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    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)
    Abstract
    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... 

    Simultaneous Impact of Multiple Boiling Droplets on a Molten Phase Change Material as a Direct-Contact Solidification Method

    , M.Sc. Thesis Sharif University of Technology Poureslami, Parham (Author) ; Shafii, Mohammad Behshad (Supervisor)
    Abstract
    Encompassing an interaction between the phase change material (PCM) and the droplets of a heat transfer fluid, the direct contact (DC) method provides a state-of-the-art solution for the meager melting and solidification rates of PCMs. In the DC procedure, when impinging on the molten PCM pool, droplets evaporate, solidifying the portion of the PCM. For the first time, the impact of single and simultaneous double ethanol droplets, having an average diameter of 2.68 mm, on the molten paraffin wax has been scrutinized exhaustively. Experiments have been carried out through high-speed imaging for various Weber numbers ranging from 179 to 464, pool temperatures from 70 to 95°C, and horizontal... 

    Fabrication and Characterization of Hydrogen Gas sensors Based on Metal Oxides/Carbon Nanotubes Hybrid System

    , Ph.D. Dissertation Sharif University of Technology Ghasempour, Roghayeh (Author) ; Iraji zad, Azam (Supervisor) ; Taghavinia, Nima (Supervisor)
    Abstract
    We have studied binary structures contain; as grown thin film of carbon nanotubes (CNTs) , CNT rich polymeric composite, Pd doped WO3 thin film, and also hybrid thin film which was mixed CNTs and WO3 nanoparticles and ternary structure which was obtained by adding Pd to hybrid structure as a hydrogen gas sensor. The structure, morphology, chemical composition and quality of as–grown and functionalized CNTs and sensitive films were studied by SEM, TEM, XRD, XPS, DLS, FTIR and Raman spectroscopy methods. Variation of film’s electrical resistance after exposure gases is utilized as the principle of gas sensing. Multi-Walled Carbon Nanotube (MWCNTs) films were obtained by Thermal Chemical Vapor... 

    Study and Fabrication of Electrical & Electromechanical Resonators Based on Nanostructures for Sensing Application

    , Ph.D. Dissertation Sharif University of Technology Fardindoost, Somayeh (Author) ; Iraji Zad, Azam (Supervisor) ; Sarvari, Reza (Supervisor) ; Mohajerzadeh, Shamsoddin (Co-Advisor)
    Abstract
    In this thesis we present fabrication, characterization, and experimental results describing electrical actuation and readout of the mechanical vibratory response of PVP, graphene-doped and ZnO fibers by employing electrical actuation. For a fiber resonator with an approximate radius of 850 nm and length of 100 µm, we observed a resonance frequency around 580 kHz with a quality factor (Q) of about 2511 in air at ambient conditions. Through the use of finite element simulations, we show that the reported frequency of resonance is relevant. Also, the measurements were performed in an enclosed chamber with controlled levels of ethanol vapor. The adsorption of ethanol causes a shift in the... 

    The Effect of Solvent Type on the Characteristic of TiO2 Nanometric Coatings Produced by Electrophoretic Method

    , M.Sc. Thesis Sharif University of Technology Farrokhi Rad, Morteza (Author) ; Ghorbani, Mohammad (Supervisor)
    Abstract
    Titania is semiconductor material and have many applications including photocatalysis, photochromic, air and water purification, sensors, and solar cell. In electrophoretic deposition, charged particles dispersed in a stable suspension move towards an oppositely charged electrode, and form dense layer of deposit on it. In this investigation electrophoretic deposition of titania nano-particles in suspensions prepared by different solvents (methanol, ethanol and butanol) with and without dispersant (triethanolamine and polyethylenimine), was studied. Well stabilized suspensions, prepared for electrophoretic deposition. The effects of solvent type, additive concentration, mechanism of particles... 

    Investigation of Fuel Physical Properties Change Effects on Performance of Fuel Delivery Systems of Si Engine

    , M.Sc. Thesis Sharif University of Technology Abdolalinejad Shiramin, Majid (Author) ; Hosseini, Vahid (Supervisor)
    Abstract
    Ethanol is a promising alternative fuel in terms of addressing future energy and environmental problems, so we can use ethanol as a fuel in passenger cars to eliminate enviremental problems. in this study, the CEV13-038 injector from ACRUS company is modeled. the research purpose is focused on the effect of ethanol , geometrical parameters, and the fuel type on the injected mass quantity and on turning the fuel supply system from a gasoline based system to ethanol based one.
    In the first step of this study, The effect of ethanol, fuel temperature, needle lift, nozzle diameter and number of nozzles... 

