Hydrocarbon refrigeration system with convection channel

Abstract

A refrigeration system including a cabinet having an outer wall defining an insulated interior, an inner wall, and an insulative material disposed between the outer and inner walls. A cooling system is disposed in a space beneath the cabinet and cools the insulated interior. A convection channel is disposed between the outer and inner walls and extends and communicates air from an area outside an upper portion of the cabinet to the space beneath the cabinet. The channel is positioned within about 1.905 cm from the inner wall. The channel may have a plurality of different widths and may include a thermal bridge extending from the inner wall to the channel. The channel may include a primary branch extending from the upper portion of the cabinet to a junction point and a plurality of secondary branches extending from the junction point to a plurality of locations beneath the cabinet.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to refrigeration systems, particularly refrigeration systems that use hydrocarbon refrigerants and means for venting hydrocarbon refrigerant leaks.

2. Description of the Related Art

Refrigerators commonly include an insulated cabinet, the interior of which is cooled by a cooling system. The cooling system is typically disposed within a housing, which is located beneath or behind the cabinet. The cooling system generally includes a compressor; a condenser fluidly connected to the compressor; and an evaporator fluidly connected to both the compressor and the condenser and in thermal communication with the interior of the cabinet. In operation, a refrigerant gas enters the compressor where it is compressed under high pressure. The compressed refrigerant gas then flows to the condenser where it is cooled in a series of coils and is condensed into a liquid. The liquid refrigerant then flows to the evaporator where the liquid refrigerant absorbs heat from the interior of the cabinet, thereby cooling the interior and converting the refrigerant liquid back to a gas. The refrigerant gas then flows back to the compressor where the cycle is repeated. A fan is typically incorporated in the cooling system to cool the compressor and force air through the condenser coils.

An effective refrigerant should be capable of readily evaporating at low temperatures and compressing at high pressure without decomposing. Consequently, compounds that are ideal for use as refrigerants are stable compounds having low evaporation temperatures. In the past, CFCs (chlorofluorocarbons) have been used as refrigerants. However, it is believed that CFCs are harmful to the environment and, as a result, hydrocarbon refrigerants, such as propane and isobutanes, have been used in place of CFCs. Unfortunately, hydrocarbon refrigerants have a Low Flammability Limit, which means that even a small hydrocarbon refrigerant leak in the housing could result in a build up of hydrocarbon refrigerant to a concentration level above the Low Flammability Limit. A concentration of hydrocarbon refrigerant above the Low Flammability Limit is sufficient to trigger an explosion in the presence of oxygen and a flame or spark.

If a hydrocarbon refrigerant leak occurs while the fan is running, the hydrocarbon refrigerant is, to some degree, flushed from the housing by the fan. However, the fan typically does not run when the temperature in the interior of the cabinet is within a specified range. If a hydrocarbon refrigerant leak occurs when the fan is off, the hydrocarbon refrigerant concentration can accumulate in the housing to a level exceeding the Low Flammability Limit, thereby creating favorable combustion conditions.

Attempts have been made to prevent hydrocarbon refrigerant leaks by reducing the number of joints in the condenser, where leaks are most likely to occur. In addition, the operating pressure may be reduced in an effort to prevent hydrocarbon refrigerant leaks. Attempts have also been made to develop systems for detecting hydrocarbon refrigerant leaks. Such systems may monitor the thermal dynamic parameters of the system and/or the electrical consumption of the compressor, or may sense the molecules of hydrocarbon refrigerant in the air. Despite these attempts, a need remains for a system that ventilates the cooling system area to effectively flush, dissipate and dilute hydrocarbon refrigerant leaks from the housing area.

SUMMARY OF THE INVENTION

The present invention provides a refrigeration system including a cabinet having an outer wall, an inner wall defining an insulated interior, and an insulative material disposed between the outer and inner walls. A cooling system is disposed in a space beneath the cabinet and cools the insulated interior of the cabinet. A convection channel is disposed between the outer and inner walls and extends from an area outside an upper portion of the cabinet to the space beneath the cabinet. The channel communicates air from the area outside the upper portion of the cabinet to the space beneath the cabinet to vent the cooling system.

