A Review of Working Fluids for Organic Rankine Cycle (ORC) Applications

Abstract

The organic Rankine cycle (ORC) systems are commercially employed for small scale and large scale thermal conversion to electricity of a large variety of abundant heat sources such as exhaust waste heat and some renewable energy sources where conventional steam Rankine and open-gas cycle turbine cycles cannot provide any viable, sustainable, techno-economic solution for power generation. The ORC operates the conventional steam Rankine cycle in subcritical level but can as well operate trans critical cycle while employing heavy molecular organic fluids in place of steam which makes the ORC suitable for medium and low grade heat conversion into electricity. No singular ideal fluid exists for any application and hence over 600 pure and zeotropic mixtures have been investigated by various researches for their best suitability for different applications and operating conditions based on performance characteristics such as efficiency, cost and environmental impacts. In this study a review of working fluids selection for different applications has been conducted. This study helps in identifying the possible most suitable organic fluids for various ORC applications depending on the operating conditions.