Performance improvement analysis of the regenerative dual-pressure organic flash cycle assisted by ejectors.

We proposed a dual-ejector-based regenerative dual–pressure organic flash cycle (DEj–RDPOFC) with higher performance than the RDPOFC. The effects of high and low pressures and the entrainment ratio of the ejector on the DEj–RDPOFC performance were analyzed from the viewpoints of thermodynamics and thermoeconomics. An exergy-flow distribution diagram revealed why the DEj–RDPOFC outperformed the RDPOFC. Next, the performances of the DEj–RDPOFC and dual–pressure organic Rankine cycle (DORC) were compared under the same boundary conditions. Finally, the performance of the DEj–RDPOFC was optimized using the nondominated sorting genetic algorithm (NSGA-II). According to the results, the power output of the high-pressure (HP) turbine of the DEj–RDPOFC can be increased by replacing the HP throttling valve (TV) with an ejector (which increases the working fluid dryness of the HP vapor separator and the mass flow rate of the HP turbine) and the low-pressure (LP) TV with an ejector (which increases the HP turbine expansion ratio). The DEj–RDPOFC achieves a higher maximum net power output (W net) and a lower corresponding levelized cost of electricity (LCOE) than the DORC. Under the optimum condition, the W net and LCOE of the DEj–RDPOFC are 9.71 % higher and 6.59 % lower, respectively, than those of the RDPOFC. • The effect of the HP and LP ejector on the performance of the regenerative DPOFC (RDPOFC) are analyzed. • The performance of the RDPOFC assisted by ejectors (DEj–RDPOFC) is compared with the dual-pressure ORC. • The DEj–RDPOFC is optimized using a multi-objective optimization algorithms. [ABSTRACT FROM AUTHOR]