Laminar burning velocity and structure of coal dust flames using a unity Lewis number CFD model

Abstract

Despite decades of research, predictive methods remain unavailable to estimate flame propagation in dust clouds under industrial scenarios. The complexity of scaling the fundamental processes occurring in multiphase flames to industrial geometries, and a lack of tools to explore and extend knowledge in this area, may be key factors missing in the research literature. The main objective of this work is to verify the ability of a CFD model based on a unity Lewis number assumption to explore laminar burning velocity in coal dust clouds. A second objective is to perform parametric analysis including the role of surface reactions, particle diameter, and initial system temperature. The third and final objective is to explore the impact of discrete particle combustion on flame structure and burning velocity. Despite a simplified treatment of gas phase transport properties, single-step devolatilization, and single-step surface reaction, the current model correctly captures the effects of particle diameter and initial temperature on burning velocity and demonstrates good agreement with previous investigations once preheating in the experimental results is accounted for. Furthermore, the reduced model complexity may allow future investigation by the current authors and other research groups into different combustible dusts, more detailed system geometry, and turbulent flow conditions. Lastly, the results of the current study provide a baseline that more comprehensive modeling methods may be compared to, which is currently missing in the literature.