Integrated thermoeconomic optimization of standard and regenerative ORC for different heat source types and capacities

An integrated thermoeconomic optimization approach of standard and regenerative Organic Rankine Cycles (ORC) is presented. The impact of different heat source temperatures and capacities is investigated. Different expander types and configurations are selected based on technical operation limits. Four working fluids are examined, in accordance with the latest European Union F-gas regulations. The optimization variables are the evaporating pressure, condensation temperature, pinch point in the heater and cooler and recuperator effectiveness. Cyclopentane was found to be the optimal fluid for small scale applications, while for larger ones propane and R1234ze exhibit the best performance. The expander selection, mainly affected by the operating pressure and condensation temperature, plays a predominant role on the economic performance of ORCs. The pinch point in the heater is also an important variable, while the pinch point in the cooler is comparatively insignificant. The recuperative ORC was found to be appealing for high temperature, closed loop (CL) systems and unfavorable for open loop (OL) ones. An economy of scale effect was observed for small system capacities, becoming decreasingly significant for larger scales. The specific investment cost is highly variable, ranging from 15,067 (sic)/kWe (R1234ze, T-hs = 100 degrees C, 1.41 kW(e)) to 770 (sic)/kWe (propane, Ths = 300 degrees C, 110.58 kW(e)). (C) 2017 Elsevier Ltd. All rights reserved.