US20170122650A1

US20170122650A1 - Cooling And/Or Freezing Device

Info

Publication number: US20170122650A1
Application number: US15/318,986
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: 2015-06-16
Publication date: 2017-05-04
Also published as: MY186703A; CN106662376B; EP3155332A1; ES2768756T3; RU2017100887A; DE102015006560A1; RU2690292C2; CN106662376A; EP3155332B1; RU2017100887A3; WO2015192960A1

Abstract

The present invention relates to a cooling and/or a freezing device comprising a cooled inner chamber (100) and a thermoelectric element (20), particularly a Peltier element (20), which is arranged such that the inner chamber (100) is cooled by means of the thermoelectric element (20), means (4, 20, 40) for evaporating the condensed water being provided comprising a heat exchanger (40) located outside of the cooled inner chamber (100).

Description

The present invention relates to a refrigerator unit and/or a freezer unit having at least one refrigerated inner space and having at least one thermoelectric element, in particular having at least one Peltier element that is arranged such that the inner space can be cooled by the thermoelectric element.
Hot air enters into the refrigerated inner space on the opening of refrigerator units and/or freezer units. The saturation vapor pressure drops due to the cooling of the air, which has the result that moisture from the air condenses at the cold surfaces of the refrigerated inner space.
In refrigerator units and/or freezer units known from the prior art, the condensed water is collected due to the configuration of the refrigeration system and is led to the outside by a drainage channel or the like. It is collected in a condensation tray there which can be located above the compressor. The water in the condensation tray evaporates due to the waste heat of the compressor.
For efficiency reasons, it is constructive in a thermoelectric refrigerator unit or freezer unit to keep the temperature difference at the heat pump much smaller than in a compression refrigeration machine. This has the result that no considerably colder surface is present in the refrigerated inner space at which the condensation takes place and that no location having a locally elevated temperature is present at the unit exterior which could be used for evaporating the condensation.
It is the underlying object of the present invention to further develop a refrigerator unit and/or a freezer unit of the initially named kind such that a reliable evaporation of the condensed water led out of the refrigerated inner space takes place.
This object is achieved by a refrigerator unit and/or freezer unit having the features of claim 1. Means are accordingly present for evaporating condensed water that have a heat exchanger located outside the refrigerated inner space. The term “heat exchanger” is to be understood as any element that has a temperature that is sufficient for evaporating condensed water.
Provision is made in an embodiment of the invention that the heat exchanger is formed by the hot side of a thermoelectric element or by an element such as a metal body that is connected in a heat-transferring manner, in particular a thermoconductive manner, to the hot side of a thermoelectric element. This thermoelectric element can simultaneously be arranged such that its cold side refrigerates the inner space of the unit.
Such an arrangement can be operated in a stationary manner by means of a control or regulation unit, i.e. the thermoelectric element is operated at a constant capacity or at a capacity that is required for maintaining the temperature in the refrigerated inner space as constant and at least independently of the condensed water that results.
In a conceivable case, there is an apparatus for this purpose at a surface in the refrigerated inner space of the unit at which the lowest temperature is present due to the positioning of the thermoelectric cooling for the collecting and leading off of the condensed water. The latter is led out of the unit and moves into a collection tray that is arranged, for example, around a region of the outer skin at which an elevated temperature is present.
This procedure can be sufficient for moderate climate conditions.
For conditions or regions having particularly high humidity, the incurred moisture quantity can be so large that, on the one hand, the condensation no longer takes place locally at the coldest point due to the small temperature spread, i.e. the small temperature gradient, in the inner space. It is a further problem that the temperature at the evaporation region is not high enough to evaporate the total condensed water.
To counter this, provision is made in a further embodiment of the invention that a control or regulation unit is present for carrying out one or more condensation cycles. This unit is configured such that it increases the temperature spread for the purpose of condensation and/or evaporation during a condensation cycle.
This means that the capacity, e.g. of a thermoelectric element, is increased during the condensation cycle such that its temperature is lowered in the refrigerated inner space with respect to normal operation in which no condensation cycle is present and/or such that its temperature of the thermoelectric element at the outside of the unit is increased with respect to normal operation in which no condensation cycle is present.
The condensation cycle can be carried out at specific, optionally regular, time intervals or can depend on one or more parameters. Such a parameter is, for example, the humidity and/or the quantity of formed condensed water. These parameters can be supplied to the control or regulation unit that then initiates a condensation cycle in dependence thereon or continues to operate the unit in normal operation.
