Predicting toxic gas concentrations at locations remote from the fire source

Wang, Z., Jia, F., Galea, E.R. and Patel, M.K. (2011) Predicting toxic gas concentrations at locations remote from the fire source. Fire and Materials, 35 (7). pp. 505-526. ISSN 0308-0501 (Print), 1099-1018 (Online) (doi:10.1002/fam.1069)

Abstract

A toxicity model capable of predicting toxic gas concentrations within fire enclosures utilizing the concept of the local equivalence ratio (LER) was recently developed. This paper describes an enhancement of the original model that improves its accuracy in predicting species concentrations at remote locations from the room of fire origin. The enhanced technique involves dividing the CFD computational domain into two regions for species calculation, a control region (CR) and a transport region. Toxic gas concentrations in the CR are calculated using the formulation developed in the earlier study whereas in the transport region, gas concentrations are determined as a result of the mixing of hot combustion gases with fresh air. The concept of a critical equivalence ratio, which is derived from the effective heat release rate (or combustion efficiency) of the fire scenario being simulated, is introduced to perform the domain division.
Predictions of temperatures and species concentrations at various locations made by the new model are compared with the results from two experiments. Compared with the earlier model, the modified model provides considerable improvements in the predictions of toxic species levels.

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