United States Patent 3724236

A compact evaporator unit for refrigerators comprising a helically coiled tubular member having an extended heat exchange surface in the form of a mass of metal wool within and in contact with the coils.

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International Classes:
F25B39/02; (IPC1-7): F25D17/06
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Primary Examiner:
Perlin, Meyer
I claim

1. A refrigerator comprising an evaporator chamber having spaced inlet and outlet passages, opposed walls between said passages and an evaporator in said chamber;

2. A refrigerator including an evaporator chamber and means for circulating a stream of air to be cooled through said chamber;

3. A refrigerator including an evaporator chamber comprising opposed walls and having an air inlet adjacent one end thereof and an air outlet adjacent the other end and an evaporator in said chamber;

4. A refrigerator according to claim 3 including metal liners on the inner surfaces of said walls in contact with said coils.

5. A refrigerator including a horizontal evaporator chamber comprising top and bottom walls and having an air inlet adjacent one end thereof and an air outlet adjacent the other end and an evaporator in said chamber;


Evaporators for refrigerators, including freezers, comprise a tubular member for the circulation of refrigerant and an extended heat transfer heat exchange surface for providing the desired heat exchange between the refrigerant and the air circulated over the evaporator.

In many modern refrigerators in which the evaporator is housed in a chamber separate from the refrigerator storage area, the evaporators comprise continuous lengths of refrigerant tubing having either plate-like fins or having one or more longitudinal flanges extending outwardly from the tubing wall, these flanges being slit to provide a plurality of individual finger-like fins which may be alternately bent laterally from the original plane of the flange or twisted to induce a better heat exchange contact between the heat exchange surfaces and the surrounding air.

In these known evaporator units, the fins form the exterior surfaces of the units and are substantially exposed to initial contact with the air stream being cooled in order to provide excellent heat exchange. However, in the manufacture of such evaporators, in order to provide the desired length of refrigerant tubing in an evaporator sized to be contained within a given space, the tubing has been formed to serpentine shape requiring either sharp bends or preformed return bends.


It is an object of the present invention to provide an evaporator structure free of sharp bends and characterized by the fact that all of the extending heat transfer surfaces are contained within the space defined by the shaped refrigerant tubing.

In accordance with the illustrated embodiment of the present invention, there is provided a refrigerator having an evaporator chamber containing a refrigerant evaporator unit comprising a helically coiled tubular member in which the coils thereof are spaced from one another. The space or volume within the helically coiled member is filled with resilient metal wool forming the extended heat transfer surface and the air to be cooled is circulated through the evaporator unit in a direction perpendicular to the axes of the coils.


In the accompanying drawing:

FIG. 1 is a vertical side elevational view through a portion of a refrigerator embodying the present invention; and

FIG. 2 is a horizontal sectional view taken generally along line 2--2 of FIG. 1.


While the present invention is applicable to any refrigerator (including freezers) having one or more storage compartments and an evaporator for cooling the compartment disposed in an evaporator chamber remote from the compartments, it will be particularly described with reference to a refrigerator such as that described in U.S. Pat. No. 3,320,761--Gelbard to which reference is made for detailed description of refrigerator components other than the evaporator component forming the subject matter of the present invention.

With reference to FIG. 1, the illustrated refrigerator comprises an upper freezer compartment 1 and a lower fresh food storage compartment 2 separated by an insulated partition generally indicated by the numeral 3. The partition 3 includes upper and lower walls 4 and 5 and opposed side walls 7 (FIG. 2) defining an evaporator chamber 6.

For the purpose of maintaining these two storage compartments at the desired operating temperatures by means of an evaporator contained within the evaporator chamber, a fan 8 is provided for withdrawing air from the two storage compartments through passages 9 and 10 in the partition at the forward or inlet end of the evaporator chamber and returning cooled air to the compartments through passages 11 and 12 at the rear or outlet end of the evaporator chamber 6.

In place of the plate-on-tube evaporator disclosed in the aforementioned Gelbard patent, there is provided in accordance with the present invention an improved evaporator structure generally indicated by the numeral 14. This evaporator is positioned transversely of the evaporator chamber 6. It comprises a tubular member 15 of aluminum forming the refrigerant conduit coiled to have a substantially helical form with adjacent coils 16 spaced from one another to form an open helix. The extended heat transfer surface for transferring heat from a stream of air passed over the evaporator to the refrigerant flowing through the tubular member 15 comprises a mass of metal wool 17, preferably shredded aluminum, which is resilient and in heat exchange engagement with the tubing 15.

The heat exchanger is preferably made from a continuous extruded aluminum tube stock formed or coiled into a helix after which the metal wool of suitable density is inserted into the hollow center of the coil. The coils may be partially flattened to an elliptical form as illustrated in FIG. 1.

In the illustrated embodiment of the invention, the evaporator 14 actually comprises two helically coiled portions extending parallel to one another and transversely of the chamber 6, one coiled section 19 of which is partially straightened and deformed to provide the connection between the two sections at one side of the evaporator.

With reference to FIG. 2 of the drawing, it will be seen that air drawn into the front or inlet end of the evaporator chamber 6 by operation of the fan 8 flows laterally or transversely between the evaporator coils, i.e., through the spaces 18 between the coils. Since the metal wool is all contained within the helix, the air initially contacts the tubular member 15 where any moisture begins to collect in the form of frost. The air passing through the passages 18 then passes through the mass of metal wool 17 and finally between the coil portions on the down stream side of the helix. By this construction frost is distributed on all of these surfaces, much of it collecting on the portions of tubing 15 initially contacted by the air stream.

A particular advantage of the evaporator of the present invention as compared with prior art evaporators is that in its finished form all of the extended surface is within the volume occupied by the tubular member or in other words the entire outer surface of the evaporator is defined by the smooth surfaces of the tubular member. Thus the evaporator can be readily handled during assembly thereof into the refrigerator.

Also, since the metal wool forming the extended surface is within the round or oval or elliptical coils, the tubing portion of the evaporator does not have to be bent around as tight a radii in order that the evaporator be contained within a reasonable volume. In this connection, it will be noted that the evaporator completely fills the chamber 6 insofar as its lateral dimensions are concerned. In other words, the portions of the coil surfaces adjacent the walls 4 and 5 are in contact therewith, thus providing for the placement of a maximum length of the tubular member within the volume of the evaporator chamber and at the same time providing adequate extended surface area.

For maximum heat transfer, the evaporator is supported directly on a metal drain pan 20 on the bottom wall 5 of the evaporator chamber and a metal liner 21 is provided on the upper wall 4 in direct engagement with the upper surfaces of the tubing 15. Both of these components thereby function as additional extended heat transfer surfaces.

In addition, the subject evaporator construction is not limited to a single heat exchanger size. Without major expenditure, the evaporator width, depth and thickness can be varied through a large range by changing the number of coils, size of the coils, the number of rows of coils and the amount of coil flattening.

Preferably, the evaporator is periodically defrosted by use of a radiant heater such as that described in Turner, U.S. Pat. No. 3,280,581. Such a heater, indicated generally by the numeral 22 in FIGS. 1 and 2 of the drawing, is positioned to one side of a coil section or when more than one section is employed is positioned between and parallel to the adjacent sections as illustrated in the drawing. Both the pan 20 and the liner 21 act as radiation reflectors so that heat from the radiant heater so placed will rapidly warm all portions of the evaporator to defrosting temperatures.

While there has been shown and described a particular embodiment of the present invention, it will be understood that it is not limited thereto and it is intended by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.