Search for: dilution
0.009 seconds
Total 46 records

    Optimization of Mucor miehei rennin production and recovery

    , Article Scientia Iranica ; Volume 9, Issue 1 , 2002 , Pages 99-104 ; 10263098 (ISSN) Kazemi Vaysari, A ; Kheirolomoom, A ; Arjmand, M ; Habibollahi, M ; Sharif University of Technology
    Sharif University of Technology  2002
    In this paper, fungal rennin production has been carried out by solid state fermentation of Mucor miehei NRRL 3420. The optimum dilution ratio, temperature and fermentation time of the enzymatic solution were determined to be 1:30, 40°C and 4 days after the beginning of the fermentation process, respectively. Also, the enzyme recovery by precipitation was studied using (NH4)2SO4, acetone and ethanol, respectively. The effects of pH, salt and solvent concentration on rennin recovery were studied and the optimum pH value as well as the optimum salt concentration were determined. The maximum specific activity of the enzyme was obtained by precipitation at pH of 6.5 and 50% saturated solution of... 

    Corrigendum to “Investigation of fuel dilution in ethanol spray MILD combustion” [Appl. Therm. Eng. 159 (2019) 113898] (Applied Thermal Engineering (2019) 159, (S1359431118371308), (10.1016/j.applthermaleng.2019.113898))

    , Article Applied Thermal Engineering ; Volume 180 , November , 2020 Karimi Motaalegh Mahalegi, H ; Mardani, A ; Sharif University of Technology
    Elsevier Ltd  2020
    The authors regret to inform that the corresponding author is altered from Hamed Karimi Motaalegh Mahalegi to Amir Mardani with the email address of: Amardani@sharif.edu updated as above. The authors would like to apologise for any inconvenience caused. © 2020 Elsevier Ltd  

    Numerical study of flame structure in the mild combustion regime

    , Article Thermal Science ; Volume 19, Issue 1 , 2015 , Pages 21-34 ; 03549836 (ISSN) Mardani, A ; Tabejamaat, S ; Sharif University of Technology
    Serbian Society of Heat Transfer Engineers  2015
    In this paper, turbulent non-premixed CH4+H2 jet flame issuing into a hot and diluted co-flow air is studied numerically. This flame is under condition of the moderate or intense low-oxygen dilution combustion regime and related to published experimental data. The modelling is carried out using the EDC model to describe turbulence-chemistry interaction. The DRM-22 reduced mechanism and the GRI2.11 full mechanism are used to represent the chemical reactions of H2/methane jet flame. The flame structure for various O2 levels and jet Reynolds numbers are investigated. The results show that the flame entrainment increases by a decrease in O2 concentration at air side or jet Reynolds number. Local... 

    Experimental Investigation on the Effect of Air Swirlers on Kerosene Spray Combustion under Highly Diluted and Preheated Conditions

    , M.Sc. Thesis Sharif University of Technology Arazi Kalat, Sadegh (Author) ; Mardani, Amir (Supervisor)
    In this study, the effects of using the co-flow air rotation on Kerosene combustion under air preheating and diluting conditions have been investigated. During this research, we have tried to achieve combustion under the MILD regime by simultaneous diluting, preheating, and swirling the co-flow air, which has also been achieved. To investigate the factors affecting the flame structure such as preheating temperature, dilution, swirl number, airflow rate, and also the type of fuel nozzle, the Sharif University MILD combustion test rig (SMCTR) has been upgraded in this research.The SMCTR has a symmetrically axial structure and provides a co-flow air with the desired temperature, swirl number,... 

    Experimental and Numerical Study of Spray Combustion under Hot-diluted Conditions

    , M.Sc. Thesis Sharif University of Technology Azimi, Amir Hossein (Author) ; Mardani, Amir (Supervisor)
    In this thesis, combustion of liquid fuel spray under the condition of hot and diluted oxidizer, has been investigated. To this end, a novel type laboratory-scale test rig was designed to study the physics governing the MILD-Spray combustion conditions with an applied approach. The underlined test rig eliminates the operational problems of its predecessor test stands and is used for a heavier fuel with much more complex chemical composition (kerosene). The test section is axially symmetrical, in which the fuel is injected by a pressure-swirl atomizer in the direction of hot and diluted co-flowing air. With the use of the aforesaid test rig, the effect of variables such as oxygen... 

