Property-based selection criteria of low GWP working fluids for organic Rankine cycle

Abstract

In the present study, an attempt is made to prepare a general guideline to compare and select the suitable working fluids for organic Rankine cycle based on their basic properties without going through rigorous numerical or experimental study. Theoretical study on organic Rankine cycle for two low grade sensible heat sources is conducted to study the effects of various fluid properties (molar mass, chemical composition, acentric factor, fluid class, fluid type, freezing point temperature, normal boiling point temperature, critical temperature, critical pressure, molecular complexity, Jacob number, figure of merit and various proposed parameters for phase diagram characteristics) on net power generation, thermal and exergetic efficiencies, turbo-machinery and heat exchanger compactness. For this, the suitable working fluids for organic Rankine cycle have been shortlisted based on operational, environmental and safety criteria. Study shows that some fluid properties have significant effect on cycle performance indexes. However, the effect of properties does not show any common criteria for the best in terms of all performance indexes. Present study summarizes the required fluid properties to get individually best for all performance indexes, which will be useful for working fluid comparison and selection for certain design target. © 2016, The Brazilian Society of Mechanical Sciences and Engineering.