Thermodynamic Analysis and Fluid Selection for Hydraulic Retarder Waste Heat Organic Rankine Cycle

An ORC (Organic Rankine Cycle) system driven by hydraulic retarder waste heat oil source is investigated in this study. The main purpose is to identify the appropriate organic working fluid in consideration of the thermodynamic properties and evaporator dimension requirements. In addition, six working fluids including dry and isentropic fluid are used as the candidates in this article. Based on a specified condition, thermal efficiency and expansion ratio flexibility in the operating condition of a wide evaporating pressure and condensing temperature range, exergy efficiency and exergy destruction rate, evaporator heat transfer, and evaporator heat transfer area are chosen as the evaluation criteria to select the optimal working fluid. The results indicate that R245ca, R265mfc, and R123 occupy a larger coverage area as for the high thermal efficiency region, meaning that the operating conditions are more flexible for these fluids in the real vehicle application. Also, a same behavior is presented by the expansion ratio results. Besides, the evaporator heat transfer areas for R245fa and R245ca are the smallest, the maximum areas for which are just 2.59 m(2) and 3.22 m(2), respectively. Consequently, the optimal working fluid for the hydraulic retarder ORC system turns out to be R245ca. (C) 2016 American Institute of Chemical Engineers Environ Prog, 36: 548-556, 2017