Search for: phase-interfaces
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    Nanostructured particles for controlled polymer release in enhanced oil recovery

    , Article Energy Technology ; Volume 4, Issue 9 , 2016 , Pages 1035-1046 ; 21944288 (ISSN) Tamsilian, Y ; Ramazani S., A ; Shaban, M ; Ayatollahi, S ; de la Cal, J. C ; Sheng, J. J ; Tomovska, R ; Sharif University of Technology
    Wiley-VCH Verlag  2016
    With the decline in oil discoveries over recent decades, it is believed that enhanced oil recovery (EOR) technologies will play a key role to meet energy demand in the coming years. Polymer flooding is used commonly worldwide as an EOR process. In this work, we propose the synthesis of protected polyacrylamide (PAM) nanoparticles (PPNs) with a hydrophobic polystyrene (PSt) shell by one-pot two-step inverse emulsion polymerization, in which the PSt shell was created by surface polymerization. The shell protects the active PAM chains from premature degradation caused by the harsh environment in the reservoirs, controls the release of the chains as rheological modifiers, and additionally, it... 

    Comparison and validation of plug and boundary layer flow models of monolithic reactors: Catalytic partial oxidation of methane on Rh coated monoliths

    , Article International Journal of Chemical Reactor Engineering ; Volume 6 , 2008 ; 15426580 (ISSN) Sari, A ; Safekordi, A ; Farhadpour, F. A ; Sharif University of Technology
    Walter de Gruyter GmbH  2008
    Catalytic partial oxidation of methane in short residence time rhodium coated monolithic reactors offers an attractive route for syngas production. The plug flow and boundary layer flow approximations are considered as computationally efficient substitutes for the full Navier-Stokes model of the reactor while including detailed heterogeneous and homogeneous chemistry. The one dimensional plug flow model has trivial computational demands but only a limited range of application. The boundary layer model provides an excellent, computationally manageable substitute for the full Navier-Stokes model over a wide range of operating conditions. Using the 38-step elementary surface reaction mechanism... 

    Investigation of iron ore particle size and shape on green pellet quality

    , Article Canadian Metallurgical Quarterly ; Volume 59, Issue 2 , 2020 , Pages 242-250 Abazarpoor, A ; Halali, M ; Hejazi, R ; Saghaeian, M ; Sheikh Zadeh, V ; Sharif University of Technology
    Taylor and Francis Ltd  2020
    Particle size and shape of iron ore concentrate are effective parameters in the production of quality green pellets. In this research, the effect of particle morphology on green pellet quality was studied. It was concluded that pellet quality improved with increasing specific surface area. Drop number and green compression strength of pellets ground by HPGR were found to be superior over those ground in the ball mill. The chief reasons were related to particle shape and the fraction of fine particles. Smaller particle size results in a higher order of bonding between particles and therefore the formation of a stronger system. Also, the rougher and less circular shape of particles resulted in... 

    Optimization of microgrooves for water–solid drag reduction using genetic algorithm

    , Article Journal of Ocean Engineering and Marine Energy ; Volume 6, Issue 3 , 2020 , Pages 221-242 Abdollahzadeh, M. J ; Moosavi, A ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2020
    The friction on the water–solid interfaces continues to be the most important factor for the energy loss in many marine and submarine applications. Therefore, different techniques have been developed and are available to reduce friction and, as a result, the overall cost. In the past decades, the use of structured surfaces has been given considerable attention because of their specific characteristics such as their abilities in pressure drop reduction. However, an appropriate optimization method is required to find the best surface structure. In the present study, we consider a microgrooved substrate and examine the performance of three shapes including rectangular, elliptical, and... 

    On the phase field modeling of crack growth and analytical treatment on the parameters

    , Article Continuum Mechanics and Thermodynamics ; 2018 , Pages 1-18 ; 09351175 (ISSN) Farrahi, G. H ; Javanbakht, M ; Jafarzadeh, H ; Sharif University of Technology
    Springer New York LLC  2018
    A thermodynamically consistent phase field model for crack propagation is analyzed. The thermodynamic driving force for the crack propagation is derived based on the laws of thermodynamics. The Helmholtz free energy satisfies the thermodynamic equilibrium and instability conditions for the crack propagation. Analytical solutions for the Ginzburg–Landau equation including the surface profile and the estimation of the kinetic coefficient are found. It is shown how kinetic coefficient affects the local stress field. The local critical stress for the crack propagation is calibrated with the theoretical strength which gives the value of the crack surface width. The finite element method is... 