    Bioactive Packaging Study to Improve the Quality of Food Products

    , M.Sc. Thesis Sharif University of Technology Safaei, Maryam (Author) ; Roostaazad, Reza (Supervisor)
    Abstract
    One of the most important concerns in food industry is decreasing the contamination of food and increasing their shelf life. Antimicrobial/antioxidant packaging, an active packaging concept, can be considered an extremely challenging technology that could have a significant impact on shelf-life extension and food safety of meat and meat products. Due to harmfulness of chemical preservatives, their use has been limited and therefore natural antimicrobial/antioxidant agents have become more popular. Propolis is a natural resinous substance, with a high polyphenol content, produced by honeybees and characterized by antimicrobial, anti-inflammatory and antioxidant properties, which make it... 

    Gas Fermentation Development Using Flux Balance Analysis

    , Ph.D. Dissertation Sharif University of Technology Sohrabi Shoabjareh, Ali (Author) ; Farhadi, Fathollah (Supervisor) ; Pishvaie, Mahmood Reza (Supervisor)
    Abstract
    In this thesis, a typical dynamic model of syngas fermentation, refered as hybrid method for biofuels production, coupled with a distillation column is developed in SimDFBA. The bioreactor is simulated in MATLAB/Simulink by using Clostridium ljungdahlii acetogenic micro-organism metabolic network. Bioreactor modeling is accomplished with a bubble column reactor in both liquid and gas phases, while the separator was simulated with ASPEN. PDE equiations of bioreactor modeing are dicretized to ODE equation by using QUICK scheme of finite volume method. A new econometric optimization study for outlet gas purification through a pressure swing adsorption unit to recycle relatively pure hydrogen is... 

    Modeling and Simulation of Alcoholic Fermentation of Sugarcane Blackstrap Molasses

    , M.Sc. Thesis Sharif University of Technology Soroush, Mohammad (Author) ; Yaghmaee, Sohila (Supervisor)
    Abstract
    Fed-batch fermentation is a valuable and cost-effective method for bio-based production of various products such as ethanol, which has various applications in various industries.In recent years, bioethanol production has been given special attention in many countries. For this reason, the mathematical modeling of production of these products is very important for their optimal and cost-effective production. Given the transient and dynamic nature of fermentation and its specific complexity, mathematical modeling of fed-batch bioreactors is difficult and complicated. In this research, an unstructured model was used to predict the production of ethanol from blackstrap sugar cane molasses based... 

    Fabrication of Gas Nanosensor based on 2D Nanostructure Titanium trisulfide/Graphene Heterojunction

    , Ph.D. Dissertation Sharif University of Technology Rafiefard, Nasim (Author) ; Iraji Zad, Azam (Supervisor) ; Sasanpour, Pezhman (Supervisor) ; Esfandiar, Ali (Co-Supervisor)
    Abstract
    Titanium trisulfide (TiS3), a transition metal chalcogenide, bears the potential to replace silicon, when taking the form of nanoflakes, due to its favorable band gap and optical response. In this work, first we investigate the response of TiS3 nanoflakes to gas detection through a careful quantum computational approach and a few succinct measurements. The computations are benchmarked and compared with a relevant experiment at each step, where their results/conclusions are discussed. The most stable surface of TiS3 particles is determined to (001), in agreement with the literature. The adsorption of 5 gas molecules is characterized through formulating and estimating their adsorption... 

    Comparative Study of Gasoline and Ethanol Combustion in a SI Engine Combustion Chamber Using Closed Cycle CFD Simulation

    , M.Sc. Thesis Sharif University of Technology Rezaie, Milad (Author) ; Hosseini, Vahid (Supervisor) ; Shafie, Behshad (Supervisor)
    Abstract
    At today’s crowded world, the importance of automobile transportation is obvious for all. The fossil fuel pollution crisis has increased the need for renewable-fueled engines with higher efficiency and lower emissions. Meanwhile, biofuels have received more attention for reasons such as carbon dioxide cycling, Affordability and availability. However, despite these benefits biofuels require crops such as corn or potatoes to produce, which in turn produce other environmental pollution. On the other hand, concerns have been raised as to whether the use of these fuels increases the amount of other pollutants, except for carbon dioxide, or not. Extensive researches in this field by experimental,... 