    Numerical Investigation of Kerosene Spray Combustion with Preheated and Diluted Airflow

    , M.Sc. Thesis Sharif University of Technology Moti Khalifeloo, Fatemeh (Author) ; Mardani, Amir (Supervisor)
    MILD combustion can be a promising technology to prevent global warming. In this study, for the first time, the numerical simulation of MILD spray combustion of kerosene fuel with preheated and diluted air has been conducted in the faculty's SMSTR test stand. The modeling framework is based on the Reynolds averaged Navier-Stokes turbulence approach and the standard k–ε model, the DPM discrete phase model, and the EDC combustion model, using the skeletal chemical mechanism of Jet A POSF10325 kerosene with the air and droplet being tracked in Lagrangian coordinates. The simulation is done in a steady state and by an axisymmetric method, and the effects of inlet oxygen concentration, inlet air... 

    Design of a Portable Dilution Sampling System for Measuring Fine Particle and Vocs Emissions from Vehicles and Stack in Iran

    , M.Sc. Thesis Sharif University of Technology Geraei, Hosna (Author) ; Hosseini, Vahid (Supervisor)
    Combustion sources such as diesel vehicles are the most of the particular matter sources in ambient air. Near the tailpipe, exhaust is very hot, condense and have high velocity. This properties cause to need special methods and instrument to collect them. Numerously of combustion sources will emitted the VOCs, IVOCs, and SVOCs. This component mixed with ambient air and changing to particle phase from gas phase. Reaction between nitrogen oxides with sunlight cause to damage ozone layer and tissue in long time. Furthermore, breathe of VOCs gases cause to eye irritation, gastrointestinal effects, Damage to the nervous system, headache, dizziness, fatigue, vibration and loss of organ... 

    Numerical Study on MILD Combustion Enhancement through Injecting Plasma

    , M.Sc. Thesis Sharif University of Technology Khanehzar, Andisheh (Author) ; Mardani, Amir (Supervisor)
    In this thesis numerical investigation on the effect of injecting plasma into the MILD combustion regime which is based on the low oxygen dilution and high preheated temperature, were carried out. The burner which was utilized in this study is a co-flow burner, consists of three coaxial channels. From the center to the outside, there is a fuel jet at the center part, a co-flowing dielectric barrier discharge (DBD), and a preheated air section that is vitiated. The DBD that was used in this study is generated between two coaxial electrodes of which the outer one (conical copper electrode) is covered with a dielectric material made of quartz. The burner is modeled in a 2D-axisymmetric... 

    Investigation of fuel dilution in ethanol spray MILD combustion

    , Article Applied Thermal Engineering ; Volume 159 , 2019 ; 13594311 (ISSN) Motaalegh Mahalegi, H. K ; Mardani, A ; Sharif University of Technology
    Elsevier Ltd  2019
    MILD combustion is a promising technique for low heating value fuels. In this paper, spray MILD combustion of diluted liquid fuel is numerically studied. The modelling framework is based on the RANS approach, the EDC combustion model with a skeletal chemical mechanism, and the Lagrangian tracking of droplets. The validated numerical model is used to simulate the combustion of ethanol diluted with water is studied for different oxidizer temperatures and O2 concentrations under MILD condition. Results indicate that a low-level fuel dilution up to 5 percent has tendency toward expansion of MILD region, but higher degrees fuel dilution within the range of 5–20 percent results in a reduction of... 

    Simulation of competition between two microorganisms in a biofilm reactor based on different growth models

    , Article Biochemical Engineering Journal ; Volume 23, Issue 1 , 2005 , Pages 63-72 ; 1369703X (ISSN) Khoyi, M. R ; Yaghmaei, S ; Sharif University of Technology
    A simple biofilm model based on a model suggested by Soda et al. [S. Soda, E. Heinzle, M. Fujita, Modeling and simulation of competition between two microorganisms for a single inhibitory substrate in a biofilm reactor, Biotechnol. Bioeng. 66 (1999) 258-264] was used to simulate the competition between two microorganisms for space and a single inhibitory substrate in a biofilm reactor. Different growth kinetics were used to describe the growth of two microorganisms A and B which utilize the inhibitory substrate and the effect of biofilm thickness on microorganism concentration in biofilm was discussed. It was assumed that the biofilm has a uniform thickness and is composed of N segments (N =... 

