Using Setpoint Changes to Defrost Evaporator Coils

Abstract

Exemplary embodiments are disclosed systems configured for using setpoint changes for defrosting evaporator coils. Also disclosed are exemplary methods of using setpoint changes for defrosting evaporator coils.

What is claimed is: 
     
         1 . A system for defrosting an evaporator coil, the system comprising a controller configured to be operable for:
 monitoring the evaporator coil to determine if a defrost of the evaporator coil is required;   after determining that defrost of the evaporator coil is required, initiating the defrost of the evaporator coil by:
 periodically changing an evaporator temperature setpoint to a value just above freezing to defrost the evaporator coil; and/or 
 periodically changing an evaporator pressure setpoint to a value just above a pressure resulting in a temperature just above freezing to defrost the evaporator coil; and 
   after determining that defrost of the evaporator coil is complete, terminating defrost of the evaporator coil by returning the evaporation temperature setpoint and/or the evaporator pressure setpoint to normal operation.   
     
     
         2 . The system of  claim 1 , wherein after the controller determines that defrost of the evaporator coil is required, the controller is configured to be operable for initiating the defrost of the evaporator coil by periodically changing the evaporator temperature setpoint to a value within a range from about 33° F. to about 35° F. to defrost the evaporator coil. 
     
     
         3 . The system of  claim 2 , wherein:
 after the controller determines that defrost of the evaporator coil is required, the controller is configured to be operable for initiating the defrost of the evaporator coil by periodically changing the evaporator temperature setpoint from about −25° F. to the value within the range from about 33° F. to about 35° F. to defrost the evaporator coil; and   after determining that defrost of the evaporator coil is complete, the controller is configured to be operable for returning the evaporation temperature setpoint to about −25° F. for normal operation.   
     
     
         4 . The system of  claim 1 , wherein after the controller determines that defrost of the evaporator coil is required, the controller is configured to be operable for initiating the defrost of the evaporator coil by periodically changing the evaporator pressure setpoint to the value just above the pressure resulting in a temperature within a range from about 33° F. to about 35° F. to defrost the evaporator coil. 
     
     
         5 . The system of  claim 1 , wherein the controller is configured such that:
 a frequency at which the periodic changes to the evaporator temperature setpoint initially occurs is frequent; and/or   a frequency at which the periodic changes to the evaporator pressure setpoint initially occurs is frequent.   
     
     
         6 . The system of  claim 5 , wherein the controller is configured such that:
 the frequency at which the periodic changes to the evaporator temperature setpoint initially occurs is at least once per hour; and/or   the frequency at which the periodic changes to the evaporator pressure setpoint initially occurs is at least once per hour.   
     
     
         7 . The system of  claim 5 , wherein the controller is configured such that the frequency at which the periodic changes to the evaporator temperature setpoint and/or the frequency at which the periodic changes to the evaporator pressure setpoint is adjustable or optimizable based on one or more condition(s) of a space in which the evaporator coil is used including one or more of a temperature of the space, a humidity of the space, and/or door opening(s) of the space. 
     
     
         8 . The system of  claim 1 , wherein the controller is configured to be operable for determining whether to initiate or terminate defrost of the evaporator coil by using camera sensor output. 
     
     
         9 . The system of  claim 1 , wherein the controller is configured to be operable for determining whether to initiate or terminate defrost of the evaporator coil based on frost formation estimated based on time. 
     
     
         10 . The system of  claim 1 , wherein the controller is configured to be operable for determining whether to initiate or terminate defrost of the evaporator coil based on frost formation detection algorithmically using relative humidity, temperature, and/or openings of a space in which the evaporator coil is used. 
     
     
         11 . The system of  claim 1 , wherein the system is configured to obtain a higher evaporator temperature setpoint and/or a higher evaporator pressure setpoint by using one or more of an evaporator pressure regulator (EPR), an evaporator pressure regulating valve, or an expansion device at an inlet to an evaporator. 
     
     
         12 . The system of  claim 1 , wherein a scroll booster system is in communication with the controller that is operable for rapid changes to the evaporator temperature setpoint and/or the evaporator pressure setpoint. 
     
     
         13 . A refrigerated case comprising the evaporator coil and the system of  claim 1 , wherein:
 the controller is a local case controller of the refrigerated case; or   the controller is a supervisory controller in communication with a local case controller.   
     
     
         14 . A method for defrosting an evaporator coil, the method comprising:
 monitoring the evaporator coil to determine if a defrost of the evaporator coil is required;   after determining that defrost of the evaporator coil is required, initiating the defrost of the evaporator coil by:
 periodically changing an evaporator temperature setpoint to a value just above freezing to defrost the evaporator coil; and/or 
 periodically changing an evaporator pressure setpoint to a value just above a pressure resulting in a temperature just above freezing to defrost the evaporator coil; and 
   after determining that defrost of the evaporator coil is complete, terminating defrost of the evaporator coil by returning the evaporation temperature setpoint and/or the evaporator pressure setpoint to normal operation.   
     
