Patent ID: 8783032

Claim:
A method for recovering heat dissipated by an internal combustion engine ( 2 ) in a recovery circuit including a pump unit ( 3 ), a heat exchanger ( 4 ), an expansion device ( 5 ), a condenser ( 6 ) and a first control unit ( 7 ) for controlling the pump unit ( 3 ) and first temperature and pressure sensors ( 7 . 1 , 7 . 2 ) connected to the first control unit ( 7 ) for sensing the temperature and pressure of the working fluid leaving the heat exchanger ( 4 ) and a second control unit ( 8 ) for controlling a lower process pressure (p u ) as well as a second pressure sensor ( 8 . 1 ) for sensing the lower process pressure, said method comprising the following steps: compressing a liquid working medium (A) from a the lower process pressure (p u ) and a first temperature (T 1 ) to an upper process pressure (p o ) and a second temperature (T 2 ) in the pump unit ( 3 ); vaporizing the working medium (A) in the heat exchanger ( 4 ) by transferring heat from a hot medium containing heat dissipated by the internal combustion engine ( 2 ) to the working medium (A), whereby the working medium (A) is heated to a third temperature (T 3 ) while being vaporized during passage through the wet vapor area (NG) of a vapor pressure-enthalpy diagram to a superheat area (TG); expanding the working medium (A) approximately to the lower process pressure (p u ), which is adjustable depending on engine operating conditions so that the working fluid is expanded and its temperature is reduced to a point which is close to a fourth temperature (T 4 ) in the expansion device ( 5 ), while generating mechanical energy; condensing the working medium (A) in the condenser ( 6 ) and transferring the working medium (A) to the pump unit ( 3 ), adjusting the upper process pressure (p o ) by the first control unit ( 7 ) in an operating region of the internal combustion engine ( 2 ) to such a value that the working medium (A) is expanded in the expansion device ( 5 ) approximately to a point close to the saturated vapor limit (S) and adjusting the lower process pressure (p u ) by the second control unit in an operating range of the internal combustion engine within a pre-settable pressure range by controlling the load on the expansion device ( 5 ).