Mixing Phenomena in a Liquid Bath Stirred by Gas Jets through Side and Inclined Nozzles

The perfect mixing time, tm, of the water bath, during gas injection through bottom (vertical and inclined) and size nozzles has been measured by using electrical conductivity technique. Effects of gas flow rate, bath depth, nozzle angle and location have been examined. The measurements indicate that under the condition of a shallow bath (H/D=0.31) and large gas flow rate (specific power ε>10–1 W/kg) influences of the nozzle angle and nozzle location on the mixing time are significant. On the other hand, effects of those parameters on tm are negligible in a deep bath (H/D=1.25). Change in the tracer concentration with time was predicted by numerical modelling. A satisfactory agreement between the computed and experimental results can be obtained by parameter fitting for the average plume rise velocity and effective viscosity in the mathematical model. It is presumed that turbulent mass transfer of the tracer is dominant in the deep bath, while the convection of liquid is more effective in the homogenization in the shallow bath.