Energy consumption to achieve macromixing revisited

• The concept of mixing time energy consumption per unit mass E/M is revisited.
• In laminar regime, E/M is proportional to fluid viscosity and impeller speed N.
• In turbulent regime, E/M is proportional to the square of impeller tip velocity.
• The relevance of mixing time energy consumption is supported by experimental data.

In this paper, macromixing of Newtonian fluids is analyzed. Mixing time and power number are commonly used to compare different blending systems in terms of macromixing. In this paper, the concept of mixing time energy consumption, defined by the product of the power consumption times the mixing time, is revisited since this concept seems appropriate to compare different mixers as far as macromixing is considered. In addition, different expressions of circulation and diffusion mixing times in laminar and turbulent regimes are considered. Finally, mixing time energy consumption is applied to data issued from Houcine et al. (2000), who compared different mixing systems in terms of power versus mixing time in the turbulent regime.