US20170131001A1

US20170131001A1 - Thermoelectrically cooled or heated container

Info

Publication number: US20170131001A1
Application number: US15/319,533
Authority: US
Inventors: Jochen Hiemeyer; Martin Kerstner; Michael Freitag
Original assignee: Liebherr Hausgeraete Lienz GmbH; Liebherr Hausgeraete Ochsenhausen GmbH
Current assignee: Liebherr Hausgeraete Lienz GmbH; Liebherr Hausgeraete Ochsenhausen GmbH
Priority date: 2014-06-16
Filing date: 2015-06-12
Publication date: 2017-05-11
Also published as: CN106662377A; EP3155330A1; ES2905146T3; CN106662377B; RU2017100886A; WO2015192953A1; EP3155330B1; RU2691880C2; RU2017100886A3; DE102015006557A1

Abstract

The present invention relates to a thermoelectrically cooled or heated container, in particular a refrigerator unit and/or a freezer unit, having at least one cooled or heated inner space and having at least one thermoelectric element, in particular having at least one Peltier element, for generating cold or heat in the inner space, wherein the thermoelectric element is arranged between two thermoconductive solid bodies of which one or both have an increasing cross-sectional area as the spacing from the thermoelectric element increases.

Description

The present invention relates to a thermoelectrically cooled or heated container, in particular to a refrigerator unit and/or a freezer unit, having at least one cooled or heated inner space and having at least one thermoelectric element, in particular having at least one Peltier element that is arranged such that is generates cold or heat in the inner space.
In a thermoelectric refrigerator unit or freezer unit, the heat transfer from the refrigerated inner side to the thermoelectric element and from the thermoelectric element to the outside of the unit can be based solely on solid body thermal conduction. Solid bodies are used for this purpose that are in thermoconductive connection with the thermoelectric element. With such a unit, the heat transfer from the solid bodies to the thermoelectric element is of great importance. If a defect in the contact occurs, it may result in a temperature drop at the border surface and thus in an inefficient generation of cold or heat. A fixed interconnection between the thermoelectric element and the solid body, e.g. via a thermoconductive adhesive, is advantageous.
Provision is furthermore made in a preferred embodiment that a thin graphite film is arranged at one side as a coupling element for the mechanical relief of the thermoelectric element in the production process, with the thermoelectric element being fixed by clamping between the two solid bodies via connection elements described in more detail in the following. At the other side, the thermoconductive adhesive is also used to compensate production tolerances in the thicknesses of the thermoelectric element, the solid bodies and the connection elements. The graphite film is preferably used at the hot side since the higher heat flows flow here and the heat transfer resistance through the thin graphite film is typically smaller than that through the thermoconductive adhesive layer somewhat thicker due to tolerance compensation.
A further special feature is that material transitions in the heat exchanger, i.e. in the solid body, are avoided as much as possible since they result in additional heat transfer resistances. In the ideal case, the heat exchanger, i.e. one of the solid bodies that can comprise aluminum, for example, and that is connected to the thermoelectric element represents the outer skin of the unit. This produces a technical production challenge in the contacting of the thermoelectric element.
In addition, there is a rigid connection between the inner container and the outer skin via the thermoelectric element.
If thermal strains occur in operation or also in the manufacture of the container, this can produce a mechanical strain and possibly a breakage of the thermoelectric element.
These considerations are by no means restricted to refrigerator units and/or freezer units, but also apply to thermally insulated containers in general.
The thermally insulated container has at least one temperature-controlled inner space, with this being able to be cooled or heated so that a temperature results in the inner space below or above the ambient temperature of e.g. 21° C.
It is the underlying object of the present invention to further develop a container of the initially named type such that the mechanical strain of the thermoelectric element is kept as small as possible and simultaneously a good thermal transport is ensured.
This object is achieved by a container having the features of claim 1. Provision is accordingly made that the thermoelectric element is arranged or received between at least two thermoconductive solid bodies of which one or both has/have an increasing cross-sectional area as the distance from the thermoelectric element increases.
The at least two solid bodies with good thermal conductivity are in thermoconductive contact with the thermoelectric element such that, in operation of the thermoelectric element, one of the solid bodies represents the cold side and the other solid body represents the hot side in operation of the thermoelectric element.
