Chapter 9, Problem 9.19P

Interpretation Introduction

Interpretation:

The correlation forms for the critical stirrer speed for the suspended particle (small and moderately large) are to be defined if the impeller speed is assumed to be multiple and exponential function of terminal velocity of the particles. Compare the derived correlation with the correlation given in the mentioned equation by Zwietering.

Concept Introduction:

The Zwietering’s correlation for critical stirrer speed given as:

$n_c{D}_a^{0.85}=S{\nu }^{0.1}{D}_p^{0.2}{\left(g\frac{\Delta \rho }{\rho }\right)}^{0.45}{B}^{0.13}$ ...... (1)

Here, $n_c$ is the critical stirrer speed, $D_a$ is the agitator diameter, $S$ is the shape factor, $\nu$ is the kinematic viscosity, $D_p$ is the average particle diameter, $g$ id the acceleration due to gravity, $\rho$ is the liquid density, $\Delta \rho$ is the density difference, and $B$ is the ratio of weight of solid to weight of liquid multiplied by 100. The value of shape factor depends on the type of impeller used and turbine diameter.