     
         15 . The method of  claim 14 , wherein after determining that defrost of the evaporator coil is required, the method includes initiating the defrost of the evaporator coil by periodically changing the evaporator temperature setpoint to a value within a range from about 33° F. to about 35° F. to defrost the evaporator coil. 
     
     
         16 . The method of  claim 15 , wherein:
 after determining that defrost of the evaporator coil is required, the method includes initiating the defrost of the evaporator coil by periodically changing the evaporator temperature setpoint from about −25° F. to the value within the range from about 33° F. to about 35° F. to defrost the evaporator coil; and   after determining that defrost of the evaporator coil is complete, the method includes returning the evaporation temperature setpoint to about −25° F. for normal operation.   
     
     
         17 . The method of  claim 14 , wherein after determining that defrost of the evaporator coil is required, the method includes initiating the defrost of the evaporator coil by periodically changing the evaporator pressure setpoint to the value just above the pressure resulting in a temperature within a range from about 33° F. to about 35° F. to defrost the evaporator coil. 
     
     
         18 . The method of  claim 14 , wherein the method includes adjusting and/or optimizing a frequency at which the periodic changes to the evaporator temperature setpoint occurs and/or a frequency at which the periodic changes to the evaporator pressure setpoint occurs based on one or more condition(s) of a space in which the evaporator coil is used including one or more of a temperature of the space, a humidity of the space, and/or door opening(s) of the space. 
     
     
         19 . The method of  claim 14 , wherein the method includes determining whether to initiate or terminate defrost of the evaporator coil by:
 using camera sensor output; and/or   estimating frost formation based on time; and/or   detecting frost formation algorithmically using relative humidity, temperature, and/or openings of a space in which the evaporator coil is used.   
     
     
         20 . The method of  claim 14 , wherein the method includes:
 obtaining a higher evaporator temperature setpoint and/or a higher evaporator pressure setpoint by using one or more of an evaporator pressure regulator (EPR), an evaporator pressure regulating valve, or an expansion device at an inlet to an evaporator; or   changing the evaporator temperature setpoint and/or the evaporator pressure setpoint by using a scroll booster system.   
     
     
         21 . A non-transitory computer-readable storage media comprising computer-executable instructions, which when executed by at least one processor, cause a controller to be operable for:
 monitoring an evaporator coil to determine if a defrost of the evaporator coil is required;   after determining that defrost of the evaporator coil is required, initiating the defrost of the evaporator coil by:
 periodically changing an evaporator temperature setpoint to a value just above freezing to defrost the evaporator coil; and/or 
 periodically changing an evaporator pressure setpoint to a value just above a pressure resulting in a temperature just above freezing to defrost the evaporator coil; and 
   after determining that defrost of the evaporator coil is complete, terminating defrost of the evaporator coil by returning the evaporation temperature setpoint and/or the evaporator pressure setpoint to normal operation.   
     
     
         22 . The non-transitory computer-readable storage media of  claim 21 , wherein the executable instructions include executable instructions, that when executed by the at least one processor, cause the controller to be operable for:
 after determining that defrost of the evaporator coil is required, initiating the defrost of the evaporator coil by periodically changing the evaporator temperature setpoint to a value within a range from about 33° F. to about 35° F. to defrost the evaporator coil.   
     
     
         23 . The non-transitory computer-readable storage media of  claim 22 , wherein the executable instructions include executable instructions, that when executed by the at least one processor, cause the controller to be operable for:
 after determining that defrost of the evaporator coil is required, initiating the defrost of the evaporator coil by periodically changing the evaporator temperature setpoint from about −25° F. to the value within the range from about 33° F. to about 35° F. to defrost the evaporator coil; and   after determining that defrost of the evaporator coil is complete, returning the evaporation temperature setpoint to about −25° F. for normal operation.   
     
     
         24 . The non-transitory computer-readable storage media of  claim 21 , wherein the executable instructions include executable instructions, that when executed by the at least one processor, cause the controller to be operable for:
 after determining that defrost of the evaporator coil is required, initiating the defrost of the evaporator coil by periodically changing the evaporator pressure setpoint to the value just above the pressure resulting in a temperature within a range from about 33° F. to about 35° F. to defrost the evaporator coil.   
     
     
         25 . The non-transitory computer-readable storage media of  claim 21 , wherein the executable instructions include executable instructions, that when executed by the at least one processor, cause the controller to be operable for adjusting and/or optimizing a frequency at which the periodic changes to the evaporator temperature setpoint occurs and/or a frequency at which the periodic changes to the evaporator pressure setpoint occurs based on one or more condition(s) of a space in which the evaporator coil is used including one or more of a temperature of the space, a humidity of the space, and/or door opening(s) of the space. 
     
     
         26 . The non-transitory computer-readable storage media of  claim 21 , wherein the executable instructions include executable instructions, that when executed by the at least one processor, cause the controller to be operable for determining whether to initiate or terminate defrost of the evaporator coil by:
 using camera sensor output; and/or   estimating frost formation based on time; and/or   detecting frost formation algorithmically using relative humidity, temperature, and/or openings of a space in which the evaporator coil is used.   
     
     
         27 . A controller for a defrosting system for an evaporator coil, the controller comprising the non-transitory computer-readable storage media of  claim 21 .