Synthesis and polymorph controlling of calcite and aragonite calcium carbonate nanoparticles in a confined impinging-jets reactor

, Article Chemical Engineering and Processing - Process Intensification ; 2020 Adavi, K ; Molaei Dehkordi, A ; Sharif University of Technology

Elsevier B.V 2020

Abstract

In this article, a confined-impinging-jets reactor (CIJR) was designed and tested successfully for the synthesis of calcium carbonate nanoparticles using the reactive precipitation method. The proposed CIJR comprised of two opposed nozzles placed in a cylindrical chamber. Effects of various operating and design parameters such as supersaturation, feed flow rate, nozzle diameter, reactor diameter, operating temperature, and surface-active agents on the mean particle size, particle size distribution, and the polymorphs of calcium carbonate nanoparticles were investigated carefully. By changing the supersaturation, reactor diameter, jets velocity, operating temperature, and the nozzle diameter,...

Synthesis and polymorph controlling of calcite and aragonite calcium carbonate nanoparticles in a confined impinging-jets reactor

, Article Chemical Engineering and Processing - Process Intensification ; Volume 159 , 2021 ; 02552701 (ISSN) Adavi, K ; Molaei Dehkordi, A ; Sharif University of Technology

Elsevier B.V 2021

Abstract

In this article, a confined-impinging-jets reactor (CIJR) was designed and tested successfully for the synthesis of calcium carbonate nanoparticles using the reactive precipitation method. The proposed CIJR comprised of two opposed nozzles placed in a cylindrical chamber. Effects of various operating and design parameters such as supersaturation, feed flow rate, nozzle diameter, reactor diameter, operating temperature, and surface-active agents on the mean particle size, particle size distribution, and the polymorphs of calcium carbonate nanoparticles were investigated carefully. By changing the supersaturation, reactor diameter, jets velocity, operating temperature, and the nozzle diameter,...

Synthesis and polymorph controlling of calcite and aragonite calcium carbonate nanoparticles in a confined impinging-jets reactor

, Article Chemical Engineering and Processing - Process Intensification ; Volume 159 , 2021 ; 02552701 (ISSN) Adavi, K ; Molaei Dehkordi, A ; Sharif University of Technology

Elsevier B.V 2021

Abstract

In this article, a confined-impinging-jets reactor (CIJR) was designed and tested successfully for the synthesis of calcium carbonate nanoparticles using the reactive precipitation method. The proposed CIJR comprised of two opposed nozzles placed in a cylindrical chamber. Effects of various operating and design parameters such as supersaturation, feed flow rate, nozzle diameter, reactor diameter, operating temperature, and surface-active agents on the mean particle size, particle size distribution, and the polymorphs of calcium carbonate nanoparticles were investigated carefully. By changing the supersaturation, reactor diameter, jets velocity, operating temperature, and the nozzle diameter,...

Synthesis of Calcium Carbonate in Impinging-jet's Reactor

, M.Sc. Thesis Sharif University of Technology Adavi, Kazem (Author) ; Molaei Dehkordi, Asghar (Supervisor)

Abstract

In this research work, a two-impinging-jets reactor (TIJR) has been designed and tested to synthesis calcium carbonate nanoparticles. The application of calcium carbonate nanoparticles in various industries including health, food industry, pharmacy, etc., and the dependence of product quality on properties such as morphology and particle size distribution, persuaded us to study the synthesis of calcium carbonate nanoparticles in the designed TIJR. The precipitation processes are fast chemical processes and mixing plays an important role in the final product quality. TIJR have come to the attention of researchers because of the low micromixing time in recent years. In this research work,...

