Performance analysis and optimisation of a reheat organic Rankine cycle

Abstract

A reheat Organic Rankine Cycle (ORC) is investigated to recuperate a low-grade heat source using six different organic working fluids (WFs). The results indicate that wet fluids produce more power output compared to dry and isentropic fluids. The reheat pressures of the selected WFs were optimised to maximise the exergy efficiency and minimise the total UA. Reheat pressure ranges of 27–48% and 45–54% of the evaporation pressure were obtained, for ORCs with and without IHE, respectively. A maximum of 49.1% exergetic efficiency is achieved by the addition of IHE: a 13.6% improvement compared to the ORC without IHE. Finally, the results indicate that R236ea and propyne are the best WFs for the ORC with and without IHE, respectively.

Keywords

• organic rankine cycle
• reheat pressure
• thermal conductance
• waste heat recovery
• exergy
• optimisation