EP0365650B1 - NOFROST COOLING PROCESS FOR A TEMPERATURE RANGE ABOVE 0oC - Google Patents

Abstract

PCT No. PCT/EP89/00464 Sec. 371 Date Dec. 22, 1989 Sec. 102(e) Date Dec. 22, 1989 PCT Filed Apr. 27, 1989 PCT Pub. No. WO89/10523 PCT Pub. Date Nov. 2, 1989.According to this invention, cold is conveyed into a cooling chamber by means of convectors, and fresh air of a higher temperature is supplied in a controlled manner so that the temperature decreases. To avoid power loss due to the quantity of heat supplied, the displaced cold air is channeled towards a heat exchanger in the condenser of the cooling machine. Since the fresh air which circulates is always above 0 DEG C., the humidity content of the fresh air supplied can be controlled and be filtered to remove odors.

Description

In recent years, Nofrost refrigerators have been brought onto the market with great success, which have the great advantage that the icing up of the cold room, which would otherwise occur, and thus the annoying defrosting of the ice infestation are avoided.

The process essentially consists in that air is deep-frozen in a separate compartment of the refrigerator at the evaporator of the refrigerator and this frozen air is conveyed by a fan into the actual cooling space until the desired mixing temperature is reached and a thermostat switches the fan off. The evaporator of the refrigeration machine condenses with the moisture in the circulating air and still freezes over. But this process does not extend to the actual cold room. The evaporator is thawed at certain intervals by heating and the melt water is drained off without disturbing.

Because of the advantages mentioned - no freezing and no defrosting - this process quickly conquered the market.

The main part of the process is that the moisture is removed from the air during freezing and therefore there is an extremely low air humidity in the refrigerator. This in turn leads to the fact that foods refrigerated in such refrigerators, if they are not packed in an airtight manner, dry out quickly and lose their taste and shelf life.

A Nofrost cooling process of the type mentioned at the beginning is already known from US-A-2 143 183. There are a drying room for the supplied air, connected in series outside the cooling room, the air being cooled and humidified in a downstream additional room. The air prepared in this way enters the actual cooling room and leaves it via a downstream exhaust air duct. However, the known cooling device does not provide temperature control using fresh air.

A temperature control by means of fresh air is shown in US-A-2 161 421. Here a refrigerator is described in which the cooling device runs continuously and the temperature in the cooling room is controlled by a flap if the temperature in the refrigerator falls below a certain value is opened, whereby the cold air can flow out and warm air can flow into the cold room.
The disadvantage of this refrigerator is that this simple regulation of the temperature by means of an exhaust air flap causes an immense waste of energy, since the cold air is simply discharged into the environment. Furthermore, the refrigerator of conventional design described here has an evaporator, so that there are disadvantages of icing the evaporator and drying of the cooled air described above.

The object of the invention is to provide a method and the device which avoids these essential disadvantages described above and which also has the advantages of the Nofrost method.

To achieve the object, the features of claims 1 and 5 are provided.

The fresh air supplied ensures that the cooling space does not become too cold and the intended cooling area is maintained.

The incoming fresh air is naturally cooled by the convectors and would mean a loss of coldness after exiting the cold room; it is therefore proposed according to the invention to supply the cooled exhaust air to a heat exchanger which, for. B. is assigned to the hot condenser of the refrigerator, so that the cold is returned to the circuit of the refrigerator.

This effect can be further increased by pretreating the exhaust air heated in the heat exchanger in a closed circuit and supplying it as fresh air again. In this context, the term fresh air is to be understood to mean that air is freshly supplied to the cooling space, a pretreatment being recommended according to the invention. This pretreatment can be, for example, heating, as described above, but also cooling. Filtering, e.g. B. useful with an activated carbon filter to avoid the effects of odors, if cigarette smoke or other cooking fumes would be sucked into the kitchen.

Accordingly, in the refrigerator according to the invention, the cooling space is acted upon by cold, starting from convectors, fresh air of higher temperature being supplied to the cooling space via a fan with temperature control, a fresh air duct and at least one exhaust air duct being provided in connection with the cooling space. It is irrelevant whether the fan is in is arranged in the fresh air or supply air duct or in the exhaust air duct.

