Hydrogen generation in a reverse-flow microreactor: 2. Simulation and analysis



The second part in this series presents parametric simulation and sensitivity analysis of methane partial oxidation in a microreactor operated with periodic flow reversal. The reverse-flow (RF) operation provides up to a 5% increase in the hydrogen yield compared to that of the unidirectional (UD) operation. The effect of varying the inlet CH4:O2 feed ratio, the inlet velocity, and the inlet gas temperature is studied. The optimal feed ratio is found to be CH4:O2 = 1.15:1 with the feed at ambient room temperature. The effects of varying the reactor length and heat losses to the ambient are also investigated. In both these cases, the performance of the UD operation degrades significantly, whereas the performance of the RF operation is more robust to the variations in reactor size and heat losses. The issue of choosing the optimal switching time is also addressed. Switching the input and output ports near the natural timescale of reaction heat release is shown to provide the optimum yield. Through these results, design and operation guidelines based on simple timescale analysis have emerged. © 2005 American Institute of Chemical Engineers AIChE J, 2005