Improvement of solid oxide fuel cell performance by using non-uniform potential operation

Theoretical study was carried out to investigate the possible improvement of SOFC performance by using a non-uniform potential operation (SOFC-NUP) in which the operating voltage was allowed to vary along the cell length. Preliminary results of a simple SOFC-NUP with a cell divided into two sections of equal size in term of range of fuel utilization (Uf) indicated that the SOFC-NUP can offer higher power density than an SOFC with uniform potential operation (SOFC-UP) without a reduction of the electrical efficiency. In this work, voltages and section splits were optimized to obtain the maximum power density of the SOFC-NUP. At the optimum splits (Sp,1 = 0.55 and Sp,2 = 0.45), the power density improvement as high as 9.2% could be achieved depending on the level of electrical efficiency. It was further demonstrated that the increase in the number of separated section (n) of the cell could increase the achieved maximum power density but the improvement became less pronounced after n > 3.