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nanofluidics
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Determination of parabolic trough solar collector efficiency using nanofluid:a comprehensive numerical study
, Article Journal of Solar Energy Engineering, Transactions of the ASME ; Volume 139, Issue 5 , 2017 ; 01996231 (ISSN) ; Shamloo, A ; Hannani, S. K ; Sharif University of Technology
Abstract
Due to significant reduction in fossil fuel sources, several researches have been conducted recently to explore modern sources of renewable energy. One of the major fields in the category of renewable energy harnessing devices is parabolic trough solar collector (PTC). Several parameters have effect on the overall efficiency of the PTCs. As the effect of these parameters is coupled to each other, a comprehensive investigation is necessary. In the present study, a numerical analysis is performed to examine the efficiency of PTCs via variation of several governing parameters (e.g., wind velocity magnitude, nanoparticles volume fraction, inlet temperature, and reflector's orientation). A...
Design and evaluation of flat plate solar collector equipped with nanofluid, rotary tube, and magnetic field inducer in a cold region
, Article Renewable Energy ; Volume 170 , 2021 , Pages 574-586 ; 09601481 (ISSN) ; Rostamzadeh, H ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Flat plate solar collectors lose a massive part of heat accumulated near the contact region because of the poor thermal characteristics of the working fluid. A new cost-effective design is numerically studied to cover up such deficiency by equipping the flat plate collector with revolutionary tubes and magnetic field inducer to affect Fe3O4/water working nanofluid in the collector tubes. Results substantiate that each of the applied rotary tubes and magnetic field inducer improves the convection mechanism in the tubes by circulating the flow inside the tubes and saves more of available solar energy. Results reveal that 27.8% and 10.44% of lost energy are restored in the solar collector...
Cu-water nanofluid flow and heat transfer in a heat exchanger tube equipped with cross-cut twisted tape
, Article Powder Technology ; Volume 339 , 2018 , Pages 985-994 ; 00325910 (ISSN) ; Esfahani, J. A ; Sharif University of Technology
Elsevier B.V
2018
Abstract
This paper presents a numerical analysis for Cu-water nanofluid flow through a circular duct inserted with cross-cut twisted tape with alternate axis (CCTA). Three dimensional (RNG) k − ϵ turbulence model is applied to simulate this problem. All simulations are performed for plain tube and nine different CCTA geometries in the range of width ratio (b/w) from 0.7 to 0.9, length ratio (s/w) from 2 to 2.5, Reynolds numbers in the range of 5000 to 15,000 and volume fraction of nanoparticles from 0 to 1.5%. The calculated results indicate that the swirl flow created by CCTA is transferred from the tube core to the near wall regions. This results in higher fluid mixing, which enhances heat...
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) ; 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...
Convective-heat transfer of magnetic-sensitive nanofluids in the presence of rotating magnetic field
, Article Applied Thermal Engineering ; Volume 116 , 2017 , Pages 329-343 ; 13594311 (ISSN) ; Molaei Dehkordi, A ; Shahrokhi, M ; Abbasi, Z ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
In this work, forced-convection heat transfer of magnetic-sensitive nanofluids has been investigated in the presence of rotating magnetic field. In this regard, the laminar, Newtonian, incompressible, and two-dimensional (2D) fluid flow in a horizontal duct subject to constant wall temperature boundary condition was modeled. Moreover, the fluid was supposed to be non-electrical conductive and the magnetic field source comprised of two time varying components perpendicular to each other. Influences of magnetic field intensity and frequency, inlet fluid velocity, and spin viscosity on the forced-convection heat transfer of the magnetic nanofluids were investigated. It was found that the...
