PDF simulation of a turbulent series-parallel reaction in an axisymmetric reactor

Because both the turbulent mixing and chemical reaction terms are modeled in the traditional moment approach, it is very difficult to isolate the effect of turbulent mixing on chemical reactions. In contrast, these two terms appear in closed form in the joint velocity-composition probability density function (PDF) formulation. A joint velocity-composition PDF code was used to study the effect of the scalar mixing rate on a series-parallel reaction (A + B --> R, R + B --> S) in a single-jet tubular reactor and the results are compared with experimental data. The turbulent flow field was obtained from the k-epsilon model and the chemical reaction terms were efficiently dealt with using a look-up table. Using PDF simulations, the effects of different scalar mixing rate models on the chemical reaction were investigated under different flow conditions. Since the first reaction step is highly sensitive to the scalar mixing rate, by comparing the yield of the desired product (R) from simulations with the experimental data, the best scalar mixing rate model is determined.