and identical components including a turbocompressor and a regenerative heat exchanger are used for both cooling in the refrigeration mode and heating in the heat pump mode a plurality of valves are arranged so that in the refrigeration mode the refrigerant air operates in a closed dry air loop to avoid problems associated with moisture in the heat pump mode the valves are arranged to cause the refrigerant air to operate open loop by using ambient air as the input to the cycle and avoiding icing problems by rejecting the refrigerant air together with any ice present back into the ambient operation closed loop in the refrigeration mode and open loop in the heat pump mode results in maximum cycle efficiency with minimum difficulty caused by moisture entrained in the refrigerant air application_number US 4484079 A description with respect to fig1 4 the components common thereto are shown by the same reference numerals and include a turbine 10 which is mechanically connected to and supplies a portion of the power required by a compressor 12 the remainder of the compressor power being supplied by an electric drive motor 14 also an essential part of each embodiment is a regenerative heat exchanger 16 located upstream of the turbine for reducing the temperature of the refrigerant at the turbine inlet to as close to ambient or source temperature as possible the ultimate purpose thereof being to cause the turbine.