High local supersaturation formation for precipitated calcium carbonate synthesis by applying a rotating disk reactor

, Article Brazilian Journal of Chemical Engineering ; 2023 ; 01046632 (ISSN) Adavi, K ; Tahery, D ; Khajouei, M ; Latifi, M ; Sharif University of Technology

Springer Science and Business Media Deutschland GmbH 2023

Abstract

A spinning disk reactor (SDR) was applied and tested successfully for precipitated calcium carbonate particles synthesis in liquid–liquid system which is poorly understood in literature. The proposed SDR reactor consists of a spinning disk rotating at 4000–16,000 rpm. The proposed SDR resulted in a high local supersaturation ratio due to the intense energy dissipation produced by a high-speed spinning disk. The higher rotational speed of SDR produces calcium carbonate nanoparticles with smaller mean particle sizes and higher aragonite content. At the rotating speed of 15,000 rpm, precipitated calcium carbonate nanoparticles with a size of around 975 nm were produced. In addition, aragonite...

Numerical Simulation of Compressible Magnetohydrodynamic Flow Using Spectral Difference Method on Quadrilateral Grids

, M.Sc. Thesis Sharif University of Technology Kafian, Hesam (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

In the present work, the numerical solution of 2D inviscid compressible Magneto-hydrodynamic flow is performed by using the spectral difference (SD) method on quadrilateral grids. In this numerical method, similar to the discontinuous Galerkin (DG) and spectral volume (SV) methods, the concept of the discontinuous and high-order local representations is used to achieve conservation property and high-order accuracy. In the SD method, the test function or the surface integral is not involved and thus it has a simpler formulation than the DG and SV methods. In this numerical method, two sets of structured points, namely unknown points and flux points, are defined in each cell to support the...

Numerical Solution of Two-dimensional Compressible Flow Using Immersed Boundary Method with Compact Finite Difference Scheme

, M.Sc. Thesis Sharif University of Technology Mashayekh, Erfan (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

In this study, the viscous compressible flow is simulated over two-dimensional geometries by using the immersed boundary method and applying a high-order accurate numerical scheme. A fourth-order compact finite-difference scheme is used to accurately discretize the spatial derivative terms of the governing equations and the time integration is performed by the fourth-order Runge–Kutta scheme. To regularize the numerical solution and eliminate spurious modes due to unresolved scales, nonlinearities and inaccuracies in implementing boundary conditions, high-order low-pass compact filters are applied. A uniform Cartesian grid that is not coincident with the body surface is used and the boundary...

Implementing Appropriate Numerical Filters in the Lattice Boltzmann Method for Solving Multiphase Incompressible Flows with Large Density Ratio

, M.Sc. Thesis Sharif University of Technology Bidi, Saeed (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

In this study, two finite-difference lattice Boltzmann methods (FDLBM) are applied and assessed for the simulation of two-phase liquid-vapor flows with high density ratios. For this aim, the He-Shan-Doolen type lattice Boltzmann multiphase model is used and the spatial derivatives in the resulting system of equations are discretized by using the second-order central difference and modified Lax-Wendroff schemes. Suitable numerical dissipation terms and filters are applied to regularize the numerical solution and remove spurious waves generated by flow nonlinearities in smooth regions and at the same time to remove the numerical oscillations in the interface region of the two phases.Three...

Synthesis and Study of Catalytic Activity of Iron (III)-bis(2-oxazolinyl) Methane complex by Urea Hydrogen Peroxide in Oxidation of Sulfides

, M.Sc. Thesis Sharif University of Technology Kazem, Nasrin (Author) ; Bagherzadeh, Mojtaba (Supervisor)

Abstract

Considerable effort has been directed in recent years towards the transition metal complex catalyzed oxidation of organic compounds. Herein the synthsis of the iron complex of bis(oxazoline) ligand as a novel catalyst is reported, and the catalytic activity of this complex in oxidation of sulfides is investigated. Bis(2-oxazolynil)methane as ligand is prepared by condensation of diethylmalonate with 2-aminoethanole in 1:2 molar ratio and finally corresponding complex is synthesized by the reaction between FeCl3.6H2O and Bis(2-Oxazolynil)methane in 1:1 molar ratio. The complex is characterized by using IR, UV-Vis, cyclic voltametery, conductometery and elemental analysis data. Moreover,...

