US2998713A - Apparatus for defrosting low temperature storage facilities - Google Patents

Description

Sept. 5, 1961 M. J. HILER 2,998,713

APPARATUS FOR DEF'ROSTING LOW TEMPERATURE STORAGE FACILITIES med May 1, 195e ino Fiied May 1, 1959, Ser. No. 810,395 7 Claims. (Cl. 62-283) The present invention relates to the defrosting of low temperature storage facilities, more particularly, to apparatus for inducing the accumulation of frost upon a lo'- calized cold spot `so as to prevent the accumulation of frost on the refrigerating surfaces of the storage facility.

Low temperature storage facilities generally comprise household refrigerators and freezers wherein the temperature in the latter is of the order of F. A problem in these low temperature storage facilities is the accumulation of frost on those surfaces which are adjacent the refrigerant evaporators. In effect, these surfaces form the refrigerating surfaces for the storage facilities. The accumulation of frost on these surfaces considerably decreases the efficiency of the evaporator as it operates in the storage compartment of the refrigerator or the freezer. Thus, in order to maintain the operation of the evaporator at maximum eliiciency, the accumulations of frost must be periodicaly removed. This defrosting process, however, may involve a substantial interruption in the refrigerating process, which interruption may cause a spoilage of foodstuffs and other perishable materials which may be stored therein. In some low temperature storage facilities, these defrosting processes require considera-ble time and labor in order to effectively remove `the accumulations of frost.

In the present invention the above disadvantages are overcome by providing a structure in the low temperature storage facility upon which the accumulation of frost is induced. This structure is maintained at a temperature which is less than the temperature of the inner Walls of the storage compartment through which the refrigerating effect is produced. The structure is readily removable from the storage facility so that it is merely necessary to periodically detach these structures and remove the accumulations of frost therefrom, to defrost the refrigerator. .This process can be accomplished Without interrupting the refrigerating process, since the structures are readily detaehable from their mountings in the storage compartment. Since conditions within the storage compartment are maintained so as to induce the accumulation of frost upon this removable surface, frost is prevented from accumulating on the remaining surfaces of the storage compartment and on the surfaces of the evaporator. Thus, this invention provides for the effective operation of the refrigerant evaporator, since there will be no accumulations of frost on the evaporator to impair the evaporating processes.

This invention essentially comprises a condensation bar which is formed of a material having a higher thermal conductivity than that of the material from which the inner liner for the storage compartment is formed. The condensation bar is detachably mounted in the extension members which are connected in heat-conducting relationship to the evaporator coils of the low temperature storage facility. Thus, this condensation bar is a supercold spot which becomes the focal point of the crystallization of the ice which forms the frost. The building up of the frost upon this supercold spot prevents the accumulation of frost upon the surfaces of the evaporator.

Thus, the defrosting of the low temperature storage facility provided with the present invention is accomplished by removing the condensation bar from the extension members and submerging the frost-laden condenatenr 2,998,7l3 Patented Sept. V 5, 1 961 ICC sation bar in hot Water so as to readily melt lthe frost therefrom.

It is therefore the principal object of this invention to provide a novel and improved apparatus for the defrosting of a low temperature storage facility such as a refrigerator or a freezer.

It is another object of this invention to provide an apparatus for inducing the accumulation of frost on a localized surface which is separate and independent from the remaining surfaces of the storage compartment.

It is a further object of this invention to provide an apparatus for the rapid removal of frost accumulations on the cold surface of a low temperature storage facility.

Other objects and advantages of this invention will become apparent upon reference to the accompanying description when taken in conjunction with the following drawings, wherein:

FIGURE 1 is a perspective view of an open home freezer of the chest type provided with the supercold surfaces of this invention;

FIGURE 2 is a sectional view taken along the line 2 2 of FIGURE 1 to show in plan view the detachable cold surface and its relationship to the inner liner of the storage compartment; and

FIGURE 3 is a `sectional view taken along the line 3-3 of FIGURE 2, showing the detachable cold surface in an elevational view.

