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(11) | EP 3 088 820 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | HOUSEHOLD REFRIGERATING AND/OR DEEP-FREEZING APPARATUS |
| (57) A household refrigerating and/or deep-freezing apparatus that comprises a housing
with a door that encloses at least one cell with at least one food storage compartment
(2), a compressor (3), at least one evaporator (4) and a condenser, has a part of
the internal surface of the rear wall (6) of the housing, which is arranged in the
area of the evaporator (4), processed in a way to have a surface with reduced wettability
compared to the wettability of the surface of the remaining internal surface of the
rear wall (6) and other internal surfaces of the cell.
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Object of Invention
[0001] The present invention relates to a household apparatus, preferably a refrigerating and/or deep-freezing apparatus comprising at least one cell with at least one food storage compartment having a temperature below or above freezing point, wherein said compartment is refrigerated by means of at least one evaporator.
Technical Problem
[0002] The technical problem to be solved by the present invention is how to conceive such refrigerating and/or deep-freezing apparatus that will eliminate or considerably reduce a crackling noise originating from an evaporator area and will at the same time also eliminate drawbacks concerning hygiene of this compartment.
Prior Art
[0003] Refrigerating and/or deep-freezing in a refrigerating/deep-freezing apparatus is provided for by a circulating refrigerating system that comprises a compressor as a source of systems operation, an evaporator extracting heat from the interior of the apparatus, and a condenser that releases heat into the environment. A refrigerating agent that circulates within the refrigerating system receives and transmits heat owing to changes in pressure and temperature. A compartment is refrigerated in phases. In a refrigerating phase when the system detects an increased temperature in the compartment, a refrigerating system turns on, warm air circulates (in a forced or natural manner) through an evaporator and discharges heat. When the temperature in the compartment reaches a pre-determined low temperature, the system turns off and a standby phase occurs. The temperature on the surface of the evaporator and in its vicinity lies below freezing point during the refrigerating phase. When the air passes through the evaporator and its close vicinity, the moisture from the air condenses and gets discharged onto all surfaces in the area of the evaporator. Since the temperature is below the freezing point, the condensed water vapour on the surface and in the area of the evaporator freezes in the form of frost and ice. During the standby phase, said frost or ice gets at least partially melted and the water is discharged through dedicated channels outside from a cell. The temperature can be increased and melting of the ice achieved due to the system being turned off for a longer period of time and/or by using additional heating bodies in the evaporator area.
[0004] The evaporator is fixed in the compartment of the apparatus dedicated to food storage, refrigeration and/or deep-freezing, usually close to the rear wall of a housing and protected towards the interior of the storage compartment by a panel that simultaneously functions also as a deflector for the circulating air. There is a minimal gap between the evaporator and the rear wall/protective panel and this provides for a better air circulation through the evaporator. The temperature on the surface of the evaporator and in its direct vicinity, i. e. on the part of the wall of the protective panel adjacent to the rear wall of the housing and the evaporator, is lower than the temperature within the cell. This is why condensed water vapour of the circulating air is also deposited on these surfaces. During a standby phase, especially during melting, the frost and ice get melted and get mostly discharged as water through discharge channels. A certain quantity of water remains on an individual surface in the form of drops, the size and shape of which depends on the wettability of each surface. During the refrigerating phase the water drops freeze and at the same time become deep-freezing seed crystals for the condensed water vapour that is discharged from the air when the latter passes through the evaporator. As a consequence, the frozen drops multiply and since there is a minimal distance between each surface and the evaporator, they hit against the surface of the evaporator and/or frozen condensed water vapour discharged on the surface of the evaporator. The drops push each other and the evaporator/its surfaces away. An increased quantity of condensed water vapour causes an increase in the frozen water drops, in which compressive forces get higher due to the evaporator being pushed away. When the compressive forces exceed the compressive strength threshold, the frozen drop of the condensed water vapour gets disintegrated and a crackling noise appears. Noise strength is proportional to the size of a water drop.
[0005] A crackling noise also occurs as a consequence of various temperature dilatations of various materials of constructional elements during the operation of the refrigerating apparatus. Shear strengths appear in a drop of frozen condensed water vapour that links two opposite surfaces as a consequence of various temperature dilatations of each material in the area. The moment the shear forces exceed the adhesion forces that act between the frozen condensed water vapour and each surface, the frozen condensed water vapour gets detached from each surface and consequently a crackling noise appears. The strength of the noise is proportional to the size of the contact surface. Reduced wettability of surfaces means smaller contact surfaces of individual drops and in fact lower necessary shear forces for detachment. This results in a reduced noise.
[0006] Since a housing of a refrigerating apparatus is normally produced in a sandwich structure with a high thermal and low sound insulating substance in-between, the housing functions as a sound amplifier that yet additionally amplifies the crackling noise which occurs on the internal surface of the wall of the housing.
[0007] So there is a need for a household refrigerating apparatus that will eliminate the mentioned disadvantages from prior art.
Solution to the Technical Problem
[0008] The technical problem that is solved by the invention is characterized in that all internal surfaces of walls of a cell that are located in the area of an evaporator, that are adjacent to the evaporator and that distant from the evaporator for a minimal required distance are preferably part of the surface of the rear wall of the cell and of a surface of a protective panel adjacent to the evaporator and fabricated in a way that their wettability is reduced, preferably considerably reduced compared to the wettability of the remaining surfaces of the internal walls of the cell.
