Optimal Operation of Tubular Solid Oxide Fuel Cell Based on Efficiency and Environmental Impact

Abstract

Solid oxide fuel cell (SOFC) technology dominates other fuel cell technologies because it is a highly efficient form of electric energy generation from natural gas, with both simple fuel cell plants and with integrated cogeneration power plants. This study proposed a tubular SOFC stack with methane gas feeding, internal reforming of hydrocarbons and internal air preheating. To achieve this goal, ‘optimal’ operating conditions for enhanced unit performance were identified. Thus, the genetic algorithm (GA) technique with the min-max method was employed to perform a multi-objective optimization on the unit performance. Simultaneous maximization of efficiency and minimization of environmental impact were considered as the two objective functions. Pareto-optimal sets of operating conditions were successfully obtained by GA with the min-max method for different process conditions and were used to achieve the effective operation of a tubular SOFC stack power generator with the diameter, the thickness of the cathode, anode and electrode, and the length being 22.0 × 10-3, 2.0 × 10-3, 1.0 × 10-4, 4.0 × 10-5 and 1.5 m, respectively. The fixed current density model produced the optimal solution with 75.52% efficiency and 16.35 × 10-2 g.s-1.kW and an environmental impact score of 221.28 kW. The fixed outlet temperature option prodcued 50.41% system efficiency, 31.15 × 10-2 g.s-1.kW and an environmental impact score of 38.22 kW.