Parametric analysis and thermal-economical optimization of a parallel dual pressure evaporation and two stage regenerative organic Rankine cycle using mixture working fluids

Abstract

The thermal-economical optimization on a parallel dual pressure evaporation and two-stage regenerative organic Rankine cycle (DTRORC) using mixture working fluid is conducted in this study. The comparison between DTRORC and other ORC systems from the viewpoint of thermodynamic performance and economic performance is discussed. The effects of six key operation parameters on exergy efficiency and LEC are addressed. The bi-objective optimization for maximizing exergy efficiency and minimizing LEC are examined. The Pareto-optimal solutions using TOPSIS, LINMAP and Shannon&GRA decision-making methods are obtained and compared using offset factors. Results indicate that DTRORC obtains 1.75% higher thermal efficiency, 3.5% higher exergy efficiency and 1 kW higher net power than DORC, and 0.8% higher thermal efficiency, 2.5% higher exergy efficiency and 0.5 kW higher net power than DRORC. The optimal solution of the LINMAP decision-making method is chosen for mixture working fluids, while that for Pentane and R245fa are LINMAP and TOPSIS decision-making methods, respectively. From the viewpoint of Pareto-optimal solution, the exergy efficiency of R245fa/Pentane is 2.40% higher than that of Pentane and 1.39% higher than that of R245fa, while the LEC of R245fa/Pentane is 0.58% lower than that of Pentane and 3.42% higher than that of R245fa.