Organic Rankine Cycle and Its Working Fluid Selection-A Review

Abstract

Renewed interest in waste heat power recovery has resulted in the development of Organic Rankine Cycle (ORC). An ORC is a technology that can convert thermal energy at relative low temperatures in the range of 80°C to 350°C into mechanical work and finally into electricity. It can play an important role to improve the energy efficiency of new or existing energy- intensive applications. It accounts for actual efficiencies of turbine and pump. It also accounts for refrigerant line pressure losses and finite boiler and condenser surface area. Depending on the industrial process the waste energy is rejected at different temperatures, which makes the optimal choice of the working fluid of great importance. This cycle program allows the use of different organic working fluids and various sources of waste heat. The current paper includes the study of ORC with due consideration to the working fluid and its application to waste recovery system. The selection of optimal working fluid for Organic Rankine Cycle is not an easy process. There are many different working fluids to choose among and many criteria should be taken inconsideration. Some working fluids have good thermodynamic properties but at the same time have undesirable environmental and safety data. Other fluids have a good environmental and safety data but they are not efficient thermodynamically. There is no ideal working fluid can achieve all the desired criteria and the fluid selection process is a trade- off between thermodynamic, environmental and safety properties.