Study of high voltage single chamber SOFC with series connected cells I. IV-IP characteristics of two segments cell

A novel small size SOFC system for generating elevated voltages is proposed. The system consists of conventional single cells for single chamber SOFC and interconnections. The single cells are connected in series and placed in the direction of the gas flow. This fuel cell was named as single chamber SOFC with series connected cells (abbreviated to SSSC). In this study, we direct our attention to the analysis of series connected segments which play an important role in the SSSC system. A single cell of SOFC is divided into two segments and the effect of the partition on the power generation characteristics is discussed. The result of the calculation for the two segments cell revealed that the IV-IP characteristics of the cell are affected considerably by the lengths of the segments. The output power of the system is described as a function of the lengths. We obtained the greatest power when the lengths of the segments are equal. The maximum power of this two segments cell is obtained when hydrogen utilization is 68% in a calculation model. The maximum power is higher than that of the one segment cell by 2.0 mW. When the utilization increases to 85%, the difference of output power between one segment and the two segments cell increases to 5.2 mW. The origin of the difference is discussed in terms of the energy loss related to electrode overpotential. When either segment is considerably smaller than the other one in the two segments system, the output power of the system remarkably decreases. This is explained as an increase in the energy loss related to the IR drop in the smaller segment.