Thermodynamic analysis and optimization of a novel zeotropic organic Rankine Cycle

The decrease of fossil energy reserves and the increase of energy prices have resulted in a strong interest in utilizing renewable heat sources or waste heat for power generation. Organic Rankine cycle (ORC) is a promising heat-to-power conversion technology. Although significant efforts have been devoted to improve the thermo-economic performance of the pure fluid ORC, the improvement is limited due to the isothermal nature of evaporation and condensation. ORC using zeotropic mixture is superior to ORC using pure fluid in thermodynamic performance due to the lower irreversibility in heat transfer process of the zeotropic mixture. In the present study, a novel zeotropic ORC with liquid-separation condensation and multi-pressure evaporation is proposed. Thermodynamic analysis and optimization model of the novel ORC is developed. The objective function of the optimization is the maximization of net power output. A case study is elaborated to test the proposed methodology. The results show that the thermodynamic performance can be significantly improved compared to the basic zeotropic ORC. (C) 2017 The Authors. Published by Elsevier Ltd.