Patent Application
20170208966
The present invention relates to refrigerated merchandisers, and more particularly to doors for refrigerated merchandisers.
Refrigerated merchandisers are used by grocers to store and display food items in a product display area that must be kept at a predetermined temperature. These merchandisers generally include a cabinet with an integrated refrigeration unit and have multiple shelves supported within the product display area. Doors positioned along the front side of the merchandiser separate the product display area from the ambient external conditions and allow for consumer access to the contents within. The doors typically include one or more panes of glass configured to minimize heat transfer while providing unimpaired visual access to the product display area.
Due to the conditions of the environment in which they operate, refrigerated merchandisers are frequently susceptible to condensation on various surfaces. Condensation typically forms on the interior and exterior faces of the glass doors as ambient air with a certain moisture content contacts a surface that has been cooled below the dew point of that air. For example, a refrigerated merchandiser in a grocery store may have a glass door with multiple panes. The pane of glass adjacent the refrigerated interior will likely be below the dew point of the store side (ambient) air. Opening the door will expose the face of this relatively cold pane to the ambient air, resulting in condensation (e.g., “fogging”) on this interior surface. In addition, the pane of glass on the store side of the door is also often at or below the dew point of the store side ambient air, which can lead to continuous condensation on this external glass surface, and, due to heat transfer between the glass and the surrounding door molding, can likewise create condensation on the cooled exterior molding surface as well.
The result of such condensation is the formation of visible water on the glass, which not only impedes the customer's line of sight from the exterior store side into the refrigerated interior, but which may also collect to form puddles of water near the door leading to a dangerous slippery condition for customers. To prevent condensation, conventional doors for refrigerated merchandisers typically include an electrically heated coating on the interior surface of the store-side glass to raise the temperature of the glass above the dew point of the store-side ambient air. But such a heated coating is constantly energized and consequently incurs energy costs for the store owner. And depending on where the coating is located on the glass surface, it may not provide sufficient heating to the surrounding door molding to hinder condensation on the molding.
In one construction, the invention provides a door for a refrigerated merchandiser including a case that defines a product display area. The door includes a frame and a first glass pane coupled to the frame. The first glass pane has heat-absorbing glass and is configured to be positioned adjacent an ambient environment surrounding the refrigerated merchandiser to absorb radiation from the ambient environment. The door also includes a second glass pane coupled to the frame and configured to be positioned adjacent the product display area. The second glass pane includes a conductive coating. The door further includes a third glass pane positioned between and spaced from the first glass pane and the second glass pane, and has a low emissivity coating.
In another construction, the invention provides a refrigerated merchandiser including a case that defines a product display area, and a door coupled to the case and enclosing a portion of the product display area. The door includes a frame and a first glass pane coupled to the frame. The first glass pane has heat-absorbing glass and is positioned adjacent an ambient environment surrounding the refrigerated merchandiser to absorb radiation from the ambient environment. The door also includes a second glass pane coupled to the frame and positioned adjacent the product display area. The second glass pane includes a conductive coating. The door further includes a third glass pane positioned between and spaced from the first glass pane and the second glass pane, and has a low emissivity coating.
In another construction, the invention provides a method of preventing condensation on a door of a refrigerated merchandiser defining a product display area and surrounded by an ambient environment. The door includes a first glass pane that is positioned adjacent the ambient environment, a second glass pane that is positioned adjacent the product display area, and a third glass pane that is positioned between and spaced apart from the first pane and the second pane. The method includes absorbing radiation from the ambient environment and incident on the first glass pane, increasing the temperature of a surface of the first glass pane facing the ambient environment above the dew point of the ambient environment, heating the second glass pane, and reflecting radiation with a low emissivity coating affixed to the third glass pane.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention 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 invention is capable of other embodiments and of being practiced or of being carried out in various ways.
With reference to
The exterior glass pane 150 includes a first surface 151 that faces away from the product display area 114 and that is exposed to the ambient environment 148, and a second surface 152 opposite the first surface 151 that faces toward the product display area 114. The exterior glass pane 150 is formed of a heat absorbing glass, which absorbs a significant quantity of incident infrared radiation from the ambient environment 148 and consequently reduces the amount of infrared radiation transmitted through the glass. The term “heat-absorbing glass” means glass that is specifically constructed for such a purpose, and includes glass containing quantities of ferrous iron or other material selected to provide a similar effect. The term “radiation” encompasses radiation across the electromagnetic spectrum, including infrared, visible light, and ultraviolet radiation. Specifically, the heat absorbing glass pane 150 absorbs approximately 35-55% of incident infrared radiation or heat from the ambient environment 148 while allowing approximately 70-90% of visible light to be transmitted. Other ranges of both absorption and transmittance for the exterior glass pane 150 are possible and considered herein. Absorbed radiation retained within the glass structure of the exterior glass pane 150 generates heat, which raises the temperature of the exterior glass pane 150, and specifically the temperature of the first surface 151, above the dew point of the ambient environment 148.
The interior glass pane 160 includes a first surface 161 that faces away from the product display area 114, and a second surface 162 that faces toward and is exposed to the product display area 114. The interior glass pane 160 is formed of tempered glass, which is heat-treated glass heated above the annealing temperature and rapidly cooled, forming an outer glass layer with compressive stresses surrounding an inner glass layer in tension. Tempered glass, when broken, fragments into relatively small pieces less likely to injure someone and is frequently used instead of annealed glass in applications requiring such safety.
With continued reference to
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The door frame 134 also includes an insert 200 that separates and spaces the exterior glass pane 150, the interior glass pane 160, and the intermediate glass pane 170 from each other and from the door frame 134. The insert 200 wraps around the perimeter of the glass panes 150, 160, 170, and includes an outer spacer 204 and an inner spacer 208. The spacers 204, 208 are sized to define a first space 212 between the exterior glass pane 150 and the intermediate glass pane 170, and a second space 216 between the interior glass pane 160 and the intermediate glass pane 170. The first and second spaces 212, 216 can have any suitable dimension (e.g., approximately 0.5″ between the second surface 152 of the exterior glass pane 150 and the first surface 171 of the intermediate glass pane 170, and between the second surface 172 of the intermediate glass pane 170 and the first surface 161 of the interior glass pane 160). The first and second spaces 212, 216 between the glass panes 150, 160, 170 can be filled with any suitable air or non-reactive gas (e.g., nitrogen). As will be appreciated by one of ordinary skill in the art, a relatively small space between glass panes 150, 160, 170 may result in greater heat transfer within the space, while a relatively large space may promote convection within the space.
An exterior portion 220 of spacer 204 engages the surface 152 of exterior pane 150 while an exterior portion 222 of spacer 208 engages the surface 161 of interior pane 160. Interior portions 224, 226 of spacers 204, 208 engage surface 171 and surface 172, respectively, of intermediate pane 170. A bridge 236 contacts the top and bottom edges 174, 176 of intermediate pane 170. A first projection 240 contacts the top and bottom edges 154, 156 of exterior pane 150 and a second projection 244 contacts the top and bottom edges 164, 166 of interior pane 160. Each of the spacers 204, 208 provides sealing contact between the door frame 134 and the glass panes 150, 160, 170 to limit infiltration of ambient air into the product display area 114. Each spacer 204, 208 can be filled with a desiccant 250 or other hygroscopic material, and is in fluid communication with one of the first and second spaces 212, 216 to attract and retain any moisture within the first and second spaces 212, 216. Aluminum tape 260 can be applied to the insert 200 to provide an additional barrier to moisture entering first and second spaces 212, 216.
A portion of the heat absorbed by the exterior glass pane 150 transfers to the door frame 134 and heats the door frame 134. Specifically, a portion of the heat absorbed by the exterior glass pane 150 will be transferred to the outer flange 194, and consequently to an exterior surface 270 of the door frame 134. As described above, heating the exterior glass pane 150, and in particular the first surface 151, as well as the exterior surface 270 of the door frame 134 above the dew point of the ambient environment 148 prevents formation of condensation on both surfaces.
The insert 200 is formed of a substantially flexible material (e.g., polypropylene) to provide a flexible partition between panes 150, 160, and 170, and the door frame 134. The exterior glass pane 150 expands in size as it is heated, and the flexibility of the door frame 134 and the insert 200 accommodates this expansion without producing excessive stresses within glass assembly 146. Additionally, the flexible nature of the door frame 134 and the insert 200, which positions and secures the intermediate glass pane 170 within the glass assembly 146, allows for relative movement between glass panes 150, 160, and 170. The flexible spacer 204, first projection 240, and bridge 236 allow for relative movement between the exterior glass pane 150 and the intermediate glass pane 170 due to expansion and retraction of exterior glass pane 150. Similarly, the flexible spacer 208, second projection 244, and bridge 236 allow for relative movement between the interior glass pane 160 and the intermediate glass pane 170 due to expansion and retraction of interior glass pane 160. This relative movement between glass panes 150, 160, and 170 further minimizes stresses within the glass assembly 146.
In operation, some incident radiation from the ambient environment 148 is directly absorbed by the heat absorbing exterior glass pane 150. The incident radiation not absorbed by the exterior glass pane 150 passes through the exterior glass pane 150 and is reflected by one or both of the low-e coatings 182, 184 of the intermediate glass pane 170 back toward the exterior glass pane 150. The reflected incident radiation increases the overall percentage of incident radiation absorbed by exterior glass pane 150. The absorption of additional incident radiation by the exterior glass pane 150 produces more heat within exterior glass pane 150, which raises the temperature of both the first surface 151 of exterior glass pane 150 and the exterior surface 270 of the door molding 134. The increased temperature on the first surface 151 and the exterior surface 270 minimizes or prevents the formation of condensation on the surfaces 151, 270.
The heated coating 180 heats the interior glass pane 160 to de-fog any condensation that forms on the second surface 162 of interior pane 160. Power can be supplied to the heated coating 180 continuously or at predetermined intervals. With no external power needed to obtain the thermal benefits associated with the exterior glass pane 150, the glass panes 150, 160, 170 cooperate with each other to provide an effective, safe, and low-cost way to eliminate condensation on the glass assembly 146 and the door frame 134.
Various features and advantages of the invention are set forth in the following claims.
This application is a continuation of U.S. patent application Ser. No. 13/186,623, filed Jul. 20, 2011, which published as U.S. Publication No. 2013/0019616 on Jan. 24 2013, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13186623 | Jul 2011 | US |
| Child | 15481933 | US |
