Search for: wetting
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    Effect of soil structure and disturbance on hydromechanical behavior of collapsible loessial soils

    , Article International Journal of Geomechanics ; Volume 17, Issue 1 , 2017 , Pages 1-15 ; 15323641 (ISSN) Mohsen Haeri, S ; Khosravi, A ; Akbari Garakani, A ; Ghazizadeh, S ; Sharif University of Technology
    American Society of Civil Engineers (ASCE)  2017
    To characterize the role of specimen disturbance and structure in the hydromechanical behavior of collapsible soils, two sets of wetting-induced collapse and suction-controlled triaxial tests were conducted on intact and reconstituted specimens of a loessial soil taken from a loess deposit in Gorgan, a city in the northeastern Golestan province of Iran. The testing approach used an advanced triaxial testing device that was specifically modified to control pressures applied to a soil specimen and to monitor and measure the amount of changes in volume and water content of the soil specimens during testing using highly sensitive digital sensors with an accuracy of 60.01 cm3. Results of the... 

    A facile approach for reducing the working voltage of Au/TiO2/Au nanostructured memristors by enhancing the local electric field

    , Article Nanotechnology ; Volume 29, Issue 1 , 2018 ; 09574484 (ISSN) Arab Bafrani, H ; Ebrahimi, M ; Bagheri Shouraki, S ; Moshfegh, A. Z ; Sharif University of Technology
    Institute of Physics Publishing  2018
    Memristor devices have attracted tremendous interest due to different applications ranging from nonvolatile data storage to neuromorphic computing units. Exploring the role of surface roughness of the bottom electrode (BE)/active layer interface provides useful guidelines for the optimization of the memristor switching performance. This study focuses on the effect of surface roughness of the BE electrode on the switching characteristics of Au/TiO2/Au three-layer memristor devices. An optimized wet-etching treatment condition was found to modify the surface roughness of the Au BE where the measurement results indicate that the roughness of the Au BE is affected by both duration time and... 

    Stick-slip behavior of sessile drop on the surfaces with irregular roughnesses

    , Article Chemical Engineering Research and Design ; Volume 160 , 2020 , Pages 216-223 Azadi Tabar, M ; Shayesteh, M ; Shafiei, Y ; Ghazanfari, M. H ; Sharif University of Technology
    Institution of Chemical Engineers  2020
    In this work, sessile drop and low-bond axisymmetric drop shape analysis methods were coupled to provide some new aspects on stick-slip behavior as well as stick time of a drop on calcite surfaces. Slightly hydrophobic calcite surfaces typified with three irregular roughnesses were used to create irregular surfaces to mimic defects for the water-calcite-air systems. Polishing papers of 200, 600, and 1200 grit and a polishing machine were used to prepare surfaces. X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier transform infrared, and atomic force microscopy techniques were employed to evaluate the chemical and physical properties of surfaces. A model was developed to predict... 

    Experimental investigation on the dominating fluid-fluid and rock-fluid interactions during low salinity water flooding in water-wet and oil-wet calcites

    , Article Journal of Petroleum Science and Engineering ; Volume 204 , 2021 ; 09204105 (ISSN) Farhadi, H ; Fatemi, M ; Ayatollahi, S ; Sharif University of Technology
    Elsevier B.V  2021
    Low salinity water flooding (LSWF) has the potential to enhance the oil recovery by affecting the fluid-fluid and rock-fluid interactions. Therefore, a systematic investigation on the effect of initial wetting state (water-wet or oil-wet) of pure calcite is conducted to study the importance of these interactions on the effectiveness of LSWF. In the case of initially water-wet cores, more oil recovery efficiency is observed for more saline water cases. To shed light on the possible involved mechanisms, dynamic IFT, dynamic contact angle (CA), oil/brine and rock/brine surfaces zeta potentials, and effluent pH are measured. It is shown that the short-term effect of IFT reduction and long-term... 

    A vacuum-re lled tensiometer for deep monitoring of in-situ pore water pressure

    , Article Scientia Iranica ; Volume 27, Issue 2 , 2021 , Pages 596-606 ; 10263098 (ISSN) Sadeghi, H ; Chiu, A. C. F ; Ng, C. W. W ; Jafarzadeh, F ; Sharif University of Technology
    Sharif University of Technology  2021
    Real-time measurement of soil water pressure has been recognized as an essential part of investigating water ow in unsaturated soils. Tensiometry, amongst di erent measuring techniques, is a common method for direct evaluation of water pressure. However, the lower limit of measurable water pressure by a conventional tensiometer becomes even more limited by increasing its length in the vertical installation. This paper describes the development of a Vacuum-Re lled Tensiometer (VRT) for monitoring soil water pressure independent of installation depth. This is achieved by xing the distance between pressure sensor and ceramic cup together with incorporating an ancillary vacuum-re lling assembly... 