When the door to the cold room is opened, warmer ambient air usually flows in, and it can take longer to return from a higher temperature to the desired cooling area. It is therefore proposed according to the invention to arrange a further supply air duct for cold air and to ensure with a further fan with temperature control that cold air instead of fresh air is supplied to the cooling space in such a case. The temperature control then ensures that the cold air supply is switched off near or when the cooling area is reached and the fresh air control takes over the function again.

Instead of a second fan, a switch valve can of course also be provided to switch from fresh air to cold air if necessary.

In order to meet the requirement that less and less cold is supplied from the convectors than heat reaches the cooling chamber when the fresh air supply is at its maximum, an arrangement according to the invention consists in that the surfaces of the convectors facing the cooling chamber are designed to be very thermally conductive in order to keep the incoming Bringing air quickly to the low temperature, but arranging less conductive layers under the surface in order to reduce the cold transfer through the wall of the convectors.

Good cold transfer from the surfaces of the convectors to the fresh air is achieved by the arrangement of cooling fins or other shapes that enlarge the surface. The design too, at least one Part of the walls of the cold room as convectors contributes to increased performance and cost-saving construction.

In a further embodiment, it is proposed to design the convectors as cold stores, it being possible to design the convectors as latent cold stores in the simplest way. Especially in a temperature range above 0 ° C, the use of water or a water mixture with little addition of an agent lowering the freezing point is possible and inexpensive.

Another constructive measure to preserve sensitive foods gently without getting into the freezing temperature range is to provide an inner container in the cold room to hold the refrigerated goods and to arrange the supply air channels in such a way that the fresh air is at least partially in the space between the inner wall of the Cold room and the inner container flows. This prevents local hypothermia.

In order to be able to convert existing refrigerators to the new method, it is further proposed according to the invention to construct the refrigerator as an independent unit in the form of a slide-in unit, the walls serving for cold transmission, through which the cold of the freezer can get into the refrigerator In such a case, it is expedient to also install the additional components required, such as fans and thermostats, in the range of the regulated temperature above 0 ° C. In such an embodiment, the fresh air ducts and exhaust air ducts can be designed as flat hoses can also be easily led outside through the door gap of the door of the freezer.

In order to be able to adapt a device according to the invention to the individual needs and the seasonal differences, it is further proposed to provide a throttle valve which can be adjusted by hand in the area of the fresh air duct and / or the exhaust air duct. A manually adjustable throttle valve serves the same purpose, which varies the supply of cold in the area of the convectors.

Figure 1 is a schematic representation of a freezer (25) according to the invention, which has a cooling space (1) in its upper part. Below is a freezer compartment (34), in which the evaporator (27) of the refrigeration machine (5) is also located. he cold room (1) and the freezer compartment (34) are separated by an intermediate wall (16) which essentially determines the inflow of cold into the cold room (1). The cold reaches this throttled passage through the intermediate plate (16) to the convector (2), which is made of a good heat-conducting material, eg. B. aluminum. In order to increase the effect of this convector, it is also carried up laterally on the walls in the form of extensions (26). The ribs (17) also serve for improvement.

The convector (2) will now cool due to the cold flow, but as soon as a certain temperature, e.g. B. + 2 ° C is reached, the temperature control (10) switches on the fan (9) and fresh air passes through the fresh air duct (6) into the cooling chamber (1). The convector (2) is warmed and kept at 2 ° C. However, as soon as the temperature exceeds 2 ° C the temperature control (10) switches off the fan (9) and the cooling chamber (1) is again exclusively under the influence of the cooling convector (2).

