HEAT EXCHANGER AND TEMPERING CONTAINER COMPRISING A HEAT EXCHANGER
A heat exchanger comprises an evacuated reaction chamber (2, 2′, 23, 33) containing at least one reaction medium and a storage chamber (25, 35) containing an activation medium which reacts with the reaction medium in such a way as to modify the temperature. The reaction chamber and the storage chamber can be brought into a communicating relationship, whereby the reaction medium and the activation medium are contacted with each other and the temperature-modifying reaction is triggered. The reaction chamber (2, 2′, 23, 33) is defined by walls made of a vacuum-tight material (3), which walls are kept at a distance from each other, at least in sections, by supporting bodies (4, 7, 10), with the supporting bodies (4, 7, 9, 10) keeping free transport paths (5, 8) for the reaction medium (11) inside the reaction chamber. The vacuum-tight material (3) forming the walls of the reaction chamber is designed as a flexible film, preferably a composite film.
The invention relates to a heat exchanger comprising an evacuated reaction chamber containing at least one reaction medium and a storage chamber containing an activation medium which reacts with the reaction medium in such a way as to modify the temperature, wherein the reaction chamber and the storage chamber can be brought into a communicating relationship, whereby the reaction medium and the activation medium are contacted with each other and the temperature-modifying reaction is triggered, the reaction chamber being defined by walls made of a vacuum-tight material, which walls are kept at a distance from each other, at least in sections, by supporting bodies, with the supporting bodies keeping free transport paths for the reaction medium inside the reaction chamber.
Furthermore, the invention relates to a tempering container comprising a heat exchanger.
Temperature-regulating packing modules are already known which enable a consumer to bring the packing material to a predefined temperature range at a desired point in time by activating the module, whereby the packing material is either cooled (by evaporation/expansion processes or by an endothermic reaction of reagents) or heated by an exothermic reaction of reagents. An important component of these temperature-regulating packing modules is the heat exchanger which must provide for an optimum temperature transmission of the generated cold/heat to the packing material.
The heat exchanger should exhibit the following properties:
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- a maximum contact area with the packing material so that an extensive heat exchange with the packing material can occur in a short time;
- a minimum volume in order to create a maximum volume for the packing material, i.e., a ratio as large as possible between the heat-exchange surface and the heat-exchange volume;
- good heat conduction to offer as little resistance as possible to the heat exchange;
- dimensional stability so that the enclosed volume will remain constant (important, e.g., for air-evacuated heat exchangers in which an evaporation process as well as a transport of vapour take place);
- imperviousness (minimum permeability, maximum impermeability) in order to prevent a material exchange (gas, vapour, flavouring agents, etc. . . . ) between the heat exchanger and the environment: no leakage of internal material of the heat exchanger into the environment and no infiltration of ambient material into the heat exchanger, and, in case of vacuum systems (e.g., absorption/adsorption cooling processes), no permeation of gas molecules into the heat exchanger;
- an adaptable shape so that the heat exchanger can be adjusted to the thermodynamic conditions and to the packaging.
In addition, temperature-regulating packages/modules are allowed to generate only a minor additional share of the costs of the packaging and, thus, the heat exchanger must be manufacturable in a very cheap and efficient manner.
From WO 2001/010738 A1, a self-cooling beverage can is known in which a cooling process is implemented based on an adsorption refrigerating machine. The self-contained system comprises two evacuated vacuum chambers. The chamber 1 consists of a complex thin-walled deep-drawn aluminium part (deep drawn twice) coated with water gel. Said chamber 1 constitutes the evaporator and the heat exchanger. The chamber 2 is filled with an absorbing/adsorbing material for water vapour. Furthermore, the chamber 2 is surrounded by a phase-changing material (Phase Change Material—PCM) as a heat sink, which, upon exposure to heat, changes from the solid into the liquid state and thereby absorbs heat without increasing its own temperature. The cooling process is activated by joining the two chambers. In doing so, the water gel evaporates from chamber 1 through the vacuum already at temperatures below 100° C. (an evaporation temperature according to the vapour-pressure curve so that evaporation is possible in a range as low as that of subfreezing ° C. temperatures) and extracts heat from the beverage surrounding the chamber 1 as a result of the evaporation process. The generated water vapour is thereby bound by the absorber/adsorber in chamber 2 and, thus, the vacuum is maintained and the evaporation and cooling process continues. At the same time, the surrounding phase change material limits the temperature of the absorber/adsorber since the latter heats up during adsorption. What is disadvantageous about this known self-cooling beverage can is the fact that the production of the aluminium cooling element deep drawn twice is time-consuming and the element is thus expensive. Since said element is located in the beverage can, it must additionally be sealed against the beverage. Furthermore, the absorber/adsorber chamber is arranged outside the can, and a vacuum-tight connection between the adsorber and the cooling element as well as a gas-tight boundary toward the environment must be produced. A similar self-cooling beverage can is also known from WO 2003/073019 A1.
