ESEL Paper Review_20130222

By Hong Guo

Mail: hongguo@gist.ac.kr

Phone: (+82) (0)10 82276568

1, Title and Author

Title: Large-eddy simulations of particles sedimentation in a longitudinal sedimentation basin of a water treatment plant: Part 2: The effects of baffles

Journal: Chemical Engineering Journal

Authors:

M.Al-Sammarraee,A.Chan

Department of Chemical and Environmental Engineering, University of Nottingham (Malaysia Campus), Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia

2. Summary of Paper

The objective of the study is to investigate the effect of the baffle installations on the particle settling performance of the sedimentation basin. The flow patterns, particle-settling velocities, the particle settling efficiency and volume fraction are computed using Large-eddy simulation (LES) and a multiphase model.

3. Results

? The inlet flow consists of two phases: the primary phase is water and the secondary phase is particles.

? The main settling velocity increase occurred with the smaller particles and the Fig.2 showed that the sedimentation efficiency improvement for individual particles is not correlated with the particle size.

? The inclusion of the baffle is beneficial for the accumulation of solid phase.

? The amount of volume fraction that is able to settle at the sump is significantly larger than that without baffle.

? The velocity profile is more complicated that than the basic design without baffles.

? Medium sized particles’ vortex is more extended than the case of the fine particles.

? The baffles divert the direction of particles toward the bottom of the tank and let them settle easily.

? The presence of baffles reduces the turbulent eddy size to that between the gaps of the baffles and near its shear zones

? The fewer baffles, the larger the extent of turbulence generated, which makes settling more difficult.

4. Contribution:

In this study, the author discussed about the effect of baffles. The installation of baffles could improve the performance the settling efficiencies. In addition, the

number of baffles is also the key issue for the sedimentation tank design. This work shows the current research of the numerical simulation for the sedimentation tanks and gives us the guideline for the sedimentation tank research.

5. Author information:

Email: andy.chan@nottingham.edu.my