    Thermal optimization of the continuous casting process using distributed parameter identification approach—controlling the curvature of solid-liquid interface

    , Article International Journal of Advanced Manufacturing Technology ; Volume 94, Issue 1-4 , 2018 , Pages 1101-1118 ; 02683768 (ISSN) Tavakoli, R ; Sharif University of Technology
    Springer London  2018
    Thermal optimization of the vertical continuous casting process is considered in the present study. The goal is to find the optimal distribution of the temperature and interfacial heat transfer coefficients corresponding to the primary and secondary cooling systems, in addition to the pulling speed, such that the solidification along the main axis of strand approaches to the unidirectional solidification mode. Unlike many thermal optimization of phase change problems in which the desirable (target) temperature, temperature gradient, or interface position are assumed to be a priori known, a desirable shape feature of the freezing interface (not its explicit position) is assumed to be known in... 

    Effects of elastic contributions on the evolution of nano-structure Al3Sc phase: A phase-field study

    , Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 1539-1547 ; 10263098 (ISSN) Ebrahimi, Z ; Ebrahimi, H ; Sharif University of Technology
    Sharif University of Technology  2016
    A micromechanical phase-field model is utilized to study the evolution of nanostructure Al3Sc phase in Al-Sc alloy. We study the formation of Al3Sc precipitates in an Al-Sc alloy by using an elastic phase-field model. Since the precipitates of Al3Sc phase are fully coherent with the Al matrix, the elastic energy will have an inuence on the resulting morphology. We have studied the effects of elastic strain energies on shape evolution of Al3Sc phase, numerically. The simulated nano-structures evolve from spherical to cubic shapes. The equilibrium shape of the coherent Al3Sc phase is found to be determined by minimizing the sum of the elastic and interfacial energies through the phase-field... 

    Phase field approach for nanoscale interactions between crack propagation and phase transformation

    , Article Nanoscale ; Volume 11, Issue 46 , 2019 , Pages 22243-22247 ; 20403364 (ISSN) Jafarzadeh, H ; Levitas, V. I ; Farrahi, G. H ; Javanbakht, M ; Sharif University of Technology
    Royal Society of Chemistry  2019
    The phase field approach (PFA) for the interaction of fracture and martensitic phase transformation (PT) is developed, which includes the change in surface energy during PT and the effect of unexplored scale parameters proportional to the ratio of the widths of the crack surface and the phase interface, both at the nanometer scale. The variation of these two parameters causes unexpected qualitative and quantitative effects: shift of PT away from the crack tip, "wetting" of the crack surface by martensite, change in the structure and geometry of the transformed region, crack trajectory, and process of interfacial damage evolution, as well as transformation toughening. The results suggest... 

    Amino-silane-grafted NH2-MIL-53(Al)/polyethersulfone mixed matrix membranes for CO2/CH4 separation

    , Article Dalton Transactions ; Volume 48, Issue 36 , 2019 , Pages 13555-13566 ; 14779226 (ISSN) Ahmadijokani, F ; Ahmadipouya, S ; Molavi, H ; Arjmand, M ; Sharif University of Technology
    Royal Society of Chemistry  2019
    Mixed-matrix membranes (MMMs) are promising candidates for carbon dioxide separation. However, their application is limited due to improper dispersion of fillers within the polymer matrix, poor interaction of fillers with polymer chains, and formation of defects and micro-voids at the interface of both phases, which all result in the decline of the gas separation performance of MMMs. In this work, we present a new method to overcome these challenges. To this end, a series of MMMs based on polyethersulfone (PES) as the continuous polymer matrix and MIL-53-derived MOFs as the dispersed filler were prepared. FTIR-ATR, XRD, TGA, FESEM, and N2 adsorption/desorption analyses were employed to... 

    Characterization of liquid bridge formed during gas-oil gravity drainage in fractured porous media

    , Article 16th European Conference on the Mathematics of Oil Recovery, ECMOR 2018, 3 September 2018 through 6 September 2018 ; 2018 ; 9789462822603 (ISBN) Harimi, B ; Masihi, M ; Ghazanfari, M. H ; Shoushtari, A ; Sharif University of Technology
    European Association of Geoscientists and Engineers, EAGE  2018
    Gas-oil gravity drainage that takes place in the gas-invaded zone of fractured reservoirs is the main production mechanism of gas-cap drive fractured reservoirs as well as fractured reservoirs subjected to gas injection. Interaction of neighboring matrix blocks through reinfiltration and capillary continuity effects controls the efficiency of gravity drainage. Existence of capillary continuity between adjacent matrix block is likely to increase the ultimate recovery significantly. Liquid bridge formed in fractures has a significant role in maintaining the capillary continuity between two neighboring matrix blocks. The degree of capillary continuity is proportional to capillary pressure in... 