    On the adsorption behavior of a fluorochemical onto carbonate rock with the application of wettability alteration to a gas wetting condition

    , Article Journal of Molecular Liquids ; Volume 326 , 2021 ; 01677322 (ISSN) Shayesteh, M ; Azadi Tabar, M ; Shafiei, Y ; Fakhroueian, Z ; Ghazanfari, M. H ; Sharif University of Technology
    Elsevier B.V  2021
    In this study, some new aspects of adsorption of a fluorochemical onto carbonate rocks as a wettability alteration agent to a gas wetting condition with the potential application for reduction of condensate blockage in gas condensate reservoirs are presented. To achieve this, kinetics, equilibrium, and thermodynamic of the adsorption process besides contact angle, imbibition, and characterization tests are investigated. Results of adsorption experiments revealed that kinetics behavior of the utilized fluorochemical–calcite system obeyed the pseudo-second order kinetics model. There was no change in adsorption after about 20 h. Also, the intraparticle diffusion mechanism was not the only rate... 

    Super gas wet and gas wet rock surface: state-of- the art evaluation through contact angle analysis

    , Article Petroleum ; 2021 ; 24056561 (ISSN) Azadi Tabar, M ; Dehghan Monfared, A ; Shayegh, F ; Barzegar, F ; Ghazanfari, M. H ; Sharif University of Technology
    KeAi Communications Co  2021
    Recently, super gas wet and gas wet surfaces have been extensively attended in petroleum industry, as supported by the increasing number of publications in the last decade related to wettability alteration in gas condensate reservoirs. In many cases, contact angle measurement has been employed to assess the wettability alteration. Even though contact angle measurement seems to be a straightforward approach, there exist many misuses of this technique and consequently misinterpretation of the corresponding results. In this regard, a critical inspection of the most recent updated concepts and the intervening parameters in the contact angle based wettability evaluation of liquid-solid-gas... 

    Chemical Vapor Processing of 2D MoS2 Nanolayers for Next Generation Inoptoelectronic Devices: Characterization and Properties

    , M.Sc. Thesis Sharif University of Technology Sovizi, Saeed (Author) ; Simchi, Abdolreza (Supervisor)
    Quite a few methods have been reported to synthesize monolayer MoS2, which has recently attracted scientist attentions. Fully controlled conditions, however, have not been achieved in these methods. In this research, two-dimensional MoS2 nanofilms have been synthesized by Chemical Vaper Deposition (CVD). Layer thickness of synthesized layer and effects of various parameters of used method have been investigated. Although every scientist synthesizes 2D MoS2 at 650°C in the CVD method by using seeds, in this research, it has been proved that MoS2 nanofilms can be produced at 575°C without using any seeds, which leads to lower consumption of time and price and increases the quality of... 

    Impact of Hydraulic Hysteresis on Hydro-mechanical Behaviour of Infilled Fractured Rocks in Unsaturated Condition

    , M.Sc. Thesis Sharif University of Technology Mousavi, Masoud (Author) ; Khosravi, Ali (Supervisor)
    Recent studies have shown that comprehensive characterization of the behavior of infilled rock fractures under saturated and unsaturated conditions requires knowledge of morphological details of fracture surface, as well as state of stress of infill materials and their initial innate conditions (e.g., void ratio, water content, degree of saturation and dry density). This study presents the details and typical results from a new testing approach to study the hydro-mechanical behavior of the infilled rock fractures under different stress states and saturation conditions. The new testing approach incorporates the axis translation technique for suction control, a flow pump for the measurement of... 

    Experimental and Modeling Investigation of Wettability Alteration to Gas Wetting Condition in Gas Condensate Reservoirs

    , M.Sc. Thesis Sharif University of Technology Erfani Gahrooei, Hamid Reza (Author) ; Ghazanfari, Mohammad Hossein (Supervisor)
    During production from gas condensate reservoirs, reservoir pressure decreses to lower than dew point pressure of the reservoir fluid. Consequently, condensates will form in near wellbore regions, which significantly decrease well productivity. One of the remediations that is recently proposed for solving this problem is wettability alteration of near wellbore region to gas wetting condition. In comparison to other methods, it provides a better permanency, which is its key advantage. The main purpose of this thesis is, quantitative, qualitative and modeling study of wettability alteration of rock to gas wetting condition and verification of modeling rsults for a reservoir rock sample. Also,... 

