Refrigerated device with enhanced defrost and condensate pan heater control

Abstract

A refrigerated device includes a compartment including an access door, and a door sensor for identifying an open condition of the access door. A refrigeration circuit for cooling the compartment includes an evaporator coil with an associated evaporator fan and a condenser with an associated condenser fan. At least one heat source is selectively activatable to provide heat. A controller is configured to selectively activate the heat source based upon an approximated an amount of water that enters the compartment during door open conditions.

What is claimed is: 
     
         1 . A refrigerated device, comprising:
 a compartment including an access door;   a door sensor for identifying an open condition of the access door;   a refrigeration circuit for cooling the compartment, the refrigeration circuit including an evaporator coil with an associated evaporator fan and a condenser with an associated condenser fan;   a controller configured to: (i) based upon an output of the door sensor, maintain a count of a number of door openings since a last defrost operation and (ii) approximate an amount of water that enters the compartment based at least in part on the count of the number of door openings.   
     
     
         2 . The refrigerated device of  claim 1 , further comprising:
 at least one heat source selectively activatable to provide heat;   wherein the controller is further configured to (iii) selectively activate the heat source based at least in part upon the approximated amount of water.   
     
     
         3 . The refrigerated device of  claim 2 , wherein the approximated amount of water is determined in grains of water. 
     
     
         4 . The refrigerated device of  claim 1 , further comprising:
 at least one sensor for detecting a temperature and a relative humidity of ambient air that surrounds the compartment;   wherein the controller is configured to determine a dew point temperature based on the temperature and the relative humidity of the ambient;   wherein the controller is configured to approximate the amount of water that enters the compartment for each door open condition based at least in part upon the dew point temperature during each door open condition.   
     
     
         5 . The refrigerated device of  claim 4 , wherein the controller is further configured to approximate the amount of water that enters the cabinet for each door open condition based at least in part upon a duration of each door open condition. 
     
     
         6 . The refrigerated device of  claim 2 , wherein the heat source is associated with the evaporator coil for use in defrost operations of the evaporator coil. 
     
     
         7 . The refrigerated device of  claim 6 , wherein the controller is configured such that a next defrost operation, following the last defrost operation, is carried out by activating the heat source sooner if the approximated amount of water is high verses if the approximated amount of water is low. 
     
     
         8 . The refrigerated device of  claim 2 , wherein the heat source is associated with a condensate pan that collects condensate from the evaporator coil. 
     
     
         9 . The refrigerated device of  claim 8 , wherein the controller is configured such that the heat source is activated for a longer period of time if the approximated amount of water is high verses if the approximated amount of water is low. 
     
     
         10 . A refrigerated device, comprising:
 a cooled compartment including an access door;   a door sensor for identifying an open condition of the access door;   a refrigeration circuit for cooling the compartment, the refrigeration circuit including an evaporator coil with an associated evaporator fan and a condenser with an associated condenser fan;   at least one heat source selectively activatable to provide heat;   a controller configured to approximate an amount of water that enters the compartment based at least in part on detected door openings and duration of the detected door openings, wherein the controller is further configured to selectively activate the heat source based at least in part upon the approximated amount of water.   
     
     
         11 . The refrigerated device of  claim 10 , wherein the heat source is associated with the evaporator coil for use in defrost operations of the evaporator coil. 
     
     
         12 . The refrigerated device of  claim 11 , wherein the controller is configured such that a next defrost operation, following the last defrost operation, is carried out by activating the heat source sooner if the approximated amount of water is high verses if the approximated amount of water is low. 
     
     
         13 . The refrigerated device of  claim 10 , wherein the heat source is associated with a condensate pan that collects condensate from the evaporator coil. 
     
     
         14 . The refrigerated device of  claim 13 , wherein the controller is configured such that the heat source is activated for a longer period of time if the approximated amount of water is high verses if the approximated amount of water is low. 
     
     
         15 . A method of controlling a defrost operation of a refrigerated device including a cooled compartment that is closeable by at least one door, comprising:
 approximating an amount of water that enters cooled compartment as a result of door open conditions; and   initiating a defrost operation based at least in part upon the approximated amount of water.   
     
     
         16 . The method of  claim 15 , wherein the step of approximating involves taking into account both a number of door openings and duration of such door openings. 
     
     
         17 . The method of  claim 16 , wherein the step of approximating involves taking into account a dew point of an ambient environment in which the refrigerated device is located.