Thermal integration of reheated organic Rankine cycle (RH-ORC) with gas turbine exhaust for maximum power recovery

Abstract

Reheating is a potential modification to the organic Rankine cycle architecture. Reheated ORC (RH-ORC) is integrated as bottoming cycle plant for topping high efficiency, recuperated gas turbine cycle with low exhaust temperature in the present study. The exit temperature of the working fluid after internal heat exchanger (IHE) sets the initial qualifying criterion. Cyclopentane, hexane and benzene qualify as potential working fluids and ORC with saturated operating conditions with these working fluids is considered as base cycle. For a power generating cycle, power recovery becomes priority over efficiency when connected to a waste heat recovery source. The performance of RH-ORC is studied at various reheat pressure ratios for different temperatures. Specific net work output of base cycle increases by retrofitting reheating and it leads to enhanced power recovery. Benzene, at a reheat pressure ratio of 0.558 produces maximum power output of 1292.033 kW and 4772.631 kW from the integration of SM-50 and Rolls-Royce WR-21 for a case of reheating at a temperature of 557.15K. The power recovery potential improves when reheating is carried out to a higher temperature. There is an increase in exergy efficiency because of reheating.