Application of a stochastic model of imperfect mixing to the combustion of fuel-lean COH₂ mixtures in air

A new stochastic model has been developed on the basis of the coalescence-redispersion mechanism. The mixing rule and collision process are shown to simulate diffusion, and an expression is derived for the equivalent diffusivity as a function of the model parameters. The model was applied to the combustion of fuel-lean mixtures of CO and H₂ in air in a toroidal jet reactor. Using only one adjustable parameter, it was possible to obtain good agreement with experiments. The derived equivalent diffusivity was found to approximate the eddy diffusivity estimated from the average energy dissipation rate. The gathered data indicate that mixing conditions in the reactor do not justify the assumption of an ideal CSTR for the lean COH₂ system.