    Simplified model for polyurethane foaming in porous media

    , Article International Journal of Numerical Methods for Heat and Fluid Flow ; Volume 27, Issue 1 , 2017 , Pages 142-155 ; 09615539 (ISSN) Sadrhosseini, H ; Bazkhane, S ; Sharif University of Technology
    Emerald Group Publishing Ltd  2017
    Purpose - The purpose of the study is to present a simplified model to replace the complicated foaming simulations for investigating the liquid polyurethane behavior just before solidification. Design/methodology/approach - This model is inspired from the traveling heater method of crystallization because of the low injection velocity. Besides, the heat generated during the reaction is considered as a heat source function in the energy equation. Findings - Various distributions of the heat generation function inside the geometry have been studied to choose the most realistic one. Effect of parameters such as the soil material and porosity on the temperature distribution and flow field are... 

    Microstructure and mechanical properties of MoSi2-MoSi2 joints brazed by Ag-Cu-Zr interlayer

    , Article Materials and Design ; Volume 49 , August , 2013 , Pages 197-202 ; 02613069 (ISSN) Hatami Ramsheh, H ; Faghihi Sani, M. A ; Kokabi, A. H ; Sharif University of Technology
    Elsevier Ltd  2013
    The present work investigates joining of two MoSi2 parts through Cusil/Zr/Cusil interlayer with Cusil being a commercial eutectic of Cu-Ag alloy. The joining operation was implemented in an inert gas tube furnace by brazing. The brazing temperature ranged from 800 to 930°C while the operation lasted for 60min. Evaluation of joints strength through shear loading identified the maximum strength 60.31MPa for the brazed sample at 830°C. Interfacial microstructure was studied by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) techniques. Applying the temperature of 830°C was led to a uniform dense joint consisting of various phases with... 

    Thermal decomposition of nanostructured Aluminum Titanate in an active Al matrix: A novel approach to fabrication of in situ Al/Al2O3-Al3Ti composites

    , Article Materials and Design ; Volume 88 , 2015 , Pages 932-941 ; 02641275 (ISSN) Azarniya, A ; Hosseini, H. R. M ; Jafari, M ; Bagheri, N ; Sharif University of Technology
    Elsevier Ltd  2015
    The thermal decomposition of Aluminum Titanate in exposure to pure Aluminum was examined both in powder and in bulk form. Optical microscopy, FE-SEM, XRD, DSC and TGA examinations were conducted to take the possible chemical reactions between Aluminum Titanate and Al into consideration. It was found that as Aluminum Titanate particles are exposed to Al matrix, the thermal stability of Aluminum Titanate is degraded and its decomposition temperature is reduced from 850°C to 550°C. Also, the chemical reactions between Aluminum Titanate and Al start along the interfaces, and the reaction products, i.e. Al3Ti, Al2O3, TiO2 and O2 gas are left there. A mechanism was suggested to describe the... 

    Laboratory evaluation of nitrogen injection for enhanced oil recovery: Effects of pressure and induced fractures

    , Article Fuel ; Volume 253 , 2019 , Pages 607-614 ; 00162361 (ISSN) Fahandezhsaadi, M ; Amooie, M. A ; Hemmati Sarapardeh, A ; Ayatollahi, S ; Schaffie, M ; Ranjbar, M ; Sharif University of Technology
    Elsevier Ltd  2019
    Nitrogen has emerged as a suitable alternative to carbon dioxide for injection into hydrocarbon reservoirs worldwide to enhance the recovery of subsurface energy. Nitrogen typically costs less than CO2 and natural gas, and has the added benefit of being widely available and non-corrosive. However, the underlying mechanisms of recovery following N2 injection into fractured reservoirs that make up a large portion of the world's oil and gas reserves are not well understood. Here we present the laboratory results of N2 injection into carbonate rocks acquired from a newly developed oil reservoir in Iran with a huge N2-containing natural gas reservoir nearby. We investigate the effectiveness of N2... 

    Influence of PEO and mechanical keying on the strength of AA 5052 alloy/polypropylene friction stir spot welded joints

    , Article International Journal of Adhesion and Adhesives ; Volume 92 , 2019 , Pages 65-72 ; 01437496 (ISSN) Aliasghari, S ; Skeldon, P ; Zhou, X ; Ghorbani, M ; Sharif University of Technology
    Elsevier Ltd  2019
    A study has been carried out of the effect of plasma electrolytic oxidation (PEO)on the strength of AA 5052 alloy/polypropylene joints prepared using friction stir spot welding (FSSW). The joint strengths were determined using lap-shear tests and failure modes were investigated using scanning electron microscopy. Comparisons were made between control joints prepared with the alloy in the as-rolled condition or the as-rolled condition with a mechanical key and with PEO-treated alloy, with or without a mechanical key. Mechanical keying alone, provided by infiltration of polymer into holes of either 3 or 4.5 mm diameter drilled in the alloy, yielded enhancements of the joint strength by a... 