The present invention also provides a refrigeration system including a cabinet having an outer wall, an inner wall defining an insulated interior, and an insulative material disposed between the outer and inner walls; a cooling system disposed in a space outside a lower portion of the cabinet for cooling the insulated interior of the cabinet; and a convection channel disposed between the outer and inner walls. The channel is spaced apart from the inner wall and extends from an area outside an upper portion of the cabinet to the space outside the lower portion of the cabinet. The channel communicates air from the area outside the upper portion of the cabinet to the space outside the lower portion the cabinet to vent the cooling system. The refrigeration system also includes at least one thermal bridge extending from the inner wall of the cabinet to the channel.

In addition, the present invention provides a refrigeration system including a cabinet having an outer wall, an inner wall defining an insulated interior, and an insulative material disposed between the outer and inner walls; a cooling system disposed in a space outside a lower portion of the cabinet for cooling the insulated interior of the cabinet; and a convection channel disposed between the outer and inner walls and extending from an area outside an upper portion of the cabinet to the space outside the lower portion of the cabinet. The channel includes a plurality of widths, each of which decreases in size as the channel extends from the upper portion of the cabinet to the lower portion of the cabinet. The channel communicates air from the area outside the upper portion of the cabinet to the space outside the lower portion the cabinet to vent the cooling system.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a front sectional view of a refrigeration system in accordance with the present invention;

FIG. 2 is a side sectional view of a refrigeration system of FIG. 1 taken along line 2-2 in FIG. 1;

FIG. 3 is a top perspective view of a cooling system in accordance with the present invention;

FIG. 4 is a top perspective view of the housing of the cooling system of FIG. 3;

FIGS. 5 and 6 are side sectional views of a prior art refrigeration system;

FIG. 7 is a front sectional view of another embodiment of the refrigeration system in accordance with the present invention;

FIG. 8 is a front sectional view of another embodiment of a refrigeration system in accordance with the present invention;

FIG. 9 is a front sectional view of another embodiment of a refrigeration system in accordance with the present invention;

FIG. 10 is a front sectional view of another embodiment of a refrigeration system in accordance with the present invention;

FIG. 11 is a side sectional view of another embodiment of a refrigeration system in accordance with the present invention;

FIG. 12 is a side sectional view of another embodiment of a refrigeration system in accordance with the present invention;

FIG. 13 is a top view of a cooling system according to one embodiment of the present invention;

FIG. 14 is a top view of a cooling system in accordance with another embodiment of the present invention;

FIG. 15 is a top view of a cooling system of a prior art refrigeration system;

FIG. 16 is a side sectional view of a prior art refrigeration system; and

FIG. 17 is a side sectional view of another embodiment of a refrigeration system in accordance with the present invention.

DETAILED DESCRIPTION

The embodiments hereinafter disclosed are not intended to be exhaustive or limit the invention to the precise forms disclosed in the following description. Rather the embodiments are chosen and described so that others skilled in the art may utilize its teachings.

Referring first to FIGS. 1 and 2, refrigeration system 10 according to the present invention generally includes cooling system 30 and cabinet 12. Cabinet 12 includes outer wall 14, inner wall 16 and insulative material 18 disposed between outer and inner walls 14 and 16. Inner wall 16 defines insulated interior 20, which is cooled by cooling system 30. Cooling system 30 is located within housing 40, which is positioned beneath cabinet 12. Cooling system 30 generally includes compressor 32; condenser 36, which is fluidly connected to compressor 32; evaporator 34, which is fluidly connected to both compressor 32 and condenser 36 and is in thermal communication with cabinet interior 20; and fan 38.

