Application of Scale-Up Methods in Pharmaceutical Engineering

The relevance list of this task consists of the target quantity (mixing power P) and the following parameters stirrer diameter d, density p, kinematic viscosity v of the liquid, and stirrer speed  

The residual matrix consists of only two parameters, therefore only two pi numbers result  

In the range Re 20, the proportionality NecxRe is found, thus resulting in the expression Ne Re = R/= const. Density is irrelevant here because we are dealing with the creeping flow region. 

In the range Re 50 (vessel with baffles) or Re 5 x 10 (unbaffled vessel), because the Newton number Ne = P/(pn d ) remains constant. In this case, viscosity is irrelevant we are dealing with a turbulent flow region. 

Understandably, the baffles do not influence the power characteristics within the creeping flow region where viscosity forces prevent rotation of the liquid. However, their influence is extremely strong at Re 5 X 10. Here, the installation of baffles under otherwise unchanged operating conditions increases the power consumption of the stirrer by a factor of 20. 

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