Refrigeration – Automatic control – Humidity sensor
Patent
1983-05-16
1985-04-30
Bennett, Henry
Refrigeration
Automatic control
Humidity sensor
62 80, 62 94, 55387, F25D 1704
Patent
active
045135797
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method in a freezer with a chamber, in which refrigerated surfaces tend to collect frost, and with a moisture adsorbing regenerable filter in order to lower the relative humidity of the freezing chamber air and counteract forming of frost therein. The invention also relates to an arrangement for the purpose.
It is known that the relative humidity of the chamber air in a freezer varies with the temperature variations in the chamber. If it is possible to lower the relative humidity of the air below the normal level, present when the freezer operates without any influence from outside on the humidity, the frost formed on the freezing system or on the coldest surfaces of the freezing chamber will by sublimation be transferred from solid body direct to vapour. This principle has been the foundation for a proposal to arrange in a freezer a separate freezing chamber air flow path having a moisture adsorbing filter and a motor driven fan. This proposal further comprises a removable filter, for instance in the shape of a shelf for goods in the cabinet. The filter can be regenerated, for instance by heat treatment in an oven. This proposal has been presented in EPO-application No. 80850170.4 published under No. 31,311.
Since certain difficulties are involved in performing the regeneration of the filter in the freezing cabinet proposed above, the arrangement for moisture adsorption is so made that the freezer cabinet can operate during long periods without regeneration of the filter. In that case the filter will be relatively bulky and expensive. In spite thereof it is required that the person handling the cabinet is alert and regenerates the filter before it has become saturated and no longer is capable of keeping the refrigerated surfaces of the freezing chamber free of frost.
The object of the invention is to remove the said drawbacks and to provide a method and an arrangement making it possible for a freezer to operate automatically without collection of frost in the freezing chamber, without any special supervision being necessary and without special precautions for regeneration of the filter being necessary. An arrangement according to the invention for this purpose is mainly characterized in that the filter is arranged in a first heat-insulated flow path, intended for freezing chamber air and containing a motor driven fan, that a second heat-insulated flow path, intended for ambient air, is connected to the first one before and after a part thereof containing the filter and the fan, and that valves are arranged for shifting of the flow paths. The method according to the invention is mainly characterized in that the freezing chamber air is conducted through a first flow path having a motor driven fan and a filter and that ambient air is conducted through the fan and the filter in a second flow path for regeneration of the filter.
In the following the invention will be described more in detail by way of example with reference to an embodiment shown in the drawings in which FIGS. 1 and 2 show an arrangement for defrosting a freezing chamber with the valves of the arrangement in different positions for keeping a freezing chamber frostfree.
In a freezer cabinet having a bottom step under which the compressor of the cabinet is arranged it is suitable to locate the arrangement according to the invention at the side of the compressor below the said bottom step. If the freezer is of some other design the arrangement may be placed at another suitable location. The Figures show a vertical section through a bottom step 10 under a freezing chamber 11. Through the bottom step 10 goes an inlet conduit 12 for air to a space 15 and an outlet conduit 13 for air from the space. The space 15 is surrounded by a heat insulation 14 and contains a regenerable filter 16 and a fan 17 driven by a motor 18 having a shaft 19 to the fan. To the space 15 goes an inlet conduit 20 for ambient air and from the space goes an outlet conduit 21 for the air. Between the two inlet conduits 12 and 20 there are valve seats
REFERENCES:
patent: 2946201 (1960-07-01), Munters
patent: 4180985 (1980-01-01), Northrup
Andersson Karl F.
Eriksson Bolik A. G.
Aktiebolaget Electrolux
Bennett Henry
Miller Alfred E.
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