Energy efficiency
For mixing in the regime of Re > Rec, IMRs do not exist. The selection of an appropriate impeller under baffled condition should be measured in terms of the mixing time and the energy required. Fig. 10 shows the dimensionless mixing time: Ntm (the product of the dimensional mixing time tm and the speed N) for three test impellers, all under baffled condition (x4 baffles). It can be seen that the modified pitch-bladed impeller (A-45PBT4) requires less mixing time compared to the radial-flow Rushton turbine (DT6). On the other hand, the mixing time data for disk impeller is not included in this figure as complete mixing did not complete in a reasonable duration. Among the three impellers shown in Fig. 10, the PR30 impeller performs relatively less effective considering the longest blend time that it requires.