THE INFLUENCE OF TURBULENT MICROMIXING ON THE COURSE OF PARALLEL CHEMICAL-REACTIONS - A CLOSURE HYPOTHESIS

A closure hypothesis based on the probability density function of inert type composition variables formed with reagents concentrations has been developed and applied to derive the mathematical forms of the average values of the nonlinear chemical kinetics terms in the differential balances of species reacting in turbulent flow. The probability density function used in the closure calculations was approximated with the use of Beta PDF. The method is general; an example of its application to investigate the turbulent impingement mixing-reaction process'' is presented. In the experimental part of these investigations the system was at first identified experimentally by using an instantaneous neutralization reaction. In this manner, the segregation intensity and the PDF distributions over the system were identified. Then, the yield of the nonpremixed parallel reactions between sodium hydroxide, hydrochloric acid and ethyl chloroacetate at complete conversion was measured in the same impingement mixing system. The experiment showed strong influence of mixing on the reaction selectivity. The closure hypothesis used together with experimentally identified intensity of segregation I(s) was applied to interpret these experimental data; the predictions of selectivity are in dose agreement with experimental data for parallel reactions.