Referring now to FIGS. 3 and 4, compressor 32, condenser 36, evaporator 34, and fan 38 are contained within housing 40. Housing 40 is substantially rectangular and includes base 42, front wall 44, back 50, and pair of sidewalls 54, 56, all of which cooperate to define interior space 41. Front wall 44 includes first air inlet 46 through which air from outside housing 40 can enter space 41. Condenser 36 is positioned adjacent first air inlet 46 such that the cool ambient air drawn into space 41 through first air inlet 46 flows over the coils of condenser 36, thereby aiding in the cooling and condensing of the hydrocarbon refrigerant contained within the coils. Back 50 includes first air outlet 52 through which air can exit space 41. It should be understood that first air outlet 52 need not be a slot defined in a back wall as depicted in FIGS. 3 and 4. Instead, back 50 can be open to the space outside housing 40 such that nearly the entirety of back 50 can serve as first air outlet 52. In addition, first air inlets 46 need not be horizontal slots defined in front wall 44. Instead, first air inlets 46 may be any shape, size, or design that will allow air to flow into housing 40, for example, vertical slots.

As illustrated in FIGS. 5 and 6, refrigeration systems are commonly positioned near a wall W of a building structure. Referring particularly to FIG. 5, when fan 38 is running, air is drawn into space 41 through air inlet 46 and is then forced out of space 41 and upward between wall W and outer wall 14 of cabinet 12, thereby dissipating any hydrocarbon refrigerant that might have leaked into space 41. When fan 38 is not running, as illustrated in FIG. 6, the temperature of the air in space 41 begins to rise due to the heat created by compressor 32. The warm air (represented by wavy arrows) then begins to rise between outer wall 14 of cabinet 12 and wall W. However, the contrastingly cool ambient air (represented by straight arrows) located above cabinet 12 begins to sink between wall W and outer wall 14. The sinking ambient air (straight arrows) counteracts the rising air (wavy arrows) from space 41, thereby preventing further upward movement of the air from space 41 and, ultimately, preventing the dissipation of any hydrocarbon refrigerant that might have leaked into space 41.

Referring back to FIGS. 1 and 2, to vent space 41 and flush out any hydrocarbon refrigerant, refrigeration system 10 includes convection channel 26. Convection channel 26 is disposed between outer wall 14 and inner wall 16 of cabinet 12 and extends from upper portion 22 of cabinet 12 to lower portion 24 of cabinet 12. Channel 26 communicates with the air outside upper portion 22 of cabinet 12 by extending at one end through outer wall 14 at the top of cabinet 12. Channel 26 communicates at its opposite end with space 41 within housing 40 by extending through outer wall 14 at the bottom of cabinet 12. Channel 26 is positioned at a distance d from inner wall 16 and has a width or diameter D. Channel 26 is cooled by transferring heat to nearby cooled interior 20 of cabinet 12.

In operation, cool ambient air from outside upper portion 22 of cabinet 12 sinks into channel 26 where it is further cooled by nearby interior 20. As the air within channel 26 cools, its density increases. The dense cool air in channel 26 overcomes the warm buoyant air from space 41, thereby forming a downward draft or flow through channel 26, as illustrated in FIG. 2.

To facilitate the cooling of the air within channel 26 and, thereby, the downward draft of air through channel 26, channel 26 is positioned from inner wall 16 at distance d, which is no greater than that which would allow adequate cooling of channel 26. More particularly, positioning channel 26 within about 1.905 centimeters (¾ inch) of inner wall 16 achieves effective cooling of the air within channel 26 and sufficient downward airflow. As shown in FIG. 8, channel 26 may be located directly adjacent inner wall 16 such that the wall of channel 26 abuts the inner wall 16 of cabinet 12. This direct thermal contact between inner wall 16 and channel 26 further facilitates the transfer of heat from channel 26 to interior 20 and, ultimately, the cooling of the air within channel 26.

To further facilitate the efficient and effective downward flow of air through channel 26, channel diameter D should be large enough to allow effective downward flow, but not so large as to require an inefficient and unnecessarily large amount of heat transfer into interior 20. Channel diameters D falling between 0.3175 cm and 2.54 cm (⅛″ and 1″) achieves effective and efficient cooling and airflow. As shown in FIG. 7, channel 26 may include multiple diameter portions, D₁, D₂. Channel 26 includes an upper portion having diameter D₁ and a lower portion having smaller diameter D₂. The larger diameter D₁ of the upper portion of channel 26 insures sufficient cooling of the ambient air entering channel 26. The smaller diameter D₂ of the lower portion of channel 26 reduces the amount of warm air that rises up from space 41 into channel 26.

