Assessment of the reactor network approach for integrated modelling of an SOFC system

Incorporation of Solid-oxide fuel cells (SOFC) into hybrid systems with CHP capabilities is an attractive option for clean and efficient decentralised electricity generation. SOFC system operation on practical liquid fuels requires an efficient preparation system for the formation of a homogeneous reformate mixture. This can be accomplished with the use of a stabilized cool flame vapouriser (SCFV) combined with a thermal partial oxidation (T-POX) reformer, and such systems are already under development. The successful and efficient thermochemical operation of an SOFC system requires an accurate determination of the optimum conditions for each constituent component (e.g. fuel processing unit, fuel cell stack, off-gas burner) and for the integrated system. The present work demonstrates a computational methodology for the thermochemical assessment of a novel SOFC system operated on liquid fuels. Simulations have been performed, both at component and system levels, using a reactor network approach, involving a simplified flow and mixing representation, while retaining full detailed chemistry. Computations are performed at a component level with reactor networks specially formulated for the SCFV and the T-POX reactors, derived on the basis of CFD calculations, coupled with detailed kinetic mechanisms for n-heptane, a reasonable diesel fuel surrogate. Model predictions are compared against experimental data, wherever possible. The individual components are integrated at a system level and parametric analyses are performed so as to determine optimum conditions for efficient and clean operation.