Heat exchanger for an appliance   

FIELD OF THE INVENTION

The present invention relates to an improved heat exchanger for an appliance. More particularly, the present invention relates to a new condenser for a refrigerator that is formed in the shape of a conical helix.

BACKGROUND OF THE INVENTION

Modern refrigerator appliances use a gas-based refrigerant to provide cooling for the fresh food and/or freezer compartment of the refrigerator. The refrigerant is circulated within a loop that includes passage through the inside compartment(s) of the refrigerator. Heat is withdrawn from inside the refrigerator by changing state from a liquid to a gas. Thereafter, the refrigerant is compressed and subsequently cooled by passage through a heat exchanger—more commonly referred to as a condenser. The condenser is typically exposed to ambient air for heat exchange therewith.

The condenser\'s exchange of heat with ambient air requires that the condenser have enough surface area to adequately dissipate the heat created by compression. Typically, this surface area is provided, for example, by configuring the condenser as metal tubing positioned on the bottom or the rear of the refrigerator. Compressed refrigerant is circulated through the metal tubing. As ambient air comes into contact with the metal tubing, heat is exchanged and the refrigerant is cooled. Natural convection created by movement of the heated air across the surface of the metal tubing can facilitate the exchange of heat by carrying heated air away from the condenser, which will be replaced by cooler air.

There are certain challenges to the use of this conventional approach. For example, the addition of metal tubing onto the rear of the refrigerator increases the depth required for placement of the refrigerator within, for example, a kitchen area. For compact applications, such as under-the-counter installations, space is limited such that it may be difficult to use enough tubing or provide sufficient ventilation to achieve the necessary amount of heat exchange. Increasing the length of the tubing used for the condenser can increase the heat exchange capacity of the refrigerator but at the expense of increased materials costs for manufacture. The use of natural convection for the movement of air across the condenser can be inefficient for certain applications. Finally, the tubing of the condenser will frequently collect dust that is infrequently (if at all) removed by cleaning. Such dust will eventually decrease the heat exchange capability of the condenser as it builds up on the tubing.

Accordingly, an improved heat exchanger for cooling of the compressed gas portion of a refrigeration loop (i.e. condenser) is needed. More particularly, a heat exchanger that can provide improved efficiency in cooling the compressed gas would be useful. Such a heat exchanger for a refrigerator condenser that can be efficiently used in compact appliance designs would also be beneficial. Additionally, a heat exchanger that can also tolerate dust would provide additional advantages.

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 invention, a refrigerator having a gas cooling device is provided. The refrigerator includes a refrigerant system having a condenser portion for cooling a refrigerant. The condenser portion is constructed from a thermally-conductive conduit wound in the shape of a conical helix. The conical helix defines a spiral axis. A plurality of radial spine fins project from the surface of the thermally-conductive conduit to provide additional surface area for heat transfer.

In another exemplary embodiment, the present invention provides a gas cooling device for use in a refrigerator. The gas cooling device includes a conduit for carrying refrigerant. The conduit is formed into the shape of a conical helix having an axis about which the conical helix is coiled. The conduit has a surface with pin-like elements projecting from the surface. The conduit and the pin-like elements are constructed from one or more thermally-conductive materials.

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 provides a front view of a refrigerator, with doors to the fresh food and freezer compartment opened, according to an exemplary embodiment of the present invention.

FIG. 2 provides a schematic of a refrigeration loop having an exemplary embodiment of a heat exchanger according to the present invention.

FIG. 3 illustrates a perspective view of an exemplary embodiment of a heat exchanger of the present invention.

FIG. 4 provides a top view of the exemplary embodiment of FIG. 3.

FIG. 5 provides a perspective, end view of an exemplary embodiment of a heat exchanger of the present invention including a conduit covered with radial spine fins.

