A laundry dryer with a heat pump system comprising a refrigerant circuit for a refrigerant and an air stream circuit for a drying air stream, wherein - the refrigerant circuit includes a compressor, a first heat exchanger, an expansion device, a second heat exchanger and an additional heat exchanger connected in series and forming a loop, - the air stream circuit includes at least one air stream fan, a laundry treatment chamber, the second heat exchanger, the additional heat exchanger and the first heat exchanger connected in series and forming a loop, - the refrigerant circuit and the air stream circuit are thermally coupled by the first heat exchanger, the second heat exchanger and the additional heat exchanger, - the first heat exchanger is provided for heating up the drying air stream and cooling down the refrigerant, - the second heat exchanger is provided for cooling down the drying air stream and heating up the refrigerant, and - the additional heat exchanger is arranged between the first heat exchanger and the second heat exchanger for pre-heating the drying air stream and cooling down the refrigerant, characterized in, that the refrigerant leaving the additional heat exchanger is sucked by the compressor as cooled down by the additional heat exchanger and the additional heat exchanger on the one hand and the first heat exchanger or the second heat exchanger on the other hand are formed as heat exchanger assembly including one air stream channel and at least two refrigerant channels (42, 44, 46), wherein the heat exchanger assembly comprises common fins and air stream channel between said fins and at least one refrigerant channel (42,44,46) in thermal connection with the fins so as to define the first heat exchanger or the second heat exchanger and the additional heat exchanger. - the refrigerant circuit includes a compressor, a first heat exchanger, an expansion device, a second heat exchanger and an additional heat exchanger connected in series and forming a loop, - the air stream circuit includes at least one air stream fan, a laundry treatment chamber, the second heat exchanger, the additional heat exchanger and the first heat exchanger connected in series and forming a loop, - the refrigerant circuit and the air stream circuit are thermally coupled by the first heat exchanger, the second heat exchanger and the additional heat exchanger, - the first heat exchanger is provided for heating up the drying air stream and cooling down the refrigerant, - the second heat exchanger is provided for cooling down the drying air stream and heating up the refrigerant, and - the additional heat exchanger is arranged between the first heat exchanger and the second heat exchanger for pre-heating the drying air stream and cooling down the refrigerant, the refrigerant leaving the additional heat exchanger is sucked by the compressor as cooled down by the additional heat exchanger and the additional heat exchanger on the one hand and the first heat exchanger or the second heat exchanger on the other hand are formed as heat exchanger assembly including one air stream channel and at least two refrigerant channels (42, 44, 46), wherein the heat exchanger assembly comprises common fins and air stream channel between said fins and at least one refrigerant channel (42,44,46) in thermal connection with the fins so as to define the first heat exchanger or the second heat exchanger and the additional heat exchanger.