System for a thermodynamic cycle, arrangement having an internal combustion engine and a system, method of lubricating an expansion device in a system for a thermodynamic cycle, and motor vehicle

The invention relates to a system (5) for a thermodynamic cycle, with an evaporator (7) and a - along a system circuit (9), viewed in the direction of flow of a working medium - downstream of the evaporator (7) arranged expander (13), between the evaporator (7) and the expander (13) comprises a separation device (11) is arranged, which is set up liquid for separating lubricant from vaporous working medium, wherein a lubricant path (19) from the separator (11) to the expander (13) is provided in such a way that the expander (13) in the separator (11) separated lubricant for lubrication can be fed.