From WO 1992/002770 A1, a vacuum-insulated, adsorbent-operated cooling device is known the cooling principle of which corresponds to that of the self-cooling beverage cans disclosed in the above-indicated documents. What is different is that, according to the disclosure of WO 1992/002770 A1, the absorbing/adsorbing body (chamber 2) is directly surrounded by the cooling element (chamber 1) and the entire module, i.e., also the absorbing/adsorbing body, floats in the packing material. This construction has the disadvantage that the geometrical design (adsorber surrounded by the cooling element) involves a lower efficiency and thus an enlargement of the module. As a result, there is less space for the packing material, which renders said cooling device relatively expensive. Furthermore, thermal cannibalizing effects reducing the cooling capacity occur, since waste heat of condensation is generated in the adsorber chamber surrounded by the evaporation chamber, which waste heat in turn causes additional evaporation in the evaporation chamber, which basically should occur exclusively due to the extraction of heat from the packing material.
From U.S. Pat. No. 4,736,599, a heat exchanger composed of at least two communicating chambers is known. One chamber contains a vacuum which reduces the boiling point of water also located in the chamber. A second chamber contains an adsorbent adsorbing/absorbing the vapour generated by the boiling water in the first chamber. Internal supporting bodies between the walls of the chambers prevent the walls of the chambers from collapsing while the vacuum exists in the chambers. The supporting bodies have pores and channels so that the water vapour can move between the chambers. The walls of the chambers are made of the same material as the cans in which they are housed, that is, from aluminium sheet. Because of this choice of material, only a restricted variety can be achieved with justifiable effort with regard to the shaping of the chambers. Significantly, the chambers illustrated in the exemplary embodiments are only cuboid-shaped. It is particularly difficult to manufacture chambers with large surfaces, as demonstrated by the exemplary embodiment of the cuboid. Therefore, the cooling effect is not optimal. Furthermore, the permeability is also unsatisfactory.
Therefore, the problem still exists of how to produce a heat exchanger which meets the initially indicated requirements and moreover is manufacturable in a cheap and efficient manner.
The present invention solves this problem by upgrading a generic heat exchanger by using a flexible film, preferably a composite film, as the vacuum-tight material forming the walls of the reaction chamber and by providing a tempering container comprising a heat exchanger according to the invention. Advantageous embodiments of the invention are set forth in the dependent claims. Due to this design, a freely shapeable heat exchanger is manufacturable which can be produced in a highly efficient manner in industrial manufacturing processes and thus is extremely low-priced, the production being adaptable to a large number of different shaping guidelines due to the use of the film. The film is preferably designed as a plastic film or a metal film, composite films are designed as plastic-metal film composites. A three-layered film having an outer layer of polyester, an intermediate layer of aluminium and an inner layer of polyethylene may be mentioned as an example of a composite film. Adjacent layers are in each case stuck together with a polyurethane 2-component adhesive.
Heat exchangers with high reliability, which can be produced in an efficient manner, are obtained if the film is sealable and/or gluable.
Furthermore, the heat exchanger according to the invention offers the following advantages:
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- a very large contact area with the packing material to be tempered so that an extensive heat exchange with the packing material can occur in a short time;
- a minimum inherent volume with a low dead weight so that the result is a very large ratio between the heat-exchange surface and the heat-exchange volume;
- good heat conduction through the thin-layered walls made of a flexible vacuum-tight material;
- high dimensional stability so that the enclosed volume will remain constant also during the progress of the tempering processes (in particular, the heat exchanger cannot collapse on itself);
- minimum permeability and maximum impermeability so that a material exchange (gas, vapour, flavouring agents, etc. . . . ) between the heat exchanger and its environment is prevented. It should be mentioned that gas diffusion processes taking place over extended periods of time are a characteristic of each known material and are acceptable for the present invention. However, leakage of reaction material from the interior of the heat exchanger into the environment is prevented just like an infiltration of ambient material (packing material) into the heat exchanger;
- an adaptable shape so that the heat exchanger can be adjusted to the thermodynamic conditions and to the tempering container in which it is to be used.
Furthermore, it should be mentioned that the heat exchanger according to the invention can comprise one or several supporting bodies.