Proceeding next to the drawings, wherein like reference symbols indicate lthe same parts throughout the various views, in FIGURE 1 there is illustrated a freezer 1 of the chest type wherein a door 2 is provided on the top surface of the freezer. This freezer is of the type commonly found in the home and is used for the purpose of storing foodstuffs and other perishables at temperatures below the freezing point of Water. These temperatures are generally of the order of `about 0 F.

The freezer l. has a Storage compartment 3 which is formed by an inner liner 4 made of steel or some other suitable metallic material. The liner 4 is surrounded by a housing 5 which is spaced from the liner so as to form a space 6 between the housing and the liner. Around the inner liner is Wrapped and soldered a refrigerant evapora-tor coil 7. The coil is preferably made from a material having a high thermal conductivity, such as copper. Insulating material 8 is then packed into the remainder of the space 6 around the coil 7.

In order to form a detachable supercold surface in the storage compartment 3, collars 9 are soldered to the coil 7. Each of said collars has an extension 10 which projects through an opening in the inner liner into the storage compartment of the freezer. 'Ihese collars are made of the same material as the coil in order to have a high thermal conductivity. There is a -bore 11 in the inner surface of each of the extensions 10. Detachably mounted in the bores 11 is a condensation bar 12 such as may b seen in FIGURE 3. The condensation 1oar 12. comprises a plurality of reverse bends 13, With the ends 14 and l15 of the condensation bar being inserted into the bores 11. The condensation bar l2 is also made of copper or some other material having a high thermal conductivity.

It will be seen that in the previously described structure,

Y the steel inner liner, which will have a lower thermal con- 3 4, very little, if any, frost will accumulate on the sur faces of the inner liner.

The condensation bars 12, as described above, are solid so as to facilitate the removal thereof from the extensions when it is desired to defrost these bars. lf desired, the condensation bars and extensions may be made hollow, so that a refrigerant may be passed through the condensation bars from the coil 7. With this modification, however, it will be necessary to provide a valve structure to shut off the flow of refrigerant through the condensation bar when it is desired to remove the bar to defrost the same.

While the present invention has been described in connection with a home freezer of the chest type, the invention can be readily used in freezers of the upright type or in the conventional household refrigerators which are maintained at a temperature above the freezing point of water.

The entire installation of the condensation bars in the extensions is very simple in structure and is economical to construct and maintain. The efficiency of this installation would be a function of the different heat conduetivities and the transfer and contact areas. Thus, while only two condensation bars have been illustrated in the freezer in FIGURE 2 incorporating this invention, it is to be understood that an additional number of condensation bars may be provided.

As can bc seen in FIGURE 2, the condensation bars are preferably positioned adjacent one of the walls of the inner liner, being spaced therefrom. This will provide a greater low temperature surface upon which frost can accumulate.

In operation, while the moisture-laden air of the storage compartment is enclosed therein, the existence of the cold spot condensation bars will enable the accumulation of frost upon the condensation bars rather than upon the surfaces of the inner liner through which the refrigerant effect is produced.

Thus it can be seen that the present invention provides a process for the defrosting of low temperature storage facilities, which process resides in providing a localized supercold spot within the storage compartment for the accumulation of frost thereon. Since these cold spots are readily removable from the storage compartment, accumulations of frost and ice can be easily removed therefrom. Since the accumulations of ice on these condensation bars will prevent the accumulation of frost on the evaporating surfaces of the storage compartment, the evaporator will be able to operate at a higher efficiency than when the evaporator surfaces are coated with accumulations of frost.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions, and accordingly, it is desired to comprehend such modifications within this invention as may fail within the scope of the appended claims.

