Conductive surface heater for a refrigerator   

Abstract: A heater is provided for elevating the temperature of a surface of a refrigerator above the dew point of air surrounding the surface so as to avoid condensation. Heat energy is recovered from the refrigeration cycle of the refrigerator by using a portion of the appliance's refrigeration loop to provide heat to the desired surface. A conductive element is connected with the desired surface and also placed into contact with a heated portion of the refrigeration loop to conduct heat energy therebetween. The surface and conductive element may be selectively removed and replaced from the refrigerator without the use of electric heating elements as conventionally required for removable surfaces.

FIELD OF THE INVENTION

The present invention provides a method and apparatus for heating a surface of a refrigerator, more particularly a removable surface of a refrigerator, in order to prevent condensation from forming on the surface.

BACKGROUND OF THE INVENTION

One problem frequently encountered with modern refrigerators is condensation on the outside of the cabinet or other surfaces of the refrigerator. Condensation occurs when a surface is at a temperature below the dew point temperature of the surrounding air. Once air contacts such surface, moisture in the air will condense on the surface. As such condensation accumulates, it may eventually drip or run onto the floor.

The lower temperature of these surfaces about the refrigerator is a result of the transfer of thermal energy between the refrigerator portions providing such surfaces and the refrigerated compartments as well as the movement of air across these surfaces when doors or compartments of the refrigerator are opened and shut. By way of example, surfaces on the mullion or divider between refrigerator doors, compartments, and drawers are prone to have condensation problems. Condensation can also occur, for example, on the front face of the refrigerator, the front portion of the outer case side and top walls adjacent the front edge of the case. By way of further example, such can also occur on the peripheral edges or walls of the doors, particularly the adjacent facing walls of the doors of multi-compartment units.

Conventionally, the condensation problem is solved by applying additional heat to a particular surface—thereby raising the temperature above the dew point of the surrounding air to prevent condensation. In some refrigerators this is accomplished by placement of an electric heater into a component of the refrigerator at a position adjacent and along the inside of the problematic surface. Other refrigerators may use heated refrigerant in a loop from the refrigeration cycle to heat the problematic surface by routing the loop through the component and placing the loop against such surface. However, in certain applications, the component having a condensation prone surface must also be removable, e.g., maintenance, cleaning, or repair. In such applications, use of a hot refrigerant loop is not practical because the integrity of the loop and containment of the refrigerant must be maintained. In such case, electric heaters can be used but are not as efficient as a heated refrigerant loop. Electric heaters must be separately powered whereas use of a heated refrigerant loop effectively captures heat produced by the refrigeration cycle that must otherwise be removed from the refrigerator. In addition, electric heaters are typically based on the use of a resistive element, which may have a shorter life span than the rest of the refrigerator.

Accordingly, an improved system for heating a surface of a refrigerator to avoid condensation problems is needed. More particularly, a system for heating a surface of a removable component of a refrigerator would be useful. A system that also recaptures energy from a heated refrigerant loop of the refrigeration cycle of the appliance would be particularly useful and efficient.

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. In one exemplary embodiment of the present invention, a conductive heater for increasing the temperature of a surface of a refrigerator is provided. The conductive heater includes a refrigeration loop providing the heat source for the conductive heater. A conductive element is attached along the inside of a component bearing the surface to be heated. The conductive element extends along at least part of the length of the component and in thermal communication therewith. The conductive element is also positioned into contact with the heat source of the refrigeration loop such that heat from the heat source may be transferred to the conductive element and to the surface of the component.

In another exemplary aspect of the present invention, a method for heating a surface of a refrigerator is provided. The method includes the steps of heating a refrigerant; circulating the refrigerant within a conduit in the refrigerator, the conduit having at least a portion that is placed in proximity to the surface to be heated; attaching a conductive element to a component of the refrigerator, the component bearing the surface to be heated; placing the conductive element into contact with the conduit; transferring heat from the refrigerant and conduit, through the conductive element, and to the surface to be heated; and raising the temperature of the surface above the dew point of air to which the surface is exposed.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 illustrates a front view of a refrigerator cabinet constructed according to an exemplary embodiment of the present invention. A partial cross-sectional view of a portion of the front is also included to show features located behind a surface that is to be heated above the dew point of the surrounding air as described more fully below. For clarity, exterior doors, internal drawers, and other features that might be included with the refrigerator are not shown as such can vary and will be well understood by one of skill in the art.

FIG. 2 illustrates a cross-sectional side view of the exemplary refrigerator cabinet of FIG. 1.

FIG. 3 is a perspective view of the inside surface of removable component or part that is heated according to an exemplary embodiment of the present invention.

FIG. 4 is a cross-sectional view, taken along lines 4-4 of FIG. 1, of the removable component that is heated according to an exemplary embodiment of the present invention.