Computational intelligence of Levenberg-Marquardt backpropagation neural networks to study the dynamics of expanding/contracting cylinder for Cross magneto-nanofluid flow model
, Article Physica Scripta ; Volume 96, Issue 5 , 2021 ; 00318949 (ISSN) ; Raja, M. A. Z ; Chu, Y. M ; Khan, W. A ; Abbas, S. Z ; Shoaib, M ; Irfan, M ; Sharif University of Technology
IOP Publishing Ltd
2021
Abstract
In the present investigation, design of integrated numerical computing through Levenberg-Marquardt backpropagation neural network (LMBNN) is presented to examine the fluid mechanics problems governing the dynamics of expanding and contracting cylinder for Cross magneto-nanofluid flow (ECCCMNF) model in the presence of time dependent non-uniform magnetic force and permeability of the cylinder. The original system model ECCCMNF in terms of PDEs is converted to nonlinear ODEs by introducing the similarity transformations. Reference dataset of the designed LMBNN methodology is formulated with Adam numerical technique for scenarios of ECCCMNF by variation of thermophoresis temperature ratio...
Computational analysis of nanofluid effects on convective heat transfer enhancement of micro-pin-fin heat sinks
, Article International Journal of Thermal Sciences ; Volume 58 , 2012 , Pages 168-179 ; 12900729 (ISSN) ; Feizbakhshi, M ; Sharif University of Technology
Elsevier
2012
Abstract
Numerical investigation on the application of nanofluids in Micro-Pin-Fin Heat Sinks (MPFHSs) has been presented in this paper. To investigate flow and heat transfer behavior in MPFHS the three-dimensional steady Navier-Stokes and energy equations were discretized using a finite volume approach and have been solved iteratively, using the SIMPLE algorithm. DI-water is used as a base coolant fluid while the nanoparticles used in the present study are CuO nanoparticles with mean diameters of 28.6 and 29 nm and Al 2O 3 nanoparticles with mean diameters of 38.4 and 47 nm. The results show that (i) a significant enhancement of heat transfer in the MPFHS due to suspension of CuO orAl 2O 3...
Comprehensive hydrothermal analysis of an inclined mini-channel with fin array: by dual/multi-relaxation-time LBM and experimental process on SiO2-glycol rheological/thermal characteristics
, Article International Journal of Numerical Methods for Heat and Fluid Flow ; Volume 31, Issue 7 , 2021 , Pages 2405-2429 ; 09615539 (ISSN) ; Hejri, S ; Akbar, N ; Hasani Malekshah, E ; Sharif University of Technology
Emerald Group Holdings Ltd
2021
Abstract
Purpose: The purpose of this study is to present a comprehensive hydrothermal analysis on an inclined mini-channel using numerical and experimental techniques. The fin array acts as heat source within the channel, and a wavy wall located at the top of the channel is heat sink. The side walls are insulated with curved profiles. Also, the channel is inclined with four known inclination angles. To solve the governing equations, the dual-multi-relaxation-time lattice Boltzmann method with D2Q9 and D2Q5 lattice models for flow and temperature fields is used, respectively. Also, the channel is filled with SiO2-glycol nanofluid. Design/methodology/approach: Identifying the behavior of a thermal...
Characterization of magnetized CNT-based hybrid nanofluid subjected to convective phenomenon
, Article International Journal of Modern Physics B ; Volume 35, Issue 28 , 2021 ; 02179792 (ISSN) ; Khan, W. A ; Aqsa ; Waqas, M ; Abbas, S. Z ; Malik, M. Y ; Alqahtani, A. S ; Sharif University of Technology
World Scientific
2021
Abstract
Hybrid nanofluid gains attention of scientists due to its dynamic properties in various fields, and thus, hybrid nanofluids can be taken as an innovative form of nanofluids. Even though analysts acquire tremendous results in the field of hybrid nanofluids but yet no study has been carried out to predict magnetohydrodynamic effects in such fluid models. In this present analysis, influence of MHD has been investigated for the micro hybrid nanofluid over a stretched surface under convective conditions. Combine boundary layer equations for the flow have been altered into a suitable form via boundary layer approximations. Further, complete nonlinear system of equations has been numerically solved...
