CLOSURE PROBLEM FOR PARALLEL CHEMICAL-REACTIONS

The effect of micromixing on parallel reactions was studied experiment ally and interpreted theoretically using closure models. A solution of sodium hydroxide was contacted with a pre-mixture of hydrochloric aci d and ethyl chloroacetate solutions in a tubular reactor equipped with an impingement mix-head. Two different impingement mix-heads were app lied: the first was T shaped with two feeding nozzles; the second was equipped with six feeding nozzles. The selectivity of the parallel rea ctions was then dependent upon the mix-head used, the Reynolds number, the concentration of reactants and the volume ratio of reagent soluti ons. The effect of the volume ratio of the reagent solutions on the se lectivity was used as the test effect for closure models. It is shown that simple closures based on moments are not able to describe properl y the behaviour of parallel reactions. A closure method based on the p robability density functions of the concentrations of chemically inert species and on the interpolation of the local concentrations of react ants between the asymptotes of infinitely slow and infinitely fast che mical reactions is verified experimentally.