Refrigerated case with low frost operation

Abstract

A refrigerated case with reduced frost operation includes a housing having an open front and defining a product storage space therein. A contact cooling device or gravity cooling device is disposed within the space to receive chilled liquid coolant from a coolant system supply header and to return warmed liquid coolant to a coolant system return header. An air flow device in an air flow path directs a flow of air over a dehumidification coil that operates frost-free at a temperature of greater than 32° F. for discharge as a dehumidified air curtain over the open front. A precooling coil is provided in the air flow path upstream of the dehumidification coil, the precooling coil receives warmed liquid coolant from the coolant system return header to precool the flow of air, so that the dehumidified air curtain operates as a humidity tempering boundary to minimize the humidity within the storage space.

1 . An open-front refrigerated case with reduced frost operation, comprising:
 a housing having an open front and defining a product storage space therein;   at least one of a contact cooling device and a gravity cooling device disposed within the space and arranged to receive chilled liquid coolant from a coolant system supply header and to return warmed liquid coolant to a coolant system return header;   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.;   a precooling coil disposed in the air flow path upstream of the dehumidification coil, the precooling coil configured to receive warmed liquid coolant from the coolant system return header to precool the flow of air;   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 cooling system comprises a secondary liquid coolant system that interfaces with a primary refrigeration system through a chiller. 
     
     
         3 . The case of  claim 2  wherein the chiller is contained within the housing. 
     
     
         4 . The case of  claim 1  wherein the coolant system return header receives warmed liquid coolant from a plurality of cases in a facility. 
     
     
         5 . A refrigerated display case comprising:
 a housing having an open front and defining a space adapted to receive products;   at least one shelf arranged to receive a flow of a liquid coolant to provide contact cooling to the products;   a cooling system providing the liquid coolant to the shelf and receiving returned liquid coolant from the shelf;   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;   a precooling coil disposed in an air flow path upstream of the dehumidification device, the precooling coil configured to receive returned liquid coolant to precool the flow of air entering the dehumidification device;   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.   
     
     
         6 . The refrigerated display case of  claim 5  wherein the air flow device comprises a fan, and the fan and dehumidification coil are located in a plenum formed by the housing. 
     
     
         7 . The refrigerated display case of  claim 5  wherein the shelf comprises a plurality of shelves oriented in a vertically stacked arrangement. 
     
     
         8 . The refrigerated display case of  claim 7  wherein the coolant system comprises a secondary cooling system that interfaces with a primary cooling system through a heat exchanger. 
     
     
         9 . The refrigerated display case of  claim 8  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. 
     
     
         10 . The refrigerated display case of  claim 5  further comprising a gravity cooling coil disposed in a top portion of the space. 
     
     
         11 . The refrigerated display case of  claim 10  further comprising a gravity cooling coil disposed directly beneath the shelf. 
     
     
         12 . 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 liquid coolant or a refrigerant. 
     
     
         13 . A refrigerated display case comprising:
 a housing having an open front and defining a space adapted to receive products;   a dehumidifying coil operating at a temperature greater than 32° F.;   an air flow device operable to direct a flow of air over the dehumidifying coil and for discharge over the open front as a dehumidified air curtain;   a cooling coil operating at a temperature below 32° F., the second coil disposed within the space to cool the products;   a cooling system providing supply coolant at a temperature below 32° F. to the cooling coil and receiving returned coolant at a temperature above 32° F. from the cooling coil;   a precooling coil disposed in an air flow path upstream of the dehumidifying coil, the precooling coil configured to receive returned coolant to precool the flow of air entering the dehumidifying coil;   wherein the dehumidifying coil operates above freezing in a substantially frost-free manner and the dehumidified air curtain maintains a low humidity environment proximate the cooling coil so that the cooling coil operates in a substantially frost-free manner.   
     
     
         14 . The refrigerated display case of  claim 13  wherein the dehumidifying coil is disposed external to the space and adjacent to the air flow device. 
     
     
         15 . The refrigerated display case of  claim 14  wherein the precooling coil is disposed between the dehumidifying coil and the air flow device. 
     
     
         16 . The refrigerated display case of  claim 15  further comprising a shelf disposed within the space and the low humidity environment and configured to receive the products. 
     
     
         17 . The refrigerated display case of  claim 16  wherein the shelf operates in a substantially frost-free manner in the low humidity environment. 
     
     
         18 . The refrigerated display case of  claim 17  further comprising another cooling coil disposed beneath the shelf and configured to receive supply coolant, the another cooling coil arranged as a gravity cooling coil and operating in a substantially frost-free in the low humidity environment. 
     
     
         19 . A refrigerated display case comprising:
 a housing having a door, the housing and door defining a space adapted to receive products;   a dehumidifying coil operating at a temperature greater than 32° F.;   an air flow device operable to direct a flow of air over the dehumidifying coil and for discharge through a plurality of apertures into the space as a dehumidifying air flow;   a cooling coil operating at a temperature below 32° F. and disposed within the space to cool the products;   a cooling system providing a supply coolant at a temperature below 32° F. to the cooling coil, and receiving returned coolant at a temperature above 32° F.;   a precooling coil disposed in an air flow path upstream of the dehumidifying coil, the precooling coil configured to receive returned coolant to precool the flow of air entering the dehumidifying coil;   wherein the dehumidifying coil operates above freezing in a substantially frost-free manner and the dehumidified air flow maintains a low humidity environment proximate the cooling coil so that the cooling coil operates in a substantially frost-free manner.   
     
     
         20 . The refrigerated display case of  claim 15  further comprising a shelf disposed within the space and the low humidity environment and configured to receive the products.