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    Experimental Investigation of Effect of Nanofluid Stability on Thermal Performance and Flow Regimes in Pulsating Heat Pipe

    , M.Sc. Thesis Sharif University of Technology Akbari, Ali (Author) ; Saeedi, Mohammad Hassan (Supervisor)
    Abstract
    Pulsating heat pipe (PHP) is a type of wickless heat pipe that has a simple structure and an outstanding thermal performance. Nanofluid is a type of fluifid in which nanoparticles are dispersed in a base fluid and has a better thermal conductivity in comparison with its base fluid. In this article, the performance of a nanofluid PHP is investigated. In order to simultaneously investigate the thermal performance and flow regimes in the PHP, a one-turn copper PHP with a Pyrex glass attached to its adiabatic section was used. A one-turn Pyrex PHP was also used to fully visualize flow patterns in the PHP. Our results showed that the material that a PHP made of and temperature of working fluid... 

    Experimental Investigation of Nano Particle Effect on Heat Transfer in a Micro Heat Exchanger

    , M.Sc. Thesis Sharif University of Technology Jafarpoor Chekab, Hamideh (Author) ; Shafii, Mohammad Behshad (Supervisor) ; Saidi, Mohammad Hassan (Supervisor) ; Saeedi, Mohammad Saeed (Supervisor)
    Abstract
    Modern microelectronic systems generate a large amount of heat which must be transferred out of the system without excessive temperature rise. Conventional forced air convection and microchannel cooling plates have reached their performance limits Nanofiuids are proposed as an innovative way to solve the problem. A nanofiuid is nanoscale solid particles dispersed in a traditional heat transfer liquid. Some studies show an anomalous increase in the thermal conductivity for stationary nanofiuids. However, there are only few previous studies on the convection heat transfer rate and viscosity of nanofiuids. Both convection and stationary measurements of the thermal conductivity are widely... 

    Modeling and Simulation of Tansport Phenomena in Irregular Microchannels

    , M.Sc. Thesis Sharif University of Technology Nikouei, Maryam Sadat (Author) ; Molaie Dehkordi, Asghar (Supervisor)
    Abstract
    In this article, the problem of mixed convection in vertical rectangular microchannels for both regular fluids and nanofluids have been solved, using the CFD technique in the entrance regions of momentum and heat transfer taking in account the influences of viscous heating, inertial force and sleep conditions. In case of nanofluid flow, both the Brownian and thermophoresis molecular transfer mechanisms were considered.The predicted results were validated using fully developed distributions of velocity and temperature. Furthermore, the influences of mixed convection parameter (Gr/Re) and Kn number values on distributions of velocity and temperature through the entrance and fully-developed... 

    , M.Sc. Thesis Sharif University of Technology Sarrafan, Kiana (Author) ; Bastani, Daruoosh (Supervisor)
    Abstract
    In liquid-liquid extraction, as in gas absorption, two phases must be brought into good contact to permit transfer of material. The presence of nanoparticles in liquid phase can enhanced the rate of gas-liquid mass transfer. The benefits of nanofluids can be used to enhance the heat and mass transfer of liquid-liquid extraction. Standard test system with low interfacial tension that recommended by EFCE: n-butanol/water/succinic acid, was used in this project. The CNTs/n-butanol that was saturated of water used as dispersed phase. Water and succinic acid used as continuous phase and solute. Since there is no chemical reaction to take place between CNTs and n-butanol, In order to obtain well... 

    The study of growth and coagulation of titania nanoparticles by chemical vapor synthesis

    , Article Journal of Nuclear Science and Technology ; No.53 , 2010 , pp. 20-29 Rahiminezhad-Soltani, M ; Saberyan, K ; Shahri, F ; Simchi, A. (Abdolreza) ; Sharif Univesity of Technology
    Abstract
    Chemical Vapor Synthesis route was used for synthesis of titanium dioxide (TiO2) nanoparticles in hot-walled reactor at 800degreeC using TiCl4 as precursor. The effect of processing parameters e.g., temperature and amount of precursor on phase structure, size, purity, coagulation and agglomeration of nanoparticles were investigated in this respect. Also, the H2O effects on the size, crystallinity, phase transformation and purity of nanoparticles were studied. Comprehensive experimental observations were confirmed by transmission electron microscopy, X-ray diffraction analysis and thermal gravimetric-differential thermal analysis results. The obtained results showed that by increasing the... 