When the fresh air flows in through the fresh air duct (6), air is displaced in the cold room and it escapes through the exhaust air duct (7). In order to avoid that cold is lost, the exhaust air is passed through a heat exchanger (3) which cools the condenser (4) of the refrigerating machine (5). In this way, the cold is returned to the primary cooling circuit and is only lost to a small extent. The primary cooling circuit, consisting of the refrigeration machine (5), the condenser (4), a throttle valve (8) and the evaporator (27), is supplied with cooling by cooling the condenser. The heat exchanger (3) can of course also be constructed separately from the condenser (4), as is customary in refrigeration systems.

Another improvement is to connect the exhaust air duct (7) through the connection (23) to the fresh air duct (6), so that a closed circuit is created.

FIG. 1 also schematically shows an expedient embodiment of the evaporator (27) in combination with a cold store (19), a latent cold store filled with liquid (20) also being suitable for the corresponding temperatures.

Since the temperature in the refrigerator rises significantly when the refrigerator is opened and when fresh food is placed in it, cooling in the desired cooling areas might be necessary as a result of the reduced temperature Cold currents through the plate (16), very slowly. In order to achieve faster cooling, there is therefore a connection from the cooling room (1) via the cold air duct (11) and the second fan (12) to the freezer compartment (34). As soon as the temperature in the refrigerator (1); after opening the door, over a value of z. B. + 4 ° C rises, the temperature control (13) switches on the fan (12) and cold air from the freezer compartment (34) enters the cooling room 81) until the temperature control (13) again at + 4 ° C the fan ( 12) switches off. Then the temperature control (10) with the fan (9) takes over its function again, ie the fan (9) is only switched on when the temperature in the refrigerator (1) drops below + 2 ° C.

In Figure 2 it is shown that instead of the two fans (9) and (12) can also work with a single fan (9) by a changeover valve (14) once the fresh air duct (6) and once the cold air duct (11) connects to the fan (9).

1 shows further details of the invention.

Since the arrangement of latent cold stores can collect larger amounts of cold in a simple manner, it is recommended to provide such a freezer with a timer (33) which controls the refrigerator (5), which, as usual, via a thermostat (32) of the freezer compartment (34) is switched to only at such times to the mains connection (31) when z. B. cheap night electricity tariffs are available. This measure not only reduces operating costs but also alleviates power supply problems.

Since a fresh air cooling according to the invention with moist air and precisely controlled temperatures with can above 0 ° C significantly improves the taste and shelf life of the food, a solution is proposed which also enables the subsequent installation of such a cooling room in existing freezers. For this purpose, the components for cold transmission are combined into one unit in the form of an insert (28). Such an insert (28) expediently also carries the fan (9) and the temperature control (19), possibly also filters or humidification devices (24).

In Figure 1, a throttle valve (35) is also shown schematically, which can change the cold transfer through the plate (16). The purpose of this is e.g. B. in summer or in hot areas to increase the flow of cold.

The throttle valve (36) serves a similar purpose and influences the air flow accordingly.

The exemplary embodiment shown in FIG. 1 and FIG. 2 shows how numerous the variants and possibilities of a refrigerator according to the invention with fresh air cooling are.

Claims (20)

