Experimental and numerical conversion of liquid heptane to syngas through combustion in porous media

The conversion of liquid heptane to syngas in a porous medium reactor consisting of a packed bed of alumina pellets is investigated numerically and experimentally. In experiments, the exhaust gas was analyzed for hydrogen, carbon monoxide, carbon dioxide, methane, and hydrocarbon species over equivalence ratios from 1.4 to 3.8 and a range of mixture inlet velocities. The efficiency of the noncatalytic fuel reformer regarding hydrogen production, carbon monoxide production and energy conversion is assessed. At constant inlet velocity, hydrogen production increases with increasing equivalence ratio, whereas hydrogen conversion efficiency reaches its peak value around an equivalence ratio of 3.0. Tests at a constant equivalence ratio of 2.5 show that conversion efficiency increases with mixture inlet velocity, and experimental values in excess of 80% are obtained for the highest tested velocity of 80 cm/s. Similar trends are observed for carbon monoxide conversion and energy efficiencies, where peak values exceed 90% and 80%, respectively. Some discrepancies are noted between the experimental and numerical results in the ultrarich regime. Overall, the results indicate favorable conditions for fuel reforming between equivalence ratios of 2.5 and 3.5 and show that the inlet velocity has a significant effect on the performance of noncatalytic fuel reforming. Substantial efficiency gains are observed for increased inlet velocities, which are attributed to increases in the reactor temperature. (C) 2008 The Combustion Institute. Published by Elsevier Inc. All rights reserved.