CFD simulation of thermal performance of hybrid oil-Cu-Al2O3 nanofluid flowing through the porous receiver tube inside a finned parabolic trough solar collector
, Article Sustainable Energy Technologies and Assessments ; Volume 50 , 2022 ; 22131388 (ISSN) ; Khodaverdian, R ; Doranehgard, M. H ; Chehrmonavari, H ; Xiong, Q ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
In this study, we perform numerical simulations to investigate the thermal and flow characteristics of a parabolic trough solar collector equipped with a porous receiver tube and internal longitudinal fins. The heat transfer medium is a synthetic oil-Cu-Al2O3 hybrid nanofluid. We examine the thermal characteristics of the nanofluid in response to variations in several system parameters. We find that at Reynolds numbers between 5 × 103 and 5 × 105, increasing the volume fraction of Cu nanoparticles can increase the temperature gain at the exit of the receiver tube by 6.4%. Furthermore, the temperature gradient in the cross-section of the collector increases as the direct normal solar...
CFD modeling of turbulent convection heat transfer of nanofluids containing green functionalized graphene nanoplatelets flowing in a horizontal tube: Comparison with experimental data
, Article Journal of Molecular Liquids ; Volume 269 , 2018 , Pages 152-159 ; 01677322 (ISSN) ; Mallah, A. R ; Hosseini, M ; Ahmadi, G ; Kazi, S. N ; Dabbagh, A ; Yeong, C. H ; Ahmad, R ; Yaakup, N. A ; Sharif University of Technology
Elsevier B.V
2018
Abstract
In this research, a series of numerical simulations were conducted utilizing computational fluid dynamics (CFD) software in order to predict the heat transfer performance of queues nanofluids containing clove-treated graphene nanoplatelets (CGNPs) flowing in a horizontal stainless steel heated pipe. The GNPs were covalently functionalized with clove buds using free radical grafting reaction using an eco-friendly process. The advantage of this synthesis method was that it did not use hazardous acids, which are typically used in traditional treatment methods of carbon nanostructures. The thermo-physical properties of the aqueous nanofluids obtained experimentally were used as inputs for the...
CFD modeling of natural convection heat transfer of TIO2-water nanofluid in a cylindrical container
, Article Frontiers in Heat and Mass Transfer ; Volume 7, Issue 1 , 2016 ; 21518629 (ISSN) ; Sharif University of Technology
Global Digital Central
Abstract
This work focuses on numerical validation of natural convection heat transfer of TiO2-water nanofluids in a cylindrical container using COMSOL. The main aim of this study is to examine different available approaches to calculate effective thermal conductivity and compare them with experimental data available in the literature. Simulation results show that for considered mixture, average Nusselt number decreases by increasing Rayleigh number and particle volume fraction. It has been found that only one model was able to represent similar trends for given particle volume fractions, compared to experimental results
Boiling heat transfer on a high temperature silver sphere in nanofluid
, Article International Journal of Thermal Sciences ; Volume 48, Issue 12 , 2009 , Pages 2215-2220 ; 12900729 (ISSN) ; Shafii, M. B ; Sharif University of Technology
Abstract
To investigate boiling heat transfer characteristics of nanofluids, transient quenching experiments of a high temperature silver sphere in water-based nanofluids with Ag and TiO2 nanoparticles were performed. A silver sphere with a diameter of 10 mm and an initial temperature of 700 °C was quenched in these nanofluids at a temperature of 90 °C. The results showed a considerable reduction in the quenching ability of nanofluids compared to that of pure water. The presence of nanoparticles in water caused the film boiling mode to vanish at lower temperatures depending on the mixture concentration. Calculated heat transfer rates in nanofluids were lower than those in pure water. In the quenching...
A self-similar approach to study nanofluid flow driven by a stretching curved sheet
, Article Symmetry ; Volume 14, Issue 10 , 2022 ; 20738994 (ISSN) ; 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...
A review on the applications of micro-/nano-encapsulated phase change material slurry in heat transfer and thermal storage systems
, Article Journal of Thermal Analysis and Calorimetry ; 2020 ; Mahmoudian, A ; Mohammadi, O ; Shafii, M. B ; Jafari Mosleh, H ; Zandieh, M ; Ahmadi, M. H ; Sharif University of Technology
Springer Netherlands
2020
Abstract
In modern heat transfer systems, thermal storage not only causes the balance between demand and supply, but also improves the heat transfer efficiency in these systems. In the present study, a comprehensive review of the applications of micro- or nano-encapsulated phase change slurries (MPCMs/NPCMs), as well as their effects on thermal storage and heat transfer enhancement, has been conducted. MPCMs/NPCMs have a myriad of applications and various usages such as pipe and channel flows, photovoltaic/thermal, solar heaters, air conditioning systems, storage tanks and heat pipes that have been categorized and studied. It was found that there are many advantageous adding MPCM/NPCM to the base...
