Abstract:
An enclosure cooling system for cooling the interior of an enclosure having therein a first shelf adjacent to an evaporator coil in a cyclic refrigeration system and a second shelf positioned on the opposite side. A thermoelectric cooling module is affixed and thermally coupled to the second shelf.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to cooling of enclosed spaces and, more particularly, to thermoelectric cooling of structures therein. 
         [0002]    Foods that require cooling to be kept fresh are often offered for sale in food stores by displaying such foods in the interiors of glass front, cooled display cases. The food that is being offered is made visible to customers through the glass front thereof by displaying same in the interior space of the case on one or more shelves in that case. The cooling in this interior space has commonly been provided by a cyclic refrigeration system based on the vapor-compression cycle of a circulating refrigerant with the system evaporator coils positioned along shelves or overhead, or both, in the display case, and often accompanied with an air circulation fan. 
         [0003]    More recently, thermoelectric cooling has been used with portable coolers and various electronic devices, and in other cooling arrangements. Thermoelectric cooling devices are entirely solid state devices using the Peltier effect in semiconductor or semimetal materials to convert controlled electrical currents into corresponding thermal gradients between an input surface of the device module, thermally coupled to that which is to be cooled, and an output surface thereof thermally coupled to some sort of heat sink. Such output surface coupling adds to the difficulty in providing a display case shelf remote from the display case interior space bottom which is the convenient location to provide such a heat sink structure, and therefore there is a desire for a more convenient thermoelectric cooling arrangement for a display shelf remote from the display case interior space bottom. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    The present invention provides an enclosure cooling system for cooling an interior space in an enclosure having therein a first shelf with a side thereof adjacent to an evaporator coil in a cyclic refrigeration system with a second shelf positioned in the interior space apart from and on a side of the first shelf opposite that to which the evaporator coil is adjacent. A thermoelectric cooling module is affixed and thermally coupled to the second shelf. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0005]      FIG. 1  shows a cross section side view of a representation of a cooled display case embodying the present invention, and 
           [0006]      FIG. 2  shows a top view of an alternative representation of the present invention. 
       
    
    
     DETAILED DESCRIPTION  
       [0007]    A cooled display case,  10 , is shown in a cross section side view in  FIG. 1 , and has a base or bottom shelf,  11 , for supporting cooled items offered for sale such as food displayed behind a pair of adjacent glass sheets,  12 , at the front of case  10  covering the interior space thereof. Shelf  11  of thermally conductive material is supported in the interior of case  10  from underneath at opposite sides thereof in  FIG. 2  by shelf supports,  13 . A companion evaporator coil,  14 , as a part of the case cyclic refrigeration system, is supported on the bottom interior surface of case  10  adjacent to bottom shelf  11  with a fan,  15 , adjacent thereto to circulate cooled air through the interior space of case  10  as is conventional. 
         [0008]    Shelf  11  relatively near the bottom of the interior space of case  10 , even with cooled items thereon being offered for sale, typically leaves substantial room above such displayed items so that one or more additional shelves can be added there remote from the bottom of the interior space of case  10  and shelf  11  to provide additional display support for offering further items for sale. The cooling of such items has usually been by use of an overhead gravity evaporator coil in the case refrigeration system or just by directing some of the cooled air circulated by fan  15  over the added shelf or shelves and the items displayed thereon. 
         [0009]    A shelf,  16 , of thermally conductive material, is shown added in  FIG. 1  in the interior space of case  10  above shelf  11  supported on shelf supports,  17 , and positioned there remote from the bottom of the interior space of case  10  and shelf  11 . A thermoelectric cooling module,  18 , is shown in that figure affixed to, and thermally coupled at its input surface to, the underside surface of added shelf  16  to form a heat sink for items such as food supported thereon. Each module  18  is also appropriately interconnected to the electrical power supply and control system provided for case  10 , and added shelf  16  is easily disconnected at the mating electrical plug and removed from the case  10  interior space with module  18  affixed thereto. The output surface of each thermoelectric cooling module  18  has a finned heat sink structure,  19 , of a thermally conductive material affixed and thermally coupled thereto. Fan  15  circulates air cooled by evaporator coil  14  over finned heat sink structure  19  to cool same by forced convection and the output surface of module  18 . Alternatively, a heat sink structure thermally coupled to the outside of a side wall of case  10 , perhaps supported on supports  17 , could be thermally coupled to the output surface of module  18  to provide sequential heat sinking thereto. In a case  10  with sufficient room above shelf  11 , other shelves cooled in the manner of shelf  16  could also be added. 
         [0010]    The better thermal coupling between the items displayed and cooled on shelf  16  and the heat sink formed by that shelf and module  18  to conduct heat away from those items better preserves them along with smaller energy consumption in doing so. Further, the degree of cooling on each of shelves  11  and  16  can differ because of the different cooling source arrangements for each. The providing of such differing cooling zones can be provided to a finer degree along a shelf of the type used for shelf  16  by segmenting it into separately cooled parts such as is shown for a segmented shelf,  16 N, in the top view thereof in  FIG. 2 . That shelf is shown segmented along its length into separate parts,  16 NN, each again of a thermally conductive material, by intervening thermally nonconductive spacers,  16 NNN. Each of shelf parts  16 NN has a thermoelectric cooling module  18  affixed and thermally coupled to the underside surface of each (shown in the center of the shelf part although this positioning need not be the one used), and which modules can be operated at a different heat transfer rates to thereby cool the shelf part to which each is affixed to a temperature that can differ from that of the others. 
         [0011]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.