Modelling of radiative properties of particles in pulverized coal flames during oxy-fuel-combustion

Oxyflame C4 Copyright: © WSA Picture top: Phase function and scattering coefficients, artistic representation; Picture below: SEM-photograph of coal particles

The aim of subproject C4 of the SFB/TR OXYFLAME is a physically reasonable modelling of the radiative properties of particles in combustion of pulverized coal. The radiative heat transfer in coal combustion is influenced by coal particles as well as by ash and soot. Knowledge of the scattering, absorption and emission behaviour of these particles is important for the modelling of the overall radiative heat transfer in coal combustion and the particles heat management.

The objective of this modelling is the use in CFD overall simulations of Oxyfuel coal combustion. Due to the availability of computational power and an advanced understanding of the different sub-processes that constitute coal combustion, the accuracy of CFD simulations increases. This leads to the requirement of an increasing accuracy in the modelling of radiative properties as well. Nevertheless, the balance of all models leads to a measure for the model’s complexity.

The basis of the modelling is the Mie theory, a detailed physical description of the interaction of electromagnetic waves with spherical particles. This theoretical description of scattering is combined with measurements of the emission and absorption behaviour of particles performed by other subprojects. This way, an accurate and fast model for the scattering and absorption properties of particles can be created. Knowledge of these properties is indispensable for a reliable simulation of coal combustion.