The at least two thermoconductive solid bodies form a primary heat exchanger which is connected to the thermoelectric element such that one of the solid bodies forms the cold side and one of the solid bodies forms the hot side in operation of the thermoelectric element.
This primary heat exchanger is preferably thermoconductively connected to at least one secondary heat exchanger. The secondary heat exchanger comprises at least one solid body and preferably two solid bodies. These solid bodies of the secondary heat exchanger can e.g. form the inner container, i.e. the wall, of the cooled or heated inner space and/or the outer skin of the container.
The solid bodies of the primary solid body and/or of the secondary solid body preferably consist of metal or comprise metal. Aluminum can be considered, for example.
The reception of the thermoelectric element in the primary heat exchanger that is formed by the at least two solid bodies protects it from excessive mechanical strains.
The primary heat exchanger that comprises the solid bodies between which the thermoelectric element is arranged has a very good thermal coupling of the generated cold and of the waste heat and brings the heat flow to a comparatively large surface due to its increasing cross-sectional area, which brings along the advantage that on a further coupling to further solid bodies such as to the above-named secondary heat exchanger a heat loss occurs which is as small as possible.
Provision is preferably made that the thermoelectric element is received between the two thermoconductive solid bodies such that forces acting on the solid body or bodies are not transferred or are only transferred to a reduced degree onto the thermoelectric element.
Provision is made in accordance with a preferred embodiment that the thermoelectric element is clamped between the solid bodies which form the primary heat exchanger. Provision is preferably made in this respect that the connection element or elements which connects/connect the solid bodies has/have a small thermal conductivity so that no significant heat bridge is produced.
In this respect, the clamping or the connection between the solid bodies is thus preferably made in that the heat bridge is as low as possible due to the connection means which connect the solid bodies.
It can generally be a single connection means or also two or more connection means.
It is conceivable to clamp the two solid bodies to one another, i.e. to pull the solid bodies together such that the connection means are tensioned.
In an embodiment, the connection means is a spacer. It is conceivable that the connection means is designed such that it is subjected to one or more of tension, compression, torsion and shear.
Provision is made in a further embodiment of the invention that one of the solid bodies is thermoconductively connected to the outer skin of the unit and one of the solid bodies is thermoconductively connected to the inner wall of the unit. This connection can be direct or indirect, with a direct connection being preferred.
Provision is made in a further embodiment of the invention that the container has a vacuum insulation as the thermal insulation of the inner space that surrounds the cooled inner space completely or partly. Another insulation such as a foaming is also conceivable.
The primary heat exchanger and/or the thermoelectric element is/are preferably located in the insulation layer which is located between the inner wall and the outer wall of the container.
The thermal insulation is located between the outer skin and the inner container of the unit and/or between the inner wall and the outer wall of a closing element such as a door, a lid or a flap, drawer, etc. The thermal insulation can e.g. have one or more vacuum insulation panels. It is also conceivable to use one or more enveloping bodies composed of a vacuum-tight envelope and in particular of a high barrier film which are filled with a support material such as Pearlite for thermal insulation. The enveloping bodies are closed structures in which there is a vacuum.
An embodiment is particularly preferred in which a thermal insulation is arranged between the inner wall bounding the inner space and the outer skin and comprises a full vacuum system. A thermal insulation is to be understood by this which comprises only or primarily an evacuated region which is filled with a support material. The bounding of this region can be formed, for example, by a vacuum-tight film and preferably by a high barrier film. Only such a film body can thus be present between the inner wall of the container, preferably of the unit, and the outer skin of the container, preferably of the unit, as the thermal insulation which has a region which is surrounded by a vacuum-tight film, in which there is a vacuum and in which a support material is arranged. A foaming and/or vacuum insulation panels is/are preferably not provided as thermal insulation or another thermal insulation is not provided, except for the full vacuum system between the inner side and the outer side of the container or unit.