As shown in FIGS. 9 and 10, refrigeration system 10 may also include one or more thermal bridges 28 extending from inner wall 16 of cabinet 12 to channel 26. Thermal bridges 28 facilitate the heat transfer from channel 26 to interior 20, thereby more effectively cooling the air within channel 26. As shown in FIG. 9, thermal bridges 28 can be comprised of a conductive material, such as aluminum, copper and/or steel. Alternatively, as shown in FIG. 10, thermal bridges 28 may comprise a gap in insulative material 18 between channel 26 and inner wall 16.

Turning now to FIG. 1, channel 26 need not necessarily extend through outer wall 14 at the top of cabinet 12, as shown in FIGS. 1-2 and 7-10. Instead, channel 26 can penetrate outer wall 14 at the upper side of cabinet 12, as shown in FIG. 11. In this particular embodiment, channel 26 includes an angled portion which is angled relative to the outer wall 14. To avoid restricting air flow through channel 26, the angle θ of the channel should be no greater than 75° with respect to the vertical.

Referring now to FIG. 12, channel 26 may also be branched to allow the venting of multiple locations in space 41. As shown in FIG. 12, channel 26 includes primary branch 27, which extends from the top of cabinet 12 to a junction point P; and two secondary branches 29A, 29B, which extend from junction point P to the bottom of cabinet 12. Secondary branches 29A, 29B penetrate outer wall 14 at the bottom of cabinet 12 in two different locations. Particularly, secondary branch 29A pierces outer wall 14 near front wall 44 just above condenser 36 to vent the condenser coils, while secondary branch 29B pierces outer wall 14 near back 50 to vent space 41 near evaporator 34. It should be understood that channel 26 can include any number of secondary branches extending to a variety of different locations in space 41. In addition, secondary branches 29A, 29B can extend at any angle with respect to the vertical, provided that the angle does not restrict the flow of air. More particularly, secondary branch angles β measuring 75° or less with respect to the vertical achieve adequate airflow.

In another embodiment of the present invention illustrated in FIGS. 13 and 14, fan 38 is positioned within housing 40 such that the axis A of fan 38 is aligned along a vertical plane that defines a non-perpendicular angle α₁ relative a vertical plane P₁ aligned perpendicular to back 50 of housing 40. Referring particularly to FIG. 13, fan 38 creates a first horizontal air flow f₁ in which air is drawn into housing 40 through first air inlet 46 and forced out of housing 40 through first air outlet 52 in a direction non-perpendicular to back 50. Fan 38 directs the exiting first horizontal air flow f₁ in one horizontal direction between wall W and back 50 of housing 40. First horizontal airflow f₁ then mixes with ambient air, thereby diluting and dissipating any hydrocarbon refrigerant.

First horizontal air flow f₁, in turn, engages the air outside housing 40 and induces a second horizontal air flow f₂ in a direction substantially parallel to the diagonal X of base 42. In other words, second horizontal air flow f₂ flows about housing 40 in a direction that is non-perpendicular to housing 40. The non-perpendicular direction of second horizontal air flow f₂ causes air flows f₁ and f₂ to meet and mix in a mixing region, which is represented by the encircled area in FIG. 13. This mixing of first and second horizontal air flows f₁ and f₂ further dilutes and dissipates any hydrocarbon refrigerant in first horizontal air flow f₁ to more effectively dilute the hydrocarbon refrigerant and maintain the hydrocarbon refrigerant concentration at a level below the Low Flammability Limit.

Referring now to FIG. 15, in prior refrigeration systems fan 38a is positioned with its axis A perpendicular to back 50a. In this configuration, fan 38a creates air flow f_1a in which air is drawn into housing 40a through air inlet 46a and forced out through outlet 52a in a direction perpendicular to back 50a. The exiting air flow is deflected by wall W in both horizontal direction. Generally, first air flow f_1a does not induce a substantial second air flow f_2a. However, the second air flow f_2a that is induced does not flow in the direction of the housing diagonal. Instead, second air flow f_2a encounters front wall 44a and is deflected in a direction parallel to wall 44a. Consequently, first and second air flows do not meet and do not further mix in a mixing region.