1. A no-frost refrigerating method for a refrigerating range below 0 °C, wherein the desired temperature in the refrigerating chamber (1) is regulated by the supply of fresh air of a higher temperature and the amount of cold supplied to the refrigerating chamber (1) per unit of time is smaller than the amount of heat supplied with the maximum supply of fresh air, wherein a controlled supply of fresh air takes place and the cold is supplied to the refrigerating chamber (1) by convectors (2), characterised in that the cooled exhaust air, displaced by the inflowing fresh air, is supplied to a heat exchanger (3) of the condenser (4) of the cooling machine (5), that a three-dimensional separation is present between the evaporator (27) and the refrigerating chamber (1) and that the cold is directed from the evaporator (27) to the refrigerating chamber (1) via components (2, 16)lying therebetween.
2. A no-frost refrigerating method according to Claim 1, characterised in that the exhaust air, after heating in the heat exchanger (3) and after a pre-treatment in a closed circuit (23), is supplied to the refrigerating chamber (1).
3. A no-frost refrigerating method according to Claim 1, characterised in that on exceeding the upper threshold temperature of the refrigerating range, cold air is supplied, instead of fresh air, until the temperature of the refrigerating chamber (1) lies in or close to the refrigerating range.
4. A no-frost refrigerating method according to Claim 1, characterised in that the supplied fresh air is pretreated, i.e. for example cooled, filtered and/or moistened and/or is provided with preservatives.
5. A no-frost refrigerating arrangement, wherein a refrigerating range is provided for the supply of cold, in which the refrigerating chamber (2) is acted upon by cold, originating from convectors (2), and wherein via a fan (9) with temperature regulation (10) fresh air at a higher temperature is supplied to the refrigerating chamber (1), wherein there are provided a fresh air duct (6) and at least one exhaust air duct (7) in connection with the refrigerating chamber (1), characterised in that in the exhaust air duct (7) a heat exchanger (3) of the condenser (4) of the cooling machine (5) is present and that the evaporator (27) is separated three-dimensionally from the refrigerating chamber (1) at least by the convectors (2).
6. A no-frost refrigerating arrangement according to Claim 5, characterised in that a further air supply duct (11) for cold air and a further fan (12) for cold air with temperature regulation (13) are present.
7. A no-frost refrigerating arrangement according to Claim 5, characterised in that a change-over valve (14) from fresh air to cold air is present.
8. A no-frost refrigerating arrangement according to Claim 5, characterised in that the surfaces of the convectors (2) facing the refrigerating chamber (1) have very good thermal conductivity and less well conducting layers (16) are arranged under the convectors (2).
9. A no-frost refrigerating arrangement according to Claim 5, characterised in that the surfaces of the convectors (2) facing the refrigerating chamber (1) are provided with refrigerating ribs (17) or other shapes increasing the surfaces.
10. A no-frost refrigerating arrangement according to Claim 8, characteriesd in that at least a part of the walls of the refrigerating chamber (1) is constructed as convectors (26).
11. A no-frost refrigerating arrangement according to Claim 8, characterised in that the convectors (2) and/or the evaporators (27) are constructed as cold reservoirs (19).
12. A no-frost refrigerating arrangement according to Claim 11, characterised in that the cold reservoirs (19) filled with fluid (20) are constructed as latent cold reservoirs.
13. A no-frost refrigerating arrangement according to one or more of the above Claims 5 to 12, characterised in that in the refrigerating chamber (1) an internal container (21) is present to hold the refrigeration goods and the fresh air ducts (6) are arranged such that the fresh air flows at least partially into the space (22) between the inner surface (15) of the refrigerating chamber (1) and the internal container (21).
14. A no-frost refrigerating arrangement according to one or more of the above Claims 5 to 13, characterised in that the refrigerating chamber (1) is constructed as a slide-in unit (28) into a freezer (25), wherein the walls serve for the transmission of cold, through which the cold of the freezer (25) arrives into the refrigerating chamber (1).
15. A no-frost refrigerating arrangement according to Claim 14, characterised in that the fresh air ducts (6) and exhaust air ducts (7) are constructed as thin flat tubes which are directed outwards through the door gap of the door of the freezer (25).
16. A no-frost refrigerating arrangement according to Claim 14, characterised in that the fan (12) and temperature regulation (13) are arranged on the slide-in unit (28).
17. A no-frost refrigerating arrangement according to Claim 16, characterised in that the fan (12) and temperature regulation (13) are arranged inside the slid-in unit (28) in the temperature range above 0 °C.
18. A no-frost refrigerating arrangement according to one or more of the above Claims 5 to 17, characterised in that in the region of the fresh air duct (6) and/or of the exhaust air duct (7) a manually adjustable throttle valve (18) is present.
19. A no-frost refrigerating arrangement according to one or more of the above Claims 8 to 18, characterised in that in the less well conducting layer (16) a manually adjustable throttle valve (18) is present to alter the transfer of cold.
20. A no-frost refrigerating arrangement according to one or more of the above Claims 5 to 19, characterised in that a switch clock (33) is present which switches the cooling machine (5) on only at particular times.

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