It is conceivable that means are provided by which it can be determined whether condensed water is present and that the control or regulation unit connected with these means can be configured such that the performance of the means for evaporating condensed water is increased and/or that the temperature is lowered at at least one point in the refrigerated inner space when the presence of condensed water is found.
To concentrate the condensate at one point or at a plurality of points, provision can be made that at least one condensate surface is present in the refrigerated inner scape whose temperature is below that of other surfaces in the refrigerated inner space so that condensate is formed at the condensate surface.
The condensate surface can be formed by at least one thermoelectric element. It can in this respect be a thermoelectric element that is anyway used for refrigerating the refrigerated inner space or also a thermoelectric element especially used for the condensate formation.
The thermoelectric element used especially for the condensate formation can be arranged such that it emits its waste heat to the refrigerated inner space. The element can thus work very efficiently and can be operated at minimal capacity. The cold generation and the condensate formation are effectively decoupled by this additional thermoelectric element so that the framework conditions of cold generation do not have to be considered in the design of the condensation geometry.
It is conceivable that a detection means is present for detecting the opening of the closing element of the unit and that the control or regulation unit is designed for cyclic cooling such that it is operated in dependence on the detected opening. An embodiment of the invention can thus comprise always initiating the condensation cycle after a door opening, i.e. when the door or another closing element is closed again, guiding the hot air newly moved in over the condensation point.
To support the deposition of humidity at the condensation surface, it can be meaningful for a fan to be present that is arranged such that it circulates the air located in the refrigerated inner space.
Alternatively or additionally, at least one fan can be provided in the evaporation region to promote the evaporation rate.
At least one outflow element can be provided by which condensed water is transported to the means for evaporation, with provision preferably being made that the outflow element is dimensioned such that the transport of the condensed water takes place by capillary forces.
In the simplest case, the outflow element is arranged such that the condensed water simply flows out of the refrigerated inner space due to gravity.
If the evaporation is to be aimed for at other points such as at the top of the unit, provision can be made to conduct the condensed water that arises via capillary forces to a specific evaporation point or evaporation region such as the unit top.
With the refrigerator unit and/or freezer unit in accordance with the invention, a full vacuum insulation is preferably located between the outer skin, i.e. the outside of the carcass and the inner wall bounding the refrigerated inner space, and/or between the inside and outside of the door or of another closing element. The vacuum insulation body can be located between the outside of the carcass in the inner container and/or between the outside and the inside of the door or another closing element.
In a preferred embodiment of the refrigerator unit and/or freezer unit in accordance with the invention, it is partly or completely insulated using a full vacuum system. It is in this respect an arrangement whose thermal insulation between the outside and the inner space at the carcass and/or at the closing element only or primarily comprises an evacuated element, in particular in the form of the envelope of vacuum-tight film or high barrier film with a core material. The full vacuum insulation is preferably formed by one or more vacuum insulation bodies that have said film, the region surrounded by the film and the core material located therein. A further thermal insulation by an insulating foam and/or by vacuum insulation panels or by another means for thermal insulation between the inside and the outside of the unit is preferably not provided.
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 core material and is subsequently sealed in a gas-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.
The envelope preferably comprises a high barrier film or is a high barrier film which terminates the vacuum one formed by the envelope in a vacuum-tight manner.
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.
The idea of introducing a thermoelectric element into the refrigerated inner space in order to form a condensate surface in this manner is not restricted to thermoelectric units. The invention thus furthermore relates to any desired refrigerator unit and/or freezer unit having a refrigerated inner space and having a thermoelectric element introduced thereto, wherein a control or regulation unit is provided which controls the thermoelectric element such that it forms a condensate surface. The condensate surface is preferably colder than adjacent surfaces or the coldest surface in the refrigerated inner space.
Provision is made in an embodiment that the refrigerator unit and/or freezer unit in accordance with the invention is a domestic appliance or a commercial refrigeration unit. 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 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.

