Refrigerator and/or freezer

Abstract

The present invention relates to a refrigerator and/or freezer with a heat transfer circuit, which comprises a magnetic cooler, a pump for delivering the heat transfer medium, a cold heat exchanger for cooling the refrigerating and/or freezing space of the appliance, and a warm heat exchanger for cooling the heat transfer medium, wherein the warm heat exchanger has a cross-sectional area between 14 mm2 and 54 mm2.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a refrigerator and/or freezer with a heat transfer circuit, which comprises a magnetic cooler, a pump for delivering the heat transfer medium, a cold heat exchanger for cooling the refrigerating and/or freezing space of the appliance and a warm heat exchanger for cooling the heat transfer medium.

In the case of magnetic cooling, a heat transfer medium flowing through a heat transfer circuit is heated and cooled by utilizing the so-called magnetocaloric effect. The process steps performed usually include the magnetization, the extraction of heat, the demagnetization and the cold use, which steps are repeated continuously.

For performing these process steps, different methods are known. It is conceivable, for instance, to use a stationarily arranged magnetocaloric material and one or more rotating magnets, which periodically magnetize and demagnetize the magnetocaloric material, wherein the same undergoes heating and cooling. Heating and cooling of the magnetocaloric material are utilized for heating or cooling the heat transfer medium flowing through the magnetic cooler. It is also conceivable to stationarily arrange the magnet or magnets and movably arrange the magnetocaloric material or to provide the magnetocaloric material in the heat transfer medium

A conceivable heat transfer circuit comprises a so-called cold heat exchanger, said magnetic cooler, a warm heat exchanger and a pump for delivering the heat transfer medium through the heat transfer circuit. During the magnetization of the magnetocaloric material, the same undergoes heating. The heat is transferred to the heat transfer medium. By means of the pump, the heat transfer medium then is delivered into the warm heat exchanger, in which it is cooled. Subsequently, the further cooling of the heat transfer medium is effected in the demagnetized and therefore cooled region of the magnetic cooler. The heat transfer medium cooled in this way then traverses the cold heat exchanger, which serves for cooling the goods to be refrigerated and/or frozen. The heat transfer medium is heated thereby and then is again heated further in the magnetized region of the magnetic cooler. Finally, it again reaches said warm heat exchanger via the pump.

SUMMARY OF THE INVENTION

It is the object underlying the present invention to develop a refrigerator and/or freezer as mentioned above such that its energy consumption is reduced as compared to known appliances.

This object is solved by a refrigerator and/or freezer with the features herein.

Accordingly, it is provided that the warm heat exchanger has a cross-section between 14 mm² and 54 mm². For instance, it can be provided that the warm heat exchanger has a cross-section between 24 mm² and 44 mm², preferably between 30 mm² and 38 mm², and particularly preferably between 32 mm² and 36 mm². A particularly preferred value is about 34 mm².

This invention furthermore relates to a refrigerator and/or freezer with the features of claim 3. Accordingly, it is provided that the cold heat exchanger has a cross-section between 30 mm² and 70 mm². For instance, it can be provided that the cold heat exchanger has a cross-section between 40 mm² and 60 mm², preferably between 46 mm² and 54 mm², and particularly preferably between 48 mm² and 52 mm². A particularly suitable value for the cross-sectional area of the cold heat exchanger is about 50 mm².

In accordance with the present invention, the term “cross-section” is understood to be the internal cross-section, i.e. the flow cross-section of the heat exchanger(s) available for the heat transfer medium. The indicated values can be absolute values or also mean values.

In principle, the advantage of a great cross-section consists in the comparatively low pressure loss and a resulting low energy consumption of the pump delivering the heat transfer medium. The advantages of a small cross-section consist in the comparatively small filling volume, which leads to a short defrosting phase and involves an improved refrigerating capacity. By means of the present invention, an optimum compromise is achieved between the refrigerating capacity on the one hand and the energy consumption of the pump on the other hand. In general, a low energy consumption of the magnetic cooler is achieved by the present invention in a refrigerator and/or freezer.

Particularly advantageously, both the cold heat exchanger and the warm heat exchanger have the above-mentioned preferred cross-sectional values. Accordingly, a preferred aspect of the invention consists in that the refrigerator is configured in accordance with the description herein.

