Thermodynamic investigation of a novel organic Rankine cycle including partial evaporation, dual-phase expander, flash tank, dry expander and recuperator for waste heat recovery

Abstract

The optimum exploitation of low-grade waste heat sources is a critical issue for producing clean electricity and promoting sustainability. Organic Rankine Cycle (ORC) is an emerging technology to produce electricity exploiting various energy sources like waste heat recovery, solar irradiation and geothermal energy. The present work suggests a novel ORC architecture that combines different solutions for increasing electricity production from low-grade waste heat sources (e.g., industrial waste heat up to 200 °C). More specifically, the present cycle includes the solution of partial evaporation, dual-phase expansion, flash tank separator, dry expander and recuperator. All these concepts together create a global optimal design which is examined with the environmentally friendly working fluid R1233zd(E). The present work examines the suggested ORC parametrically, and then the design is optimized. According to the results, the present novel configuration was found to outperform compared to the trilateral cycle, classical ORC without superheating, flash tank cycle, and partial evaporation ORC, for waste heat stream temperatures from 80 °C up to 200 °C. Furthermore, the analysis for the novel systems proved that the optimal system energy efficiency was found to range from 2.3% for Tin = 80 °C up to 13.3% for Tin = 200 °C, while the respective exergy efficiency from 27.3% for Tin = 80 °C up to 62.5% for Tin = 200 °C.