboard leads, as described at the beginning, to a filigree line system through whose individual, in a large number parallel individual channels running parallel to one another, a liquid can be passed without doing so To suffer damage to the structure of the corrugated cardboard. Of course, other material flows can also be routed through the individual chambers of the corrugated cardboard accordingly.

FIG. 1 shows a solar absorber which is constructed on the basis of the heat exchanger unit described above. The corrugated cardboard 1 has two surfaces 2, 3, each of which includes an inner support structure or duct system 4. For the sake of a clearer visual representation, the solidified resin layer, which seals the corrugated cardboard covering the entire surface, has been omitted. The surface 2 has been coated with a layer 5 which absorbs the solar radiation flux and which, for example in the simplest embodiment, can consist of a soot layer. Of course, it is also possible to deposit selectively absorbing or emitting layers on the surface of the corrugated cardboard structure. Chromoxynitride (CrON) or titanium oxynitride (TiON) layers are particularly suitable for this, which can be deposited on the surface as part of sputtering or steaming processes. At least one side edge of the corrugated cardboard structure has an inlet or outlet 6 for the water to be heated by the solar heat, which is fed into the system via the opposite edge.

The simply designed form of a solar absorber shown in FIG. 1 is simple and inexpensive to manufacture and can be widely used in many locations, preferably in third world countries.

In addition to the use of the heat exchanger unit designed according to the invention as a solar absorber, the corrugated cardboard coated with a water-resistant or liquid-resistant protective layer is also suitable as wall or floor heating elements which can be incorporated into wall or floor surfaces and passed through the appropriate heating means, preferably hot water. The wall or floor surfaces can be heated effectively and inexpensively via the large areas of the heat exchanger unit.

Due to the high resistance of epoxy or polymer resin layers, which can be applied to the corrugated cardboard construction in the manner described above, the use of aggressive media which are passed through the channel system of the corrugated cardboard construction is also conceivable. The use of heat exchanger elements in this regard as absorber elements in seawater desalination or solar air conditioning with liquid adsorbents, for example calcium chloride and water, is quite conceivable.

It is also possible with the polymer resins currently available, which have a high temperature resistance of up to 250 ° C., to vapor-coat corrugated cardboard constructions of this type with any metal layers in order to enlarge their range of use. The invention is not limited solely to the coating of corrugated cardboard with epoxy or polymer resins, but basically includes all conceivable support structures which, in connection with a surface, include chamber systems and are of any geometrical configuration and at least partially have CeUulosematerial.

LIST OF REFERENCE NUMBERS

corrugated cardboard

surface

Support structure, channel system

absorber layer

Infeed or discharge

Claims

claims

1. Heat exchanger unit with at least one heat energy absorbing or emitting surface (5) and a thermally coupled to the surface chamber system (4) through which a heat energy absorbing or emitting fluid can flow, characterized in that the surface (5) and Chamber system (4) are formed from a carrier structure which has CeUulosematerial and whose carrier structure surface is covered with a fluid-impermeable layer at least on the carrier structure surface wettable with the heat energy absorbing or emitting fluid.

2. Heat exchanger unit according to claim 1, characterized in that the carrier structure consists entirely of CeUulosematerial.

3. Heat exchanger unit according to claim 1 or 2, characterized in that the carrier structure is corrugated cardboard or is formed in the manner of a corrugated cardboard, has two surfaces (2, 3) which are spaced apart from an inner structure (4) which also represents the chamber system ,

4. Heat exchanger unit according to one of claims 1 to 3, characterized in that the liquid-impermeable layer is a polymer layer and preferably consists of epoxy or polyester resin.

5. Heat exchanger unit according to claim 4, characterized in that the polymer has a temperature stability of up to 250 ° C.

6. Heat exchanger unit according to one of claims 1 to 5, characterized in that the fluid is gaseous or liquid.

7. Heat exchanger unit according to one of claims 1 to 6, characterized in that the, solar radiation absorbing surface with a, the solar radiation absorbing and emitting layer (5) is coated, which is applied to the water-impermeable layer.

8. Heat exchanger unit according to claim 7, characterized in that the selectively absorbing and emitting layer (5) has CrON or TiON, which can be applied to the water-impermeable layer by means of sputtering or vapor deposition processes.

9. The method according to any one of claims 1 to 8, characterized in that the entire surface of the support structure is covered with the fluid-impermeable layer.

10. A method for producing a heat exchanger unit according to one of claims 1 to 9, characterized in that a, at least one surface (5) and a chamber system (4) having, consisting essentially of CeUulosematerial support structure covering the entire surface of its support structure with a flowable polymer solution in Contact is made that the polymer then solidifies to a surface-covering polymer layer, and that the chamber system is flowed through by a fluid that absorbs or releases the thermal energy.

11. The method according to claim 10, characterized in that the carrier structure is immersed in a polymer resin solution, removed therefrom and then positioned so inclined to the horizontal that the pourable polymer resin largely consists of the Chamber system escapes except for a residual portion of polymer resin covering the surface of the support structure and not closing the chambers.

12. The method according to claim 10 or 11, characterized in that the carrier structure covered with the polymer resin is dried by means of heat input, so that the polymer resin solidifies.

13. The method according to any one of claims 10 to 12, characterized in that corrugated cardboard or corrugated material is used as the carrier structure.

14. The method according to any one of claims 10 to 13, characterized in that at least one surface of the support structure is covered with a layer material which absorbs solar radiation.

15. The method according to claim 14, characterized in that CrON or TiON is applied to the surface by means of sputtering or vapor deposition processes.

16. Use of the heat exchanger unit according to claims 1 to 9 with at least one, solar radiation absorbing surface, as a soiar absorber.

17. Use according to claim 16, characterized in that the surface which absorbs the solar radiation is warmed up by the solar radiation, the heat quantity of which is largely completely given off to the fluid flowing through the chamber system.

18. Use according to claim 17, characterized in that the fluid flowing through the chamber system is water, sea water, liquid adsorbents, for example. CaCI + H ₂ 0 or gaseous.

19. Use according to one of claims 16 to 18, characterized in that the heat exchanger unit designed as a solar absorber is suitable for desalination of sea water.

20. Use of the heat exchanger unit according to claims 1 to 9 for wall or floor heating by passing a heating medium, for example hot water, through the chamber system, the heat quantity of which is largely emitted via at least one surface of the support structure.