Design of the Organic Rankine Cycle (ORC) System Using R600 and R600a as Working Fluid

Abstract

Organic Rankine Cycle (ORC) is one of the alternative technologies for generating electricity from low to medium level heat sources. ORC operates at low temperatures and pressures using two types of organic working fluids. The organic working fluids as the refrigerants were chosen in the ORC system instead of water, which is suitable for high pressure and temperature applications. Since the performance and configuration of the ORC system rely on its working fluids, the selection of the working fluid for the ORC system becomes crucial. The system utilizes low-temperature heat sources as a supply of heat energy that flows through the evaporator and is then received by the working fluid to operate the cycle. In this study, two dry type working fluids, namely butane (R600) and isobutane (R600a), were used to thermally design an ORC to recover geothermal waste heat. The working fluids were designed using mathematical calculations based on thermodynamic laws. The results revealed that a slightly higher thermal efficiency value was achieved when using R600 as the working fluid, which was 12.8% compared to R600a.