A Comparative Thermodynamic Analysis of the Rankine Cycle Using Various Organic Working Fluids

Abstract

A comparative thermodynamic analysis of the Organic Rankine Cycle (ORC) using various working fluids was done using models developed in this work with the ASPEN Plus software to determine the thermal and exergy efficiencies of the ORC when running on six selected promising working fluids. The process was designed for power generation using a low heat source of about 40 o C. Two layouts were considered; one was a typical ORC while the other was an ORC with a recuperator for heat energy savings. The process was run with two temperature conditions of 30 degrees superheat and 30 o C at the turbine inlet. Six working fluids; three wet (R-152a, R-134a, and R-32)) and three dry (R-600, R-600a and R-245fa) were selected based on their physical, chemical, environmental and economic criteria. The results showed that no single fluid perfectly met all requirements but in a trade-off, their overall performances at the turbine inlet temperature of 30 o C were preferred and R-32 emerged as the best ranked followed by R-600a and then R-134a; next was R-152a then R-600 and lastly R-245fa. for Layout-2 making a total of twenty-four simulations