Modeling radiation in particle clouds: On the importance of inter-particle radiation for pulverized solid fuel combustion

TL;DR

This paper investigates the significance of inter-particle radiation in particle clusters during pulverized solid fuel combustion, highlighting its impact on radiative cooling and the importance of particle positioning.

Contribution

It introduces a mean radiative particle cooling term for simulations, emphasizing the role of inter-particle radiation in combustion processes and analyzing effects of particle size distribution.

Findings

Radiative cooling varies strongly with particle position in clusters.

Inter-particle radiation significantly affects furnace operations.

Size distribution broadening has minor impact on radiative cooling.

Abstract

The importance of inter-particle radiation for clusters of gray and diffuse particles is investigated. The radiative cooling of each individual particle is found to vary strongly with its position in the cluster, and a mean radiative particle cooling term is proposed for single particle simulations of particle clusters or for high detail simulation, like Direct Numerical Simulations of small sub-volumes of large clusters of particles. Radiative cooling is shown to be important both for furnaces for coal gasification and coal combustion. Broadening the particle size distribution is found to have just a minor effect on the radiative particle cooling. This is particularly the case for large and dense particle clusters where there is essentially no effect of size distribution broadening at all. For smaller and more dilute particle clusters, the effect of distribution broadening is clear but still not dominant.