Parametric Optimization of Zeotropic Mixtures Used in Low-Temperature Organic Rankine Cycle for Power Generation

In the design and optimization of the ORC system, the selection of working fluid is one of the most important factors that should be considered. In this work, considering different heat sources with their temperatures ranging from 80 to 120 °C, 8 different zeotropic mixtures were proposed and their thermodynamic and economic performance for two types of traditional ORC systems (i.e. basic organic Rankine cycle, BORC and organic Rankine cycle with internal heat exchanger, IHORC) were investigated. Firstly, economic analysis were performed for both systems; Secondly, genetic algorithm (GA) was then introduced to determine the optimal fractions and other operation parameters for zeotropic mixtures under different working conditions and systems, the algorithm implementation process was described. Thirdly, the optimization studies were performed by using annual cash flow as the objective function. The optimal thermodynamic performance of different zeotropic mixtures and their components were both calculated and compared. For the different heat sources temperatures, the optimal zeotropic mixtures and their optimal fraction were recommended according to the calculated results.Copyright © 2014 by ASME