What I claim is:

1. In a low temperature storage structure, a storage compartment having an inner lining of heat-conductive material, a refrigerant evaporating coil surrounding said liner to maintain the storage compartment at a low ternperature, said coil being formed from a material having a higher thermal conductivity than the material from which said inner liner is formed, and a condensation bar detachably mounted within said storage compartment and connected to said evaporator coil, said condensation bar having a higher thermal conductivity than the material from which said inner lining is formed for inducing the accumulation Iof frost on at least a portion of said condensation bar so as to prevent the accumulation of frost on the inner liner of said storage compartment.

2. In a low temperature storage structure, a storage compartment having a metallic inner liner, a housing surrounding said inner and spaced therefrom, a refrigerant evaporator coil in the space between said house and said inner liner and surrounding said inner liner to refrigerate the same, an insulating material in the space between said inner liner and said housing, an extension formed from a material of high thermal conductivity connected to said coil and extending through said inner liner into Said storage compartment, and a condensation bar of a material having a higher thermal conductivity than said inner liner and detachably mounted in said extension for inducing the accumulation of frost on at least a portion thereof so as to prevent the accumulation of frost on any other surfaces of said inner liner.

3. In a iow temperature storage structure, a storage compartment having a metallic inner liner, a housing surrounding said inner liner and spaced therefrom, a refrigerant evaporator coil in the space between said housing and said inner liner and surrounding said inner liner to refrigerate the same, an insulating material in the space between said inner liner and said housing, an extension formed from a material of high thermal conductivity connected to said coil and extending through said inner liner into said storage compartment, and a condensation bar of a material having a higher thermal conductivity than said inner liner and detachably mounted in said extension for inducing the accumulation of frost on at least a portion thereof so as to prevent the accumulation of frost on any other surfaces of said inner liner, said condensation bar being spaced from the surface of said inner liner.

4. In a low temperature storage compartment as claimed in claim 2 with said inner liner being formed from steel and said coil, extension, and condensation bar being formed from copper.

5. In a low temperature storage structure, a storage compartment having a metallic inner liner, a housing surrounding said inner liner and spaced therefrom, a refrigerant evaporator coil in the space between said housing and said inner liner and surrounding said inner liner to refrigerate the same, an insulating material in the space between said inner liner and said housing, a pair of extensions formed from a material of a higher thermal conductivity than said metallic inner liner connected to said evaporator coil and extending through said inner liner into said storage compartment, a condensation bar having a series of reverse bends with the ends of said bar being detachably mounted in said pair of extensions so that frost is accumulated on at least a portion of said condensation bar rather than on the other surfaces of said storage compartment.

6. In a low temperature storage structure, a storage compartment having an inner liner, a housing surrounding said inner liner and spaced therefrom, a refrigerant evaporator coil in the space between said housing and said inner liner and surrounding said inner liner to refrigerate the same, an insulating material in the space between said inner liner and said housing, means comprising a material of high thermal conductivity connected to said coil and extending through said inner liner into said storage compartment, and a condensation bar of a material having a higher thermal conductivity than said inner liner detachably mounted in said storage compartment for inducing the accumulation `of frost on at least a portion thereof so as to prevent the accumulation of frost on any other surfaces of said inner liner, said condensation bar being spaced from the surface of said inner liner.

7. ln a low temperature storage structure, a storage compartment having a heat conductive inner liner, a housing surrounding said inner liner and spaced therefrom, a refrigerant evaporator coil in the space between said housing and said inner liner and surrounding said inner liner to refrigerate the same, an insulating material in the space between said inner liner and said housing, means comprising a material of high thermal conductivity connected to said coil and extending through said inner liner into said storage compartment, and a condensation 5 s f bar of a material having a higher thermal conductivity References Cited in the le of this patent than said inner liner and detachably mounted in said storage compartment for inducing the accumulation of UNITED STATESVPATENTS. frost on at least a portion thereof so as to prevent the 2,442,978 Jones June 8, 1948 accumulation of frost on any other surfaces of said inner 5 2,478,017 Shoemaker AUS- 2, 1949 liner, 2,487,182 Richard Nov. 8, 1949

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