and filling 82 lines are therefore in closed position for lines 72 and 78 whereas valve 86 is in open position for line 42 pump 84 is inactive and compressor 12 is driven in rotation by its electric motor in this configuration the water leaves compressor 12 in liquid form at a pressure of the order of 10 bars and a temperature close to 50 u00b0 c this compressed water circulates in line 42 and ends in evaporator 22 control valve 86 being open it cannot circulate in lines 72 and 78 that are closed by valves 76 and 82 this compressed water flows through the evaporator so as to be converted to vapour under the effect of the heat sweeping this evaporator and coming from the exhaust gas of engine 28 the water vapour flowing from the evaporator is carried by line 44 and flows through expander 30 while transmitting thereto the energy it contains the expanded water vapour leaving this expander circulates in line 46 and flows through condenser 36 where it is converted to liquid water this liquid water is then brought through line 48 to compressor 12 in order to be compressed when the rankine cycle circuit is turned off the processing unit controls control valve 86 so as to prevent any circulation of the compressed water contained in line.