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Three-dimensional numerical simulation of a novel electroosmotic micromixer
, Article Chemical Engineering and Processing: Process Intensification ; Volume 119 , 2017 , Pages 25-33 ; 02552701 (ISSN) ; Madadelahi, M ; Abdorahimzadeh, S ; Sharif University of Technology
Elsevier B.V
2017
Abstract
Lab-on-a-chip (LOC) systems have been widely used in chemical and medical analyses. In this study, a novel T-shaped electroosmotic micromixer was simulated and the effects of different parameters on the mixing process were examined. These parameters include; inlet angle, number of conducting hurdles, arrangements of the hurdles, geometry of hurdles and chambers, aspect ratios of the channel cross-sectional profile, hurdle radius, and depth. It was found that the inlet angle has a direct influence on mixing index (σ). The effect of various number of hurdles (one, two, three and four hurdles) and their orientations was investigated. Simulations revealed that using two conducting hurdles is the...
Theoretical Study of Segregation of Particles in Gas-Fluidized Bed
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor) ; Safe Kordi, Ali Akbar (Supervisor)
Abstract
In this work, the segregation of solids in 2D gas-solid fluidized beds has been investigated carefully doing DPM approach. In this regard, various types of mixing index reported in the literature were need. Lacey index was chosen to study to study the segregation for different conditions. Effects of jetsam concentration, bed aspect ratio, solids density, restitution coefficient, initial arrangement and operation pressure and temperature were investigated. It was found that for beds with the mixed initial conditions, with an increase in the superficial gas velocity, the mixing index decreases and then increases. In addition, the mixing index increases with an increase in the jetsam...
Study of Mixing Binary Solids in Tapered Beds with Inlet Jets Using DPM Technique
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
In this study, mixing of binary solids in Tapered beds with inlet jet using solid particle particle techniques was investigated. A two-dimensional model in which the motion of solid particles and gas in two dimensions is studied is used to simulate the conical beds. For the particle phase by solving the equations obtained with the gas phase equations simultaneously considering the equations and collisions between particles and the gas with the particle is simulated using DEM model. In this study, mixing of binary solids with two different sizes and the influence of simulation parameters such as inlet jet velocity, jet position, using multiple jets instead of single jet with same inlet flow,...
Prediction of equilibrium mixing state in binary particle spouted beds: Effects of solids density and diameter differences, gas velocity, and bed aspect ratio
, Article Advanced Powder Technology ; Volume 26, Issue 5 , 2015 , Pages 1371-1382 ; 09218831 (ISSN) ; Dehkordi, A. M ; Sharif University of Technology
Elsevier
2015
Abstract
The state of solids mixing can be considered as a key factor in accomplishment of high efficiency and a uniform product in gas-solid fluidized-beds operating with several different particle sizes. In the present work, coupled DEM-CFD approach was used to carefully investigate the mixing process of binary particles in flat-bottom spouted beds. In this regard, simultaneous effects of particle specifications, operating conditions, and bed dimensions on the equilibrium mixing state of solid mixture were evaluated in detail. Moreover, taking into account the contribution of various parameters, the obtained simulation results were used to draw a correlation for predicting the equilibrium mixing...
Simulation of Solids Mixing Process in Tapered Fluidized Beds
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
There is extensive use of solid-gas fluidized beds in the petrochemical, energy, chemical, and metallurgical industries. They provide fast heat- and mass-transfer because of the good mixing of solids. Tapered fluidized beds (TFBR) are more appropriate for this type of particle because they have axial velocity changes. This feature allows large particles to remain at the bottom of the bed and fine particles near the bed surface. In this work, the process of the solids mixing in a two-dimensional tapered fluidized bed with a bottom diameter of0/07 m and a height of 0.7 m was studied using computational fluid dynamics (CFD) techniques and applying a two-fluid model approach. The solids mixing...