Waste Heat Recovery by Organic Fluid Rankine Cycle

The use of Organic Rankine Cycle for waste heat recovery presents several characteristics which are analyzed in details. After a short comparison with steam cycles, the Organic Rankine Cycle is described : its simplicity is shown and achievable efficiencies versus heat source temperature are given. Available fluids are presented. The choice of the fluid allows a good adaptation to temperature and power for each application. The most interesting field for Organic Rankine Cycles are low mechanical powers of a few megawatts and medium temperatures, about 500 C/600 C, for flue gas. The very simple technology of turbines is shown. Three examples are presented. The first one is a test loop of 300 thermal kW built in BERTIN & Cie laboratory to experiment a supersonic turbine designed by the same company for organic vapor at 250 C. The second gives the main characteristics of recovery from exhaust gas of Diesel engines. The last deals with possible recovery from air quenching of clinker in cement plants