This preferred form of thermal insulation in the form of a full vacuum system can extend between the wall bounding the inner space and the outer skin of the carcass and/or between the inner side and the outer side of the closing element such as a door, flap, lid, or the like.
The full vacuum system can be obtained such that an envelope of a gas-tight film is filled with a support material and is subsequently sealed in a vacuum-tight manner. In an embodiment, both the filling and the vacuum-tight sealing of the envelope take place at normal or ambient pressure. The evacuation then takes place by the connection to a vacuum pump of a suitable interface worked into the envelope, for example an evacuation stub which can have a valve. Normal or ambient pressure is preferably present outside the envelope during the evacuation. In this embodiment, it is preferably not necessary at any time of the manufacture to introduce the envelope into a vacuum chamber. A vacuum chamber can be dispensed with in an embodiment to this extent during the manufacture of the vacuum insulation.
A vacuum-tight or diffusion-tight envelope or a vacuum-tight or diffusion-tight connection or the term high barrier film is preferably understood as an envelope or as a connection or as a film by means of which the gas input into the vacuum insulation body is reduced so much that the increase in the thermal conductivity of the vacuum insulation body caused by gas input is sufficiently low over its service life. A time period of 15 years, preferably of 20 years, and particularly preferably of 30 years, is to be considered as the service life, for example. The increase in the thermal conductivity of the vacuum insulation body caused by gas input is preferably <100%, and particularly preferably <50%, over its service life.
The surface-specific gas permeation rate of the envelope or of the connection or of the high barrier film is preferably <10-5 mbar*I/s*m²and particularly preferably <10-6 mbar*I/s*m²(measured according to ASTM D-3985). This gas permeation rate applies to nitrogen and to oxygen. There are likewise low gas permeation rates for other types of gas (in particular steam), preferably in the range from <10-2 mbar*I/s*m²and particularly preferably in the range from <10-3 mbar*I/s*m²(measured according to ASTM F-1249-90). The aforesaid small increases in the thermal conductivity are preferably achieved by these small gas permeation rates.
An enveloping system known from the sector of vacuum panels are so-called high barrier films. Single-layer or multilayer films (which are preferably able to be sealed) having one or more barrier layers (typically metal layers or oxide layers, with aluminum and an aluminum oxide preferably being used as the metal or oxide respectively) are preferably understood by this within the framework of the present invention which satisfy the above-named demands (increase in thermal conductivity and/or surface-specific gas permeation rate) as a barrier to the gas input.
The above-named values or the make-up of the high barrier film are exemplary, preferred values which do not restrict the invention.
Provision is preferably made that the thermoelectric element is mechanically fixedly clamped to the solid bodies.
Provision is preferably made that the one connection means or the plurality of connection means clamps/clamp the at least two thermoconductive solid bodies via a clamping connection.
To keep the thermal conduction through the connection means of the solid bodies as small as possible, provision can be made that the two solid bodies are connected, and preferably clamped, to one another by connection means, with the connection means having a smaller thermal conductivity than the solid bodies.
The connection means preferably comprise a different material than the solid bodies which form the primary heat exchanger and/or the secondary heat exchanger.
It is conceivable that the connection means consist of plastic or comprise plastic. Polyamide or also another plastic can be considered, for example.
Provision is made in a further preferred embodiment of the invention that the connection means fix the spacing of the thermoconductive solid bodies from one another.
As stated above, a preferred embodiment of the invention comprises the solid bodies consisting of metal, and preferably of aluminum, or comprising it.
The single connection means or the plurality of connection means can be arranged at a spacing from the thermoelectric element which is as large as possible. Since the most critical strains are deformations at the total unit or container that are led off onto the thermoelectric element via the rigid primary heat exchanger as a lever, a stabilization at all sides as far as possible outside the thermoelectric element is of advantage.
The spacing of the connection means from the thermoelectric element is preferably larger than the edge length of the thermoelectric element.