    Modification of Electrode Substrates Using Nanocomposites Including Carbon Nanomaterials and Multimetallic Nanoparticles for Electrocatalysis of some Fuel Cells Reactions

    , Ph.D. Dissertation Sharif University of Technology Rezaee, Sharifeh (Author) ; Shahrokhian, Saeed (Supervisor)
    Abstract
    In this research, nanocomposite containing reduced graphene oxide nanosheets (RGO) and trimetallic three-dimensional (3D) Pt-Pd-Co porous nanostructures was fabricated by galvanic replacement technique. First, GO suspension was drop-casted on the electrode surface, then GO film reduction was carried out by cycling the potential in negative direction to form the RGO on GCE (RGO/GCE). Then, electrodeposition of the cobalt nanoparticles (CoNPs) as sacrificial seeds was performed onto the RGO/GCE by using cyclic voltammetry. Afterward, Pt-Pd-Co 3D porous nanostructures fabrication occurs through galvanic replacement method based on a spontaneous redox process between CoNPs and solution... 

    An Investigation of SI Engine Performance Characteristics Changes under Fuel Switch from Gasoline to Bioethanol

    , M.Sc. Thesis Sharif University of Technology Imani, Amin (Author) ; Hosseini, Vahid (Supervisor) ; Shafii, Behshad (Supervisor)
    Abstract
    Alternative fuels are considered as a solution to increase energy security, reduce dependence on conventional fossil fuels (gasoline and diesel), and reduce greenhouse gas emissions. In this context, bioethanol has been very much considered in recent years. This fuel is combined with gasoline and used by cars. Flexible fuel vehicles are cars that can be used in various blend of gasoline and ethanol. Ethanol has a higher octane number than gasoline, and its mixture with gasoline increases the number of octane fuels. However, this fuel has a lower thermal energy than gasoline, which increases the fuel consumption of ethanol and gasoline relative to pure gasoline. The purpose of this study is... 

    Synthesis and Characterization of 2D-WS2 Nanostructures for Gas Sensing Applications

    , Ph.D. Dissertation Sharif University of Technology Ahmadvand, Hassan (Author) ; Iraji Zad, Azam (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
    Abstract
    Nowadays, beside of two-dimensional tungsten disulfide nanosheets, its hybrid nanostructures also provide active sites for physisorption of gas molecules due to their high surface-to-volume ratio, surface active site (such as sulfur vacancies, surface defects, and p-n junctions) and active edges, and are very attractive for gas sensing applications. In this research, tungsten disulfide layered crystallines were grown by chemical vapor phase transport and its two-dimensional nanoflakes were prepared by liquid exfoliation method. So, a thin film of the nanoflakes was deposited on a silicon oxide substrate by drop casting method, and its gas sensing properties were investigated for water and... 

    Model-based analysis for kinetic complexation study of Pizda and Cu(II)

    , Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 70, Issue 3 , August , 2008 , Pages 674-681 ; 13861425 (ISSN) Vosough, M ; Maeder, M ; Jalali Heravi, M ; Norman, S. E ; Sharif University of Technology
    2008
    Abstract
    In the present work, the multivariate kinetic complexation of a new synthesized ligand, 1-(2″-hydroxyl cyclohexyl)-3′-[aminopropyl]-4-[3′-aminopropyl]piperazine (Pizda) and Cu2+ in 50% ethanol-water solution is investigated using the UV-vis stopped-flow technique and state-of-the-art multi-wavelength numerical analysis. Model-based least squares fitting analysis or hard modeling is a specific part of chemometrics which is based on mathematical relationships for describing the measurements. Some recent developments include the incorporation of the effects of non-ideal experimental conditions into the fitting algorithm so it can substantially simplify experimental procedures. In this study no... 

    Stable dye-sensitized solar cells based on a gel electrolyte with ethyl cellulose as the gelator

    , Article Applied Physics A: Materials Science and Processing ; Volume 120, Issue 3 , September , 2015 , Pages 869-874 ; 09478396 (ISSN) Vasei, M ; Tajabadi, F ; Jabbari, A ; Taghavinia, N ; Sharif University of Technology
    Springer Verlag  2015
    Abstract
    A simple gelating process is developed for the conventional acetonitrile-based electrolyte of dye solar cells, based on ethyl cellulose as the gelator. The electrolyte becomes quasi-solid-state upon addition of an ethanolic solution of ethyl cellulose to the conventional acetonitrile-based liquid electrolyte. The photovoltaic conversion efficiency with the new gel electrolyte is only slightly lower than with the liquid electrolyte, e.g., 6.5 % for liquid electrolyte versus 5.9 % for gel electrolyte with 5.8 wt% added ethyl cellulose. Electrolyte gelation has small effect on the ionic diffusion coefficient of iodide, and the devices are remarkably stable for at least 550 h under irradiation... 