DETAILED DESCRIPTION

The present invention relates to an improved heat exchanger for an appliance. More particularly, the present invention relates to a new condenser for a refrigerator that is formed from conduit wound into the shape of a conical helix. Extensions from the surface of the conduit provide additional area for heat exchange. 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 representative refrigerator 10 incorporating an exemplary embodiment of a heat exchanger 66 of the present invention. For illustrative purposes, the present invention is described with a refrigerator 10 having a construction as shown and described further below. As used herein, a refrigerator includes appliances such as a freezer, refrigerator/freezer combination, compact, and any other style or model of a refrigerator. Accordingly, other configurations including multiple and different styled compartments could be used with refrigerator 10, it being understood that the configuration shown in FIG. 1 is by way of example only.

Refrigerator 10 includes a fresh food storage compartment 12 and a freezer storage compartment 14. Freezer compartment 14 and fresh food compartment 12 are arranged side-by-side within an outer case 16 and defined by inner liners 18 and 20 therein. A space between case 16 and liners 18 and 20, and between liners 18 and 20, is filled with foamed-in-place insulation. Outer case 16 normally is formed by folding a sheet of a suitable material, such as pre-painted steel, into an inverted U-shape to form top and side walls of case 16. A bottom wall of case 16 normally is formed separately and attached to the case side walls and to a bottom frame that provides support for refrigerator 10. Inner liners 18 and 20 are molded from a suitable plastic material to form freezer compartment 14 and fresh food compartment 12, respectively. Alternatively, liners 18, 20 may be formed by bending and welding a sheet of a suitable metal, such as steel. The illustrative embodiment includes two separate liners 18, 20 as it is a relatively large capacity unit and separate liners add strength and are easier to maintain within manufacturing tolerances. In smaller refrigerators, a single liner is formed and a mullion spans between opposite sides of the liner to divide it into a freezer compartment and a fresh food compartment.

A breaker strip 22 extends between a case front flange and outer front edges of liners 18, 20. Breaker strip 22 is formed from a suitable resilient material, such as an extruded acrylo-butadiene-styrene based material (commonly referred to as ABS). The insulation in the space between liners 18, 20 is covered by another strip of suitable resilient material, which also commonly is referred to as a mullion 24. In one embodiment, mullion 24 is formed of an extruded ABS material. Breaker strip 22 and mullion 24 form a front face, and extend completely around inner peripheral edges of case 16 and vertically between liners 18, 20. Mullion 24, insulation between compartments, and a spaced wall of liners separating compartments, sometimes are collectively referred to herein as a center mullion wall 26. In addition, refrigerator 10 includes shelves 28 and slide-out storage drawers 30, sometimes referred to as storage pans, which normally are provided in fresh food compartment 12 to support items being stored therein.

Refrigerator 10 is controlled by a microprocessor (not shown) according to user preference via manipulation of a control interface 32 mounted in an upper region of fresh food storage compartment 12 and coupled to the microprocessor. A shelf 34 and wire baskets 36 are also provided in freezer compartment 14. In addition, an ice maker 38 may be provided in freezer compartment 14.

A freezer door 42 and a fresh food door 44 close access openings to fresh food and freezer compartments 12, 14, respectively. Each door 42, 44 is mounted to rotate about its outer vertical edge between an open position, as shown in FIG. 1, and a closed position (not shown) closing the associated storage compartment. Freezer door 42 includes a plurality of storage shelves 46, and fresh food door 44 includes a plurality of storage shelves 48.

FIG. 2 is an elevational schematic view of refrigerator 10 (shown in FIG. 1) including an exemplary sealed cooling system 60. In accordance with known refrigerators, refrigerator 10 includes a machinery compartment 62 that at least partially contains components for executing a known vapor compression cycle for cooling air. The components include a compressor 64, a heat exchanger or condenser 66, an expansion valve 68, and an evaporator 70 connected in series and charged with a refrigerant. Evaporator 70 is also a type of heat exchanger which transfers heat from air passing over the evaporator to a refrigerant flowing through evaporator 70 thereby causing the refrigerant to vaporize. As such, cooled air is produced and configured to refrigerate compartments 12, 14 of refrigerator 10.