    Analysis of entropy generation and convective heat transfer of Al 2O 3 nanofluid flow in a tangential micro heat sink

    , Article International Journal of Heat and Mass Transfer ; Volume 55, Issue 15-16 , July , 2012 , Pages 4366-4375 ; 00179310 (ISSN) Shalchi Tabrizi, A ; Seyf, H. R ; Sharif University of Technology
    2012
    Abstract
    Effect of using Al 2O 3-water nanofluids with different volume fractions and particle diameters on generated entropy, hydrodynamic performance and heat transfer characteristics of a tangential micro-heat sink (TMHS) was numerically investigated in this research. Results indicated that considerable heat transfer enhancement is possible when using Al 2O 3-water nanofluids as coolant and clearly the enhancement improves with increasing particles concentration and decreasing particles size. However, using nanofluid has also induced drastic effects on the pumping power that increases with particles volume fraction and Reynolds number. Finally, it was found that generated total entropy decreases... 

    Numerical study on free convection in a U-shaped CuO/water nanofluid-filled cavity with different aspect ratios using double-MRT lattice Boltzmann

    , Article Thermal Science and Engineering Progress ; Volume 14 , 2019 ; 24519049 (ISSN) Hasanzadeh Fard, A ; Hooshmand, P ; Mohammaei, M ; Ross, D ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    The lattice Boltzmann simulation of natural convection fluid flow and heat transfer is performed. The double-MRT lattice Boltzmann method is employed. The D2Q5 and D2Q9 lattice models are used to simulate the temperature field and flow field, respectively. The configuration of the cavity is U-shaped, and the cavity is filled with CuO-water nanofluid. The KKL (Koo-Kleinstreuer-Li) model is utilized to estimate the thermal conductivity and dynamic viscosity; as well as, the nanoparticle shape effect on the thermo-physical properties of nanofluid is considered. The streamlines, temperature distribution, local entropy generation map, average Nusselt number, magnitude of total entropy generation... 

    Utilization of hybrid nanofluids in solar energy applications: A review

    , Article Nano-Structures and Nano-Objects ; Volume 20 , 2019 ; 2352507X (ISSN) Ahmadi, M. H ; Ghazvini, M ; Sadeghzadeh, M ; Alhuyi Nazari, M ; Ghalandari, M ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    Hybrid nanofluids have several advantages compared with the conventional types due to their modified properties. Their enhanced thermophysical and rheological properties make them more appropriate for solar energy systems. In this review paper, an overview of solar energy systems is represented, and afterwards, applications of hybrid nanofluids in various solar technologies, especially solar thermal, are reviewed. Comparison between the nanofluidic systems, and the conventional ones is performed in order to gain a deeper insight into the advantages of using nanofluids. According to the results of the reviewed studies, the most important reason for performance enhancement of nanofluidic solar... 

    Free convection analysis in a Γ-shaped heat exchanger using lattice Boltzmann method employing second law analysis and heatline visualization

    , Article International Journal of Numerical Methods for Heat and Fluid Flow ; Volume 29, Issue 9 , 2019 , Pages 3056-3074 ; 09615539 (ISSN) KhakRah, H ; Mohammaei, M ; Hooshmand, P ; Bagheri, N ; Hasani Malekshah, E ; Sharif University of Technology
    Emerald Group Publishing Ltd  2019
    Abstract
    Purpose: The nanofluid flow and heat transfer within a heat exchanger, with different thermal arrangements of internal active bodies, are investigated. Design/methodology/approach: For the numerical simulations, the lattice Boltzmann method is utilized. The KKL model is used to predict the dynamic viscosity of CuO-water nanofluid. Furthermore, the Brownian method is taken account using this model. The influence of shapes of nanoparticles on the heat transfer performance is considered. Findings: The results show that the platelet nanoparticles render higher average Nusselt number showing better heat transfer performance. In order to perform comprehensive analysis, the heatline visualization,... 

    Energetic and exergetic performance enhancement of heat exchangers via simultaneous use of nanofluid and magnetic swirling flow: A two-phase approach

    , Article Thermal Science and Engineering Progress ; Volume 20 , 2020 Bezaatpour, M ; Rostamzadeh, H ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    A high-efficient method has been considered for simultaneously improving the hydrothermal and exergetic performance of heat exchangers. Two-phase Eulerian model is employed in a 3-D numerical study to precisely study the hydrothermal and entropic behaviors of Fe3O4/water ferrofluid, under the effect of a magnetic field inducer. The findings reveal that employing the magnetic field can improve the energetic and exergetic performance by generating a swirling flow in the heat exchanger. The pressure drop and entropy generation minimization are also achieved by the induced flow in comparison with other passive techniques due to the lack of any additional obstacle in the flow path. Results show... 

