Refrigerated case with low frost operation

Abstract

An open-front refrigerated case with reduced frost operation includes a housing having an open front and defining a product storage space therein. An air flow device is operatively coupled to an air flow path to direct a flow of air over a dehumidification coil for discharge as a dehumidified air curtain over the open front. The dehumidification coil operates substantially frost-free at a temperature of greater than 32° F. A contact cooling device and/or a gravity cooling device is disposed within the space and arranged to receive a coolant from a coolant system, where the dehumidified air curtain operates as a humidity tempering boundary to minimize the humidity within the storage space, so that the case operates in a substantially frost-free manner.

1 . An open-front refrigerated case with reduced frost operation, comprising:
 a housing having an open front and defining a product storage space therein;   an air flow device operatively coupled to an air flow path to direct a flow of air over a dehumidification coil for discharge as a dehumidified air curtain over the open front, the dehumidification coil operating substantially frost-free at a temperature of greater than 32° F.;   at least one of a contact cooling device and a gravity cooling device disposed within the space and arranged to receive a coolant from a coolant system;   wherein the dehumidified air curtain operates as a humidity tempering boundary to minimize the humidity within the storage space.   
   
   
       2 . The case of  claim 1  wherein the coolant system comprises a refrigeration system and the coolant is a refrigerant. 
   
   
       3 . The case of  claim 1  wherein the coolant system comprises a secondary liquid coolant system. 
   
   
       4 . The case of  claim 3  wherein the secondary liquid coolant system interfaces with a primary refrigeration system through a chiller. 
   
   
       5 . The case of  claim 4  wherein the chiller is contained within the housing. 
   
   
       6 . The case of  claim 1  wherein the chiller is a centrally located chiller operable for use with a plurality of cases in a facility. 
   
   
       7 . A refrigerated display case comprising:
 a housing having an open front and defining a space adapted to receive products;   a dehumidification device operating at a temperature greater than 32° F.;   an air flow device operable to direct a flow of air over the dehumidification device and for discharge over the open front as a dehumidified air curtain;   at least one shelf arranged to receive a flow of a coolant to provide contact cooling to the products;   a cooling system providing coolant to the shelf;   wherein the dehumidification device operates above freezing in a substantially frost-free manner and the dehumidified air curtain maintains a low humidity environment proximate the shelf so that the shelf operates in a substantially frost-free manner.   
   
   
       8 . The refrigerated display case of  claim 7  wherein the air flow device comprises a fan, and the fan and dehumidification coil are located in a plenum formed by the housing. 
   
   
       9 . The refrigerated display case of  claim 7  wherein the coolant comprises a refrigerant. 
   
   
       10 . The refrigerated display case of  claim 7  wherein the shelf comprises a plurality of shelves oriented in a vertically stacked arrangement. 
   
   
       11 . The refrigerated display case of  claim 10  wherein the coolant comprises a liquid coolant provided by a secondary cooling system that interfaces with a primary cooling system through a heat exchanger. 
   
   
       12 . The refrigerated display case of  claim 11  wherein the secondary coolant system comprises at least one flow regulation device operable to maintain a first shelf at a first temperature and a second shelf at a second temperature. 
   
   
       13 . The refrigerated display case of  claim 7  further comprising a gravity cooling coil disposed in a top portion of the space. 
   
   
       14 . The refrigerated display case of  claim 7  further comprising a gravity cooling coil disposed directly beneath the shelf. 
   
   
       15 . The refrigerated display case of  claim 7  wherein the dehumidification device comprises a coil configured to receive a supply of at least one of the coolant or a refrigerant. 
   
   
       16 . The refrigerated display case of  claim 7  wherein the dehumidification device comprises a desiccant wheel. 
   
   
       17 . A refrigerated display case comprising:
 a housing having an open front and defining a space adapted to receive products;   a first coil operating at a temperature greater than 32° F.;   an air flow device operable to direct a flow of air over the first coil and for discharge over the open front as a dehumidified air curtain;   a second coil operating at a temperature below 32° F., the second coil disposed within the space to cool the products;   a cooling system providing coolant to the second coil;   wherein the first coil operates above freezing in a substantially frost-free manner and the dehumidified air curtain maintains a low humidity environment proximate the second coil so that the second coil operates in a substantially frost-free manner.   
   
   
       18 . The refrigerated display case of  claim 17  wherein the first coil comprises a dehumidification coil disposed external to the space and adjacent to the air flow device. 
   
   
       19 . The refrigerated display case of  claim 17  wherein the second coil comprises a gravity cooling coil disposed in a top portion of the space. 
   
   
       20 . The refrigerated display case of  claim 17  further comprising a shelf disposed within the space and the low humidity environment and configured to receive the products. 
   
   
       21 . The refrigerated display case of  claim 20  wherein the shelf is configured to receive a supply of the coolant to provide contact cooling to the products and. 
   
   
       22 . The refrigerated display case of  claim 21  wherein the shelf operates in a substantially frost-free manner in the low humidity environment. 
   
   
       23 . The refrigerated display case of  claim 22  further comprising a third coil disposed beneath the shelf and configured to receive a supply of the coolant, the third shelf arranged as a gravity cooling coil and operating in a substantially frost-free in the low humidity environment. 
   
   
       24 . A method of operating a refrigerated display case for low frost performance, comprising:
 providing a housing defining a storage space for products, the storage space having an open front, and an air flow passage communicating with the open front;   providing a dehumidification coil communicating with the air flow passage;   providing an air flow device operable to direct a flow of air over the dehumidification coil for discharge as a dehumidified air curtain over the open front;   providing a cooling device comprising at least one of a contact-cooling shelf and a gravity cooling coil within the space for cooling products;   circulating a coolant to the cooling device; and   operating the dehumidification coil at a temperature above 32° F.   
   
   
       25 . The method of  claim 24 , further comprising the step of circulating a refrigerant through the dehumidification coil. 
   
   
       26 . The method of  claim 24  wherein the cooling device comprises a contact cooling shelf and a gravity cooling coil, and the coolant circulated to the contact cooling shelf comprises a liquid coolant and the coolant circulated to the gravity cooling coil comprises a refrigerant.