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Enhancing the Efficiency of SOFC‐Based Auxiliary Power Units by Intermediate Methanation
Author(s) -
Göll S.,
Samsun R. C.,
Peters R.
Publication year - 2012
Publication title -
fuel cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.485
H-Index - 69
eISSN - 1615-6854
pISSN - 1615-6846
DOI - 10.1002/fuce.201100203
Subject(s) - methanation , methane , catalytic reforming , methane reformer , process engineering , steam reforming , solid oxide fuel cell , syngas , environmental science , auxiliary power unit , nuclear engineering , cathode , diesel fuel , waste management , materials science , chemical engineering , chemistry , power (physics) , thermodynamics , hydrogen production , engineering , catalysis , electrical engineering , anode , organic chemistry , electrode , biochemistry , physics
Fuel‐cell‐based auxiliary power units benefit from the high power density and fuel flexibility of solid oxide fuel cells (SOFCs), facilitating straightforward onboard fuel processing of diesel or jet fuel. The preferred method of producing the fuel gas is autothermal reforming, which to date has shown the best practical applicability. However, the resulting reformate is poor in methane, so that cell cooling is not supported by internal methane steam reforming. Accordingly, large flow rates of excess air are required to cool the stack. Hence, the power demand of the cathode air blower significantly limits the net electrical power output of the system and large cathode flow channels are required. The present work examines attempts to further increase the system efficiency in middle‐distillate‐fueled SOFC systems by decreasing the cathode air flow rates. The proposed concept is generally based on inducing endothermic methane steam reforming (MSR) inside the cells by augmenting the methane content in an upstream methanation step. Methanation, however, can only yield significant methane production rates if the reaction temperature is limited. Therefore, four process layouts are presented that include different cooling measures. Based on these setups, the general feasibility and the benefit of intermediate methanation are demonstrated.