Search for: nanofluidics
0.008 seconds
Total 238 records

    , M.Sc. Thesis Sharif University of Technology Sarrafan, Kiana (Author) ; Bastani, Daruoosh (Supervisor)
    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
    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
    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
    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
    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
    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
    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... 

    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
    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
    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
    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
    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
    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
    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... 

    Energy saving in HVAC systems using nanofluid

    , Article Applied Thermal Engineering ; Volume 31, Issue 8-9 , 2011 , Pages 1543-1545 ; 13594311 (ISSN) Firouzfar, E ; Soltanieh, M ; Noie, S. H ; Saidi, S. H ; Sharif University of Technology
    The present study tries to use the methanol-silver nanofluid filled thermosyphon heat exchanger and compares the effectiveness as well as energy saving with pure methanol. Experimental results show that using methanol-silver nanofluid, leads to energy saving around 8.8-31.5% for cooling and 18-100% for reheating the supply air stream in an air conditioning system  

    An experimental study on the effect of ultrasonication on thermal conductivity of ferrofluid loaded with carbon nanotubes

    , Article Thermochimica Acta ; Volume 617 , October , 2015 , Pages 102-110 ; 00406031 (ISSN) Shahsavar, A ; Salimpour, M. R ; Saghafian, M ; Shafii, M. B ; Sharif University of Technology
    Elsevier  2015
    Nanofluids containing Fe3O4 and carbon nanotubes nanoparticles emulsified and dispersed using gum arabic (GA) and tetramethylammonium hydroxide (TMAH) were made and characterized for potential use as heat transfer fluids. Due to the interaction between the TMAH and GA molecules, the magnetic nanoparticles and CNTs were physically adsorbed. This paper reports an experimental work on the effect of ultrasonication on thermal conductivity of this aqueous suspension. The characterization and surface morphology of the dried samples were studied by using XRD and TEM measurements. Experiments were conducted in the magnetic nanoparticles mass concentration range 0.494-2.428%,... 

    A novel method for producing unequal sized droplets in micro- and nanofluidic channels

    , Article European Physical Journal E ; Volume 38, Issue 9 , September , 2015 ; 12928941 (ISSN) Bedram, A ; Moosavi, A ; Kazemzadeh Hannani, S ; Sharif University of Technology
    Springer New York LLC  2015
    Abstract: We propose a novel method for producing unequal sized droplets through breakup of droplets. This method does not have the disadvantages of the available methods and also reduces the dependence of the droplets volume ratio on the inlet velocity of the system by up to 26 percent. The employed method for investigating the proposed system relies on 3D numerical simulation using the VOF algorithm and the results have been obtained with various valve ratios for both the micro- and nanoscale. The results indicate that the droplet length during the breakup process increases linearly with time. The droplet length at the nanoscale is smaller than that at the micro scale. It has been shown... 

    Application of electrostatically actuated carbon nanotubes in nanofluidic and bio-nanofluidic sensors and actuators

    , Article Measurement: Journal of the International Measurement Confederation ; Volume 73 , September , 2015 , Pages 127-136 ; 02632241 (ISSN) Seyyed Fakhrabadi, M. M ; Rastgoo, A ; Ahmadian, M. T ; Sharif University of Technology
    Elsevier  2015
    The paper investigates the effects of fluid flow on the static and dynamic behaviors of electrostatically actuated carbon nanotubes using nonlocal elasticity theory. The influences of various parameters of fluid flow including fluid viscosity, velocity, mass and temperature on the mechanical behaviors of the carbon nanotubes under static and step DC voltages are studied using this theory. The results computed from the nonlocal elasticity theory are compared with those estimated using the classical elasticity theorem and the outcomes demonstrate the applicability of the electrostatically actuated carbon nanotubes as nano sensors and nano actuators in nanofluidic systems. The nanosystem can be... 

    Numerical investigation of thermal performance augmentation of nanofluid flow in microchannel heat sinks by using of novel nozzle structure: sinusoidal cavities and rectangular ribs

    , Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 41, Issue 10 , 2019 ; 16785878 (ISSN) Khodabandeh, E ; Akbari, O. A ; Toghraie, D ; Pour, M. S ; Jönsson, P. G ; Ersson, M ; Sharif University of Technology
    Springer Verlag  2019
    In this paper, we present a numerical simulation of a laminar, steady and Newtonian flow of f-graphene nanoplatelet/water nanofluid in a new microchannel design with factors for increasing heat transfer such as presence of ribs, curves to enable satisfactory fluid mixing and changing fluid course at the inlet and exit sections. The results of this study show that Nusselt number is dependent on nanoparticles concentration, inlet geometry and Reynolds number. As the nanofluid concentration increases from 0 to 0.1% and Reynolds number from 50 to 1000, the Nusselt number enhances nearly up to 3% for increase in fluid concentration and averagely from 15.45 to 54.1 and from 14.5 to 55.9 for... 

    A numerical investigation on natural convection heat transfer in annular-finned concentric horizontal annulus using nanofluids: a parametric study

    , Article Heat Transfer Engineering ; 2020 Ashouri, M ; Zarei, M. M ; Hakkaki Fard, A ; Sharif University of Technology
    Taylor and Francis Ltd  2020
    Natural convection heat transfer in a concentric horizontal annulus with annular fins is numerically studied. Due to the low thermal conductivity of water, CuO-water and Al2O3-water nanofluids were used as heat transfer fluids. The effect of three different parameters, including fin spacing, fin eccentricity, and fin thickness at different fin diameters and Rayleigh number range of 104 to 9 (Formula presented.) 105, were studied. The obtained results revealed that Al2O3-water nanofluid has the highest heat transfer rate. The calculated heat transfer rates for Al2O3-water nanofluid for Rayleigh numbers of 9 (Formula presented.) 105, 105, and 104 were respectively up to 12.1%, 26.2%, and 31.6%... 

    Entropy analysis and thermal optimization of nanofluid impinging jet using artificial neural network and genetic algorithm

    , Article International Communications in Heat and Mass Transfer ; Volume 119 , December , 2020 Mahmoudabad Bozchelou, M ; Eghtesad, A ; Jamali, S ; Afshin, H ; Sharif University of Technology
    Elsevier Ltd  2020
    Optimized and informed design of impinging jets can effectively enhance their rate of heat transfer. One practical pathway for such designing is to add nanoparticles to a background fluid. Here, we determine the effects of nanoparticle chemistry, their size, and their total volume fraction in water on the rate of heat transfer. We perform a comprehensive optimization using artificial neural network (ANN) and genetic algorithm (GA) to systematically study the enhanced heat transfer in nanofluids compared to pure water in obtaining a uniform cooling on a constantly heated surface in a turbulent flow. Our results indicate that increasing the size and concentration of nanoparticles enhances the...