Further details and advantages of the invention will be described in more detail with reference to the embodiment shown in the Figures and described in the following. There are shown in the Figures:

FIG. 1: a longitudinal sectional view through a refrigerator unit and/or a freezer unit in accordance with the invention; and

FIG. 2: a detailed view of the region of a thermoelectric element whose hot side promotes the evaporation of condensed water.

In FIG. 1, the carcass of a cabinet-like refrigerator unit and/or freezer unit is marked by the reference numeral 10.

The carcass 10 has two side walls 12, a top 14 and a bottom 16. They bound the cooled inner space 100 together with the rear wall and a door.
As can be seen from FIG. 1, a respective thermoelectric element 20, 20′ is provided in the two side walls 1, in the top wall 14, and in the bottom 16.
Exactly one such thermoelectric element can generally be provided per wall. However, the case is also covered by the invention that two or more than two thermoelectric elements are present in one or more walls.
The arrangement of one or more thermoelectric elements at the rear side of the unit is also conceivable and covered by the invention.
Each of the thermoelectric elements 20 is connected in a heat-transferring manner, in particular in a thermoconductive manner, to a respective one heat exchanger 30, 40 both on the cold side facing the inner space 100 and on the outwardly directed hot side. These primary heat exchangers 30, 40 are metal bodies, e.g. composed of aluminum.
In the operation of the thermoelectric elements 20, heat is extracted from the cooled inner space over their cold sides and by means of the heat exchanger 30 and of the inner wall I. This heat is discharged to the environment via the hot side of the thermoelectric element 20, via the heat exchanger 40 and via the outer wall A.
As can further be seen from FIG. 1, the cross-section of the primary heat exchangers 1, 40 increases, starting from the thermoelectric element 20 toward the outer wall A and also toward the inner wall I which bounds the cooled inner space 100 together with the inside of the door. In this manner, the waste heat which is extracted from the inner space 100 by means of the thermoelectric elements 20 can be distributed over a larger surface without a larger temperature gradient.
The outer unit side is formed by the outer wall A which comprises in total or regionally a metal sheet, preferably an aluminum metal sheet.
In the embodiment shown here, this metal sheet forms the outer side A of the side walls 12, of the top 14 and also of the bottom 16. The rear side and/or the door can also be correspondingly formed on the outer side.
The metal sheet forming the outer wall A forms the secondary heat exchanger which is connected in a heat-transferring manner, in particular in a thermoconductive manner, to the primary heat exchangers 40.
The inner wall I is likewise formed by a metal sheet, in particular by an aluminum metal sheet. The inner wall I is connected in a heat-transferring manner, in particular in a thermoconductive manner, to the primary heat exchangers 30.
The term “heat exchanger” in accordance with the present invention includes any desired element that is suitable for transferring heat. In the preferred embodiment, the heat exchangers are formed by metallic bodies.
Reference numeral 50 denotes the heat insulation which extends between the inner wall I and the outer wall A of the carcass. This thermal insulation comprises a volume which is bounded by one or more vacuum-tight films and in which a core material, in particular pearlite, is located. Further insulating materials such as foaming and/or vacuum insulation panels are preferably provided between the inner wall I and the outer wall A.
A corresponding full vacuum thermal insulation can also be provided for the door or for another closing element.
The Peltier elements 20 or the other thermoelectric elements are distributed over the unit geometry such that their waste heat is distributed as much as possible over the outer skin A of the unit. The outer skin A can be made up of an aluminum metal sheet having a thickness of 1 to 2 mm for the distribution of the waste heat over the complete outer skin A.
Since the cooling energy which is generated is smaller than the waste heat, the demands on the heat exchanger are not so high in the unit interior 100. A metal sheet (e.g. an aluminum metal sheet) is preferably equally used for the inner wall of the unit and can have a smaller thickness than the metal sheet forming the outer skin A or can have an identical configuration.
The cold side of the thermoelectric element 20′ arranged at the bottom is connected to the heat exchanger 30 that forms a condensation surface at its upper side O, i.e. a surface that has a smaller temperature with respect to adjacent surfaces or that represents the lowest temperature in the refrigerated inner space.
A detailed view of the region of the thermoelectric element 20′ arranged at the bottom is shown in FIG. 2. A condensation region 1 is formed around and at the condensation surface of the heat exchanger 30. Starting from this condensation region 1 at the inner side of the thermally insulating unit wall, an outflow 2 for the condensate leads to the evaporation region 200.
The evaporation region 200 is formed by an evaporation tray 4 that collects the condensed water and that is in good thermal coupling to the Peltier element 20′. The evaporation tray 4 is in particular in direct or thermally conductive contact with the heat exchanger 40.
As can furthermore be seen from FIG. 2, the Peltier element 20′ can have, in the same way as the other Peltier elements of the unit in accordance with the invention, connection elements 33 that mechanically fixedly clamp the Peltier element 20′ to the heat exchangers 30 and 40.
The thermoelectric element or the Peltier element 20′ arranged in the base surface is controllable separately by a control or regulation unit, not shown, and indeed such hat its performance is increased within the framework of a condensation cycle or as required. This has the result that the upper cold side O adopts a still lower temperature and the lower hot side W adopts an even higher temperature.
The condensation and the evaporation are improved in this manner.
In normal operation, the thermoelectric element 20′, like the further thermoelectric elements, can be used in dependence on the measured inner space temperature, i.e. for temperature regulation.
It is also conceivable to use an additional thermoelectric element that lies, for example, on the base surface of the unit and forms the coldest point there. This thermoelectric element thus does not extend between the outside and inside of the unit, but is rather completely located in the refrigerated inner space and emits its waste heat therein.