    Novel thermal aspects of hybrid nanofluid flow comprising of manganese zinc ferrite MnZnFe2O4, nickel zinc ferrite NiZnFe2O4 and motile microorganisms

    , Article Ain Shams Engineering Journal ; Volume 13, Issue 5 , 2022 ; 20904479 (ISSN) Ahmad, S ; Akhter, S ; Imran Shahid, M ; Ali, K ; Akhtar, M ; Ashraf, M ; Sharif University of Technology
    Ain Shams University  2022
    Abstract
    An enhancement in heat transfer due to nanofluids is essentially required in various thermal systems. Hybrid nanofluids possess high thermal conductivity and, have ability to embellish and enhance the thermal strength of common fluids. Our concern in this paper is to examine the innovative attributes of hybrid nanofluids like Manganese zinc ferrite (MnZnFe2O4) and Nickel zinc ferrite (NiZnFe2O4) in the bio-convective flow of motile gyrotactic microorganisms subject to Darcy Forchheimer medium. The effect of activation energy has also been taken into account. Mathematical treatment is carried out via MATLAB software. The use of MnZnFe2O4 - NiZnFe2O4/H2O exhibits improved thermal... 

    Molecular interaction and magnetic dipole effects on fully developed nanofluid flowing via a vertical duct applying finite volume methodology

    , Article Symmetry ; Volume 14, Issue 10 , 2022 ; 20738994 (ISSN) Ali, K ; Ahmad, S ; Ahmad, S ; Jamshed, W ; Hussain, S. M ; Tag El Din, E.S.M ; Sharif University of Technology
    MDPI  2022
    Abstract
    Interpreting the complex interaction of nanostructured fluid flow with a dipole in a duct, with peripherally uniform temperature distribution, is the main focus of the current work. This paper also sheds light on the changes in the Nusselt number, temperature profiles, and velocity distributions for the fully developed nanofluid flow in a vertical rectangular duct due to a dipole placed near a corner of the duct. A finite volume approach has been incorporated for the numerical study of the problem. It is interesting to note the unusually lower values of the Nusselt number for the higher values of the ratio Gr/Re. Due to the nanostructure in the fluid, an enhancement in the Nusselt number has... 

    A self-similar approach to study nanofluid flow driven by a stretching curved sheet

    , Article Symmetry ; Volume 14, Issue 10 , 2022 ; 20738994 (ISSN) Ali, K ; Jamshed, W ; Ahmad, S ; Bashir, H ; Ahmad, S ; Tag El Din, E.S.M ; Sharif University of Technology
    MDPI  2022
    Abstract
    Nano-fluids have considerable importance in the field of thermal development that relates to several industrial systems. There are some key applications in recent construction systems flow, as well as microscale cooling gadgets and microstructure electric gadgets for thermal migration. The current investigation concludes the study of electrically conducting nano-fluid flow and heat transfer analysis in two-dimensional boundary layer flow over a curved extending surface in the coexisting of magnetic field, heat generation and thermal radiation. The small sized particles of copper (Cu) are taken as nanoparticles and water is assumed to be the base fluid. We used quasi-linearization and central... 

    Imposed magnetic field impact on vortex generation in the laminar nanofluid flow: A computational approach

    , Article International Communications in Heat and Mass Transfer ; Volume 139 , 2022 ; 07351933 (ISSN) Ali, K ; Prakash, M ; Jamshed, W ; Ibrahim, R. W ; Ahmad, S ; Raizah, Z ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    Metal manufacturing plants, nuclear power plants (which produce steam, by using thermal energy yielded during the nuclear fission, for spinning enormous turbines to generate electricity), and geothermal power plants are a few in the extensive list of technologies where different processes occur in high temperature environment in the presence of strong magnetic fields. Nanofluids (NFs), on the other hand, have been successful in achieving wide acceptance as the next generation coolant in the above mentioned industries as well as in the automobiles, heat exchangers, and steam boilers, owing to their remarkable thermal performance. These observations motivate the authors to explore the change... 

    Heat transfer and entropy generation analysis of hybrid graphene/Fe3O4 ferro-nanofluid flow under the influence of a magnetic field

    , Article Powder Technology ; Volume 308 , 2017 , Pages 149-157 ; 00325910 (ISSN) Mehrali, M ; Sadeghinezhad, E ; Akhiani, A. R ; Tahan Latibari, S ; Metselaar, H. S. C ; Kherbeet, A. S ; Mehrali, M ; Sharif University of Technology
    Elsevier B.V  2017
    Abstract
    The heat transfer characteristics and entropy generation rate of hybrid graphene-magnetite nanofluids under forced laminar flow that subjected to the permanent magnetic fields were investigated. For this purpose, a nanoscale reduced graphene oxide-Fe3O4 hybrid was synthesized by using graphene oxide, iron salts and tannic acid as the reductant and stabilizer. The thermophysical and magnetic properties of the hybrid nanofluid have been widely characterized and thermal conductivity has shown an enhancement of 11%. The experimental results indicated that the heat transfer enhancement of hybrid magnetite nanofluid compared to the case of distilled was negligible when no magnetic field was... 

