Thesis(M.Eng.)--Chulalongkorn University, 2006

This study was carried out to investigate the possible improvement of SOFC performance by using multiple stacks arranged in series in which the operating voltages were allowed to vary among the different stacks. The comparative study on the operation in conventional SOFC configuration in which multiple stacks are typically arranged in parallel and the alternative ones in which stacks are networked in series is considered in both case i.e with and without considering the effect of pressure drop. By connected the stacks in series instead of in parallel, the power and electrical efficiency improvement as high as 5.0% can be achieved. Moreover, the improvement by the arrangement in series becomes less significant after the number of stacks more than 2. The configuration in series with one compressor installed only at the inlets of the first stack is the best option when taking into account the pressure drop. However, the pressure drops are about 4.7 and 3.75 times in the anodic and cathodic channels, respectively, compared with those from the case with stack arrangement in parallel. Therefore it requires higher consumption of compression power. It was suggested that, to compensate a part of power consumption from installed compressors, the heat recovery system should be installed to offer the practical operation.