Claims

1. A refrigerator unit and/or a freezer unit having a refrigerated inner space and having a thermoelectric element, in particular having a Peltier element, that is arranged such that the inner space is refrigerated by means of the thermoelectric element, characterized in that means for evaporating condensed water are present that have a heat exchanger located outside the refrigerated inner space.

2. A refrigerator unit and/or a freezer unit in accordance with claim 1, characterized in that the heat exchanger is formed by the hot side of a thermoelectric element or is connected to the hot side of a thermoelectric element.

3. A refrigerator unit and/or a freezer unit in accordance with claim 2, characterized in that the thermoelectric element is arranged such that it cools the inner space of the unit by its cold side or by a heat exchanger connected to the cold side.

4. A refrigerator unit and/or a freezer unit in accordance with claim 1, characterized in that means are provided by which it can be determined whether condensed water is present; and in that a control or regulation unit connected to these means is provided that increases the performance of the means for evaporating condensed water when the presence of condensed water is determined.

5. A refrigerator unit and/or a freezer unit in accordance with claim 1, characterized in that a condensate surface is present in the refrigerated inner space whose temperature is below the temperature of other surfaces in the refrigerated inner space so that condensate is formed at the condensate surface, with provision preferably being made that the condensate surface is formed by a thermoelectric element; and/or in that a control or regulation unit is provided by which the condensate surface is cyclically cooled.

6. A refrigerator unit and/or a freezer unit in accordance with claim 5, characterized in that a detection means for detecting the opening of the closing element of the unit is present; and in that the control or regulation unit is configured such that it carries out the cyclic cooling in dependence on the detected opening.

7. A refrigerator unit and/or a freezer unit in accordance with claim 1, characterized in that a fan is present that is arranged such that it circulates the air located in the refrigerated inner space.

8. A refrigerator unit and/or a freezer unit in accordance with claim 5, characterized in that the condensate surface is formed by a thermoelectric element that is arranged such that it emits the waste heat into the refrigerated inner space.

9. A refrigerator unit and/or a freezer unit in accordance with claim 1, characterized in that an outflow element is provided through which condensed water is transported to the means for evaporation.

10. A refrigerator unit and/or a freezer unit in accordance with claim 9, characterized in that the outflow element is dimensioned such that the transport of the condensed water takes place by capillary forces.

11. A refrigerator unit and/or a freezer unit having a refrigerated inner space and having a thermoelectric element introduced thereto, characterized in that a control or regulation unit is provided which controls the thermoelectric element such that it forms a condensate surface.