    The study of magnetic field implementation on cylinder quenched in boiling ferro-fluid

    , Article Applied Thermal Engineering ; Volume 64, Issue 1-2 , March , 2014 , Pages 331-338 ; ISSN: 13594311 Habibi Khoshmehr, H ; Saboonchi, A ; Shafii, M. B ; Jahani, N ; Sharif University of Technology
    Abstract
    It has been shown that nanofluids in different investigations increase or decrease heat transfer rate in boiling phenomenon. The present study examined the effects of ferro-fluid concentrations and magnetic field implementation on the fluid throughout the boiling process. Obtained are the quenching curve and boiling curve on specified surface roughness in both water and ferro-fluid with two different concentrations. A silver cylinder with Aspect ratio of 10, and surface roughness of 689 nm was heated up to 350 C and then was overwhelmed in the fluid under study. Temperatures were measured by a thermocouple which installed in the center of the cylinder. The test was carried out 5 times. The... 

    Nanofluidic transport inside carbon nanotubes

    , Article Journal of Physics D: Applied Physics ; Volume 47, Issue 6 , 12 February , 2014 ; ISSN: 00223727 Moghimi Kheirabadi, A ; Moosavi, A ; Akbarzadeh, A. M ; Sharif University of Technology
    Abstract
    Using non-equilibrium molecular dynamics simulations, we investigate the effects of nanotube size, mean flow velocity, ion concentration and temperature of an electrolyte water solution on shearing stress and nominal viscosity. It is shown that the distributed electric field arising from the electrolyte water solution has significant influences on fluid properties. Also, the temperature of the solution, which causes thermal movement, affects nanofluidic transport in nanoenvironments. The nominal viscosity and shearing stress increases as the tube diameter increases. When the temperature of solution increases or ion concentration decreases, the shearing stress and nominal viscosity increase.... 

    Promising technology for electronic cooling: Nanofluidic micro pulsating heat pipes

    , Article Journal of Electronic Packaging, Transactions of the ASME ; Volume 135, Issue 2 , 2013 ; 10437398 (ISSN) Jahani, K ; Mohammadi, M ; Shafii, M. B ; Shiee, Z ; Sharif University of Technology
    2013
    Abstract
    Currently, the thermal management of microelectromechanical systems (MEMS) has become a challenge. In the present research, a micro pulsating heat pipe (MPHP) with a hydraulic diameter of 508 lm, is experimented. The thermal performance of the MPHP in both the transient and steady conditions, the effects of the working fluid (water, silver nanofluid, and ferrofluid), heating power (4, 8, 12, 16, 20, 24, and 28 W), charging ratio (20, 40, 60, and 80%), inclination angle (0 deg, 25 deg, 45 deg, 75 deg, and 90 deg relative to horizontal axis), and the application of magnetic field, are investigated and thoroughly discussed. The experimental results show that the optimum charging ratio for water... 

    Study of droplet behaviour along a pulsed liquid-liquid extraction column in the presence of nanoparticles

    , Article Canadian Journal of Chemical Engineering ; Volume 91, Issue 3 , 2013 , Pages 506-515 ; 00084034 (ISSN) Khoobi, N ; Bahmanyar, A ; Molavi, H ; Bastani, D ; Mozdianfard, M. R ; Bahmanyar, H ; Sharif University of Technology
    2013
    Abstract
    In this article, droplet size and its distribution along a pulsed liquid-liquid extraction column, is studied where SiO2 nanoparticles with concentrations of 0.01, 0.05 and 0.1vol.% and different hydrophobicities are applied to the dispersed phase. Using ultrasonication, nanoparticles were dispersed in kerosene as the base fluid. Nanofluids' stability was ensured using a UV-vis spectrophotometer. Some 22,000 droplets were measured by photographic technique and results were compared with systems containing no-nanoparticles (Water-Acetic acid-Kerosene). Addition of nanoparticles changed the droplet shape from ellipsoidal to spherical. Also, there was a marked influence on droplet breakage and... 

    Copper corrosion in sodium dodecyl sulphate solutions and carbon nanotube nanofluids: A modified Koutecky-Levich equation to model the agitation effect

    , Article Corrosion Science ; Volume 53, Issue 12 , December , 2011 , Pages 4241-4247 ; 0010938X (ISSN) Baghalha, M ; Kamal Ahmadi, M ; Sharif University of Technology
    2011
    Abstract
    Copper corrosion in sodium dodecyl sulphate (SDS) solutions and carbon nanotube (CNT) nanofluids were studied by potentiodynamic polarization. For the corrosion current densities calculations, Koutecky-Levich equation was modified to model the combined charge and mass transport. 0.005. M SDS reduced the copper corrosion current density by 81%. Higher SDS concentrations enhanced corrosion. Stirring SDS solutions increased the corrosion current density by ∼75%. By adding CNT to SDS solution, the corrosion current density first decreased and then remained constant. Stirring CNT nanofluids didn't change the corrosion current density. An adsorbed CNT layer on copper controlled the corrosion...