Using Statistical and Experimental Methods to Investigate the Mixing of Dense Slurries with Coaxial Mixers: Effects of Design Parameters and Novel Equations for Power and Reynolds Numbers
Prakash Mishra, Farhad Ein‐Mozaffari
Abstract
A thorough literature review demonstrates that the correlations to determine the Reynolds number and the power number of a dense slurry system furnished with a coaxial mixer have not been reported. The prime objectives of this research work were to analyze the effects of various design factors and their interactions on the mixing of highly concentrated slurries with the coaxial mixers (a wall scrapping outer anchor and an inner axial impeller) via the response surface methodology (RSM) and to develop the novel correlations for the power and Reynolds numbers of this complex slurry mixing system. RSM was adopted to analyze the influences of three numeric factors (average particle size, solid content, and central impeller spacing) and one categoric factor (central axial impeller types) on two response variables, namely, the effective just-suspended speed ratio and the total power consumption required to attain the just suspension state. Two expressions developed in this study through RSM and multi-regression analysis accurately predicted the effective just-suspended ratio and the power required to achieve just suspension conditions. An effort was also made in this work to develop new equations for the power number and the Reynolds number of a slurry system equipped with a coaxial mixer, taking into account the geometric configurations and properties of the slurry. Several tests for different operating conditions were conducted to verify the consistency and accuracy of the proposed correlations.