doi:10.3850/978-981-08-7724-8_12-02

ABSTRACT

Approaches for predicting CO production in compartment fires are explored, based on the solution of a dedicated balance equation for CO. Finite-rate chemistry is addressed via two approximations for the CO source term: (i) neglecting the turbulent fluctuations and adopting appropriate quasi-laminar chemistry, and (ii) constructing the CO rate flamelets and effecting closure through `presumed probability density function (pdf)' transport method. In both cases two-step chemistry is assumed, with rate constants drawn from simplified reaction mechanisms for oxidation of hydrocarbon fuels in flames. The models are tested against relevant experimental data from underventilated compartment fire scenarios. Predictions of the rate flamelet model can differ markedly from the steady flamelet yields but accuracy is variable and strongly dependent on the generality of the kinetic scheme adopted. Quasi-laminar chemistry can only realistically be used for lower turbulence regions but if linked to a formation model which accommodates mixing would provide a more flexible approach, in which liberation of CO via solid-phase pyrolysis could be incorporated.

Keywords: Carbon monoxide, Toxic species, Rate flamelets, Quasi-laminar.

© 2011 CPD Unit, University of Leeds