Refrigerated air dryers shell part are designed to remove moisture from compressed air by transferring heat from the air to the refrigerant. Direct expansion is the most efficient form of heat transfer technology used in dehumidifying compressed air. Compressed air comes in direct contact with the refrigerant circuit and therefore offers the most efficient method for drying air.

Refrigerated air dryers shell part provide dew points of 38°F for many indoor compressed air applications. Incoming air enters an air-to-refrigerant heat exchanger where the air is cooled to 38ºF by the liquid refrigerant. This process causes the moisture to condense into liquid water and it is drained away. The outgoing air then enters the air-to-air heat exchanger and is warmed up to prevent pipe condensation.