Systems and Methods to Defrost an Evaporator

Abstract

A system including a refrigerant circuit, a sensor unit and a controller is disclosed. The sensor unit may be configured to measure one or more parameters associated with the system. The controller may be configured to determine a real-time coefficient of performance (COP) associated with the refrigerant circuit based on the parameters measured by the sensor unit. The controller may be further configured to determine that the real-time COP may be equivalent to or less than a threshold COP value. The controller may initiate a new defrost cycle of the refrigerant circuit responsive to determining that the real-time COP is equivalent to or less than the threshold COP value.

That which is claimed is: 
     
         1 . A system comprising:
 a refrigerant circuit;   a sensor unit configured to measure one or more parameters associated with the system; and   a controller configured to:
 determine a real-time coefficient of performance (COP) associated with the refrigerant circuit based on the one or more parameters; 
 determine that the real-time COP is equivalent to or less than a threshold COP value; and 
 initiate a new defrost cycle of the refrigerant circuit responsive to determining that the real-time COP is equivalent to or less than the threshold COP value. 
   
     
     
         2 . The system of  claim 1 , wherein the refrigerant circuit comprises a compressor, a condenser, an expansion valve and an evaporator, and wherein the new defrost cycle is initiated to defrost ice formed on the evaporator. 
     
     
         3 . The system of  claim 2 , wherein the one or more parameters comprise at least one of an electric energy input into the system or a thermal energy delivered to the condenser. 
     
     
         4 . The system of  claim 1 , wherein the controller is further configured to:
 monitor the one or more parameters from a predefined start time; and   determine an average COP associated with the refrigerant circuit based on the monitoring, wherein the threshold COP value is the average COP.   
     
     
         5 . The system of  claim 4 , wherein the predefined start time is an initiation time of a previous defrost cycle of the refrigerant circuit. 
     
     
         6 . The system of  claim 1 , wherein the controller determines that the real-time COP is equivalent to or less than the threshold COP value when the refrigerant circuit is operating in a normal mode or a non-defrost mode. 
     
     
         7 . The system of  claim 1 , wherein the one or more parameters comprise at least one of an ambient temperature, an ambient pressure value, an evaporator temperature, a condenser temperature or an ambient humidity level. 
     
     
         8 . The system of  claim 7  further comprising a memory configured to store a first mapping of a plurality of COP values with a plurality of parameters. 
     
     
         9 . The system of  claim 8 , wherein the controller is further configured to:
 correlate the first mapping with the one or more parameters measured by the sensor unit; and   determine the real-time COP based on correlating the first mapping with the one or more parameters measured by the sensor unit.   
     
     
         10 . The system of  claim 8 , wherein the memory is further configured to store a second mapping of a plurality of expected COP values in no frost conditions with a plurality of ambient temperatures, and wherein the controller is further configured to:
 correlate the ambient temperature measured by the sensor unit with the second mapping; and   determine the threshold COP value based on correlating the ambient temperature measured by the sensor unit with the second mapping.   
     
     
         11 . The system of  claim 7 , wherein the controller determines the real-time COP when the ambient temperature is equivalent to or less than a threshold temperature and when the refrigerant circuit is operating in a normal mode or a non-defrost mode. 
     
     
         12 . The system of  claim 7 , wherein the controller is further configured to:
 determine an optimal time duration for the new defrost cycle based on at least one of the ambient temperature, the ambient pressure value or a difference between the real-time COP and the threshold COP value; and   cause the refrigerant circuit to operate in the new defrost cycle for the optimal time duration.   
     
     
         13 . The system of  claim 2 , wherein the controller is further configured to:
 determine a real-time opening percentage of the expansion valve;   compare the real-time opening percentage with a threshold opening percentage; and   initiate the new defrost cycle when the real-time opening percentage is less than the threshold opening percentage.   
     
     
         14 . The system of  claim 13 , wherein the threshold opening percentage is based on at least one of an ambient temperature or an ambient pressure value. 
     
     
         15 . A system comprising:
 a refrigerant circuit, wherein the refrigerant circuit comprises an expansion valve;   a sensor unit configured to measure one or more parameters associated with the system; and   a controller configured to:
 determine a real-time opening percentage of the expansion valve; 
 compare the real-time opening percentage with a threshold opening percentage, wherein the threshold opening percentage is based on the one or more parameters; and 
 initiate a new defrost cycle of the refrigerant circuit when the real-time opening percentage is less than the threshold opening percentage. 
   
     
     
         16 . The system of  claim 15 , wherein the one or more parameters comprise at least one of an ambient temperature or an ambient pressure value. 
     
     
         17 . The system of  claim 15 , wherein the refrigerant circuit further comprises a compressor, a condenser, and an evaporator, and wherein the new defrost cycle is initiated to defrost ice formed on the evaporator. 
     
     
         18 . A method to optimally defrost an evaporator, the method comprising:
 determining, by a controller, a real-time coefficient of performance (COP) of a refrigerant circuit based on one or more parameters associated with the refrigerant circuit;   determining, by the controller, that the real-time COP is equivalent to or less than a threshold COP value; and   initiating, by the controller, a new defrost cycle of the refrigerant circuit responsive to determining that the real-time COP is equivalent to or less than the threshold COP value.   
     
     
         19 . The method of  claim 18 , wherein the refrigerant circuit comprises a compressor, a condenser, an expansion valve and the evaporator, and wherein the new defrost cycle is initiated to defrost ice formed on the evaporator. 
     
     
         20 . The method of  claim 19 , wherein the one or more parameters comprise at least one of an electric energy input into the refrigerant circuit or a thermal energy delivered to the condenser.