A comprehensive study and tri-objective optimization for an efficient waste heat recovery from solid oxide fuel cell

Since the solid oxide fuel cell (SOFC) has fuel flexibility, high electrical efficiency, and environmental benefits, it is considered a promising electrochemical energy-conversion device. However, it is important to include a waste heat recovery (WHR) unit in SOFC due the high operating temperature. In the present work, the integration of SOFC and WHR is developed. Accordingly, a parametric evaluation of the critical variables from energy, exergy, exergoeconomic, and environmental (4E) viewpoints is carried out. To determine the optimal decision variables, a tri-objective optimization is performed on the novel integrated SOFC-WHR system; the Pareto frontier solution is also provided. On the Pareto curve, the ultimate solution is selected employing the TOPSIS method. The objective functions are cost rate, output power, and CO₂ emission, and the corresponding optimal values are identified as 28.5 $/GJ, 1368 kW, and 0.205 kg/kWh, respectively. Moreover, the scattered distribution of nine design variables is explored, and the behavior of decision variables is obtained.