The cross-sectional area of the warm and/or cold heat exchanger can be constant, i.e. hardly change along the flow path or not at all.

However, it is also conceivable that the cross-sectional area of the warm and/or of the cold heat exchanger is variable, i.e. changes along the flow path of the heat transfer medium through the heat exchanger(s), and that the cross-sectional values are mean values.

In a further aspect of the invention it is provided that the warm heat exchanger and/or the cold heat exchanger is made of one tube or of two or more than two tubes, which can extend in parallel. Thus, it is conceivable to distribute the heat transfer medium to several tubes.

If the warm heat exchanger and/or the cold heat exchanger is made of two or more than two tubes, the cross-sectional values can be the entire cross-sectional area of the two or more than two tubes, i.e. the sum of the cross-sections of the individual tubes. In this case, a plurality of tubes with a smaller cross-sectional area thus could be provided instead of one tube.

The tubes can be round in cross-section or also have any other cross-sectional shape.

The present invention furthermore relates to a refrigerator and/or freezer with the following features. Accordingly, it is provided that the cross-sectional area of the cold heat exchanger is greater than the cross-sectional area of the warm heat exchanger. If these are cross-sectional areas which vary along the flow path, it can provided that the mean value of the cross-sectional area of the cold heat exchanger is greater than the mean value of the cross-sectional area of the warm heat exchanger. However, the invention of course also covers an embodiment with constant or substantially constant cross-sectional areas, i.e. cross-sectional areas which do not or not substantially vary along the flow path. It is conceivable, for instance, that the cross-sectional area of the cold heat exchanger exceeds that of the warm heat exchanger by values in the range from >0 to 25 mm².

In principle, however, the invention also covers the case that the cross-sectional areas of both heat exchangers are identical.

BRIEF DESCRIPTION OF THE DRAWINGS

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

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference numeral 10 designates the magnetic cooler, which comprises two heat exchanger units 12, 14, which can be configured as a constructional unit or also separate from each other.

The heat exchanger untis 12, 14 are made of a magnetocaloric material or include such material.

They are cyclically magnetized and demagnetized, for which purpose a non-illustrated magnet is provided, which rotates about the heat exchanger units 12, 14. Depending on the position of the magnet, the heat exchanger units 12, 14 are magnetized or demagnetized, which results in the heating or cooling thereof and also in the heating or cooling of the heat transfer medium which flows through the heat exchanger units 12, 14.

The heat transfer circuit of the refrigerator and/or freezer furthermore includes a cold heat exchanger 20, which is arranged in the refrigerating and/or freezing space or in the vicinity of the refrigerating and/or freezing space of the appliance and provides for cooling the same. A warm, preferably air-cooled heat exchanger 50 is arranged on the outside of the appliance and serves to dissipate heat from the heat transfer medium to the surroundings.

The pump 100 provides for the flow of the heat transfer medium through the illustrated heat transfer circuit.

Downstream of the cold heat exchanger 20 a valve 40 is arranged, and downstream of the warm heat exchanger 50 a further valve 30 is arranged. The valves are for instance bistable or monostable valves. In cooling operation, the valves 30, 40 are actuated such that the heat transfer medium from the warm heat exchanger 50 always gets into that heat exchanger unit 12, 14 which is just cooled or demagnetized, and from there into the cold heat exchanger 20. The valve 40 is actuated such that the heat transfer medium which has traversed the cold heat exchanger 20 is supplied to that heat exchanger unit 12, 14 which is in the magnetized condition and therefore heated.

In the embodiment illustrated here it is provided that the mean flow cross-section of the cold heat exchanger 20 is about 50 mm² and that the mean flow cross-section of the warm heat exchanger 50 is about 34 mm².

In this way, it is ensured that the energy consumption of the pump is comparatively low and the refrigerating capacity of the heat exchanger comparatively high. The present invention represents an optimum compromise between these parameters and thus allows to provide a refrigerator and/or freezer with magnetic cooling, which has a low energy consumption.