    Prediction of limiting activity coefficients for binary vapor-liquid equilibrium using neural networks

    , Article Fluid Phase Equilibria ; Volume 433 , 2017 , Pages 174-183 ; 03783812 (ISSN) Ahmadian Behrooz, H ; Bozorgmahry Boozarjomehry, R ; Sharif University of Technology
    Elsevier B.V  2017
    The activity coefficient at infinite dilution is a representative of the limiting non-ideality of a solute in a mixture. Various methods for the prediction of infinite dilution activity coefficients (IDACs) have been developed. Artificial neural networks are powerful mapping tools for nonlinear function approximations. Accordingly, an artificial neural network model is proposed for the prediction of the IDACs of binary systems where the properties of the individual components are used as inputs to the network. The input parameters of the neural network are the mixture temperature, critical temperature, critical pressure, critical volume, molecular weight, dipole moment and the acentric... 

    Orbit Design and Optimization of Regional Navigation Satellite Constellation

    , M.Sc. Thesis Sharif University of Technology Sharif Ahmadian, Alireza (Author) ; Assadian, Nima (Supervisor)
    In this thesis, optimum set of satellite constellations for regional navigation has been investigated. The cost function is the required multiple coverage for navigation in the Iran region with the lowest possible positioning error. In the satellite navigation systems the GDOP (Geometric Dilution of Precision) is a quantitative measure which is usually used to determine the effect of satellites’ orbits geometry on position error estimation. The lower the GDOP, the more precise the navigation would be. In fact, GDOP relates computed satellite-receiver range error to position estimation error. This thesis has two major parts; modeling and optimization. In the modeling of the problem,... 

    "investigation on the Effects of Number of Rows in SMAW on Properties of Stainless Steel Clad with Carbon Steel Base Metal and Optimizing Properties of the Clad"

    , M.Sc. Thesis Sharif University of Technology Oryan, Sareh (Author) ; Kokabi, Amir Hossein (Supervisor) ; Dolati, Abolghasem (Supervisor)
    Dilution is a parameter with significant effects in SMAW process. As this factor is in a range of 25-35% in SMAW process, it can increase the portion of base metal in the weld metal. During cladding carbon steel by stainless steel, this parameter causes reaching different composition as the number of weld rows increases. The aim of this project firstly is to investigate the effects of this parameter and then achieving the same properties in different welding rows. Suggested electrodes are as follows; E316-L16 three-row, KST 309-L16 for two-row and KST 310-16 for one-row welds. Corrosion behavior of each clad have been studied and the results show that; although by changing the electrodes the... 

    Numerical Investigation of Turbulent Spray Combustion in Hot Diluted Co-Flow

    , Ph.D. Dissertation Sharif University of Technology Karimi Motaalegh Mahalegi, Hamed (Author) ; Mardani, Amir (Supervisor)
    The Moderate or Intense Low-oxygen Dilution (MILD) combustion of liquid fuels has attracted attention to use its advantages in industrial burners and gas turbines applications. Here numerical investigation has been conducted on a research experimental MILD turbulent spray burner (Deft Spray in Hot Co-flow, DSHC). RANS approach has been adopted for modeling of the reactive turbulent flow field of continues phase with the Lagrangian approach for droplet modeling of pressure-swirl atomizer fuel spray. The EDC combustion model is used which has the ability to take into account the detailed chemical mechanisms. The accuracy of different turbulence and droplet injection sub-models are examined and... 

    Modeling of laser thermal and hydrodynamic effects on a dilute suspension of micro-particles in water

    , Article Journal of Mechanical Science and Technology ; Vol. 28, issue. 3 , 2014 , p. 1017-1026 Zabetian, M ; Saidi, M. H ; Saidi, M. S ; Shafii, M. B ; Sharif University of Technology
    Particle manipulation using laser beam is almost a new and contactless technique in particulate sciences. The method is based on the radiation pressure of light photons on the particles suspended in a semi-transparent fluid. Applications of the technique mainly cover microscopic separation and detection of biological objects. In this work, a theoretical study is conducted to investigate the hydrodynamic and thermal effects on a particulate flow in a mini-channel. Laser thermal effects are studied as a result of light absorption either in fluid or dispersed phase. An analytical model is developed to be the real simulator of a test bed developed by the authors. The main objective of performed... 

