The present invention relates to a laundry dryer (1) of the type comprising a heat pump system (20) having a refrigerant circuit (30) for a refrigerant (R) and comprising a process air circuit (10) in communication with a laundry container (9) suited for receiving laundry to be dried using process air (A). The refrigerant circuit (30) comprises: a first heat exchanger (21) for heating the process air (A) and cooling the refrigerant (R); a second heat exchanger (23) for cooling the process air (A) and heating the refrigerant (R); a refrigerant expansion device (22) arranged in the refrigerant circuit (30) between the first heat exchanger (21) and the second heat exchanger (23); and a compressor (24) arranged in the refrigerant circuit (30) between the second heat exchanger (23) and the first heat exchanger (21). The compressor (24) comprises a compressor chamber (260) and the product of the volume (Vd) of the compressor chamber (260) and the latent heat of evaporation (LHS) of the refrigerant (R) at the evaporation temperature is preferably higher than 2500 cm3*kJ/m3, when the heat pump system (20) is in steady state condition.