Development of Characteristic Boundary Conditions with Artificial Compressibility Method by Compact Finite-Difference Discretization

, Ph.D. Dissertation Sharif University of Technology Parseh, Kaveh (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

In the present study, the preconditioned incompressible Navier‐Stokes equations with the artificial compressibility (AC) method formulated in the generalized curvilinear coordinates are numerically solved by using a high‐order compact finite‐difference scheme for accurately and efficiently computing the incompressible flows. A fourth‐order compact finite‐difference scheme is utilized to discretize the spatial derivative terms of the resulting system of equations and the time integration is carried out based on the dual time‐stepping method. The capability of the proposed solution methodology for computing the steady and unsteady incompressible viscous flows in a wide range of Reynolds...

Numerical Simulation of Natural Convection Using Smoothed Particle Hydrodynamics with Artificial Compressibility Method

, M.Sc. Thesis Sharif University of Technology Attari, Reza (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

In this research, the numerical simulation of the natural convection is performed by using the smoothed particle hydrodynamics based on the artificial compressibility method. For this aim, the formulation of the artificial compressibility method in the Eulerian reference frame for the mass and momentum equations is written in the Lagragian reference frame and the Lagrangin form of the energy equation is also considered to compute the thermal effects. The benefit of the artificial compressibility-based incompressible SPH (ACISPH) method over the weakly compressible SPH (WCSPH) method for computing the natural convection is that there is no need in the formulation considered here to use any...

Numerical Simulation of 2D Compressible Cavitation Flow Using Compact Finite-Difference Method

, M.Sc. Thesis Sharif University of Technology Irani, Mohammad (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

In the present study, the numerical simulation of 2D inviscid compressible cavitation flow is performed by using the compact finite-difference method. The problem formulation is based on the multiphase compressible Euler equations with the assumption of the homogeneous equilibrium model and the system of baseline differential equations is comprised of the continuity, momentum and energy equations for the vapor-liquid mixture. To complete the system of governing equations, the ideal gas relation is used for the vapor phase and the Tait relation is applied for the liquid phase, and therefore, the compressibility effects are considered for both the vapor and liquid phases. To analyze the flow...

Numerical Simulation of Shock-Disturbances Interaction in 2-D Compressible Flows Considering Real Gas Effects by Using WENO Method

, M.Sc. Thesis Sharif University of Technology Rahmani, Saman (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

In the present study, the shock-disturbances interaction in hypersonic inviscid ﬂows considering real gas eﬀects is numerically studied by using a high-order WENO scheme. To account for real gas effects, the equilibrium air model is utilized. The strong conservative form of the two-dimensional unsteady Euler equations in the generalized curvilinear coordinates is considered as the governing equations and a shock-capturing technique is applied. The resulting system of equations is discretized by using the ﬁfth-order WENO ﬁnite-diﬀerence scheme in space and the explicit third-order TVD Runge-Kutta scheme in time to provide a high-order accurate ﬂow solver. The WENO scheme is a stable scheme...

Numerical Solution of Hypersonic Axisymmetric Flows Including Real Gas Effects Using Compact Finite-Difference Scheme

, M.Sc. Thesis Sharif University of Technology Khodadadi, Polin (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

The numerical solution of the parabolized Navier-Stokes (PNS) equations for accurate computation of hypersonic axisymmetric flowfield with real gas effects is obtained by using the fourth-order compact finite-difference method. The PNS equations in the general curvilinear coordinates are solved by using the implicit finite-difference algorithm of Beam and Warming type with a high-order compact accuracy. A shock fitting procedure is utilized in the compact PNS scheme to obtain accurate solutions in the vicinity of the shock. To stabilize the numerical solution, numerical dissipation term and filters are used. The main advantage of the present formulation is that the basic flow variables...

Developing a Compact Finite Difference Method for Solving Fluid - Solid Interaction in Incompressible Flow

, M.Sc. Thesis Sharif University of Technology Parseh, Kaveh (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

In this study, fluid-solid interaction (FSI) is simulated computationally by using a high-order accurate numerical method. The two-dimensional incompressible viscous flows are considered in the fluid domain. The primary problem with solutions of the incompressible Navier–Stokes equations is the difficulty of coupling changes in the velocity field with changes in the pressure field while satisfying the continuity equation. Herein, the artificial compressibility method is used to overcome this difficulty. Preconditioning is implemented to reduce the stiffness of the system of equations to increase the convergence rate of the solution. Using preconditioning, physical solutions even at low...

