Refrigerated merchandiser system

Abstract

A refrigerated display case includes a heat exchanger with circuits that route secondary fluid in a counterflow direction with respect to the airflow through the heat exchanger. At least one circuit directs secondary fluid from the entrance end to the exit end of the heat exchanger to exchange heat with air exiting the heat exchanger. The higher fluid temperature raises the air dry bulb and lowers the air relative humidity to improve the capability of the air to absorb moisture in the display case.

1 . A refrigerated merchandiser system comprising:
 a chiller for cooling a fluid; and   a display case comprising:
 a product display area; 
 an air circulation compartment in air flow communication with the product display area; 
 an air circulation fan system for circulating air returned from the product display area through the air circulation compartment to the product display area, wherein the air has a relative humidity; and 
 a heat exchanger connected in fluid communication with the chiller, the heat exchanger including a plurality of tubes for circulating fluid from the chiller to exchange heat with air passing from an upstream end to a downstream end through the heat exchanger, wherein the tubes are connected to form at least a first circuit and a second circuit, the first circuit circulating fluid in a counterflow direction toward the upstream end to cool the air, and the second circuit having a first portion for circulating fluid in a counterflow direction toward the upstream end followed by a portion for circulating fluid toward the downstream end to reheat the air as it exits the heat exchanger and lower the relative humidity of the air. 
   
     
     
         2 - 3 . (canceled) 
     
     
         4 . A refrigerated merchandiser including a cabinet defining a product display area, an air circulation compartment in air flow communication with the product display area, an air circulation fan, and a heat exchanger whereby air flow passes from the air circulation fan through the heat exchanger in heat exchange relationship with chilled fluid passing through the heat exchanger, characterized in that the heat exchanger comprises:
 a first circuit in which the chilled fluid passes in counterflow relationship to the air flow; and   a second circuit in which chilled fluid first passes in counterflow relationship with the air flow to an upstream end of the heat exchanger, and then passes towards a downstream end of the heat exchanger to heat air exiting the heat exchanger.   
     
     
         5 . The system of  claim 1 , the chiller further comprising:
 a compressor;   a condenser connected to the compressor;   an expansion valve connected to the condenser;   a chiller heat exchanger connected to the expansion valve and to the compressor; and   a pump for passing coolant from the chiller heat exchanger to the display case.   
     
     
         6 . The system of  claim 1 , wherein the heat exchanger is a coil-type heat exchanger. 
     
     
         7 . The system of  claim 1 , wherein the air circulation compartment is defined by a lower inner wall, a rear inner wall, a top inner wall, and an outer wall of the display case. 
     
     
         8 . The system of  claim 1 , wherein the air circulation compartment further comprises:
 a return duct for receiving air from the product display area;   a rear duct connected to the return duct; and   a discharge duct connected to the return duct, wherein at least a portion of the air is discharged back into the product display area.   
     
     
         9 . The system of  claim 8 , wherein the air circulation fan system is located within the return duct. 
     
     
         10 . The system of  claim 8 , wherein the heat exchanger is located within the return duct. 
     
     
         11 . The system of  claim 1 , further comprising:
 a supply line for passing fluid from the chiller to the heat exchanger; and   a return line for passing fluid from the heat exchanger to the chiller.   
     
     
         12 . The system of  claim 11 , further comprising:
 an inlet header connecting the supply line to the heat exchanger; and   an outlet header connecting the return line to the heat exchanger.   
     
     
         13 . The system of  claim 11 , wherein the supply line has a flow control valve. 
     
     
         14 . The system of  claim 1 , wherein the fluid is selected from the group consisting of propylene glycol, brines, and other fluids suitable for heat transfer. 
     
     
         15 . A refrigeration merchandiser system comprising:
 a chiller system having a first heat exchanger; and   a display case comprising:
 an air circulation circuit having a return duct and a discharge duct; 
 a fan system for circulating air from the return duct to the discharge duct; and 
 a second heat exchanger in communication with the air circulation circuit and the chiller system, the heat exchanger having a first circuit, a second circuit, an upstream end, and a downstream end, wherein the fan system passes air through the heat exchanger from an upstream end of the heat exchanger to a downstream end of the heat exchanger, the first circuit passes coolant from the chiller system from the downstream end towards the upstream end, and the second circuit passes coolant from the downstream end towards the upstream end and back towards the downstream end to dry the air. 
   
     
     
         16 . The system of  claim 15 , wherein the second heat exchanger is located in the return duct of the display case. 
     
     
         17 . The system of  claim 15 , wherein the coolant is selected from the group consisting of propylene glycol, brines, and other fluids suitable for heat transfer. 
     
     
         18 . The system of  claim 15 , wherein the first circuit and the second circuit are each comprised of multiple tubes. 
     
     
         19 . The system of  claim 15 , wherein the chiller system further comprises:
 a compressor connected to the first heat exchanger;   a condenser connected to the compressor;   an expansion valve connected to the condenser and the first heat exchanger; and   a pump for passing coolant from the first heat exchanger of the chiller to the display case.   
     
     
         20 . The system of  claim 19 , further comprising:
 a flow control valve between the pump and the second heat exchanger to control flow of coolant to the second heat exchanger.   
     
     
         21 . A method for circulating air in a refrigerated merchandiser system comprising:
 circulating air from a product display area through a heat exchanger;   passing coolant through a first section of the heat exchanger from a downstream end of the heat exchanger towards an upstream end of the heat exchanger;   passing coolant through a second section of the heat exchanger from the downstream end of the heat exchanger towards the upstream end of the heat exchanger and back towards the downstream end of the heat exchanger to form dry air;   circulating dry air from the heat exchanger back to the product display area.   
     
     
         22 . The method of  claim 21 , and further comprising:
 pumping coolant from a chiller system to the heat exchanger through a supply line; and   pumping coolant from the heat exchanger back to the chiller system through a return line.