Soot Deposition and Gravitational Settling Modeling and the Impact of Particle Size and Agglomeration

Soot concentrations are generally over predicted during the typical application of fire models. The addition of soot deposition and gravitational settling mechanisms to Fire Dynamics Simulator (FDS) results in improved predictions; however, those predictions are highly dependent upon assumptions of soot particle size. Large particle sizes appear to be needed to get FDS predictions on soot concentration to match measured data. Simple predictions of (and experimental data on) aerosol agglomeration show that compartment fires can result in significant amount of large particles sizes; however, the simple predictions do not fully account for the particle sizes needed to match the measured data. Recommendations on additional research and data collection are made to develop improved soot modeling capabilities.