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.

thermal power plant works on principle of the Rankine Cycle shown in Fig. 2[5]The cycle consists of four processes: (1-2) Isentropic compression on pump; (2-3) Constant pressure heat addition in a boiler; (3-4) Isentropic expansion in a turbine; (4-1) Constant pressure heat rejection in a condenser.

The superheated vapor passes through a turbine, which allows electricity generation by its expansion. The Rankine cycle is closed by a condenser (using cooling water) that convert saturated vapor at low pressure from the turbine generator into condensate, which is pumped back to the heat exchanger to restart the cycle.

A heat pump upgrades lower temperature heat source and lifts it to a higher temperature, whereas the Organic Rankine Cycle (ORC) converts waste heat to power (mechanical or electrical).