Method for recovering heat from internal combustion engines and for converting the recovered heat into mechanical energy

A device for recovering heat from a combustion engine and for converting recovered heat into mechanical energy, the device comprising:

• a primary circuit having at least one primary pump, at least one first heat exchanger, a heat accumulator and a first annular line connecting said first heat exchanger to said heat accumulator, wherein said primary circuit is disposed, structured and dimensioned to guide, using said at least one primary pump, a heat accumulator fluid in said primary circuit, the heat accumulator fluid thereby being heated with waste heat of the combustion engine using said at least one first heat exchanger, transferred into said heat accumulator and recirculated to said at least one first heat exchanger;
• and
• a secondary circuit having an expansion machine, a condenser, disposed downstream of said expansion machine, a second annular line and at least one secondary pump, wherein said secondary circuit is disposed, structured and dimensioned to guide the heat accumulator fluid in said secondary circuit, to extract the heat accumulator fluid in a vapor state from said heat accumulator, to supply the heat accumulator fluid in the vapor state to said expansion machine, to condense the heat accumulator fluid in the vapor state by means of said condenser and to recirculate the heat accumulator fluid into the heat accumulator using said at least one secondary pump, wherein said primary circuit is connected to said secondary circuit exclusively via said heat accumulator and is otherwise separated from said secondary circuit.