Further details and advantages of the invention will be explained in more detail with reference to an embodiment shown in the drawing.

The only FIGURE shows a perspective view of a primary heat exchanger having a thermoelectric element arranged therein. It can be configured as a Peltier element.

The thermoelectric element is clamped between two solid bodies 10, 12 of good thermoconduction, with the solid body 10 reducing in cross-section when passing across the insulation plane from left to right in accordance with the FIGURE and with the solid body 12 increasing in cross-section when passing across the insulation plane from left to right in accordance with the FIGURE.
The thermoelectric element is located between the two solid bodies. The solid bodies can be arranged with specular symmetry relative to an axis extending through the thermoelectric element.
The two solid bodies form a primary heat exchanger. It is preferably thermoconductively connected to at least one secondary solid body or heat exchanger via the outwardly disposed surfaces 10′ and 12′ of the solid bodies 10, 12 that are preferably planar. The secondary heat exchanger is preferably arranged directly at the surfaces 10′ and 12′.
The secondary heat exchanger can have two or more solid bodies that form the outer skin of the container, on the one hand, and the inner wall of the container, on the other hand, or can be connected thereto, for example. The inner wall bounds the heated or cooled inner space of the container in accordance with the invention.
The term “container” is to be understood generally and comprises every arrangement that has at least one inner space that is heated or cooled. In a preferred embodiment of the invention, a “container” is understood as a refrigerator unit and/or a freezer unit. This unit preferably does not have any conventional refrigerant circuit, but rather only has the Peltier element or another thermoelectric element as the heat source or for cold generation.
The temperature-controlled inner space is either cooled or heated depending on the type of the unit (cooling appliance, heating cabinet, etc.)
Provision is made in an embodiment that the container in accordance with the invention is a refrigerator unit and/or a freezer unit, in particular a domestic appliance or a commercial refrigerator. Such units are, for example, covered which are designed for a stationary arrangement at a home, in a hotel room, in a commercial kitchen or in a bar. It can, for example, be a wine cooler. Chest refrigerators and/or freezers are furthermore also covered by the invention. The units in accordance with the invention can have an interface for connection to a power supply, in particular to a domestic mains supply (e.g. a plug) and/or can have a standing aid or installation aid such as adjustment feet or an interface for fixing within a furniture niche. The unit can, for example, be a built-in unit or also a stand-alone unit.
In an embodiment, the container or the unit is configured such that it can be operated at an AC voltage such as a domestic mains voltage of e.g. 120 V and 60 Hz or of 230 V and 50 Hz. In an alternative embodiment, the container or the unit is configured such that it can be operated with DC current of a voltage of, for example, 5 V, 12 V or 24 V. Provision can be made in this embodiment that a plug-in power supply is provided inside or outside the unit via which the unit is operated. An advantage of the use of thermoelectric heat pumps in this embodiment is that the whole EMC problem only occurs at the power pack.
Provision can in particular be made that the refrigerator unit and/or freezer unit has a cabinet-type design and has a useful space which is accessible to a user at its front side (at the upper side in the case of a chest). The useful space can be divided into a plurality of compartments which are all operated at the same temperature or at different temperatures. Alternatively, only one compartment can be provided. Storage aids such as trays, drawers or bottle-holders (also dividers in the case of a chest) can also be provided within the useful space or within a compartment to ensure an ideal storage of refrigerated goods or frozen goods and an ideal use of the space.
The useful space can be closed by at least one door pivotable about a vertical axis. In the case of a chest, a lid pivotable about a horizontal axis or a sliding cover is conceivable as the closing element. The door or another closing element can be connected in a substantially airtight manner to the carcass by a peripheral magnetic seal in the closed state. The door or another closing element is preferably also thermally insulated, with the thermal insulation being able to be achieved by a foaming and optionally by vacuum insulation panels or also preferably by a vacuum system and particularly preferably by a full vacuum system. Door storage areas can optionally be provided at the inside of the door in order also to be able to store refrigerated goods there.
It can be a small appliance in an embodiment. In such units, the useful space defined by the inner wall of the container has, for example, a volume of less than 0.5 m³, less than 0.4 m³or less than 0.3 m³.
The outer dimensions of the container or unit are preferably in the range up to 1 m with respect to the height, width and depth.
The invention is, however, not restricted to refrigerator units and/or freezer units, but rather generally applies to units having a temperature-controlled inner space, for example also to heat cabinets or heat chests.
In the case of a container or unit having a heated inner space, a thermal conduction takes place from the environment or from the outer skin of the container by means of the solid body to the thermoelectric element and from it by means of a solid body through heat conduction to the inner space or to the inner wall of the container bounding the inner space.
The solid bodies 10, 12 preferably comprise aluminum.
Connection elements are marked by reference numeral 20 that fixedly mechanically clamp the at least one thermoelectric element to the thermoconductive solid bodies 10, 12.
The clamping preferably takes place by a clamp connection. The element with little thermal conductivity or the connection element or elements 20 clamps/clamp the two solid bodies 10, 12 via a clamp connection.
The connection elements 2 form a non-thermoconductive fastening or a fastening with little thermal conductivity of the two solid bodies 10, 12 to one another. The connection elements 20 fix the spacing of the solid bodies 10, 12 from one another.
The spacing of the connection elements 20 from the thermoelectric element is selected as large as possible. In the embodiment shown here, the spacing of one of the connection elements 20 from the thermoelectric element is larger than its edge length.
Exactly one connection element 20 can generally be provided. The use of more than one connection element 20 is also conceivable and covered by the invention.
In the embodiment, the four connection elements 20 are located in the corner regions of the solid bodies 10, 12. They are all exactly at the same distance from the thermoelectric element.
The primary heat exchanger comprising the molded bodies 10, 12 provides a very good thermal coupling of the generated cold or heat of the thermoelectric element. Due to the cross-sectional area increasing starting from the thermoelectric element, the thermal flow is brought to a larger surface so that heat loss arises which is as small as possible on a coupling to a further element such as to a further thermoconductive element.
The thermoelectric element is preferably clamped between the molded bodies 10, 12 without a significant heat bridge arising due to the connection element or elements.
The molded bodies 10, 12 are aluminum bodies that are seated on the thermoelectric element.
As can be seen from the FIGURE, the molded bodies are clamped via plastic connections having a small or having a smaller thermal conductivity.
It is conceivable to use screws as the connection element or connection elements.
It is also possible to use a part such as an injection molded part as a connection element or as connection elements that is fastened to one of the molded parts 10, 12 and that latches at another molded part on assembly.
Since plastic binders and also other connection elements represent heat bridges, a cross-selection is used for them that is as small as possible, whereby the construction support is reduced, on the other hand. Since the critical loads are deformations at the total unit that are transmitted to the thermoelectric element via the rigid primary heat exchanger, i.e. via the molded parts 10, 12, a stabilization—as can be seen from the FIGURE—is preferred at all sides and as far away as possible from or outside the thermoelectric element.
The described primary heat exchangers can be used sensibly wherever a temperature difference is to be built up via an insulation with the aid of a thermoelectric element.

