Energy Engineering & Management

In this paper, we have continued doing a research project which had done previously. Three types of power plants include an Organic Rankine Cycle (ORC), a Dual-Fluid-Hybrid (DFH) and a single-fluid hybrid-fueled (HYB); were re-modeled. After model validation, thermodynamic studies and exergy analysis were extended for the defined cases using the first and second laws of thermodynamics. Then thermoeconomic analysis by three various parametric capital cost functions was conducted to select the best model accurate. Based on new results, from thermodynamics viewpoint, the HYB plant with cyclohexane is the best option, as it had been concluded already, but the new results show that from the economical view, the DFH plant with R245fa and R236fa are suitable choices. Based on the results of the first step, the DFH plant has better overall performance; thus, in the next step, more and variant organic fluids were evaluated as an operating fluid for its low pressure cycle. It is observed that, in the thermodynamic view, toluene is the best option, and,in the economical view,R236faand toluene are suitable for DFH plants. Through a comprehensive survey, R717 is selected as the best operating fluid for DFH plants.