According to the invention, the supporting bodies can be implemented in several ways. In a first variant, the supporting bodies are formed from a granular material, the granular material preferably being porous. In a particularly preferred embodiment, the granules are spherical. The granules define transport paths for the reaction media between each other. In a second variant, the supporting bodies are formed from moulded articles. The transport paths are defined between and on the moulded articles, respectively, wherein, in a preferred embodiment, the moulded articles are open-pored and the pores also form transport paths for reaction media. In a third variant, the supporting bodies comprise a framework. The framework can have different straight, curved, angular, corrugated beams, distance pieces etc. It can be designed as a latticework. For an optimum temperature transmission it is furthermore suitable that some or all supporting bodies are formed from a material with good heat conduction.
In an advanced embodiment of the invention, the supporting bodies are constructed as storage elements for the reaction medium (e.g. in pores of the supporting elements) or are completely or partially composed of the reaction medium. There are numerous reaction media which remain dimensionally stable during their endothermic or exothermic reaction. Silica gels can be mentioned as examples.
If the heat exchanger according to the invention is to be used for cooling applications, it is provided that the reaction media stored in the reaction chamber of the heat exchanger comprise evaporation media and/or endothermic reactants. For heating applications, it is provided that the reaction media stored in the reaction chamber of the heat exchanger comprise exothermic reactants.
The reaction chamber of the heat exchanger according to the invention is connected or connectable to a storage chamber which, optionally, has been evacuated. On the one hand, the storage chamber can be directly integrated in the heat exchanger, wherein it is connected to the flexible vacuum-tight material of the heat exchanger preferably by gluing, sealing or other fastening techniques. Alternatively, the storage chamber can be designed as a separate replaceable unit which, for activating the heat exchanger, is brought into a communicating relationship with the reaction chamber thereof. For using the heat exchanger according to the invention for cooling purposes, it is provided that an adsorbing medium and optionally a heat sink such as, e.g., a phase-changing agent (PCM) are placed in the storage chamber. For using the heat exchanger according to the invention for heating purposes, the storage chamber is provided with an activation agent which, upon contact with the reactant contained in the reaction chamber, triggers an exothermic reaction, optionally with a PCM device such as, e.g., a phase-changing agent (PCM) being arranged in the reaction chamber in order to keep the temperature in the reaction chamber within a predetermined temperature range.
Prior to the activation of the heat exchanger, the reaction chamber is suitably separated from the storage chamber by a membrane or a valve, wherein the valve may comprise, for example, a valve sheet. For activating the heat exchanger, the membrane is cut in two by an actuator or, respectively, an actuator is used for opening the valve.
The heat exchanger according to the invention can easily be integrated in containers such as a beverage can, a PET plastic bottle, a cardboard composite packing or a party barrel and enables excellent tempering of the liquids stored in said containers.
The invention is now illustrated in further detail based on non-limiting exemplary embodiments with reference to the drawings.
In the drawings,
The basic structure of a heat exchanger 1 according to the invention is now explained on the basis of
The heat exchanger 1 according to the invention is manufactured by drawing the flexible vacuum-tight material 3 beyond the supporting bodies 4 (or by inserting the supporting bodies 4 into a configuration of the flexible vacuum-tight material 3). Subsequently, the reaction chamber 2 thus defined is evacuated and the heat exchanger 1 is sealed. The negative pressure (vacuum) in the reaction chamber 2 of the heat exchanger 1 results in external compressive forces acting upon the outer surfaces of the flexible vacuum-tight material 3 and pressing the flexible vacuum-tight material 3 firmly against the supporting bodies 4, whereby the flexible vacuum-tight material 3, in combination with the supporting bodies 4, is bound to form a rigid heat-exchanger geometry. If the heat exchanger 1 is used as a cooling module, the vacuum in the reaction chamber 2 simultaneously enables the evaporation of cooling liquid as a reactant at low temperatures.
A thin multilayer film (10 μm to 300 μm), which is gluable and/or sealable, respectively, is preferably selected as the flexible vacuum-tight material 3. The small wall thickness of the film ensures good heat conduction and, due to its gluability and/or sealability, respectively, high impermeability against the environment. This is important for air-evacuated heat exchangers (just as in exothermic processes within the heat exchanger during which the reactants must not get into contact with the environment and must exhibit good barrier properties). Due to the highly flexible geometrical design, the heat-exchange surfaces can be arranged in very close proximity to each other, the ratio between the surface and the volume is thus maximized. Furthermore, the distance structure according to the invention guarantees a consistently small distance between the heat-exchange surfaces.
Apart from the construction of the supporting bodies 4 as a framework, the invention also provides the following variants for designing a distance structure:
As a result of the evacuation of the reaction chamber 2′, the granules 7, 9 are firmly pressed against each other by external compressive forces, whereby, if the flexible vacuum-tight material is configured accordingly, high degrees of freedom are possible with regard to the design of the shape of the heat exchanger. In
In the following, two examples of using heat exchangers according to the invention in tempering containers are illustrated.