From evaporator 70, vaporized refrigerant flows to compressor 64, which operates to increase the pressure of the refrigerant. This compression of the refrigerant raises its temperature, which is lowered by passing the gaseous refrigerant through condenser 66 where heat exchange with ambient air takes place so as to cool the refrigerant. A fan 72 is used to pull air across condenser 66, as illustrated by arrows A, so as to provide forced convection for a more rapid and efficient heat exchange between the refrigerant and the ambient air.

Expansion valve 68 further reduces the pressure of refrigerant leaving condenser 66 before being fed as a liquid to evaporator 70. Collectively, the vapor compression cycle components in a refrigeration circuit, associated fans, and associated compartments are sometimes referred to as a sealed refrigeration system operable to force cold air through refrigeration compartments 12, 14. The refrigeration system depicted in FIG. 2 is provided by way of example only. It is within the scope of the present invention for other configurations of the refrigeration system to be used as well.

Referring now to FIG. 3, a close-up of an exemplary embodiment of the heat exchanger or condenser 66 is provided. As shown, condenser 66 is constructed from a thermally-conductive conduit 74 wound into the shape of a conical helix having axis T-T. A conical (a/k/a conic) helix can be described as a spiral wrapped over a conical surface. Each loop 76 of the conical helix of conduit 74 is at a radius R. Preferably, the radius R of each successive loop 76 increases along axis T-T in the direction of air flow shown by arrows A. Stated differently, the conical helix of condenser 66 tapers in a direction opposite to that of the air flow induced by fan 72. However, it should be understood that the opposite direction for air flow A may also be used as well.

In addition, for the exemplary embodiment of FIG. 3, fan 72 is located at an end 78 of conduit 74 having the largest radius R for loops 76. The blades of fan 72 are configured to pull air across the conduit 74 of condenser 66. As shown in FIG. 4, the interior 80 of conduit 74 remains unobstructed so that air may flow freely within the interior 80 of conduit 74 as well.

The use of a conical helix as shown for the construction of conduit 74 increases the heat transfer capability of condenser 66. It is believed that this configuration improves contact between condenser 66 and air flowing across it. More specifically, the use of fan 72 further increases the heat transfer efficiency by providing for a more rapid supply of non-heated air to condenser 66 and by increasing the overall heat transfer coefficient therebetween by increasing the velocity of the air flow above that which would occur solely by natural convection if fan 72 were not used. Additionally, the conical helix improves the flow of air across all portions of conduit 74, thereby reducing the tendency for a build-up of dust on condenser 66 that would otherwise reduce its heat exchange efficiency.

To further improve the flow of air for heat exchange, condenser 66 may be positioned within a compartment created by walls 82 positioned about condenser 66 and fan 72. Walls 82 assist fan 72 in providing for a flow of air across condenser 66 to further improve heat transfer. Walls 82 can be, for example, positioned within machinery compartment 62 to help direct the flow of unheated air from outside the refrigerator 10 and across condenser 66. Furthermore, by using fan 72 and/or walls 82, the velocity of air across condenser 66 can be increased which aids in reducing the build-up of dust that can reduce the heat exchange capability of condenser 66.

As shown more particularly in FIG. 5, the surface of conduit 74 is covered with multiple, pin-like elements or fins 84 that project out radially from conduit 74. Radial spine fins 84 increase the area available for heat transfer with the air. As heated refrigerant flows through conduit 74, heat energy is conducted from the refrigerant and into radial spine fins 84 where additional surface area is provided for heat exchange with air passing across condenser 66. As such, radial spine fins 84 further increase the heat transfer capability of condenser 66.

Preferably condenser 66 and radial spine fins 84 are constructed from a thermally-conductive material such as one or more metals. For example, condenser 66 may be readily constructed from copper that can be wound into the conic helix as discussed above. However, other conductive materials may be used 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.