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.

An Organic Rankine Cycle (ORC) system is a closed thermodynamic cycle used for power production from low to medium-high temperature heat sources ranging from 80 to 400°C and for small-medium applications at any temperature level.

ORC: How it works Where heat pumps use electrical power to create thermal energy for various purposes, an ORC system uses heat energy to generate electricity. In a typical ORC design, a thermal energy source feeds an evaporator to drive an expander or “reverse compressor”, which in turn generates the electricity.

The ORC-concept has two circuits, one for thermal oil and another for organic fluid. Heat from burning fuel or industrial waste is led in via the oil-filled circuit at a temperature of 250–300 °C to the heat exchanger, creating steam and super heating the organic silicon fluid.