Abstract: A sub-cooler for a refrigeration system is located between the condenser and the expansion device for the evaporator. The sub-cooler has a sealed cylindrical housing with a main inlet coupled to the outlet of the condenser. This inlet is connected to a spray bar located along the length of the housing near its top, and spray apertures are distributed along the length of the spray bar to spray the refrigerant into the interior of the sub-cooler housing. The temperature controlled expansion valve supplies a tapped off portion of the refrigerant from the condenser to a distributor located within the housing. Three to six separate cooling coils, having multiple turns, extend from the distributor throughout the interior of the housing. The other ends of the cooling coils are coupled with a collector in the housing, and the outlet from the collector is injected into the main suction line coupled to the inlet of the compressor.