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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Numerical Study of Ethanol Reforming in Micro-Channels

Get access (open in a dialog) DOI: 10.1615/IHTC15.nmm.009453
pages 5515-5529

Аннотация

The study of steam reforming of ethanol in micro-channels has been carried out to understand the fluid mechanics, heat transfer and kinetics of ethanol conversion to hydrogen in fuel-cell applications. Heat exchange between alternate channels of combustion flue and steam-ethanol mixture has been considered, involving co-flow or counter-flow configurations. Combustion reactions are observed to be completed close to the entry. This results in higher rates of conversion for the co-flow configuration, owing to higher heat transfer rates at the entry. The conversion rate does not show much improvement after a certain axial distance along the channel. Hence, larger channel lengths or serpentine configurations are undesirable for certain flow configurations. Furthermore, for typical dimensions of the reformer, the flow within the microchannel is not fully developed. This results in high values of heat transfer coefficient for the heat transfer across the channel wall. Also, the fuel concentration variation shows specific characteristics such as rapid depletion at the wall region near the entry, followed by diffusion from mid-portion towards the wall at downstream cross-sections. Hence, plug flow assumptions for modeling the reforming reactions within the channel may not provide accurate predictions. Further, the conjugate heat transfer characteristics in the micro-channels have been investigated and found to be highly efficient.