Organic Rankine Cycle (ORC) systems utilise waste heat produced from industrial processes such as gas engine exhausts to provide additional electrical power. They can be used to generate additional electrical power for cogeneration plants using a surplus heat.

ORC is the Rankine process, where instead of the water some organic compound is used as a flowing medium (toluene, isobutene, isopentane or silicon fluids). ORC is one way to generate electricity and heat in lower temperatures. Heat from evaporation of organic fluid is less than that of water.

A simple Rankine cycle is based on pressurizing water with a pump, heating the pressurized water beyond its boiling point to produce superheated steam in the boiler, expanding the steam through a steam turbine, cooling the residual steam to regenerate water, and returning the water to the pump to start through the ...

The working principle of the organic Rankine cycle is the same as that of the Rankine cycle: the working fluid is pumped to a boiler where it is evaporated, passed through an expansion device (turbine, screw, scroll, or other expander), and then through a condenser heat exchanger where it is finally re-condensed.