The cold heat exchanger and/or the warm heat exchanger can be made of one single tube or of two or also more than two tubes which are traversed by the heat transfer medium. The two or more than two tubes can be installed in parallel. However, this is not absolutely necessary.

Claims

1. A refrigerator and/or freezer with a heat transfer circuit, which comprises a magnetic cooler, a pump for delivering the heat transfer medium, a cold heat exchanger for cooling the refrigerating and/or freezing space of the appliance and a warm heat exchanger for cooling the heat transfer medium, wherein the warm heat exchanger has a cross-sectional area between 14 mm2 and 54 mm2.

2. The refrigerator and/or freezer according to claim 1, wherein the warm heat exchanger has a cross-sectional area between 24 mm2 and 44 mm2, preferably between 30 mm2 and 38 mm2, and particularly preferably between 32 mm2 and 36 mm2.

3. A refrigerator and/or freezer with a heat transfer circuit, which comprises a magnetic cooler, a pump for delivering the heat transfer medium, a cold heat exchanger for cooling the refrigerating and/or freezing space of the appliance and a warm heat exchanger for cooling the heat transfer medium, wherein the cold heat exchanger has a cross-sectional area between 30 mm2 and 70 mm2.

4. The refrigerator and/or freezer according to claim 3, wherein the cold heat exchanger has a cross-sectional area between 40 mm2 and 60 mm2, preferably between 46 mm2 and 54 mm2, and particularly preferably between 48 mm2 and 52 mm2.

5. The refrigerator and/or freezer according to claim 3, wherein the appliance is configured in accordance with the warm heat exchanger having a cross-sectional area between 14 mm2 and 54 mm2.

6. The refrigerator and/or freezer according to claim 1, wherein the cross-sectional area of the warm and/or of the cold heat exchanger is constant.

7. The refrigerator and/or freezer according to claim 1, wherein the cross-sectional area of the warm and/or of the cold heat exchanger is variable and a mean value values.

8. The refrigerator and/or freezer according to claim 1, wherein the warm heat exchanger and/or the cold heat exchanger is made of one tube or of two or more than two tubes which preferably extend in parallel.

9. The refrigerator and/or freezer according to claim 8, wherein the warm heat exchanger and/or the cold heat exchanger is made of two or more than two tubes extending in parallel and the cross-sectional value is the total cross-sectional area of the two or more than two tubes.

10. A refrigerator and/or freezer with a heat transfer circuit, which comprises a magnetic cooler, a pump for delivering the heat transfer medium, a cold heat exchanger for cooling the refrigerating and/or freezing space of the appliance and a warm heat exchanger for cooling the heat transfer medium, wherein the cross-sectional area of the warm heat exchanger is smaller than the cross-sectional area of the cold heat exchanger.

11. The refrigerator and/or freezer according to claim 10, wherein the appliance is configured in accordance with the warm heat exchanger having a cross-sectional area between 14 mm2 and 54 mm2.

12. The refrigerator and/or freezer according to claim 4, wherein the appliance is configured in accordance with the warm heat exchanger having a cross-sectional area between 14 mm2 and 54 mm2.

13. The refrigerator and/or freezer according to claim 12, wherein the cross-sectional area of the warm and/or of the cold heat exchanger is constant.

14. The refrigerator and/or freezer according to claim 2, wherein the cross-sectional area of the warm and/or of the cold heat exchanger is constant.

15. The refrigerator and/or freezer according to claim 3, wherein the cross-sectional area of the warm and/or of the cold heat exchanger is constant.

16. The refrigerator and/or freezer according to claim 4, wherein the cross-sectional area of the warm and/or of the cold heat exchanger is constant.

17. The refrigerator and/or freezer according to claim 5, wherein the cross-sectional area of the warm and/or of the cold heat exchanger is constant.

18. The refrigerator and/or freezer according to claim 17, wherein the cross-sectional area of the warm and/or of the cold heat exchanger is variable and a mean value.

19. The refrigerator and/or freezer according to claim 16, wherein the cross-sectional area of the warm and/or of the cold heat exchanger is variable and a mean value.

20. The refrigerator and/or freezer according to claim 15, wherein the cross-sectional area of the warm and/or of the cold heat exchanger is variable and a mean value.