A coal particle burns in air at 1145 K and atmospheric pressure.The process is limited by diffusion of the oxygen counterflow tothe CO2 and CO that are formed at the particle surface.Twice as much CO is formed as CO2. Assume that the coalis pure carbon with a density of 1280 kg/m3 and that theparticle is spherical with an initial diameter of 0.015 cm. Underthe conditions of the combustion process, the diffusivity of oxygenin the gas mixture may be assumed to be 10-4m2/s. If the combustion is instantaneous:
Find an algebraic equation for the combustion rate of oxygen,WA. State all assumption and boundaryconditions.
Determine the time that is necessary to reduce the diameter to0.005 cm.
mass transfer course
