In this paper we have continued to studying a previously done research. Three types of power plants include an organic Rankine cycle (ORC), a dual-fluid-hybrid (DFH) and a single-fluid hybrid-fuelled (HYB) have been re-modeled. After model validation, thermodynamic studies and exergy analysis have been 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 with more exactitude. As had been already concluded, from the viewpoint of thermodynamics the HYB plant with cyclohexane is the best option, but the new results shows that from the economical approach the DFH plant with R245fa and R236fa are suitable chooses. According to the results of first step, the DFH plant has better overall performance thus in the next step, it was studied more and variant organic fluids were evaluated as operating fluid for its low pressure cycle. It was observed that as the thermodynamic approach toluene was the best option and as the economical approach R236fa and toluene were suitable for DFH plant. With a comprehensive survey, R717 is the best choice as operating fluid for DFH plant.