Organic Rankine Cycles (ORC) are systems that can effectively recover low-grade heat for electric power generation. For ORC to be a viable technology, it should operate safely and efficiently under variable operating conditions due to exogenous and operating specifications changes.

The Rankine cycle is an idealized thermodynamic cycle describing the process by which certain heat engines, such as steam turbines or reciprocating steam engines, allow mechanical work to be extracted from a fluid as it moves between a heat source and heat sink.

Rankine cycle is an ideal cycle of heat engine which uses water and steam as a working fluid to generate power with the help of a steam turbine. Process 1-2: Isentropic compression in Pump. Process 2-3: Constant pressure heat addition in the Boiler. Process 3-4: Isentropic expansion in Turbine.

The organic Rankine cycle is is similar to the Rankine steam cycle, but uses an organic fluid such as refrigerants and hydrocarbons instead of water as the working fluid. The ordinary Rankine cycle uses thermal power to convert water to steam, which expands through a turbine in order to generate electricity.