Referring back to FIG. 13, angle α₁ of fan 38 can be any angle that is non-perpendicular to back 50. However, favorable air flow results are achieved when fan 38 is positioned such that non-perpendicular angle α₁ is between about 5° and 75° relative to a vertical plane P₁ aligned perpendicular to the back 50 of housing 40.

Referring now to FIGS. 3, 4 and 14, refrigeration system 10 may include partition 60 which extends from front wall 44 to side wall 54 to create compressor enclosure 62. Compressor 32 may then be positioned within compressor enclosure 62 to shield the compressor, which includes electrical components having the potential of producing a spark, from the condenser, which is the component from which hydrocarbon refrigerant leaks most likely occur. In this arrangement the potential for combustion is reduced by physically separating the spark source from the leak source. Still referring to FIGS. 3, 4 and 14, housing 40 may also include a second air inlet 48 defined in front wall 44 and second air outlet 58 defined in side wall 54. Both second air inlet 48 and second air outlet 58 are in communication with the interior of compressor enclosure 62 to vent compressor 32. As noted above, second horizontal air flow f₂ flows about housing 40 in a direction non-perpendicular to housing 40. Second horizontal airflow f₂ induces a third horizontal airflow f₃, which enters compressor enclosure 62 through second air inlet 48 and exits compressor enclosure 62 through second air outlet 58, thereby cooling compressor 32.

Referring now to FIG. 16, in prior systems fan 38a is positioned such that a horizontal plane aligned along axis A defines a perpendicular angle relative to back 50a. In this configuration air flows into housing 40a through air inlets 46a and exits housing 40a through air outlets 52a. The air exiting housing 40a flows in a direction perpendicular to back 50a such that when the air meets the wall W it is deflected in both the upward and downward directions. The air flowing in the downward direction then flows under housing 40a. When the air exits the area beneath housing 40a, the air can be drawn back into housing 40a through air inlet 46a. Consequently, the air flowing downward never leaves the area beneath cabinet 12a and can be re-circulated back into space 41a of housing 40. This may ultimately result in a hydrocarbon refrigerant accumulation to a level above the Low Flammability Level.

Referring now to FIG. 17, according to the present invention, fan 38 may also be inclined, as shown in FIG. 17. More specifically, fan 38 may be positioned such that a horizontal plane aligned along axis A defines a second non-perpendicular angle α₂ relative to a horizontal plane P₂ aligned perpendicular to back 50 of housing 40. In this embodiment fan 38 induces a vertical air flow f₄ in which air exiting first air outlet 52 is directed upward, thereby preventing the flow of air beneath housing 40 and preventing the re-circulation of air into housing 40. Angle α₂ can be any angle non-perpendicular to horizontal plane P₂. However, favorable vertical air flow results are achieved when fan 38 is positioned such that a horizontal plane aligned along the axis A defines a non-perpendicular angle α₂ of between about 15° and 65° relative to horizontal plane P₂, which is aligned perpendicular to back 50 of housing 40.

While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.

Claims

1. A refrigeration system comprising:

a cabinet having an outer wall, an inner wall and an insulative material disposed between said outer and inner walls, said inner wall defining an insulated interior;

a cooling system for cooling said insulated interior of said cabinet, said cooling system disposed in a space beneath said cabinet; and

a convection channel disposed between said outer and inner walls and extending from an area outside an upper portion of said cabinet to said space beneath said cabinet, said channel communicating air from said area outside said upper portion of said cabinet to said space beneath said cabinet to vent said cooling system.

2. The refrigeration system of claim 1 further comprising at least one thermal bridge extending from said inner wall of said cabinet to said channel.

3. The refrigeration system of claim 2 wherein said at least one thermal bridge is comprised of a conductive material.

4. The refrigeration system of claim 2 wherein said insulative material is disposed between said inner wall and said channel; and said at least one thermal bridge is comprised of a gap in said insulative material.