A review on application of nanofluid in various types of heat pipes
, Article Journal of Central South University ; Volume 26, Issue 5 , 2019 , Pages 1021-1041 ; 20952899 (ISSN) ; Ahmadi, M. H ; Sadeghzadeh, M ; Shafii, M. B ; Goodarzi, M ; Sharif University of Technology
Central South University of Technology
2019
Abstract
Nanotechnology is widely used in heat transfer devices to improve thermal performance. Nanofluids can be applied in heat pipes to decrease thermal resistance and achieve a higher heat transfer capability. In the present article, a comprehensive literature review is performed on the nanofluids’ applications in heat pipes. Based on reviewed studies, nanofluids have a high capacity to boost the thermal behavior of various types of heat pipes such as conventional heat pipes, pulsating heat pipes, and thermosyphons. Besides, it is observed that there must be a selected amount of concentration for the high-performance utilization of nanoparticles; high concentration of nanoparticles causes a...
A review of thermal conductivity of various nanofluids
, Article Journal of Molecular Liquids ; Volume 265 , 2018 , Pages 181-188 ; 01677322 (ISSN) ; Mirlohi, A ; Alhuyi Nazari, M ; Ghasempour, R ; Sharif University of Technology
Abstract
In the present paper, several experimental and theoretical studies conducted on the thermal conductivity of nanofluids are represented and investigated. Based on the reviewed studies, various factors affect thermal conductivity of nanofluids such as temperature, the shape of nanoparticles, concentration and etc. Results indicated the increase in temperature and concentration of nanoparticles usually leads to the higher thermal conductivity of nanofluids. In addition, it is concluded that there are some novel approaches in order to obtain nanofluids with more appropriate thermal properties including using binary fluids as the base fluid or utilizing hybrid nanofluids. © 2018 Elsevier B.V
Application of M5 tree regression, MARS, and artificial neural network methods to predict the Nusselt number and output temperature of CuO based nanofluid flows in a car radiator
, Article International Communications in Heat and Mass Transfer ; Volume 116 , July , 2020 ; Ghazvini, M ; Mohseni Gharyehsafa, B ; Ahmadi, M. H ; Pourfarhang, A ; Shokrgozar, M ; Zeinali Heris, S ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In the current study, CuO nanoparticles were dispersed in a mixture of Ethylene Glycol-Water (60/40 wt. %) to prepare stable nanofluid in different concentrations (0.05 − 0.8 vol. %). The samples were used as the coolant fluid in a specific car radiator to evaluate the thermal performance of nanofluid and base fluid in the system. Five different and novel Machine-learning methods were applied over experimental data to predict the Nusselt number and output temperature of the coolant in the system. These methods are M5 tree regression, Linear and Cubic Multi-Variate Adaptive Regression Splines (MARS), Radial Basis Function (RBF), and Artificial Neural Network-Levenberg Marquardt Algorithm...
Application of hybrid nanofluids in a novel combined photovoltaic/thermal and solar collector system
, Article Solar Energy ; Volume 239 , 2022 , Pages 102-116 ; 0038092X (ISSN) ; Salari, A ; Ma, T ; Lu, H ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Because of the low outflow temperature of the conventional photovoltaic thermal systems and lack of electrical production of the solar thermal collectors, a novel combined system is proposed to solve the two mentioned drawbacks. This novel system is achieved by connecting a photovoltaic thermal unit to a solar thermal collector in series. To increase the overall performance of this novel combined system, different hybrid nanofluids include (1) multiwall carbon nanotube-aluminum oxide (2) multiwall carbon nanotube-silicon carbide (3) graphene-aluminum oxide, and (4) graphene-silicon carbide are compared. The investigation is performed based on the three-dimensional simulation, and the...
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) ; Rastgoo, A ; Ahmadian, M. T ; Sharif University of Technology
Elsevier
2015
Abstract
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...