The first example of use shows the application of a heat exchanger 22 in a tempering container 20 designed as a can be to cooled, which tempering container is shown in longitudinal section in
During production, the two chambers 23, 25 are evacuated and subsequently separated from each other by the membrane 24. As long as the membrane 24 is intact, a continuous reaction is unable to proceed in the reaction chamber 23, since the vapour pressure generated suddenly in the reaction chamber adjusts itself according to the temperature of the packing material 21 and thus an evaporation process in the reaction chamber 23 stops by itself. Hence, there will be no further evaporation as long as the vapour sink (storage chamber 25) is not connected to the reaction chamber 23. As a result, the tempering container 20 can be stored inactively over an extended period of time and can be activated only when required.
The activation of the cooling process is effected, as illustrated in
It should be mentioned that, in this exemplary embodiment, the storage chamber 25 is integrated in the heat exchanger 22.
Based on
The activation of the heating process is effected, as shown in
The heating process comes to a standstill when the liquid 37 has dissolved completely in the reactant and the quantity of heat stored in the PCM device has been delivered entirely to the packing material. According to the melting temperature of the PCM device it is ensured that the desired packing material temperature is not exceeded.
In
Claims
1. A heat exchanger, comprising
- an evacuated reaction chamber containing at least one reaction medium and a storage chamber containing an activation medium which reacts with the reaction medium in such a way as to modify the temperature, wherein the reaction chamber and the storage chamber can be brought into a communicating relationship, whereby the reaction medium and the activation medium are contacted with each other and the temperature-modifying reaction is triggered, the reaction chamber being defined by walls made of a vacuum-tight material, which walls are kept at a distance from each other, at least in sections, by supporting bodies, with the supporting bodies keeping free transport paths for the reaction medium inside the reaction chamber, wherein the vacuum-tight material forming the walls of the reaction chamber is a flexible film, preferably a composite film.
2. The heat exchanger according to claim 1, wherein the film is sealable and/or gluable.
3. The heat exchanger according to claim 1, wherein the reaction medium comprises evaporation media, endothermic reactants or exothermic reactants.
4. The heat exchanger according to claim 1, wherein the storage chamber contains an adsorbing medium as the activation medium and optionally a heat sink.
5. The heat exchanger according to claim 1, wherein the storage chamber contains an activation agent as the activation medium, which, upon contact with the reactant, triggers an exothermic reaction, optionally with a PCM device.
6. The heat exchanger according to claim 1, wherein supporting bodies are formed from granules which are pressed against each other due to the vacuum in the reaction chamber, the granules preferably being porous.
7. The heat exchanger according to claim 1, wherein supporting bodies are formed from moulded articles, which preferably are open-pored.
8. The heat exchanger according to claim 1, wherein supporting bodies are constructed as a framework against which the film is pressed due to the vacuum in the reaction chamber.
9. The heat exchanger according to claim 1, wherein supporting bodies are formed from a material with good heat conduction.
10. The heat exchanger according to claim 1, wherein supporting bodies are constructed as storage elements for the reaction medium or that supporting bodies are composed of the reaction medium provided as a solid body.
11. The heat exchanger according to claim 1, wherein the storage chamber is integrated in the heat exchanger, the storage chamber being kept on the heat exchanger preferably via a connection with the flexible vacuum-tight material.
12. The heat exchanger according to claim 1, wherein the storage chamber is constructed in a separate unit.
13. The heat exchanger according to claim 1, wherein the reaction chamber is separated from the storage chamber by a membrane and an optional partition wall or a valve.
14. The heat exchanger according to claim 13, further comprising at least one actuator for cutting through the membrane and the optional partition wall or for opening the valve.
15. The heat exchanger according to claim 1, wherein the storage chamber is evacuated.
16. A tempering container comprising an intake space for receiving a product to be tempered, wherein a heat exchanger according to claim 1 is connected to the intake space in a heat conducting manner.
17. The tempering container according to claim 16, wherein it is designed as a beverage can or a PET plastic bottle or a cardboard composite packing or a party barrel.
18. The heat exchanger according to claim 4, wherein the heat sink is a phase-changing agent.
19. The heat exchanger according to claim 5, wherein the PCM device is a phase-changing agent being arranged in the reaction chamber.
Type: Application
Filed: Jul 5, 2006
Publication Date: May 7, 2009
Inventors: Peter Lang (St. Magdalen), Gerd Sumah (Graz)
Application Number: 11/994,994
International Classification: F28D 1/06 (20060101); F28D 21/00 (20060101);