Use of highly efficient working media for heat engines

Abstract

The invention relates to a heat engine for performing an organic Rankine cycle (ORC) which comprises an evaporator, an engine, a condenser and a circuit comprising a fluid working medium, wherein the working medium has a critical pressure (p c ) between 4000 kPa and 6500 kPa, preferably between 4200 kPa and 6300 kPa, the working medium has a critical temperature (T c ) between 450 K and 650 K, preferably between 460 K and 600 K, the working medium has a molar mass between 50 g/mol and 80 g/mol, preferably between 60 g/mol and 75 g/mol, and the gaseous working medium partially condenses out during adiabatic expansion. The invention further relates to the use of a working medium having a critical pressure (p c ) between 4000 kPa and 6500 kPa, preferably between 4200 kPa and 6300 kPa, having a critical temperature (T c ) between 450 K and 650 K, preferably between 460 K and 600 K, and having a molar mass between 50 g/mol and 80 g/mol, preferably between 60 g/mol and 75 g/mol, in a heat engine, wherein the gaseous working medium partially condenses out during an adiabatic expansion in an organic Rankine cycle (ORC).

1 . A heat engine for performing an organic Rankine cycle (ORC), the heat engine comprising
 an evaporator,   an engine,   a condenser and   a circuit comprising a fluid working medium, wherein   the working medium is methyl formate, and   the heat engine is operated with a heat source at a temperature ranging from 80° C. to 150° C.   
     
     
         2 . The heat engine according to  claim 1 , wherein, during adiabatic expansion during the organic Rankine cycle (ORC), 1% to 30% of the mass of the working medium condenses out. 
     
     
         3 . (canceled) 
     
     
         4 . The heat engine according to  claim 1 , wherein the heat engine is an expansion machine. 
     
     
         5 . The heat engine according to  claim 1 , wherein a pump is disposed between the condenser and the evaporator in the circuit of the heat engine, said pump allowing the fluid working medium to be conveyed from the condenser to the evaporator. 
     
     
         6 . The heat engine according to  claim 1 , wherein the circuit of the heat engine does not comprise a recuperator. 
     
     
         7 . The heat engine according to  claim 1 , wherein an erosion rate of the working medium unalloyed steel is less than 0.05 mm/a at 150° C. and/or an erosion rate of the working medium towards alloyed steel (1.4571) is less than 0.005 mm/a at 150° C. 
     
     
         8 . The heat engine according to  claim 1 , wherein the working medium exhibits no endothermic or exothermic reactions or first or second order phase transitions in the temperature range between 70° C. and 200° C. when subjected to temperature changes over time. 
     
     
         9 . A process, comprising operating a heat engine with methyl formate as a working medium, wherein the heat engine is operated with a heat source at a temperature ranging from 80° C. to 150° C. 
     
     
         10 . The process according to  claim 9 , wherein, during adiabatic expansion during the organic Rankine cycle (ORC), 1% to 30% of the mass of the working medium is condensed out. 
     
     
         11 - 12 . (canceled) 
     
     
         13 . The process according to  claim 9 , wherein the heat engine is operated with an organic Rankine cycle (ORC). 
     
     
         14 . The process according to  claim 9 , wherein an expansion machine is used as the heat engine. 
     
     
         15 . (canceled)