Thermodynamic performance evaluation of low-GWP working fluids combined with polymeric material in advanced organic rankine cycle configurations

Abstract This study evaluates the performance of low-global-warming-potential (GWP) and zero-ozone depletion potential (ODP) fluids—R245fa, HFE7000, and HFE7100—paired with micronized polytetrafluoroethylene (PTFE) slurry and composite materials to enhance Organic Rankine Cycle (ORC) efficiency. The research addresses environmental concerns with traditional working fluids and the need for improved heat transfer and durability in ORC systems. R245fa, HFE7000, and HFE7100 were selected for their low environmental impact, thermal stability, and similar critical point temperatures, enabling effective comparisons across different ORC configurations. These include the saturated ORC, ORC with a heat exchanger, and ORC with a feedwater heater. PTFE slurry enhances system performance by reducing wear, improving lubrication, and increasing heat transfer efficiency. Micronized PTFE (Polytetrafluoroethylene) powder is dispersed in ethanol with sodium dodecyl sulfate (SDS) as a surfactant and polyvinyl alcohol (PVA) as a stabilizer for suspension stability. Simulations using the Engineering Equation Solver (EES) show R245fa achieving the highest thermal efficiency (10.5%), followed by HFE7000 (9.8%) and HFE7100 (9.6%), with exergetic efficiencies of 46.2%, 44.8%, and 43.5%, respectively. Uncertainty analysis revealed ±2% for thermal efficiency and ±1.5% for exergetic efficiency. These findings support the selection of optimal fluids and materials for sustainable ORC applications.