    Adsorption performance of UiO-66 towards organic dyes: effect of activation conditions

    , Article Journal of Molecular Liquids ; 2020 Vaghar Mousavi, D ; Ahmadipouya, S ; Shokrgozar, A ; Molavi, H ; Rezakazemi, M ; Ahmadijokani, F ; Arjmand, M ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    The Zr-based metal-organic framework (MOF, UiO-66) was synthesized solvothermally. The synthesized UiO-66 was activated using different solvents (acetone, chloroform, and ethanol) via two activation methods of centrifugation and Soxhlet extraction over different periods (1–10 days). The crystalline structure and morphology of the synthesized UiO-66s were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, and field-emission scanning electron microscopy (FESEM) techniques. The adsorption behaviors of the synthesized UiO-66s were then investigated by selecting anionic methyl red (MR) and cationic methylene blue (MB) as the model dyes. It was found that a change in... 

    Adsorption performance of UiO-66 towards organic dyes: Effect of activation conditions

    , Article Journal of Molecular Liquids ; Volume 321 , 2021 ; 01677322 (ISSN) Vaghar Mousavi, D ; Ahmadipouya, S ; Shokrgozar, A ; Molavi, H ; Rezakazemi, M ; Ahmadijokani, F ; Arjmand, M ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    The Zr-based metal-organic framework (MOF, UiO-66) was synthesized solvothermally. The synthesized UiO-66 was activated using different solvents (acetone, chloroform, and ethanol) via two activation methods of centrifugation and Soxhlet extraction over different periods (1–10 days). The crystalline structure and morphology of the synthesized UiO-66s were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, and field-emission scanning electron microscopy (FESEM) techniques. The adsorption behaviors of the synthesized UiO-66s were then investigated by selecting anionic methyl red (MR) and cationic methylene blue (MB) as the model dyes. It was found that a change in... 

    Optimization of carbohydrate productivity of Spirulina microalgae as a potential feedstock for bioethanol production

    , Article International Journal of Environmental Science and Technology ; Volume 16, Issue 3 , 2019 , Pages 1303-1318 ; 17351472 (ISSN) Tourang, M ; Baghdadi, M ; Torang, A ; Sarkhosh, S ; Sharif University of Technology
    Center for Environmental and Energy Research and Studies  2019
    Abstract
    The main goal of this research is to use the biomass productivity, carbohydrate content, and carbohydrate productivity as useful responses for optimization of macronutrients concentrations (K2HPO4, NaHCO3, and NaNO3) in cultivation of Spirulina microalgae as a feedstock for bioethanol production. In this study, individual and synergistic effects of medium components on the mentioned responses were investigated. The culture medium was optimized using central composite design for achieving the maximize biomass productivity (165 mg L−1 day−1 at K2HPO4: 438 mg L−1, NaHCO3: 15.92 g L−1, and NaNO3: 0.5 g L−1), carbohydrate content (42.0% of dry mass at K2HPO4: 192 mg L−1, NaHCO3: 5.71 g L−1, and... 

    The effect of liquid environment on size and aggregation of gold nanoparticles prepared by pulsed laser ablation

    , Article Journal of Nanoparticle Research ; Volume 9, Issue 5 , 2007 , Pages 853-860 ; 13880764 (ISSN) Tilaki, R. M ; Iraji zad, A ; Mahdavi, S. M ; Sharif University of Technology
    2007
    Abstract
    The effects of liquid environment on nucleation, growth and aggregation of gold nanoparticles were studied. Gold nanoparticles were prepared by pulsed laser ablation in deionised water with various concentrations of ethanol and also in pure ethanol. UV/visible extinction and TEM observations were employed for characterization of optical properties and particle sizes respectively. Preparation in water results in smaller size, shorter wavelength of maximum extinction and stable solution with an average size of 6 nm. Nanoparticles in solution with low concentration ethanol up to 20 vol% are very similar to those prepared in water. In the mixture of deionised water and 40 up to 80 vol% ethanol,...