Naturally Driven Flow, Heat and Mass Transfer in Soil Saturated With Light Fuel Vapor and Heated Asymmetrically

Natural convection heat and mass transfer in a soil saturated with light fuel vapor and heated from one side is modeled and solved numerically. The system is simulated as a porous medium in a large horizontal enclosure exposed to ambient air from the top and saturated with a fuel vapor from the bottom. It is assumed that one of the vertical boundaries is heated to a constant temperature while the other vertical boundary kept cold at the ambient temperature. The problem is approximated as a two-dimensional, steady state, laminar flow with constant properties. The rate of outflow of species is calculated together with the rates of heat and mass transfer. Also, flow, temperature and species distributions are shown. For a thermally driven flow, i.e., N<1.0, the flow is driven into the cavity from a distance if the strength of the heat source and/or the permeability of the porous medium is high. For N>1.0, solutal plumes and complex flow pattern are formed as N increases. Such results will aid in providing guidelines for reducing the fire hazards from fuel wetted soils.