Apparatus and method for monitoring super-heating of refrigerant to improve compressor efficiency and lower energy usage

Abstract

Apparatus and methodologies are provided to monitor temperature from at least two locations on an evaporator in a refrigeration system. Operational characteristics of one or more of the compressor, condenser and evaporator cooling fans are adjusted based on the difference in temperature between the two locations on the evaporator. In some systems a second evaporator may be provided along with a refrigerant control valve. Cooling air flow across the second evaporator and refrigerant distribution between the plural evaporators may also be control.

What is claimed is: 
     
         1 . A refrigerator, comprising:
 a controller;   a compressor;   a condenser;   a condenser fan configured to provide air flow across said condenser;   an evaporator;   an evaporator fan configured to provide air flow across said evaporator; and   at least two temperature sensors located on the evaporator,   wherein said controller is configured to control operating characteristics of at least one of said compressor, said condenser fan, and said evaporator fan based on the difference in temperature between said first temperature sensor and said second temperature sensor.   
     
     
         2 . A refrigerator as in  claim 1 , wherein said controller is configured to modulate the speed of the compressor based on the difference in temperature between said first temperature sensor and said second temperature sensor. 
     
     
         3 . A refrigerator as in  claim 1 , wherein said controller is configured to adjust the speed of the evaporator fan based on the difference in temperature between said first temperature sensor and said second temperature sensor. 
     
     
         4 . A refrigerator as in  claim 1 , wherein said controller is configured to adjust the speed of the condenser fan based on the difference in temperature between said first temperature sensor and said second temperature sensor. 
     
     
         5 . A refrigerator as in  claim 1 , wherein said temperature sensors are thermistors. 
     
     
         6 . A refrigerator as in  claim 5 , wherein said thermistors are coupled together to form one or more voltage divider circuits configured to provide reduced number of voltage inputs to said controller representative of the difference in temperature between the thermistors. 
     
     
         7 . A refrigerator as in  claim 1 , wherein said controller is configured to control operating characteristics in accordance with a proportional-integral-differential (PID) control system based on the difference in temperature between said first temperature sensor and said second temperature sensor. 
     
     
         8 . A refrigerator as in  claim 1 , further comprising:
 a second evaporator;   a second evaporator fan configured to provide air flow across said second evaporator; and   a refrigerant control valve configured to control distribution of refrigerant between said evaporator and said second evaporator,   wherein said controller is configured to control at least one of said compressor, said condenser fan, and said evaporator fan, said second evaporator fan, and said refrigerant control valve based on the difference in temperature between said first temperature sensor and said second temperature sensor.   
     
     
         9 . A method for improving compressor efficiency and lowering energy consumption in a refrigeration system, comprising:
 providing a refrigeration system including a compressor, a condenser, and an evaporator;   monitoring temperature from at least two locations on the evaporator; and   modulating one or more of the operational speed of the compressor and air flow across one or more of the condenser and evaporator based on the difference in temperature between the at least two locations on the evaporator.   
     
     
         10 . A method as in  claim 9 , wherein modulating comprises modulating the speed of the compressor based on the difference in temperature between the at least two locations on the evaporator. 
     
     
         11 . A method as in  claim 9 , wherein modulating comprises modulating the speed of air flow across the evaporator based on the difference in temperature between the at least two locations on the evaporator. 
     
     
         12 . A method as in  claim 9 , wherein modulating comprises modulating the speed of air flow across the condenser based on the difference in temperature between the at least two locations on the evaporator. 
     
     
         13 . A method as in  claim 9 , wherein monitoring temperature comprises providing thermistors at two or more location on the evaporator. 
     
     
         14 . A method as in  claim 13 , wherein the difference in temperature is obtained by coupling the thermistors together to form one or more voltage dividers. 
     
     
         15 . A method as in  claim 9 , further comprising:
 providing a second evaporator;   providing a refrigerant control valve configured to control distribution of refrigerant between the evaporator and the second evaporator; and   modulating one or more of the operational speed of the compressor, air flow across one or more of the condenser, the evaporator, and the second evaporator, and refrigerant distribution between the evaporator and the second evaporator based on the difference in temperature between the at least two locations on the evaporator.