BACKGROUND
The present invention relates to refrigerated merchandisers, and more particularly to refrigerated merchandisers including open commercial refrigerated merchandisers.
Refrigerated merchandisers are typically used in retail food store settings such as grocery stores and convenience stores where fresh food product is displayed in a refrigerated environment. In general, refrigerated merchandisers include a case defining a product display area for supporting and displaying food products to be visible and accessible through an access opening in the case. Some merchandisers include doors to enclose the product display area and other refrigerated merchandisers are open to the ambient environment. Open refrigerated merchandisers utilize one or more air curtains that flow over the access opening to form a barrier between the refrigerated product display area and the ambient environment.
Refrigerated merchandisers also typically include one or more shelves that are used to support and display the food product. The shelves extend generally horizontally from a rear wall of the refrigerated merchandiser and are arranged vertically relative to one another within the display area. Existing refrigerated merchandisers cool food products on the shelves from the rear wall of the merchandiser forward by discharging cooling air from rear wall apertures. Cooling fans circulate the cooling air forward.
A particular challenge of open refrigerated merchandisers is maintaining a uniform temperature within the display area. The front of the display is not only further from the discharged cooling air but is also exposed to warmer ambient air infiltrating the air curtain. Therefore, the front of the display is warmer than the rear of the display. Current methods for homogenizing the temperature within the display area include increasing air velocity within the case and additional convection cooling apparatuses. The current solutions, however, require more energy usage and have variable efficacy depending on product layout and snowing-up patterns of the evaporator.
SUMMARY
In one aspect, the present invention provides a refrigerated merchandiser including a case defining a product display area and including an air inlet and an air outlet in communication with the product display area to form an air curtain across a front of the product display area. The refrigerated merchandiser also includes a shelf that is coupled to the case within the product display area. The shelf includes insulation between a top and a bottom of the shelf, and a passive heat exchanger that has a heat pipe embedded in the shelf within the insulation and that extends from a front of the shelf to a back of the shelf. Ambient air infiltrating the air curtain initiates passive heat transfer within the plurality of heat tubes.
In another aspect, the invention provides a shelf configured to be attached to a merchandiser. The shelf includes a top wall, a front wall coupled to the top wall, side walls coupled to the front wall and the top wall, and a bottom wall coupled to the front wall and the sidewalls to enclose a space between the top wall, the front wall, the side walls, and the bottom wall. The shelf also includes insulation disposed in the space and a passive heat exchanger disposed in the space. The passive heat exchanger has a heat pipe that is embedded within the insulation and that extends from a front of the shelf to a back of the shelf. Passive heat transfer is configured to be initiated by ambient air infiltrating the merchandiser.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross-section view of a refrigerated merchandiser embodying the present invention and illustrating a plurality of shelves.
FIG. 2 is a schematic perspective view of one of the shelves of FIG. 1 including heat pipes.
FIG. 3 is a schematic perspective view of a portion of the shelf of FIG. 2.
FIG. 4 is a front perspective view of the shelf of FIG. 2 supporting food product and temperature measurement equipment.
FIG. 5 is a graph illustrating surface temperatures associated with the shelf of FIG. 4.
FIG. 6 is another graph illustrating temperatures associated with food product supported by the shelf of FIG. 4.
FIG. 7 is a chart illustrating surface temperatures of the shelf of FIG. 4.
FIGS. 8 is another chart illustrating temperatures food product supported by the shelf of FIG. 4.
FIG. 9 is a section view of an exemplary heat pipe for the shelf of FIGS. 2-4.
Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The application is capable of other embodiments and of being practiced or of being carried out in various ways.
DETAILED DESCRIPTION
FIG. 1 illustrates a refrigerated merchandiser 10 that may be located in a supermarket or a convenience store for displaying fresh food product 14 to consumers. The merchandiser 10 includes a case 18 having a base 22, a rear wall 26, sidewalls (not shown), a canopy 30, and a customer access opening 34. The rear wall 26, base 22, sidewalls, and canopy 30 cooperate to define a partially enclosed product display area 38. The product display area 38 supports the food product 14 in the case 18. The food product 14 is displayed on a plurality of shelves 42 within the product display area 38. Each shelf 42 projects forward from the rear wall 26 and is accessible through the access opening 34.
