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mokhtabad-amrei--mana
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Numerical Study of Diffusion Flame in Micropropulsion Systems
, M.Sc. Thesis Sharif University of Technology ; Darbandi, Masoud (Supervisor)
Abstract
Modern technology is accompanied by miniaturized devices. With increasing the use of micro satellites and micro airial vehicles (MAVs), finding new power-generating resources is inevitable. Batteries were always an option however high efficiency, long life-span and environmental consideration have encouraged the researches to focus on micro combustion. On the other hand, hydrocarbon fuel contains about 100 times more energy per unit mass than lithium-ion batteries. Micro combustion is defined as a combustion which is occurred bellow quenching distance and old literatures were uncertain about occurrence of such combustion. In this paper we present the fundamental concepts of micro combustion...
Research and Study of Mechanical Properties and Corrosion Behavior of Welded Joint of Ductile Cast Iron to AISI 304 Austenitic Stainless Steel with Buttering of Nickel on Cast Iron Side
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossein (Supervisor)
Abstract
The current work is carried out to characterize welding of AISI 304 Austenitic Stainless Steel to Ductile Cast Iron. The welding method was SMAW and the welds were produced using a Nickel-Buttering by a pure Nickel electrode(ENi1) on Cast Iron side, then by 4 types of filler materials the joints were produced; Ni-base electrode(Ni1), E308 and E309 Austenitic stainless steel electrodes and E7018 electrode. The preheat temperature of Cast Iron has been selected to be 250○ and 500 ○C to avoid crack of weldments. The comparative evaluation was based on metallography, chemical composition, hardness and corrosion behavior on two different preheat temperatures. According to metallography, the best...
Discretized n-dimensional population balance for agglomeration
, Article Industrial and Engineering Chemistry Research ; Volume 52, Issue 49 , December , 2013 , Pages 17487-17500 ; 08885885 (ISSN) ; Molaei Dehkordi, A ; Sharif University of Technology
2013
Abstract
In this article, a new method for solving multidimensional population balance (PB) equations for agglomeration is presented. First, discretized 2-dimensional PB (DPB) is derived and by applying probability approach, this method is extended to n-dimensional PB. The discretization of size intervals is in the form of v(j) = 2j-i v(i) and the volume based PB is used. Because of conservative nature of volume, all internal coordinates are converted to some independent volumes. A simple and clear procedure for solving multidimensional PB is proposed using probability concept. In addition, various types of birth and death mechanisms involved in PB are analyzed separately. Moreover, results of...
Modeling and CFD simulation of a mixed-convection flow of regular fluids and nanofluids in vertical porous and regular channels
, Article Heat Transfer - Asian Research ; Vol. 43, issue. 3 , May , 2014 , pp. 243-269 ; ISSN: 1523-1496 ; Dehkordi, A. M ; Sharif University of Technology
2014
Abstract
In this article, the problem of combined forced and free convection in vertical porous and regular channels for both regular fluids and nanofluids has been solved using the CFD technique in the entrance regions of momentum and heat transfer taking into account the influences of viscous heating and inertial force. In this regard, various types of viscous dissipation models reported in the literature such as the Darcy model, the power of the drag force model, and the clear fluid-compatible model were applied. In the case of nanofluid flow, both the Brownian and thermophoresis molecular transfer mechanisms were considered. The dimensionless distributions of velocity, temperature, and the volume...
Comprehensive modeling and CFD simulation of absorption of CO2 and H2S by MEA solution in hollow fiber membrane reactors
, Article AIChE Journal ; Vol. 60, issue. 2 , 2014 , pp. 657-672 ; ISSN: 00011541 ; Memardoost, S ; Dehkordi, A. M ; Sharif University of Technology
2014
Abstract
A comprehensive mathematical model has been developed for the simulation of simultaneous chemical absorption of carbon dioxide and hydrogen sulfide by means of Monoethanolamine (MEA) aqueous solution in hollow fiber membrane reactors is described. In this regard, a perfect model considering the entrance regions of momentum, energy, and mass transfers was developed. Computational Fluid Dynamics (CFD) techniques were applied to solve governing equations, and the model predictions were validated against experimental data reported in the literature and excellent agreement was found. Effects of different disturbances on the dynamic behavior of the reactor were investigated. Moreover, effects of...
Modeling of Spray Granulation
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
Fluidized bed spray granulation is an important powder production process with several key advantages compared to other powder production processes, such as spray drying. Moreover, in fluidized bed granulators, whole process takes place in just one apparatus and there is no need to side processing. Most important characteristics and essential part of fluidized bed granulation is the wetting of primary particles by atomized liquid binder to coating the primary particles and producing granules. To date, a lot of research has focused on modeling and understanding of the separate particle growth mechanisms which have been integrated into the population balance models. Although, these concepts...
Transient and steady-state analysis of heat, mass, and momentum transfer in developing and fully-developed regions of homogeneous tubular reactors with non-Newtonian fluid flow
, Article Energy Conversion and Management ; Volume 65 , 2013 , Pages 308-321 ; 01968904 (ISSN) ; Hashemi Amrei, S. M. H ; Molaei Dehkordi, A ; Haghi, M ; Sharif University of Technology
2013
Abstract
In this article, the problem of simultaneous heat, mass, and momentum transfer in the developing region of tubular reactors with homogeneous chemical reaction and laminar power-law fluid flow under unsteady-state conditions has been solved. In this regard, the general governing equations were solved using finite-difference method and analyzed carefully. Moreover, the influences of various parameters and dimensionless numbers such as power-law index, heat of reaction, reaction order, and Damköhler number value on the numerical results were investigated. In addition, the numerical results obtained for the fully-developed velocity distribution of Newtonian fluid flow and Sherwood number value...