A themodynamic model for analysis and selection of a working fluid for an organic rankine cycle with a closed feeding fluid heater

The main purpose of this paper is to develop a method for working fluid selection for an organic Rankine cycle with a closed feeding fluid heater operating in a subcritical cycle with superheating. The fluid selection method proposed the obtaining of the best working fluid for each operating range. The study started with the thermodynamic analysis of the proposed model, followed by the definition of the operating parameters and its operating ranges. Thus, a thermal performance simulation for each selected working fluid was performed. The results allowed to analyze the influence of each operating parameter over the cycle thermal efficiency and over the specific net work. The results also allowed the development of multiple linear regressions able to express the thermal performance for each working fluid according to the most relevant operating parameters. Lastly, the method for fluid selection considered both cycle thermal efficiency and specific net work as thermal performance indicators. Among wet fluids, methanol presented the best performance both for cycle thermal efficiency and specific net work as the R141b fot the dry category. For the isentropic fluids, the best result for cycle thermal efficiency was presented by R113 and the best specific net work value was presented by isopentane.