Thermoeconomic optimization of an ORC system utilizing main engine and cargo oil pump turbine heat

This study presents a thermoeconomic analysis and a genetic algorithm (GA)-based optimization of a dual-mode Organic Rankine Cycle (ORC) system employing R1233zd(E) as the working fluid, designed for waste heat recovery aboard a 116,000 deadweight tonnage (DWT) tanker vessel. The system harnesses waste heat from two distinct operational phases: the main engine during navigation and the cargo oil pump turbines (COPTs) during cargo discharge, a configuration rarely explored in the existing literature. Comprehensive energy and exergy analyses are conducted using the Engineering Equation Solver and Aspen Plus. In the baseline configuration, the system achieves a net power output of 664.6 kW, an energy efficiency of 14.87%, an exergy efficiency of 61.68%, and a unit electricity cost of $0.04315/kWh. Following GA-based thermoeconomic optimization, the system delivers 731.3 kW net power, 15.69% energy efficiency, 64.94% exergy efficiency, and a reduced unit electricity cost of $0.03902/kWh, with a total equipment purchase cost of $677,500. Parametric analysis reveals that elevated turbine inlet pressures, reduced outlet pressures, and lower exhaust gas outlet temperatures enhance system performance, while higher ambient temperatures improve efficiency and reduce electricity costs. The results demonstrate the significant potential of dual-mode COPT-integrated ORC systems for sustainable and cost-effective maritime power generation.