5. The refrigeration system of claim 1 wherein said channel is positioned within a distance of about 1.905 cm from said inner wall.

6. The refrigeration system of claim 5 wherein said channel is positioned directly adjacent said inner wall.

7. The refrigeration system of claim 1 wherein said channel has a plurality a different widths.

8. The refrigeration system of claim 1 wherein a portion of said channel extends at an angle with respect to said outer wall.

9. The refrigeration system of claim 8 wherein said angle is less than about 75°.

10. The refrigeration system of claim 1 wherein said channel is branched, said branched channel comprising a primary branch extending from said area outside said upper portion of said cabinet to a junction point; and a plurality of secondary branches extending from said junction point to a plurality of locations in said space beneath said cabinet to vent said plurality of locations.

11. A refrigeration system comprising:

a cabinet having an outer wall, an inner wall and an insulative material disposed between said outer and inner walls, said inner wall defining an insulated interior;

a cooling system for cooling said insulated interior of said cabinet, said cooling system disposed in a space outside a lower portion of said cabinet;

a convection channel disposed between said outer and inner walls, said channel spaced apart from said inner wall and extending from an area outside an upper portion of said cabinet to said space outside said lower portion of said cabinet, said channel communicating air from said area outside said upper portion of said cabinet to said space outside said lower portion said cabinet to vent said cooling system; and

at least one thermal bridge extending from said inner wall of said cabinet to said channel.

12. The refrigeration system of claim 111 wherein said at least one thermal bridge is comprised of a conductive material.

13. The refrigeration system of claim 11 wherein said insulative material is disposed between said inner wall and said channel; and said at least one thermal bridge is comprised of a gap in said insulative material.

14. The refrigeration system of claim 11 wherein said channel is positioned within a distance of about 1.905 cm from said inner wall.

15. The refrigeration system of claim 11 wherein a portion of said channel extends at an angle with respect to said outer wall.

16. The refrigeration system of claim 11 wherein said angle is less than about 75°.

17. The refrigeration system of claim 11 wherein said channel is branched, said branched channel comprising a primary branch extending from said area outside said upper portion of said cabinet to a junction point; and a plurality of secondary branches extending from said junction point to a plurality of locations in said space outside said lower portion of said cabinet to vent said plurality of locations.

18. A refrigeration system comprising:

a cabinet having an outer wall, an inner wall and an insulative material disposed between said outer and inner walls, said inner wall defining an insulated interior;

a cooling system for cooling said insulated interior of said cabinet, said cooling system disposed in a space outside a lower portion of said cabinet; and

a convection channel disposed between said outer and inner walls and extending from an area outside an upper portion of said cabinet to said space outside said lower portion of said cabinet, said channel having a plurality of widths, said plurality of widths decreasing in size as said channel extends from said upper portion of said cabinet to said lower portion of said cabinet, said channel communicating air from said area outside said upper portion of said cabinet to said space outside said lower portion said cabinet to vent said cooling system.

19. The refrigeration system of claim 1 wherein said channel is spaced apart from said inner wall and said channel is positioned within a distance of about 1.875 cm from said inner wall.

20. The refrigeration system of claim 19 further comprising at least one thermal bridge extending from said inner wall of said cabinet to said channel.

21. The refrigeration system of claim 20 wherein said at least one thermal bridge is comprised of a conductive material.

22. The refrigeration system of claim 20 wherein said insulative material is disposed between said inner wall and said channel; and said at least one thermal bridge is comprised of a gap in said insulative material.

23. The refrigeration system of claim 18 wherein said channel is positioned directly adjacent said inner wall.

24. The refrigeration system of claim 18 wherein a portion of said channel extends at an angle of between about 7° and 75° with respect to said outer wall.

25. The refrigeration system of claim 18 wherein said channel is branched, said branched channel comprising a primary branch extending from said area outside said upper portion of said cabinet to a junction point; and a plurality of secondary branches extending from said junction point to a plurality of locations in said space outside said lower portion of said cabinet to vent said plurality of locations.