Open Access

ARTICLE

COMBUSTION AND EMISSIONS CHARACTERISTICS OF METHANEAIR MIXTURES IN CATALYTIC MICRO-COMBUSTORS: A COMPUTATIONAL FLUID DYNAMICS STUDY

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Department of Energy and Power Engineering, School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo, Henan, 454000, China

* Corresponding Authors: Email: ;

Frontiers in Heat and Mass Transfer 2018, 11, 1-15. https://doi.org/10.5098/hmt.11.2

Abstract

The combustion and emissions characteristics of methane-air mixtures in high-temperature catalytic micro-combustors were studied numerically. Both the heterogeneous and homogeneous chemistry were modeled simultaneously using detailed reaction mechanisms in order to better understand the role of each pathway in determining the product distributions. Computational fluid dynamics simulations were performed at a variety of pressures, temperatures, compositions, and combustor dimensions to determine their effects on the combustion and emissions characteristics. Comparisons were made between the results obtained for a purely heterogeneous case, a purely homogeneous case, and a coupled homogeneousheterogeneous case. It was shown that homogeneous and heterogeneous chemistry take place on similar time-scales with each predicting complete conversion of methane in the system. The contribution of homogeneous and heterogeneous reactions depends strongly upon the operating conditions. The heterogeneous chemistry significantly inhibits the homogeneous chemistry due in part to the radical quenching occurring on the catalytic surfaces, which results in lack of homogeneous chemistry. The inhibiting effect also accounts for the low emissions of nitrogen oxides, as these species are formed by a homogeneous reaction pathway. Nitric oxide is the main nitrogen pollutant formed under lean-burn conditions.

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