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Effect of the gas-phase reaction on hydrogen microcombustion in a Pt/γ-Al2O3 catalytic plane channel with detailed chemical kinetic mechanisms

Posted on 11. February, 2015.

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Micro-combustors are emerging as a powerful tool for the portable production of energy. The combustion-based micro-power generation systems may eventually replace environmentally non-benign and expensive lithium batteries in many devices due to the high energy density of hydrocarbon fuels (40 for hydrocarbon fuels versus 0.5 MJ kg-1 for lithium batteries).

There are some challenges to sustain stable combustion inside micro-combustors in practice. As the characteristic dimension decreases and the large surface area-to-volume ratio increases, the mass and heat transfer at the walls of micro-combustors play a significant role in defining the micro-combustion characteristics. The increased heat losses can significantly restrain gasphase combustions. In order to improve micro-combustion stability and thermal efficiency, many useful strategies such as Swiss-Roll (excess enthalpy) and Heat-Recirculating micro-combustors have been proposed to reduce heat losses. Several other approaches have been employed to sustain gas-phase combustion inside micro-combustors at sub-millimeter dimension. Shannon et al. studied theoretically and experimentally the laminar diffusion flames of methane-oxygen mixtures inside alumina micro-combustors, the results showed that gas-phase combustion is achievable at sub-millimeter dimensions by using chemically treated and annealed walls. However, the flames structure differs from the continuous laminar diffusion flame profiles in a macro-structured configuration under similar conditions. Vlachos et al. reported sustainable lean propane-air combustion in two platinum-catalysed parallel plates with gaps as low as 0.3 mm, and found that the mass transport and transverse heat strongly depend on the thermal conductivity and the inlet flow rate.

Read the full article in Progress in Reaction Kinetics and Mechanism, Volume 40, Number 1, 2015, pp. 1-21.

Authors: Junjie Chen, Longfei Yan and Wenya Song
School of Mechanical and Power Engineering, Henan Polytechnic University, 2000 Century Avenue, Jiaozuo, Henan, 454000, P.R.China
 
Keywords: micro-channels, micro-combustion characteristics, gasphase reaction, catalytic reaction, chemical kinetic mechanisms

DOI: 10.3184/146867815X14212355041114

Image: OH mass fractions along the 0.8 mm plane channel with 1400 K wall temperature at different inlet mass fluxes