In the embodiment of FIG. 1, the refrigerated merchandiser 10 is an open-front merchandiser with access opening 34 exposed to an ambient environment. In other embodiments, the access opening 34 may be enclosed by one or more doors (e.g., separated by mullions). The merchandiser 10 includes a refrigeration system 44 (not entirely shown) that is in communication with the product display area 38 to provide refrigerated air (denoted by arrows 48) to the product display area 38. As shown, the refrigeration system 44 includes an evaporator 52 that is disposed in an air passageway 56 of the case 18, a compressor (not shown), and a condenser (not shown) connected in series. Refrigerated airflow 48 exits the evaporator 52 and is directed through the air passageway 56 and is discharged into the display area 38 as an air curtain that maintains proper temperature conductions for food product 14 on display.
The airflow 48 is discharged through the canopy 30 through an air outlet 60 and is directed downward through the product display area 38 toward the base 22. At least a portion of the airflow 48 is returned to the air passageway 56 of the refrigeration system 44 via an air inlet 64. As shown in FIG. 1, the airflow 48 is drawn into the air passageway 56 by a fan 68 upstream of the evaporator 52. The air inlet 64 is located adjacent a bottom end of the display area 38 and the air outlet 60 is located adjacent a top end of the product display area 38.
With continued reference to FIG. 1, the rear wall 26 includes an inner panel 72 that at least partially defines the air passageway 56. The inner panel 72 includes a plurality of perforations 76 that are in communication with the air passageway 56. The perforations 76 allow a portion of the airflow 48 to discharge from the air passageway 56 along a rear portion of the refrigerated merchandiser 10 and into the product display area 38. In some embodiments, the perforations 76 include a matrix of circular openings through the inner panel 72. In other embodiments, the perforations 76 may be vents that are constructed as elongate (e.g., rectangular) openings through the inner panel 72. It will be appreciated that various other shapes, sizes, and arrangements for the perforations 76 are also possible in other embodiments.
Referring to FIG. 2, each of the shelves 42 includes a top wall 80, two sidewalls 84, and a front wall 88. Some or all of the walls 80, 84, 88 may be separate pieces that are coupled together, or some or all of the walls 80, 84, 88 may be formed by bending or shaping a single piece of material such that edges are defined between the walls (i.e. the walls are coupled together at the edge). It will be appreciated that two or more of the walls may be coupled together by insulation 89. In the illustrated embodiment, the top wall 80, the sidewalls 84, and the front wall 88 cooperate to define an interior volume of the shelf 42. In some embodiments, the walls 80, 84, 88 form a solid shelf 42 (i.e. filled with insulation 89). With reference to FIGS. 1 and 2, the shelf 42 is coupled to the rear wall 26 (e.g., via brackets 90) and projects forward toward the front of the merchandiser 10. As shown, the top wall 80 projects generally perpendicular from the inner panel 72 and the sidewalls 84 and the front wall 88 extend substantially perpendicular to the top wall 80. In some embodiments, the shelves 42 may include a bottom wall 92.
With reference to FIGS. 2 and 3, one or more of the shelves 42 includes a passive heat exchanger 100. The illustrated passive heat exchanger 100 is formed by one or more thermally conductive heat pipes 102 (e.g., with a thermal conductivity range between 1,000 and 10,000 W/m° K). As shown in FIGS. 2, 3, and 9, each heat pipe 102 is defined by an elongate tube (e.g., a cylindrical or rectangular prism) that supports a wick 103 and a working fluid 104, and that has a first end 106 positioned at or adjacent the front wall 88 and a second end 110 positioned at or adjacent the inner panel 72. Each heat pipe 102 may be embedded in the shelf 42 and may be coupled to the interior of the shelf via elongate grooves 114 (e.g., defined within insulation 89). The heat pipes 102 can be secured within the elongate grooves 114 by a press-fit attachment, soldering or welding, thermal epoxies, or any other suitable attachment mechanism. It will be appreciated that the heat pipes 102 may be coupled to an underside of the top wall 80 without grooves (e.g., adhered or otherwise attached to the top wall 80, sandwiched between the top wall and the bottom wall 92, etc.).
