Thermo-economic evaluations of novel dual-heater regenerative organic flash cycle (DROFC)

Organic Flash Cycle (OFC) is a promising waste heat utilization technique for low and medium temperature. However, throttling exergy loss in the flash and throttling processes substantially reduces the efficiency of basic organic flash cycle (BOFC). The regenerative organic flash cycle (ROFC) can avoid the exergy loss in the throttling process and enhance the thermodynamic performance of OFC. This paper proposes a novel dual-heater regenerative organic flash cycle (DROFC), which can obtain more power output by reducing the flash process exergy loss and eliminating the mixer exergy loss in ROFC. The thermo-economic performance of DROFC was compared with BOFC and ROFC to evaluate its application potential. Eight low-GWP pure organic fluids were selected and the heat sources were 100–200 °C. Results indicate that DROFC could produce more net power output than BOFC and ROFC with a lower specific investment cost. Specifically, with R600 as an example, the maximum net power output percentage gain of DROFC is 41.19% and 29.09%, respectively. DROFC is more suitable for application scenarios where the heat source temperature exceeds the critical temperature of organic fluid. To balance the net power output and levelized cost of electricity, Hydrocarbons with a high critical temperature are appropriate for DROFC.