    Three-Dimensional Polyamide Nanofibrous Scaffolds for Needle Trap Microextraction of Chlorobenzenes from Water Samples and Comparing them with Two-Dimensional Nanofibres

    , M.Sc. Thesis Sharif University of Technology Manshaei, Faranak (Author) ; Bagheri, Habib (Supervisor)
    In the past decades, electrospinning has been widely used for the production of micro/nanofibers. In spite of the simplicity and effectivity of the conventional electrospinning for fabricating nanofibers, compact structure and small pores of the nanofibers hinder the efficient penetration of analytes during the extraction process. In order to overcome this issue, an applicable strategy called wet electrospinnig has been employed to enlarge the pore size of the electrospun scaffolds. By applying this technique, a collector was placed at the bottom of a solvent bath and highly porous foam from polyamide nanofibers was produced immediately after freeze-drying (3D electrospinning).... 

    Experimental and Numerical Investigation of Reactive Absorption in the presence of Nanofluid and Magnetic field

    , M.Sc. Thesis Sharif University of Technology Kheirkhah Ravandi, Zahra (Author) ; Molaei Dehkordi, Asghar (Supervisor)
    The importance of gases and liquids absorption in the liquid falling film is mostly due to the wide applications of liquid falling film reactors in the chemical industries. In such a reactor the mass and heat transfer occur simultaneously, but in most cases, the importance of mass transfer is predominant. Therefore, the study of heat transfer in this kind of reactor is neglected. In order to improve the efficiency of absorption, different methods have been employed by researchers. Owing to the rapid growth of nanotechnology, nanofluids have widely been used for increasing the absorption of solution, recently. Magnetic fluids due to their unique combination, among different kinds of... 

    Investigation of Water Consumption Reduction and Exergoeconomic Analysis of Hybrid Cooling Towers

    , M.Sc. Thesis Sharif University of Technology Azizi Kordkandi, Mohammad (Author) ; Saidi, Mohammad Hassan (Supervisor) ; Asghari, Mohsen (Supervisor)
    Nowadays, cooling towers are widely used in power plants, refineries, petrochemicals and ventilation industries, but the water consumption of these towers is high and because of water crisis in Middle East and Iran, it is necessary to devise in order to reduce the water consumption of these towers. In this study separated hybrid cooling tower are used to investigate the water consumption at power plants. The rigorous Poppe method are used in order to estimate the exact amount of water loss due to evaporation in wet cooling towers. First, the effect of ambient condition, wet cooling tower cells and dry cooling tower size on the performance of hybrid cooling tower are investigated, then the... 

    Investigating the Performance of Fluidized bed Dryer in Immobilization and Drying of A-amylase Enzyme

    , M.Sc. Thesis Sharif University of Technology Sharifi, Baha (Author) ; Roostaazad, Reza (Supervisor)
    Enzyme immobilization/drying operations are among the important operations of many biotechnological industrial units. The enzyme used in this study is bacterial alpha-amylase, which is widely used in various industries, including detergents. The production of alpha-amylase enzyme contains a large percentage of water in its composition; therefore, a wet wall tower was designed to conduct the experiments to evaporate the water present in the enzyme liquor, analyze its effects on activity, and also to validate the device. The results showed that in a flow of air around 240m3/hr and ambient temperature of 20◦C, enzyme liquor has a 250% increase in biological activity, which indicates the... 

    Mechanistic Studies of Improved Oil Recovery under Forced Gravity Drainage GAGD Process

    , Ph.D. Dissertation Sharif University of Technology Rostami, Behzad (Author) ; Kharrat, Riyaz (Supervisor) ; Ghotbi, Cyrus (Supervisor) ; Pooladi Darvish, Mehran (Co-Advisor)
    Gas-oil displacement, when stabilized by gravity forces leads to high displacement efficiency, as manifested in high recovery factor associated with gas-cap drive and gravity drainage. The main objective of this research is improved understanding of drainage behavior and changes in flow properties when the importance of viscous, gravity and capillary forces varies. The influence of interplaying between controlling forces on relative permeabilities is also studied. Another objective of this work is to study effect of wettability on recovery under forced gravity drainage. To study drainage behavior under various dominant driving/resistive forces, a number of forced gravity drainage experiments... 

