De-icing coating for evaporator

Abstract

A refrigeration appliance includes a body defining a compartment, and an evaporator configured to flow air from the compartment over a heat exchange surface. The evaporator has a deicing nanocoating coated on a portion of the heat exchange surface. The refrigeration appliance also includes an evaporator fan directing cooled air from the evaporator to the compartment. The deicing coating is a hydrogel forming a coated surface on the portion of the heat exchange surface with an ice nucleation temperature of −15 to −40 degrees C. and a water contact angle of 100 to 140 degrees.

1 . A refrigeration appliance comprising:
 a body defining a compartment;   an evaporator configured to flow air from the compartment over a heat exchange surface, the evaporator having a deicing nanocoating coated on a portion of the heat exchange surface; and   an evaporator fan directing cooled air from the evaporator to the compartment,   wherein the deicing coating is a hydrogel with a thermoresistive material dispersed therein forming a coated surface on the portion of the heat exchange surface with an ice nucleation temperature of −15 to −40 degrees C. and a water contact angle of 100 to 140 degrees, and, upon application of a current to the de-icing coating, the thermoresistive material heats the coated surface to melt ice formed thereon.   
     
     
         2 . The refrigeration appliance of  claim 1 , wherein the portion of the heat exchange surface includes heat exchange fins of the evaporator. 
     
     
         3 . The refrigeration appliance of  claim 1 , wherein the portion of the heat exchange surface includes both coil surfaces and heat exchange fins of the evaporator. 
     
     
         4 . (canceled) 
     
     
         5 . The refrigeration appliance of  claim 1 , wherein the thermoresistive material is carbon or graphene oxide. 
     
     
         6 . The refrigeration appliance of  claim 5 , wherein the thermoresistive material is carbon nanotubes. 
     
     
         7 . The refrigeration appliance of  claim 1 , wherein the hydrogel is a silica gel. 
     
     
         8 . The refrigeration appliance of  claim 1 , wherein the ice nucleation temperature is −20 to −30 degrees C. 
     
     
         9 . An evaporator for a refrigeration appliance comprising:
 a heat exchange surface including coil surfaces, evaporator fins, or combinations thereof, with the evaporator configured to flow air from a refrigeration compartment over the heat exchange surface and to the refrigeration compartment; and   a deicing nanocoating on at least a portion of the heat exchange surface to form heating elements associated with a discrete heating area, the deicing coating including a thermoresistive material dispersed therein and forming a thermoresistive network by interconnection of the heating elements,   wherein the deicing coating forms a coated surface on the at least a portion of the heat exchange surface, the coated surface having an ice nucleation temperature of −15 to −40 degrees C. and a water contact angle of 100 to 140 degrees, and upon selective application of a current to the heating elements, melting ice build-up associated with the discrete heating area.   
     
     
         10 . The evaporator of  claim 9 , wherein the portion of the heat exchange surface includes the evaporator fins. 
     
     
         11 . The evaporator of  claim 9 , wherein the deicing coating is a hydrogel layer formed from a selected monomer, water-soluble initiator, and cross-linker. 
     
     
         12 . (canceled) 
     
     
         13 . The evaporator of  claim 9 , wherein the thermoresistive material is carbon or graphene oxide. 
     
     
         14 . The evaporator of  claim 9 , wherein the thermoresistive material is carbon nanotubes. 
     
     
         15 . The evaporator of  claim 9 , wherein the ice nucleation temperature is −20 to −30 degrees C. 
     
     
         16 . A method of defrosting an evaporator, the method comprising:
 coating a portion of a heat exchange surface of the evaporator with a hydrogel-based deicing coating including a thermoresistive material dispersed therein to form a coated surface associated with a discrete heating area with an ice nucleation temperature of −15 to −40 degrees C. and a water contact angle of 100 to 140 degrees; and   operating the evaporator during a defrost cycle such that a current is selectively applied to the coated surface to melt ice buildup on the hydrogel-based deicing coating in the discrete heating area.   
     
     
         17 . The method of  claim 16 , further comprising formulating the hydrogel-based deicing coating from a selected monomer, water-soluble initiator, and cross-linker. 
     
     
         18 . The method of  claim 17 , wherein formulating the hydrogel-based deicing coating further includes dispersing the thermoresistive material therein. 
     
     
         19 . The method of  claim 18 , wherein the thermoresistive material is carbon or graphene oxide. 
     
     
         20 . The method of  claim 16 , wherein the ice nucleation temperature is −20 to −30 degrees C.