Claims

1. A thermoelectrically cooled or heated container, in particular a refrigerator unit and/or a freezer unit, having at least one cooled or heated inner space and having at least one thermoelectric element, in particular having at least one Peltier element, for generating cold or heat in the inner space, characterized in that the thermoelectric element is arranged between two thermoconductive solid bodies of which one or both have an increasing cross-sectional area as the spacing from the thermoelectric element increases.

2. A container in accordance with claim 1, characterized in that the thermoelectric element is received between the two thermoconductive solid bodies such that forces acting on the solid body or bodies are not transferred or are only transferred to a reduced degree onto the thermoelectric element.

3. A container in accordance with claim 1, characterized in that the thermoelectric element is clamped between the solid bodies; and/or in that the thermoelectric element is mechanically fixedly clamped to the solid bodies.

4. A container in accordance with claim 1, characterized in that one of the solid bodies is thermoconductively connected to the outer skin of the unit and one of the solid bodies is thermoconductively connected to the inner wall of the unit.

5. A container in accordance with claim 1, characterized in that the container has a vacuum insulation or another insulation as the thermal insulation of the inner space that completely or partly surrounds the cooled inner space, with provision preferably being made that the thermoelectric element and/or one or both of the two solid bodies are arranged in the insulation layer.

6. A container in accordance with claim 5, characterized in that a heat insulation which consists in total or regionally of a full vacuum system is arranged between an inner wall bounding the inner space and an outer skin of the container.

7. A container in accordance with claim 1, characterized in that the two solid bodies are connected, and preferably clamped, to one another by one or more connection means, with the connection means preferably having a smaller thermal conductivity than the solid bodies, with provision preferably being made that the connection means consist of plastic or comprise plastic.

8. A container in accordance with claim 7, characterized in that the single connection means or plurality of connection means fixes/fix the spacing of the solid bodies.

9. A container in accordance with claim 7, characterized in that the single connection means or plurality of connection means is/are arranged at a spacing from the thermoelectric element which is as large as possible; and/or in that in the case of a plurality of connection means they have the same spacing from the thermoelectric element.

10. A container in accordance with claim 7, characterized in that the spacing of the single connection means or plurality of connection means from the thermoelectric element is larger than the edge length of the thermoelectric element.

11. A container in accordance with claim 1, characterized in that the solid bodies consist of metal and preferably of aluminum or comprise it.