    Investigation of structural and mechanical properties of magnetic pulse welded dissimilar aluminum alloys

    , Article Journal of Manufacturing Processes ; Volume 37 , 2019 , Pages 292-304 ; 15266125 (ISSN) Pourabbas, M ; Abdollah zadeh, A ; Sarvari, M ; Pouranvari, M ; Miresmaeili, R ; Sharif University of Technology
    Elsevier Ltd  2019
    The present study aimed to join AA4014 to AA7075 by using magnetic pulse welding (MPW). In addition, acceptable joints were achieved by selecting welding parameters such as collision angle and discharge energy appropriately. Changing collision angle and discharge energy can influence the velocity, leading to the formation of three different types of welding interfaces with wavy, molten wavy and porous morphologies. The formation of these various morphologies is mainly associated with different collision angle parameters. The hardness of the welding interface with molten layer was significantly higher than that of the base metals due to the grain refinement phenomenon occurring through the... 

    Efficient CO oxidation over palladium supported on various MOFs: Synthesis, amorphization, and space velocity of hydrogen stream

    , Article International Journal of Hydrogen Energy ; Volume 45, Issue 41 , 2020 , Pages 21450-21463 Abbasi, F ; Karimi Sabet, J ; Ghotbi, C ; Sharif University of Technology
    Elsevier Ltd  2020
    Amine-functionalized MIL-101(Cr) has been synthesized by hydrothermal (MNH2) and post-synthetic modification (MNH2-p) approaches. Pd/MNH2 and Pd/MNH2-p have been tested in CO oxidation reaction as a gas phase reaction to clarify the difference between two synthesis approaches. Their performance has also been compared with that of Pd supported on MIL as a common MOF and CuBTC as a commercial one. The results show the significant difference between Pd/MNH2-p and Pd/MNH2, where CO conversion of 100% was not observed for Pd/MNH2-p, whereas Pd/MNH2 outperformed the others and exhibited the high reaction rate thanks to the active sites created by amorphization during the reduction process because... 

    Modeling of reactive acid transport in fractured porous media with the Extended–FEM based on Darcy-Brinkman-Forchheimer framework

    , Article Computers and Geotechnics ; Volume 128 , December , 2020 Khoei, A. R ; Salehi Sichani, A ; Hosseini, N ; Sharif University of Technology
    Elsevier Ltd  2020
    In this paper, a fully coupled numerical model is developed based on the X-FEM technique to simulate the reactive acid transport in fractured porous media. The porous medium consists of the solid and fluid phases, in which the fluid phase includes water and acid components, and chemical reactions can be occurred between acid component and solid phase at the solid–fluid interfaces. The governing equations include the mass and momentum conservation laws for fluid phase, and the advective–diffusive transport of acid component that must be solved to obtain the primary unknowns, including the pore fluid pressure, acid concentration, and fluid velocity vector. Applying the... 

    Solidification enhancement in triplex thermal energy storage system via triplets fins configuration and hybrid nanoparticles

    , Article Journal of Energy Storage ; Volume 34 , 2021 ; 2352152X (ISSN) Hosseinzadeh, K ; Montazer, E ; Shafii, M. B ; Ganji, A. R. D ; Sharif University of Technology
    Elsevier Ltd  2021
    Latent thermal energy storage dependent on Phase Change Materials (PCMs) proposes a possible answer for modifying the availability of alternating energy from renewable sources such as wind and solar. They can possibly store large amounts of energy in moderately tiny dimensions as well as through almost isothermal procedures. Notwithstanding, low thermal conductivity values is a significant disadvantage of the present PCMs which critically restrict their energy storage usage. Likewise, this unacceptably decreases the solidification/melting rates, hence causing the system response time to be excessively lengthy. The present examination accomplished a better PCM solidification rate with a... 

    Atomistic simulation of creep deformation mechanisms in nickel-based single crystal superalloys

    , Article Materials Science and Engineering A ; Volume 809 , 2021 ; 09215093 (ISSN) Khoei, A. R ; Tolooei Eshlaghi, G ; Shahoveisi, S ; Sharif University of Technology
    Elsevier Ltd  2021
    In this paper, the creep deformation mechanisms are investigated in nickel-based single crystal superalloys. Two-dimensional molecular dynamics (MD) simulations are conducted to model various temperatures, stress conditions, and phase interface crystal orientations. Ni-based single-crystal superalloys are of great importance in the aircraft industry due to their excellent high temperature creep resistance. This characteristic mainly originates from two features considered in their structure; firstly, their two-phase micro-structure comprising gamma γ and gamma prime γ′, and secondly the nature of this superalloy itself, which is a single-crystal. MD is a powerful tool to gain insight into...