The ORC technology is particularly suitable for the exploitation of medium-to-low enthalpy sources. It is a cost-effective solution with power outputs reaching up to 40 MWe per single generator for sources with water temperature from 100°C to 200°C or higher.

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.

The exergy efficiency of the ORC system is defined as the ratio of the net power output to the exergy of waste heat before entering evaporation and is written as [37](8) η ex = W net m h [ ( h 9 - h 0 ) - T 0 ( s 9 - s 0 ) ] , where T₀ is the environment temperature; h₀ and s₀ are the specific enthalpy and specific ...

7.5 shows a schematic of a basic ORC system. The system consists of four key components: a pump, an evaporator, an expander (a turbine), and a condenser.