PURPOSE: To enable cold and hot air to be generated, respectively, making use of a centrifugal compressor alone, by allowing compressed air to rotate a turbine rotor after cooling and by reducing air flow to expand air, thereby reducing the pressure of air without lowering its temperature.

CONSTITUTION: A motor 1 rotates a centrifugal compressor 10 with the aid of a shaft 2. When a damper 9 is opened, high-temperature and high-pressure air generated by the rotation of the centrifugal compressor 10 passes through a heat exchanger 8 to be converted into low-temperature and high-pressure air, and is ejected out of a nozzle type fine hole 6 after passing through a compressed air chamber 7. The ejected air changes its direction by a baffle plate 18 and impinges against a turbine blade 17 to rotate a turbine rotor 5. If the rotation of the turbine rotor 5 is braked by a water-cooled controller 4, the energy of an ejected air speed is converted into frictional heat to be taken out to the exterior together with cooling water, and the air is cooled to be discharged. When the damper 9 is closed and a damper 19 is opened, the high-temperature and high-pressure air flows inside a choke tube 11 to be led to an exhaust tube 12 and moves a cylindrical regulating valve 13 pressed with a spring 14 to be discharged through an exhaust port 20. The throttle tube 11 is formed into a triple turn passage through which air flows. Accordingly, air flow is repeatedly inverted to be reduced, and consequently the pressure of air is lowered without the change of its temperature, and the air is converted into utilizable hot air.