    Investigation on Wettability Alteration of Reservoir Rocks by Functionalized Silica Nanoparticles using Molecular Dynamics Simulations

    , M.Sc. Thesis Sharif University of Technology Sepehrinia, Kazem (Author) ; Mohammadi, Aliasghar (Supervisor) ; Seyfkordi, Aliakbar (Supervisor)
    The properties of 3 nm-diameter fluorinated silica nanoparticles with different coverage percent of CF3 groups as water and oil repellents were investigated at the water-rock and decane-rock interface using molecular dynamics simulation. Simulating a pore of rock in presence of water and decane molecules separately, resulted in liquid bridging for both of liquids. The density profiles of liquids in the pore clearly show several highly ordered layers packing of the molecules close to the rock surface. Distribution of liquid molecules around the nanoparticles is much influenced with increasing CF3 groups on the nanoparticle surface. Results show that adsorption of functionalized silica... 

    Synthesize and Characterization of 2D WS2 Nano-layers for Next Generation Optoelectronic Devices

    , M.Sc. Thesis Sharif University of Technology Rahmani Taji Boyuk, Mohammad Reza (Author) ; Simchi, Abdolreza (Supervisor)
    Transition Metal Dichalcogenids (TMD) are types of 2D materials that exibit wide range of electronic, optical, mechanical, chemical, and thermal properties. These materials with MX2 general formula, have atract attentions with respect to their unusual properties because of their very limited dimensions. Their tunable properties and materials availibility make them attractive for wide range of applications. In recent years, chemical vapor deposition (CVD) methods are promising in preparing high quality TMD with scalable size, controllable thickness, and very excellent electronic properties. Also, chalenges are remaining in synthesis and transfering of TMD are difficulty for most of... 

    , M.Sc. Thesis Sharif University of Technology Hedayat, Mahdi (Author) ; Soltanieh, Mohammad (Supervisor) ; Seifkordi, Ali Akbar (Supervisor)
    Using membrane contactors for acid gas removal, combines the advantages of membrane based separation processes and traditional ones. In this project we aim to study the use of a membrane absorption system for sweetening gas streams containing mixed acid gases with composition similar to raw natural gas. H2S and CO2 exist in the gas stream simultaneously which can be removed by mixture of alkanolamine solvents, including MDEA, DEA and MEA, are used for treating. A lab-scale membrane absorption setup with feed capacity of 2 lit/min, was designed, constructed and commissioned. Several hollow fiber modules equipped with PSf and PVDF membranes were fabricated. Our results revealed that reaching... 

    Preoxidation Study of Fe-Ni-Co (KOVAR) Alloy on Glass to Metal Sealing Performance

    , M.Sc. Thesis Sharif University of Technology Toloue Farrokh, Najibe (Author) ; Askari, Masoud (Supervisor) ; Kaflou, Ali (Supervisor)
    The Fe-Ni-Co alloy to borosilicate glass seals have been used for many years as hermetic and electrically insulating seals. It is not only excellent in thermal expansion matching but also in good wettability and bond strength too. Oxidation of Kovar was performed in Water vapor, Saturated Nitrogen and N2-H2-H2O atmosphere in tube furnace. Oxide layer composition and thickness changed by varying in oxidation temperature and time. XRD analysis showed different Iron oxides in oxide layer, FeO, Fe3O4 and Fe2O3. However in the third atmosphere no Hematite observed. Increasing oxidation temperature and time result in increasing sample weight gains and roughness. Oxide layer microstructure also was... 

    Experimental Study of Effect of Capillary Pressure on Archie Parameters for one of Iranian Petroleum Rock

    , M.Sc. Thesis Sharif University of Technology Hasani Ahmadzadeh, Peyman (Author) ; Masihi, Mohsen (Supervisor)
    The most fundamental concept in considering electrical properties of reservoir rocks are formation Resistivity factor and Resistivity index which are defined by Archie and are useful in interpretation of well logging, evaluation of porosity and saturation. A theory on the relationship between formation resistivity factor and porosity, also resistivity index and saturation are presented by use of parameters Cementation factor and Saturation exponent. The Archie equation is valid only when the rock is strongly water-wet and clay free, which is not the case in carbonate rocks. Therefore the Archie equation cannot be generalized over the entire carbonate reservoirs. On the other hand influence...