Numerical Simulation Cavitating Flows Using Compact Finite-difference Scheme

, M.Sc. Thesis Sharif University of Technology Shokri, Maryam (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

In the study, the simulation of two-dimensional cavitating flows is performed by applying a high-order accurate numerical method to the preconditioned, homogenous, multiphase Navier-Stokes equations. The baseline differential equations system is comprised of the mixture volume, mixture momentum and constituent volume fraction equations. A coordinate transformation is applied and the resulting system of governing equations in curvilinear coordinates is discretized using a fourth-order compact finite-difference scheme. The high-order accurate numerical scheme employing the suitable linear and nonlinear filters to account for density jumps across the cavity interface is shown to yield an...

Numerical Simulation of Incompressible Flows over two Dimensional Geometries by Means of Immersed Boundary Method

, M.Sc. Thesis Sharif University of Technology Shahmardi, Armin (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

Two-dimensional incompressible flow analysis is one the most important applied issues in engineering and applied science field. Numerical solution of governing equations of flow requires exact computational grid generation.In complex geometries, generation of the grid which is coincident to the body is very difficult and time consuming. Immersed boundary method is an appropriate superseded method of body conformal grid generation in flow field numerical solution. In this method a grid which is not coincidentto bodyis generated and flow field properties are modified on points adjacent to the boundary of the object (Ghost Cell Method) to satisfy boundary conditions.
The purpose of this...

Numerical Simulation of Cavitating Flows with Compressibility Effects

, M.Sc. Thesis Sharif University of Technology Mahmoudi, Zakaria (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

In this study, the numerical simulation of cavitating flows with compressibility effects is performed. The algorithm employs the multiphase Euler equations with homogeneous equilibrium model. The baseline differential equations system is similar to the one-phase system of equations and comprised of the mixture density, mixture momentums and mixture energy equations. Thephases considered for cavitating flows is liquid-vapor and liquid-gas fields. The system of governing equations is discretized using a cell-centered finite volume AUSM’s upwind scheme. The computations are presented for steady noncavitating/cavitating flows around 1D/2Dproblems for different conditions. A sensitivity study is...

Numerical Simulation of Turbulent Cavitating Flows Using Two-Equation k-ϵ Turbulence Model

, M.Sc. Thesis Sharif University of Technology Dehghanan, Sara (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

In the current study, the numerical simulation of the turbulent cavitating flows is performed by solving the preconditioned, homogenous, multiphase Navier-Stokes equations. For the turbulence modeling, the standard two-equation k-ϵ model is used. The baseline differential equations system is comprised of the mixture volume, mixture momentum and constituent volume fraction equations together with two equations for the turbulence kinetic energy k and the turbulence energy dissipation rate ϵ. For the calculation of the eddy viscosity near the wall boundary, appropriate turbulence damping functions are applied to modify the source terms of the ϵ equation. The system of governing equations is...

Central Difference Finite Volume Lattice Boltzmann Method for Simulation of Incompressible Electro-Magneto-Hydrodanamic Flows

, M.Sc. Thesis Sharif University of Technology Taheri, Sina (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

In the present study, the simulation of incompressible Electro-Magneto-hydrodynamic flows is performed using a finite volume lattice Boltzmann method (FVLBM). The Boltzmann transport equation is solved using a cell-centered finite volume method on structured meshes. A central difference scheme is used to discretize the spatial derivatives and the fourth-order numerical dissipation term is added to stabilize the solution. To discretize the temporal derivative, the fourth-order Runge-Kutta time stepping scheme is applied. The standard collision-streaming lattice Boltzmann method has been used to simulate EMHD flows in the literature, however, it has several deficiencies such as the...