    Separation of microparticles suspended in a minichannel using laser radiation pressure

    , Article Applied Optics ; Volume 52, Issue 20 , 2013 , Pages 4950-4958 ; 1559128X (ISSN) Zabetian, M ; Saidi, M.S ; Shafii, M. B ; Saidi, M. H ; Sharif University of Technology
    Optical Society of American (OSA)  2013
    Optical separation, which is a contactless and accurate technique, has been mostly used to manipulate single particles. This work mainly aims to present an effective technique for optical propulsion and separation of a group of microscopic particles that are suspended in liquids. An experimental study is conducted to assess the effect of radiation pressure of a high-power laser on a dilute dispersion of microparticles in water using microscopic image analysis. Results of separation experiments indicate that the manipulation mechanism is capable of sorting the microscopic particles in two size classes. Compared to common optical separators, this configuration has a benefit of separating many... 

    Immobilization of Acidithiobacillus ferrooxidans on monolithic packing for biooxidation of ferrous iron

    , Article Iranian Journal of Biotechnology ; Volume 6, Issue 3 , 2008 , Pages 137-143 ; 17283043 (ISSN) Kahrizi, E ; Alemzadeh, I ; Vossoughi, M ; Sharif University of Technology
    The oxidation of ferrous iron (Fe2+) in solution using Acidithiobacillus ferrooxidans has industrial applications exclusively in the regeneration of ferric iron (Fe3+) as an oxidizing agent for the removal of hydrogen sulfide from waste gases, desulfurization of coal, leaching of non-ferrous metallic sulfides and treatment of acid mine drainage. The aim of this investigation was to increase the bio-oxidation rate of ferrous sulfate by using immobilized cells. Rate of Fe2+ oxidation was determined in a packed-bed bioreactor configuration with monolithic particles being used as support material. Biooxidation of ferrous iron by immobilized cells was investigated in repeated batch culture and... 

    Overall behavior of composites with periodic multi-inhomogeneities

    , Article Mechanics of Materials ; Volume 37, Issue 2-3 SPEC. ISS , 2005 , Pages 343-353 ; 01676636 (ISSN) Shodja, H. M ; Roumi, F ; Sharif University of Technology
    When applying the equivalent inclusion method (EIM) to a composite material with non-dilute distribution of reinforcement particles, due to the complex interaction between the particles, the homogenizing eigenstrain field will in general be highly nonlinear. The interaction becomes more complex, when the reinforcements are multi-phase particles, i.e., the core inhomogeneity is surrounded by many layers of coatings. In this paper, a treatment for an accurate determination of the distribution of homogenizing eigenstrain fields corresponding to composites with non-dilute periodic distribution of multi-phase reinforcement particles is given. The proposed method is applicable to problems, where... 

    Numerical Investigation of MILD Combustion in a Gas Turbine Model

    , M.Sc. Thesis Sharif University of Technology Fazlollahi-Ghomshi, Alireza (Author) ; Mardani, Amir (Supervisor)
    MILD combustion under high preheating and high dilution condition illustrates some interesting characteristics. Very low oxygen concentration in the reaction zone and reduced chemical reaction rates compared to conventional combustion are some of these features which make MILD combustion to be an unique type of combustion. In this work numerical investigation of a gas turbine model combustor (GTMC) was aimed to done using model of the EDC as turbulence-chemistry interaction combustion model. Modeling was performed by solving RANS equations and RSM equations for a 2D axisymmetric computational domain. The combustion chamber was investigated for both reacting and non-reacting conditions. A... 

    Numerical study of CO and CO2 formation in CH4/H2 blended flame under MILD condition

    , Article Combustion and Flame ; Volume 160, Issue 9 , September , 2013 , Pages 1636-1649 ; 00102180 (ISSN) Mardani, A ; Tabejamaat, S ; Hassanpour, S ; Sharif University of Technology
    Reduction of air pollutants formation from hydrocarbon combustion process requires improvements in combustion systems. The moderate and intense low oxygen dilution (MILD) combustion technique is an opportunity to achieve such a goal. MILD combustion is a combustion regime which can be attained by high temperature preheating and high level dilution. In this paper, the mechanism of CO and CO2 formation for a CH4/H2 fuel mixture is studied under MILD combustion condition of a jet in hot coflow (JHC) burner. This investigation is done using the computational fluid dynamics (CFD) and also zero dimensional well-stirred reactor (WSR) analysis. The RANS equations with modified k-ε equations are...