[0009] Reduced wettability of a surface and/or of a part of a surface in the area of the evaporator is achieved in any known way and is not the object of the invention. Reduced wettability can be achieved by applying a coating of a material having a considerably reduced wettability or by physically treating a contact surface with known methods for reducing wettability.
[0010] During a standby phase, in which frost and ice get melted, a larger quantity of water flows off the surface due to reduced wettability of a surface, the remaining water remains in smaller drops and at a smaller angle of wettability due to reduced wettability. The growth of the drops which represent the freezing seed crystals for condensed water vapour is oriented in a direction away from the surface; the drops have lower compressive strength and need a longer period of time to fill the gap between the surface and the evaporator. This results in disintegration at a lower compressive strength and less crackling noise is present. Since the period of time, in which the frozen drops of condensed water vapour fill in the gap is extended, or the gap gets not filled at all, the drops get melted due to their reduced side in the standby phase and no crackling noise occurs due to the exertion of normal forces on drops.
[0011] Smaller drops of frozen water also have a lower shear strength which results in disintegration at lower shear forces that are a consequence of various temperatures of dilatation of materials that are in contact with them. The strength of the noise due to shear forces is herewith reduced as well.
[0012] A further advantage of the surfaces with reduced wettability in the area of the evaporator is their cleaning and thus the hygiene of the refrigerating apparatus. The evaporator is fixed in an area of the apparatus close to the rear wall of the housing and is protected towards the interior of the storage compartment by a panel that prevents the user to access the evaporator and at the same time acts as a deflector of the circulating air and directs hot air from the cell to pass through the evaporator. The fixed evaporator and the protective panel do not enable cleaning of the surfaces in the area of the evaporator, especially the surface of the rear wall of the housing behind the evaporator. This results in an accumulation of impurities on these surfaces which impacts the quality of food in the refrigerating compartment.
[0013] Since the wettability of the surfaces in the area of the evaporator is reduced, the water gets more intensely discharged from the surfaces in the area of the evaporator. The water on said surfaces also takes impurities with it and discharges them out from the storage compartment of the apparatus. The presence of impurities on said surfaces represents additional condensation and deep-freezing seed crystals, so the reduction thereof yet additionally contributes to a smaller quantity of frost and ice on said surfaces.
[0014] The invention will be described in more detail by way of an embodiment and the enclosed drawing, in which
Fig. 1 shows a longitudinal view of a refrigerating apparatus with an evaporator.
[0015] A household apparatus, preferably a refrigerating and/or deep-freezing apparatus comprises a housing 1 with a door that encloses at least one cell 2 with at least one food storage compartment below or above freezing temperature, and a circulating cooling system that contains a compressor 3 as a source of system operation, at least one evaporator 4 that refrigerates the interior of the apparatus by taking away heat from the internal air, and a condenser 5 that discharges the heat into the environment. The evaporator 4 is fixed in the cell 2 of the apparatus, preferably close at a rear wall 6 of the housing 1 and at a minimal distance from the rear wall 6. The evaporator 4 is protected towards the interior of the cell 2 by a panel 7 that is arranged at a certain distance from the evaporator 4. The protective panel 7 which prevents the user from accessing the evaporator 4 is at the same time also a deflector of the air that passes through the evaporator 4. The rear wall 6 with its internal surface 9 facing the interior of the cell 2 is adjacent to the evaporator 4; the protective panel 7 with its surface 10 facing the rear wall 6 is adjacent to the evaporator 4. There is a minimal gap 8 between the evaporator 4 and each surface 9, 10, wherewith air circulation through the evaporator 4 is provided for in order to reach the efficiency of the evaporator.
[0016] A part of the internal surface 9 of the rear wall 6 of the housing 1 that is arranged in the area of the evaporator 4, that is adjacent to it, is processed to have a surface with reduced wettability, preferably a considerably reduced wettability compared to the wettability of the surface of the remaining internal surface 9 of the rear wall 6 and other internal surfaces of the cell 2.
[0017] The surface 10 of the protective panel 7 is processed to have reduced wettability, preferably a considerably reduced wettability compared to the wettability of the opposite surface of the protective panel 7.
[0018] Reduced wettability of the surface and/or of a part of the surface is achieved in any known way such as by applying a coating of a material having a considerably reduced wettability, by physically processing the contact surface with known methods for reducing wettability, by nanotechnology, wherein the materials must comply with food standard requirements.
1. A household refrigerating and/or deep-freezing apparatus comprising a housing with
a door that encloses at least one cell with at least one food storage compartment,
a compressor, at least one evaporator and a condenser, wherein the evaporator is arranged
at a distance from the rear wall of the housing whose internal surface faces the interior
of the cell, characterized in that a part of the internal surface (9) of the rear wall (6) of the housing (1), which
is arranged in the area of the evaporator (4) and is adjacent to it, is processed
in a way to have a surface with reduced wettability, preferably a considerably reduced
wettability compared to the wettability of the surface of the remaining internal surface
(9) of the rear wall (6) and other internal surfaces of the cell (2).
2. Household refrigerating and/or deep-freezing apparatus according to claim 1, characterized in that the evaporator (4) is protected towards the interior of the cell (2) by a panel (7)
having a surface adjacent to the evaporator, said surface having reduced wettability
compared to the wettability of the surface of its other surface.
3. Household refrigerating and/or deep-freezing apparatus according to any of preceding
claims, characterized in that reduced wettability of the surface and/or of a part of the surface is achieved by
applying a coating of a material having a considerably reduced wettability, by physically
treating the contact surface with methods for the reduction of wettability.