FIG. 5 is a perspective view of the inside surface of another removable component or part that is heated according to an exemplary embodiment of the present invention.

FIG. 6 is a cross-sectional view, taken along lines 4-4 of FIG. 1, of another removable component that is heated according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

The present invention provides for heating a surface of a refrigerator above the dew point of air surrounding the surface so that condensation does not occur. Heat energy is recovered from a heat source within the refrigerator such as e.g., the refrigeration cycle of the refrigerator by using a portion of the appliance\'s refrigeration loop to provide heat to the desired surface. The present invention allows for the surface to be selectively removed and replaced from the refrigerator without the use of electric heating elements as conventionally required for removable surfaces. Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

FIG. 1 provides a front view of a refrigerator 100 having a cabinet 102 constructed according to an exemplary embodiment of the present invention. Cabinet 102 includes a freezer compartment 104 and fresh food compartment 106 arranged in an over-under configuration. Doors, drawers, and additional compartments as might otherwise be provided with refrigerator 100 are not shown as such can vary in style and location between different refrigerators and will be understood by one of skill in the art. In addition, the present invention can be used with different cabinet 102 constructions such as e.g., both top and bottom mount refrigerators.

Cabinet 102 includes what can be referred to as a mullion or partition 107, along with a removable covering 108, which divides compartments 104 and 106. Covering 108 includes a surface 110 for which heating is needed in order to prevent condensation. For example, surface 110 may be one that is exposed to cold air from the inside compartments 104 and/or 106 when doors to these compartments are opened. As such, surface 110 is cooled to a temperature below that of the ambient air surrounding refrigerator 100, and condensation will form on surface 110 upon exposure to such air. The heating of surface 110 or covering 108 is provided by way of example only. The present invention may be used to heat other surfaces (interior or exterior) of the refrigerator as well including, for example, along doors, drawers, flanges, and other components.

As will be understood by one of skill in the art, refrigerator 100 includes a refrigerant based cooling system that uses compression and vaporization of the refrigerant to remove heat (i.e. cool) from the inside compartments 104 and 106 of the refrigerator. As part of this conventional refrigeration cycle, the refrigerant is necessarily compressed to a higher pressure, which in turn heats up the refrigerant. This refrigerant must be further cooled and liquified before it can be vaporized to remove heat from the contents of the inside compartments 104 and 106 of the refrigerator 100. Typically, this cooling is accomplished by circulating the refrigerant after compression through coils (e.g., condenser coils) located on the rear of the refrigerator where heat can be exchanged with ambient air. The present invention efficiently uses at least a portion of the heat present in the refrigerant at this stage of the cycle to provide heat to the surface 110 for which raising the temperature is desired. Accordingly, the present invention efficiently recovers energy imparted to the refrigerant by compression so as provide heating for the desired surface 110.

More specifically, FIGS. 1 and 2 shows a loop 112 containing refrigerant that has been heated from being pressurized by compressor 114. Loop 112 may form the exothermic, condenser portion of the refrigeration cycle for refrigerator 100 or may be a sub-portion or a smaller loop thereof. Regardless, as the refrigerant flows out of compressor 114, it is at a higher temperature than the ambient air and/or casing of the refrigerator. Accordingly, as the refrigerant circulates about loop 112, heat is released and is available for exchange with air and/or components in contact with loop 112. By selecting a particular routing for loop 112 within cabinet 102, this heat may be made available at various locations in the refrigerator as needed for the heating of surfaces such as surface 110. For simplicity in explanation, other portions of a conventional refrigeration loop such as the evaporator, expander, and others are not shown in FIGS. 1 and 2 but will be understood by one of skill in the art.

FIG. 3 illustrates a rear view of covering 108 with an inside surface 114. FIG. 4 illustrates a cross-sectional view covering 108 installed on refrigerator 100. As shown, covering 108 includes a conductive element 116 positioned along the length of covering 108 and in thermal communication with covering 108 through e.g., contact with inside surface 110. Conductive element 116 is also in thermal communication with a conduit 120, through which heated refrigerant is flowing as described more fully below. For this exemplary embodiment, conductive element 116 is constructed as a round tube or heat pipe that extends along nearly the entire length of covering 108. However, longer or shorter configurations of element 116 may be used depending upon, for example, the amount of heat transfer needed or the extent of surface 110 over which temperature elevation is needed.

In a preferred embodiment, conductive element 116 forms a sealed interior 118 and includes a fluid that facilitates heat transfer. More particularly, by choosing a fluid with a relatively low boiling point, the fluid can operate as a thermosyphon within conductive element 116 to further effectuate the transfer of heat. By way of example, the fluid within conductive element 116 may be water or an alcohol such as methanol.

