Abstract: A mobile cold air supply unit which comprises, as housed in a single casing, an air compressor-expander constituted of an integral combination of a motor, an air compressor and an air expander, an air-to-water heat exchanger and an air-to-air heat exchanger, is furnished in the casing with air tubing for interconnecting the aforesaid components at an air pressure not higher than 5 kg/cm.sup.2, and is provided with a cold air discharge connection, a return air intake connection, a cooling water outlet connection and a cooling water intake connection.

Abstract: An air refrigerant ice forming equipment having formed therein a refrigeration cycle using air as a working medium, said refrigeration cycle comprising a passage for air circulation incorporating an air compressor, a compressed air cooler, an air expander and a heat exchanger for ice formation disposed in the indicated order along the flow of air characterized in that said equipment further comprises a heat exchanger for heat recovery wherein the air before entering the air expander is heat exchanged with the air which has passed through the heat exchanger for ice formation and that said air expander has a rotor caused to rotate by the action of air flowing through said passage for air circulation, a rotating shaft of said rotor is connected via a one-way clutch to a rotating shaft of a motor for driving said air compressor.