The heat pipes 102 are metallic and are vacuumed-sealed. As shown in FIG. 9, the wick 103 defines a capillary lining that may be fixed to the inner walls of the heat pipe 102 and may include a metallic material (e.g., sintered copper, screen mesh, grooved metal, etc.). Other wicking materials that are suitable for flow of the working fluid 104 through the wick 103 may be used in combination with or in lieu of metallic material. The first end 106, which is proximate to the customer access opening 32 and the front of the shelf 42, defines an evaporator side of the heat pipe 102. The second end 110, which is proximate to the inner panel 72 and the rear of the shelf 42 defines a condenser side of the heat pipe 102.
Referring to FIG. 2, the passive heat exchanger 100 includes six linear heat pipes 102 that extend between the rear wall of the shelf 42 and the front wall 88 in a direction that is perpendicular to the front wall 88. The illustrated heat pipes 102 also are parallel to each other. It will be appreciated that the shelf 42 may have fewer than six heat pipes or more than six heat pipes. The heat pipes 102 form a one- or two-phase heat transfer mechanism to transfer infiltrating heat adjacent the front of the shelf 42 toward the rear of the shelf 42. to maintain more uniform temperature within the product display area 38, especially in regions adjacent the heat pipe 102 on the shelf 42. The passive heat exchanger 100 limits temperature fluctuations by cooling the portion of the shelf 42 adjacent the access opening 34 to reduce or eliminate the warmer region. This results in a uniform temperature profile across the shelf 42 and a more consistent overall temperature within the merchandiser 10.
The passive heat exchanger 100 can be retrofit into existing merchandisers (e.g., by replacing existing shelves with shelves 42 that have the passive heat exchanger 100. Separately or in addition, the passive heat exchanger 100 may be integrated into different parts of the merchandiser 10 to facilitate even distribution of conditioning air relative to warm and cold areas within the merchandiser 10. For example, and with reference to FIG. 1, the merchandiser may include a deck plate 134 that partially defines the display area 38 (i.e. a lower boundary of the display area 38). The deck plate 134 is positioned above the base 22 and, in some embodiments, a passive heat exchanger that is the same as the passive heat exchanger 100 may be embedded in the deck plate 134 (e.g., in an insulation-filled cavity in the deck plate 134).
In operation, refrigerated airflow 48 may be discharged through the plurality of perforations 76 and into the display area 38. In some constructions, conditioned air may only be distributed to the product display area 38 via the air outlet 60 (e.g., when the merchandiser 10 does not include the perforations 76), or in combination with the perforations 76. Ambient air may infiltrate the display area 38 through the access opening 34. The ambient air is generally warmer than the refrigerated airflow 48 forming the air curtain 48 at the front of the customer access opening 34. The ambient air heats the working fluid within the first end 106 of the heat pipe 102. The working fluid vaporizes on the evaporator side and increases pressure within the heat pipe 102. As the pressure increases, the vaporized working fluid flows rearward via the wick toward the condenser side, proximate the inner panel 72. At the second end 110, the vaporized working fluid discharges heat as it is cooled and condensed. The condensed working fluid travels back toward the warmer first end 106, evenly distributing a cooling effect within the display area 38.
FIG. 4 illustrates an exemplary refrigerated merchandiser 10 with a passive heat exchanger 100 including a heat pipe 102 that is embedded in the shelf 42, which supports food product 14. Temperature sensors 118 are coupled to the top wall 80 (e.g., in a test environment) to measure temperatures of the shelf 42 in different locations (e.g., over a section 120 of the shelf 42). For example, and as shown in FIG. 4, one or more sensors 118 are positioned on the exterior side of the top wall 80 directly over the heat pipe 102, and other sensors 118 are positioned on the top wall 80 opposite sides of the heat pipe 102 (e.g., on a side to the left of the heat pipe 102 and on a side to the right of the heat pipe 102). The portions of the shelf 102 to the left and the right of the heat pipe 102 define left and right test sections of the shelf 42, respectively, and the portion of the shelf 102 that is centered over the heat pipe defines a center test section.
