An evaporator or a condenser includes a surface on which the operating liquid is arranged. Further, turbulence generators are provided to generate turbulences in the operating liquid located on the operating surface. In the condenser, alternatively or additionally, a laminarizer is present to make the vapor stream laminar provided by the compressor. On the evaporator side, the evaporation efficiency is increased and, on the condenser side, the condenser efficiency is increased, which may be used for a substantial reduction in size without loss of power of these components, in particular for a heat pump for heating a building.