In this paper, the effect of Lewis number on the structure of one-dimensional flame of biomass combustion is analyzed. This effect can be observed by considering the non-unity Lewis number in the governing equations. The fuel particles vaporize first to yield a gaseous fuel of known chemical structure. The analysis is performed in the asymptotic limit, where the value of the characteristic Zeldovich number is too large and the equivalence ratio is larger than unity σ≥u1. The presumed biomass fuel is consisted of four components, moisture, volatile species, fixed carbon and ash. The incineration process of fuel can be described by some chained chemical sub-processes: evaporation of moisture from the fuel particles, volatile release/char formation, burning of the hydrocarbon volatiles in the gaseous space, and the combustion of char and tar components. The flame structure consists of three different zones which are, a preheat vaporization zone where the rate of the gas-phase chemical reaction is small, a reaction zone that consists of gas and Char combustion where convection and the rate of vaporization of the fuel particles are small and a convection zone where diffusive term in the conservation equation is negligible. The obtained results from the presented model declare that the temperature and burning velocity profiles are extremely affected by the variation of Lewis numbers.
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