The Organic Rankine Cycle (abbreviation ORC) is a method of operating steam turbines with a working fluid other than water vapor. The name of the case goes back to William John Macquorn Rankine, a Scottish-British physicist and engineer in the 19th century. As a working medium, organic liquids are used with a low evaporation temperature.
The method is mainly used when the available temperature gradient between the heat source and sink is too low for the operation of a turbine driven by steam. This is especially the case with power generation with the help of geothermal energy, combined heat and power and biomass power plants. The expansion machines (turbine, screw expander, steam motor / reciprocating expander) are typically operated with silicone oil, refrigerant or combustible gas.
The Organic Rankine Cycle is similar to the classic Clausius-Rankine cycle in terms of the individual components. The main differences lie in the process parameters pressure and temperature both are far below the values, as prevail in steam power plants and in the deviation of the evaporation and the condensation from the isothermal course.
The selection criteria for a suitable working medium result from the temperature and the cooling curve of the available heat source. Due to the strong influence of the thermodynamic losses on the overall efficiency at low process temperatures, the selection of the optimized process for the specific heat source is far more important than with conventional thermal power plants.
We supply ORC systems in a power class from 20 kW to 5000 kW as a single unit.
The net active power is approx. 12% of the respective thermal power.