Humidity control sensor for a refrigerator

Abstract

An improved humidity control sensor is provided that cost effectively allows for a more efficient operation of a refrigerator by using two temperature sensors to determine ambient conditions of a room housing the refrigerator. Based on the two temperature sensor measurements, the humidity control sensor may e.g., use a processing device to efficiently control a heating element in thermal communication with an exterior surface of the refrigerator's cabinet to prevent condensation from forming on that exterior surface.

What is claimed is: 
     
         1 . A refrigerator appliance, comprising:
 a cabinet having an exterior surface,   a heating element in thermal communication with the exterior surface of said cabinet; and   a humidity control sensor, said humidity control sensor comprising:
 a receptacle configured for holding a pool of water; 
 a first temperature sensor configured to measure a wet bulb temperature, wherein said first temperature sensor is positioned at the receptacle so as to provide temperature measurement of the pool of water; 
 a second temperature sensor configured to measure a dry bulb temperature; and 
 a processing device in communication with said first and second temperature sensors, said processing device configured for:
 receiving a first temperature measurement from said first temperature sensor and a second temperature measurement from said second temperature sensor; and 
 controlling the heating element based on the first temperature measurement and the second temperature measurement from said step of receiving. 
 
   
     
     
         2 . A refrigerator appliance as in  claim 1 , wherein said step of controlling further comprises determining a relative humidity, an absolute humidity, a dew point temperature, or combination thereof using the first temperature measurement and the second temperature measurement from said step of receiving. 
     
     
         3 . A refrigerator appliance as in  claim 1 , further comprising a refrigeration system, said refrigeration system comprising a fan, wherein said processing device is further configured for operating the fan for a predetermined amount of time prior to receiving the wet bulb temperature measurement from said first temperature sensor. 
     
     
         4 . A refrigerator appliance as in  claim 1 , further comprising a refrigeration system, said refrigeration system comprising a fan, wherein said processing device is further configured for operating the fan until the temperature of the water in said receptacle is within a predetermined range of a steady-state temperature. 
     
     
         5 . A refrigerator appliance as in  claim 1 , wherein said humidity control sensor further comprises a third temperature sensor in communication with said processing device, wherein said third temperature sensor is configured to measure the temperature of an exterior surface of said cabinet, and wherein said processing device is further configured for heating the exterior surface of said cabinet when the temperature of the exterior surface of said cabinet falls within a predetermined range of the dew point temperature. 
     
     
         6 . A refrigerator appliance as in  claim 1 , wherein said receptacle is configured to retain water generated from a defrost cycle of the refrigerator appliance. 
     
     
         7 . A refrigerator appliance as in  claim 1 , wherein said processing device comprises at least one microprocessor, a memory, or both. 
     
     
         8 . A refrigerator appliance as in  claim 1 , wherein at least one of said first or second temperature sensors is a thermistor. 
     
     
         9 . A refrigerator appliance as in  claim 1 , wherein said cabinet further comprises:
 a compartment configured for the storage of items to be refrigerated, said compartment defining a compartment opening;   a first door rotatably mounted about a vertical axis adjacent the compartment opening of said compartment;   a second door rotatably mounted about a vertical axis adjacent the compartment opening of said compartment, said first door and said second door rotatable between an open position and a closed position; and   a mullion having an exterior surface, wherein said mullion is mounted to said first door to form a seal between said first door and second door when they are in the closed position, and wherein the exterior surface of said mullion is in thermal communication with said heating element.   
     
     
         10 . A refrigerator appliance as in  claim 1 , wherein said cabinet further comprises:
 a first compartment defining a first compartment opening;   a second compartment defining a second compartment opening, said first and second compartments configured for the storage of items to be refrigerated or frozen;   a wall separating said first and second compartments; and   a mullion positioned at the exterior of said wall and adjacent to the first and second compartment openings of said first and second compartments, wherein said mullion is in thermal communication with said heating element.   
     
     
         11 . A refrigerator appliance as in  claim 1 , wherein said heating element is a variable output heating element. 
     
     
         12 . A method for operating a refrigerator appliance, comprising:
 providing a refrigerator comprising a cabinet having an exterior surface, a heating element in thermal communication with the exterior surface of the cabinet, and a humidity control sensor, wherein the humidity control sensor comprises:
 a receptacle configured for holding a pool of water; 
 a first temperature sensor configured for measuring a wet bulb temperature, wherein the first temperature sensor is positioned at the receptacle so as measure the temperature of the pool of water; 
 a second temperature sensor configured to measure a dry bulb temperature; and 
 a processing device in communication with the first and second temperature sensors; 
   moving air across the first temperature sensor for a length of time;   measuring the wet bulb temperature after the length of time using the first temperature sensor and the dry bulb temperature using the second temperature sensor; and   controlling the heating element based on the wet bulb temperature measurement and the dry bulb temperature measurement from said step of measuring.   
     
     
         13 . A method for operating a refrigerator appliance as in  claim 12 , wherein said step of controlling further comprises determining a relative humidity, an absolute humidity, a dew point temperature, or combination thereof using the first temperature measurement and the second temperature measurement from said step of receiving. 
     
     
         14 . A method for operating a refrigerator appliance as in  claim 12 , wherein the processing device comprises at least one processor, a memory, or both, and wherein the processing device determines the relative humidity, absolute humidity, or both by referencing a chart stored in the memory. 
     
     
         15 . A method for operating a refrigerator appliance as in  claim 12 , wherein the refrigerator further comprises a refrigeration system, wherein the refrigeration system comprising a fan, and wherein air is moved across the first temperature sensor using the fan. 
     
     
         16 . A method for operating a refrigerator appliance as in  claim 12 , wherein the humidity control sensor further comprises a third temperature sensor in communication with the processing device, wherein the third temperature sensor is configured for measuring the temperature of an exterior surface of the cabinet, and wherein the processing device is further configured for heating the exterior surface of the cabinet when the temperature of the exterior surface of the cabinet falls within a predetermined range of the dew point temperature. 
     
     
         17 . A method for operating a refrigerator appliance as in  claim 12 , wherein the heating element is a variable output heating element. 
     
     
         18 . A method for operating a refrigerator appliance as in  claim 12 , wherein the cabinet further comprises:
 a compartment configured for the storage of items to be refrigerated, the compartment defining a compartment opening;   a first door rotatably mounted about a vertical axis adjacent the compartment opening of the compartment;   a second door rotatably mounted about a vertical axis adjacent the compartment opening of the cabinet, the first door and second doors rotatable between an open position and a closed position; and   a mullion having an exterior surface, wherein the mullion is mounted to the first door to form a seal between the first and second doors when they are in the closed position, and wherein the exterior surface of the mullion is in thermal communication with the heating element.   
     
     
         19 . A method for operating a refrigerator appliance as in  claim 12 , wherein the cabinet further comprises:
 a first compartment defining a first compartment opening and a second compartment defining a second compartment opening, each configured for the storage of items to be refrigerated or frozen;   a wall separating the first and second compartments; and   a mullion positioned at the exterior of the wall and adjacent to the first and second compartment openings of the first and second compartments, wherein the mullion is in thermal communication with the heating element.   
     
     
         20 . A method for operating a refrigerator appliance as in  claim 12 , wherein the receptacle is configured to retain water generated from a defrost cycle of the refrigerator appliance.