Fabrication and experimental investigation of a laboratory-scale organic Rankine cycle and data-driven optimization

Abstract

Electricity harvesting from low-medium grade heat sources through the organic Ranking cycle (ORC) is still immature in many countries (like India). Hence, a laboratory-scale ORC system has been designed and developed for the source temperature of 90–180 °C. The experimentation involves component selection, fluid selection, design, fabrication and testing. A custom-designed separator has been fabricated and used to ensure saturated vapor at the expander inlet. Isopentane has been used as a powering fluid due to its environmental-friendly nature. Effects of heat input (5–11.5 kW), source fluid (oil) flow rate (40–60 lpm), and cold air inlet temperature (29–37 °C) on the system performance have been examined. Maximum net power, thermal efficiency, pump isentropic efficiency and expander isentropic efficiency of 0.939 kW, 8.08 %, 66 % and 78 %, respectively, have been achieved. Based on test data, the RSM-ANOVA tool identifies the optimal operating conditions (11.5 kW heat input, 35 °C cold air inlet temperature and 48 lpm oil flow rate) to predict net power output (0.920 kW) and cycle efficiency (8.037 %), which are closely matched the experimental values. Desirability analysis confirms that the effect of heat input is more crucial on performance, as compared to the effects of cold air inlet temperature and hot oil flow rate.