Similar to a simple Rankine cycle, a basic organic Rankine cycle (ORC) consists of four processes: increasing pressure of the working fluid through a pump, high temperature heat addition through an evaporator, expansion of the high temperature as well as high pressure fluid through a turbine, and low temperature heat ...

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.

An organic Rankine cycle (ORC), is fundamentally the same as a steam Rankine cycle; however, it uses a lower boiling point organic fluid to better match its operation to lower temperature heat sources. ORC systems can achieve better efficiencies than steam turbines for smaller systems (less than a few MW_e).

A basic ORC consists of four main components: an evaporator, an expander, a condenser, and a pump. Figure 1 shows the simplest ORC configuration. As can be seen, liquid in saturated conditions (1) is pumped, increasing its pressure, into the evaporator (2) where it is evaporated by supplying energy in the form of heat.