Citation

Prasad K, Li C, Kailasanath K. Fire Safety J. 1999; 33(3): 185-212.

Copyright

(Copyright © 1999, Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

The focus of this paper is on numerical modeling of methanol liquid pool fires and the suppression of these fires using water mist. A mathematical model is first developed to describe the evaporation and burning of liquid methanol. The complete set of unsteady, compressible Navier-Stokes equations are solved along with an Eulerian sectional water mist model. Heat transfer into the liquid pool and the metal container through conduction, convection and radiation are modeled by solving a modified form of the energy equation. Clausius-Clapeyron relationships are invoked to model the evaporation rate of a two-dimensional pool of pure liquid methanol.The interaction of water mist with pulsating fires stabilized above a liquid methanol pool and steady fires stabilized by a strong co-flowing air jet are simulated. Time-dependent heat release/absorption profiles indicate the location where the water droplets evaporate and absorb energy. The relative contribution of the various suppression mechanisms such as oxygen dilution, radiation and thermal cooling is investigated. Parametric studies are performed to determine the effect of mist density, injection velocity and droplet diameter on entrainment and suppression of pool fires. These results are reported in terms of reduction in peak temperature, effect on burning rate and changes in overall heat release rate. Numerical simulations indicate that small droplet diameters exhibit smaller characteristic time for decrease of relative velocity with respect to the gas phase, and therefore entrain more rapidly into the diffusion flame than larger droplet. Hence for the co-flow injection case, smaller diameter droplets produce maximum flame suppression for a fixed amount of water mist.