Efficient power generation through combined modified organic flash and dual-pressure organic rankine cycles: A comprehensive analysis from thermodynamic, exergoeconomic, and exergoenvironmental perspectives

Abstract

The growing adoption of renewable energy sources in the power supply market emphasizes the need for efficient and environmentally friendly systems. This study presents an advanced setup combining a modified organic flash cycle with a dual-pressure organic Rankine cycle to enhance power generation efficiency. The flash cycle features a two-stage separation process, substituting an ejector with an expansion valve, while oil tanks stabilize the energy supply by storing excess thermal energy from solar collectors. A zeotropic mixture is utilized as the working fluid for the organic Rankine cycle, with multiple candidates evaluated under dynamic conditions. The system is analyzed from thermodynamic, exergoeconomic, and exergoenvironmental perspectives and subjected to multi-objective optimization. Results reveal that solar collectors are the largest contributors to exergy destruction, with a rate of 69.43 MW out of a total 79.24 MW. At the base operating mode, the setup achieves a net power generation of 17.64 MW, an exergy efficiency of 18.20 %, a cost rate of 848.39 $/h, and an exergoenvironmental impact rate of 64.87 Pt/h. Optimization under the exergy-economic scenario improves performance, achieving a net power generation of 17.78 MW, an exergy efficiency of 18.36 %, a cost rate of 834.73 $/h, and an exergoenvironmental impact rate of 66.35 Pt/h. The optimized design also yields a net present value of $65.38 million over the system's lifecycle. These findings highlight the system's potential for sustainable and cost-effective power generation.