As used herein, thermosyphon refers to a method of heat exchange that uses natural convection to circulate a fluid without the use of a pump. Convective movement of the fluid within conductive element 116 starts when a portion of the fluid is heated by conduction of heat from the refrigerant in conduit 120. This heat causes a portion of the fluid to expand and become less dense, which in turn makes the heated portion of the fluid more buoyant than cooler portions of the fluid in conductive element 116. As a result, convection moves the heated portions of the fluid upward within the conductive element 116, which in turn is simultaneously replaced by cooler fluid under the effect of gravity. Accordingly, a circulation of fluid will occur within conductive element 116 that further facilitates heat transfer from conduit 120 to covering 108 such that conductive element 116 operates as a heat pipe supplying heat to raise the temperature of covering 108.

Using the teachings disclosed herein, one of skill in the art will understand that other constructions may be used for conductive element 116. FIG. 5, for example, provides another exemplary embodiment of conductive element 116 that has been formed with an arcuate shape. The arcuate shape enhances the thermosyphon effect for the fluid within conductive element 116 by providing height differences along its length. These differences in height will promote the flow of less buoyant, cooler fluid by operation of gravity to the lower portions of conductive element 116. In turn, by placing these lower portions into contact with conduit 120, this same fluid will then be heated and rise to the higher portions of conductive element 116 as circulation of the fluid occurs from natural convection.

By way of further example, conductive element 116 could be constructed without an interior fluid and could even be a solid piece of conductive material with interior 118. Regardless, conductive element 116 is constructed preferably from a thermally conductive material such as a metal. Conductive element 116 can also be formed with one or more flat surfaces to improve thermal contact and, therefore, the conduction of heat between conduit 120 and covering 108. For example, in FIG. 6, conduit 120 includes flat sides 126 in contact with conduit 120 and covering 108. These flats sides 126 increase the amount of surface area for contact thereby improving conductive heat transfer.

Referring to FIGS. 4 and 6, cabinet 102 and covering 108 form an interior space 122 through which conduit 120 passes. Conductive element 116 is also received into such interior space 122. A plurality of connectors 124 allow covering 108 to be removed or replaced onto cabinet 102 as needed. The ability to selectively remove covering 108 may be necessary, for example, so that maintenance, cleaning, repair, other functions may be performed.

Referring now more particularly to FIGS. 4 and 6, conductive element 116 is placed into thermal communication with conduit 120, through which refrigerant is flowing as indicated by arrows A. More particularly, conductive element 116 and conduit 120 preferably contact each other to facilitate effective heat transfer between the two. Although shown as contacting at right angles to one another in FIG. 4, other orientations including parallel, zig-zag, and numerous others may be applied so as to increase the amount of contact between conduit 120 and conductive element 116 and thereby improve heat transfer. Conduit 120 may be a portion of loop 112 or may be connected to or within loop 112 such that it is in receipt of the heated refrigerant flowing within loop 112.

Accordingly, during operation of refrigerator 100, refrigerant in loop 112 is heated by pressurization from pump or compressor 114. This refrigerant is circulated about loop 112. As shown in FIGS. 1, 2, 4 and 6, loop 112 is routed in proximity to covering 108 having surface 110 for which it is desired to raise its temperature to avoid condensation.

As the heated refrigerant passes around loop 112 and eventually travels within conduit 120, heat is transferred from the refrigerant, through conduit 120, and into and through conductive element 116. As a result, covering 108 is heated by contact of its rear surface 114 with conductive element 116. Eventually, as this heating continues, the temperature of surface 110 of covering 108 will be raised. By routing sufficiently heated refrigerant through conduit 120, the temperature of surface 110 can be raised to a level sufficient to remain above the dew point of air contacting or surrounding surface 110 while at the same time avoiding a surface too hot for human contact or the materials used for construction.

Accordingly, the present invention avoids electrical heating elements such as resistive wires in covering 108 by efficiently recovering heat energy from loop 112. In addition, covering 108 remains readily removable from cabinet 102.

It should be understood the present invention may be used with a variety of different appliance configurations including, for example, side-by-side fresh food and freezer compartments or all freezer or all fresh food appliances as well. In addition, the present invention may be applied to any refrigerator surface where condensation may present a problem provided heat from the refrigerant loop is available. More particularly, components other than covering 108 may also be heated using the present invention. Where needed, it should also be understood that multiple different surfaces of a refrigerator may also be heated using the present invention whereby condensation at multiple different locations may be avoided.

The exemplary embodiments of FIGS. 1 through 6 have been described using the exothermic portion of refrigeration loop 112 as a heat source. However, the present invention is not limited to the exothermic portion of refrigeration loop 112 and other warm sections of refrigerator loop 112 that are capable of providing heat energy for conductive element 116 may be used as a heat source as well.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.