Selection of Working Fluid for an Organic Rankine Cycle Based Concentrating Solar Thermal Power Plant

Line-focusing concentrating solar collectors such as parabolic trough collector (PTC) and linear Fresnel reflector (LFR) may be employed for power generation through organic Rankine cycle (ORC). Dry fluids are the most preferred working fluids for an ORC. It offers higher thermodynamic efficiency and better part load performance compared to steam Rankine cycle (SRC) up to medium scale applications with medium temperature heat sources. In this paper, thermo-economic comparisons between SRC and ORC based concentrating solar power (CSP) plants are presented. An approximate methodology for these power generating cycles is proposed to generate selection diagram. Selection diagram helps in selecting appropriate power generating cycle and corresponding working fluid, for the CSP plant.