Method of operating a heat pump dryer and heat pump dryer

Abstract

Heat pump dryer (1) comprising a process air circuit and a heat pump unit (5) having a primary refrigerant evaporator (6) for cooling process air (4) and a primary refrigerant condenser (7) for heating process air (4), further comprising either—an auxiliary refrigerant evaporator (16) connected between the primary refrigerant evaporator (6) and a compressor (8) of the heat pump unit (5) and an auxiliary refrigerant condenser (17) connected between the primary refrigerant condenser (7) and refrigerant expansion means (14), both arranged outside the process air circuit or—an auxiliary heat exchanger (27) arranged outside the process air circuit wherein the auxiliary heat exchanger (27) is a dual mode heat exchanger operable in refrigerant evaporator mode or in refrigerant condenser mode.

Dependencies are inferred from the claim text.