Abstract:
An air treatment device (1) and a method for heating of aft, in a heating mode, at an air handling unit (2), which comprises a heat recovery device (3). The device further comprises a heat pump (6), comprising an evaporator (7), arranged in a first air stream (4), in the flow direction, after the heat recovery device (3), and a condenser (8) arranged in a second air stream (5), in the flow direction, after the heat recovery device (3). The device further comprises an auxiliary heater (9) for supplying, in addition to the recovered energy, external heat energy. The auxiliary heater (9) is positioned in the first air stream (4), in the flow direction, after the heat recovery device (3) and before the evaporator (7) for heating and thereby the heat pump (6) operation is maintained and a better total efficiency for the plant is achieved.
Abstract:
Method and device for defrosting of an evaporator (1) in a heat pump (2) connected to an air handling unit (9), which comprises a controllable heat recovery device (10). The heat pump (2) comprises a refrigerant system (3) with a refrigerant (4), a compressor (5), a condenser (6), a first expansion valve (7) and an evaporator (1). A four-way valve (8) is arranged after the compressor (5) and before the condenser (6), for changing a flow direction of the refrigerant (4) to the evaporator (1) instead of the condenser (6). The heat recovery device (10) recovers energy from first air stream (11) and transfer energy to second air stream (12). When frost formation occurs, the refrigerant temperature is increased and the recovery device (10) is regulated down so that heating of the evaporator (1) is accomplished, both from inside and outside to defrost the evaporator (1).