ESEL Paper Review_20120917
By Hong Guo
Mail: hongguo@gist.ac.kr
Phone: (+82) (0)10 82276568
1, Title and Author
Title: CFD simulation of particle suspension in a stirred tank
Journal: Particuology
Authors:
Nana Qi a, Hu Zhang b,1, Kai Zhang a,*, Gang Xu a , Yongping Yang a
a State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206,China
b School of Chemical Engineering, The University of Adelaide, Adelaide, SA 5005, Austrilia
2. Summary of Paper
In this paper, a two fluid model along with a standard k-epsilon turbulence model is applied for elucidating the effect of particle properties and effective slurry viscosity on particle suspension behavior in solid-liquid stirred tanks driven by an ST impeller. In a conclusion, author found that solid concentration distribution depends on the flow field in the stirred tank. Higher particle density or larger particle size results in less homogenous distribution of solid particles, in the tanks. In addition, increasing initial solid loading has an adverse impact on the homogeneous suspension of solid particles in a low-viscosity liquid, whilst more uniform particle distribution was found in a high-viscosity liquid.
3. Results
For the effect of particle properties, the results shows that uniformity of solid particles increases with a decrease in either the density difference between particle and liquid or particle diameter while the other operating conditions are kept the same. Higher density and larger size of particle lead to the faster settling velocity and less homogenous distribution of particles.
When the author considered the liquid viscosity, the higher viscous drag and the higher flow resistance in a more viscous liquid lead to smaller settling velocity of a single particle, thus preventing a particle from returning to the bottom after suspension. In addition, less energy is required to maintain it in suspension.
The initial solid loading is main issue. When author set the initial solid concentration as 1.1 % at an initial solid loading of 2. 5 vol. %, and 2.3 % at an initial solid loading of 11.0 vol. %, the results indicated that a quite similar and more homogeneous solid particle distribution is obtained in a more viscous liquid.
4. Contribution:
In this paper, flow pattern, power number, and particle suspension characteristics are the main simulating factor for CFD study. Also , those components are used in the field of sedimentation study, which I want to develop now. CFD study on the various closed system are widely discussed today’s world. Moreover, these kinds of work could be widely applied in the different fields of water treatment. I think this paper could be a good guideline for future design work.
4. Author information: