(550d) Residence Time Distributions in a Stirred Tank – Comparison of Cfd Predictions with Experiment

Residence time distributions (RTD) are measured for both a baffled and unbaffled laboratory reactor of the same size with several internal pipes and a Rushton turbine operating at different feed flow rates and impeller rpm's. Ideal behavior as determined by the mean and the variance of the RTD was observed at an impeller Reynolds number of 2,327 for the baffled tank and 3,878 for the unbaffled tank both in the turbulent transition range. The experimental results for the baffled tank are compared to computational fluid dynamics predictions of the RTD using k-?' turbulence model in Fluent?µ for transitional flow regime in the tank, i.e. impeller Reynolds number between 10 and 10,000. All the qualitative aspects of the predicted RTD's are similar to those measured experimentally. The mean residence times as well as the variances of the residence time are accurately predicted by computational fluid dynamics in the transition flow regime.