FIG. 5 graphically illustrates an average temperature profile of an exemplary shelf 42 that includes the heat pipe 102 when the evaporator 52 has a setpoint of 26° Fahrenheit. FIG. 7 illustrates temperature data provided by the sensors 118 in the left test section, the center test section, and the right test section. As shown, the heat pipe 102 maintains a more uniform surface temperature on the shelf 42 (at the center) when compared to the left and right test sections that do not include a heat pipe. More specifically, and with reference to FIG. 7, the average temperature difference or variation on the top wall 80 in the center test section, from adjacent the front of the shelf 42 to adjacent the inner panel 72, is approximately 2.1° Fahrenheit, whereas the average temperature differences on the top wall 80 in the left test section and the right test section (from front-to-back on the top wall 80) are approximately 7.4° and 7.3° Fahrenheit, respectively. Stated another way, the heat pipe 102 decreases the temperature variation on the top wall 80, on average, from front to back by approximately 70% relative to sections or portions of the shelf 42 without a heat pipe. The second chart in FIG. 7 illustrates the temperature profile of the shelf 42 in the left, center, and right test sections when the refrigeration system 44 is in a defrost mode. As will be appreciated by one of ordinary skill in the art, even during defrost the heat pipe 102 maintains a more uniform (e.g., a decrease in temperature variation of approximately 58%) and lower overall surface temperature on the shelf 42 relative to the sections to the left and right of the heat pipe 102. The third chart in FIG. 7 illustrates the temperature profiles of the left, center, and right test sections of the shelf 42 soon after defrost has been terminated (e.g., before frost buildup in the evaporator 52) and shows that the heat pipe 102 maintains a more uniform temperature profile from front to back on the shelf 42 than in the left and right test sections (e.g., a 70% decrease in temperature variation on the top wall 80 from front to back relative to sections or portions of the shelf 42 without a heat pipe).
FIGS. 6 and 8 illustrate similar uniformity in the temperature variation, from front to back, for food product (tested using food product simulators) that is supported on the shelf 42 over the heat pipe 102 and a decrease in temperature variation relative to food product that is supported on the shelf 42 to the left and right of the food product supported over the heat pipe 102. More specifically, and with reference to FIG. 8, the average temperature difference or variation for food product in the center test section, from adjacent the front of the shelf 42 to adjacent the inner panel 72, is approximately 5.9° Fahrenheit, whereas the average temperature differences for food product in the left test section and the right test section (from front-to-back) are approximately 8.2° and 8.1° Fahrenheit, respectively. Stated another way, the heat pipe 102 decreases the temperature variation of food product, on average, from front to back by approximately 27% relative to food product on sections or portions of the shelf 42 without a heat pipe. The second chart in FIG. 8 illustrates the temperature profile of food product in the left, center, and right test sections when the refrigeration system 44 is in a defrost mode. Even during defrost, the heat pipe 102 maintains a more uniform (e.g., approximately a 25% decrease in temperature variation) and lower overall temperature of food product relative to the sections to the left and right of the heat pipe 102. The third chart in FIG. 8 illustrates the temperature profiles of food product supported in the left, center, and right test sections of the shelf 42 soon after defrost has been terminated (e.g., before frost buildup in the evaporator 52) and shows that the heat pipe 102 maintains a more uniform temperature profile from front to back on the shelf 42 than in the left and right test sections (e.g., a 27% decrease in temperature variation from front to back relative to food product in sections or portions of the shelf 42 without a heat pipe).
In some embodiments, the top wall 80 be encapsulated by a shelf cover and may be formed of a material suitable to spread the cooling impact of the heat pipe 102 (e.g., metal) toward and at least partially into the sections of the shelf 42 that are adjacent and to the left or right of the heat pipe 102. The heat pipe(s) 102 may be embedded in insulation 89 to facilitate a more significant and direct impact on the temperature of the shelf 42 and food product supported on the shelf 42. Also, by using several heat pipes 102 in a given shelf 42 (and or/in the deck plate 134), the heat pipes 102 can be spaced so that sections of the shelf 42 between the heat pipes 102 are minimized to avoid less uniform temperature variations from front to back on the shelf 42. In general, the embedded heat pipe 102 makes the cooling effect predictable and reliable regardless the layout or loading of product on the shelf 42. Existing systems that use an evaporator coil in a shelf cannot achieve the uniformity of temperature, from front to back in the product display area 38, associated with the invention described herein.
Various features of the disclosure are set forth in the following claims.
Patent Application
20230225523
