Sarcouncil Journal of Engineering and Computer Sciences

Abstract: This study conducts a comprehensive thermo-economic analysis and exergy optimization of Organic Rankine Cycle (ORC) systems for waste heat recovery (WHR) from industrial processes, specifically marine diesel engines (200–300°C exhaust) and aluminum production plants (150–250°C flue gases). Four configurations—basic ORC (BORC), regenerative ORC (RORC), recuperative ORC, and dual-pressure ORC (DORC)—are evaluated using low-global warming potential (GWP) fluids: R245fa, toluene, cyclohexane, and pentane/isopentane mixtures. Multi-objective optimization via Non-dominated Sorting Genetic Algorithm II (NSGA-II) maximizes exergy efficiency (ηex) while minimizing specific investment cost (SIC) and levelized cost of energy (LCOE). Results show that regenerative transcritical ORC with toluene achieves ηex=75% , with 18–25% higher net power than BORC, and SIC reductions of 7–12%. Evaporators contribute 35–45% of exergy destruction, with 60% identified as avoidable via advanced analysis. Payback periods range from 4–7 years at 0.10 $/kWh, with CO₂ savings of 600–900 tons/year per MW. Compared to Kalina cycles (10–14% efficiency) and thermoelectric generators (<8%), ORC offers superior performance for low-grade heat. This integrated approach, leveraging transient heat profiles and environmental metrics, provides scalable insights for industrial WHR, suitable for Q1 journals like Applied Energy.