Abstract: A refrigeration-type dehumidifying system includes a rotary dehumidifier having a dehumidifying chamber, a defrost chamber and a cooling chamber radially formed within a casing and a dehumidifier wheel with plural heat-exchanger blades rotatably mounted in the casing to rotatively pass the three chambers whereby upon the counterclockwise rotation of the wheel, a dehumidifying air stream is directed into the dehumidifying chamber to deposit its lading moisture on the cooled wheel blades which in turn is defrosted when heated in the defrost chamber and further cooled in the cooling chamber to operate the dehumidification recirculatively.