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nanofluidics
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Experimental Study of Internal Forced Convection of Ferrofluid Flow in Porous Media
, M.Sc. Thesis Sharif University of Technology ; Sadrhosseini, Hani (Supervisor) ; Shafii, Mohammad Behshad (Co-Advisor)
Abstract
The present work illustrates the results of an experimental study of ferrofluid flow in a tube subjected to a constant heat flux on its wall and filled with permeable material under the effect of magnetic field. The aim of this project is investigating the enhancement of heat transfer and obtaining a uniform temperature distribution inside the pipe. In order to achieve this, a porous medium with a porosity of 0.39 and ferrofluid with volume fractions of 0.6, 1.0 and 1.5 are used simultaneously, in the presence of magnetic field. The experiments are held for four different Reynolds numbers of 147.1, 167.3, 184.3 and 205.1. Also, four various modes of the oscillatory magnetic field are applied...
Experimental Investigation of Surface Properties and Wettability Using Super Gas Wetting Surface Modified Multi-Nano-Composites
, M.Sc. Thesis Sharif University of Technology ; Ghazanfari, Mohammad Hossein (Supervisor) ; Fakhroueian, Zahra (Supervisor)
Abstract
Recently, the researchers try to identify the application of nanofluids for wettability alteration. Changing the wettability of reservoirs, which gas injects to them, to gas wet can lead to enhanced oil recovery. Although several studies have been conducted to introduce proper nanofluids for altering the wettability of reservoirs to gas wet, there is not enough study to investigate the application of nanocomposites for wettability alteration of carbonate reservoirs. In this study, 20 nanoparticles with different compositional structures were synthesized, and then various nanofluids were prepared for the experimental survey. Also, the potential of these nanofluids for wettability alteration...
Wettability Alteration and its Effect on Oil Recovery by using Colloidal Nano-Silica in Oil Reservoirs
, M.Sc. Thesis Sharif University of Technology ; Ayatollahi, Shahabodin (Supervisor) ; Goodarznia, Iraj (Supervisor) ; Badakhshan, Amir (Co-Supervisor)
Abstract
As many oil fields are reaching their final stage of production, new technologies are required in order to maintain production and increase recovery of hydrocarbons. Among these techniques of enhanced oil recovery (EOR), chemical injection method focuses on increasing the effectiveness of waterflooding. Due to the relatively high costs and considerable adsorption on the rock formations, this method is no longer used. In Recent years nanofluids (nanoparticles dispersed in brine) have been used as a cheap, efficient and environmentally friendly alternative more than any other chemicals. It has been stated that the Smart Water method and enhanced oil recovery by SiO2 nanoparticles are effective...
Determine the Thickness of Boundary Layer in Free Convection on the Vertical Plate With Uniform Heat Flux
, M.Sc. Thesis Sharif University of Technology ; Shafie, Behshad (Supervisor)
Abstract
Experiments were performed to explore the free convective hat transfer characteristics of water based nanofluids. Experiments of natural convection over a vertical flat plate with constant heat flux in water-based nanofluids with Ag and TiO2 nanoparticles were performed. Velocity boundary layer measured using PIV method. Also convective heat transfer coefficient obtained using three thermometers behind the wall. Various test cases with different heat fluxes on the wall are considered. Two volumetric concentrations of Ag nanofluid, 1% and 2%, and TiO2 nanofluid, 1% and 2%, were tested in the present study. It was shown that, with increasing nanofluid concentration, velocity boundary layer...
Visualization of Pool Boiling Heat Transfer of Magnetic Nano-Fluid
, M.Sc. Thesis Sharif University of Technology ; Shafiee, Mohammad Behshad (Supervisor) ; Moosavi, Ali (Co-Supervisor)
Abstract
The use of nano-fluid, which is a stable solid liquid mixture, has been proposed as a new strategy for heat transfer operations. Much research has been done on heat transfer of nano-fluids until now, whereas the study of phenomena associated with phase change, such as boiling where there is heat transfer in larger scales is very necessary. The boiling process based on its potential for transferring high amounts of heat at low temperatures is a very effective and common mechanism, and it occurs in many engineering systems, including boilers at plants, evaporators in refrigeration systems and nuclear reactors. Also, a considerable amount of research was done recently in the field of...
Influences of Magnetic Nanoparticles and Magnetic Field on the Performance of the Redox Flow Batteries
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor) ; Gharibi, Hossein (Supervisor)
Abstract
The novel concept of using magnetic nanofluidic electrolyte for redox flow batteries (RFBs) is demonstrated for the first time. In this regard, the stable magnetic nanofluidic electrolytes are prepared by dispersing magnetic modified multiwalled carbon nanotubes (MMWCNTs) in the positive electrolyte of a polysulfide-iodide redox flow battery at mass concentrations of less than 0.3 g L−1. The electrochemical behavior of magnetic nanofluidic electrolyte was examined using cyclic voltammetry at different mass concentrations of MMWCNTs with a carbon felt electrode. Higher and stable peak current densities were observed at larger mass concentrations of MMWCNTs. A polysulfide-iodide redox flow...
Experimental and Numerical Investigation of Reactive Absorption in the presence of Nanofluid and Magnetic field
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
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 Drop Phase Mass Transfer Coefficient During Rising Drops in a Pulse Sieved Plate Column in Presence of Nano Particles
, M.Sc. Thesis Sharif University of Technology ; Bastani, Daruoosh (Supervisor) ; Bahmanyar, Hossein (Supervisor)
Abstract
Nanofluids are new engineering materials with great potential for application in process industries. Their enhanced heat-transfer properties are reported in recent literatures. However, with respect to the influence of nanoparticles on mass transfer characteristics, limited number of studies available in the literature, deal primarily with gas-liquid systems. In this work, mass transfer performance and droplet behavior along a pulsed liquid-liquid extraction column, is studied where SiO2 nanoparticles with concentrations of 0.01, 0.05 and 0.1 vol% and different hydrophobicities are applied to the dispersed phase. Using ultrasonication, nanoparticles were dispersed in kerosene as the base...
Simulation of Fluid Flow in Nanotubes by Non-Equilibrium Molecular Dynamics
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor) ; Kazemzadeh Hannani, Siamak (Supervisor)
Abstract
One of the critical challenges in droplet based micro- and nanofluidic devices is handling the droplet breakup such that a controllable droplet size is produced. The experimental and numerical investigations at the microscale indicate that the droplet size can be well controlled by T junction geometries. In the present study we use non-equilibrium molecular dynamics (NEMD) simulations to investigate this phenomenon at the nanoscale. In order to generalize the study the Lennard-Jones type potential between the fluids and the walls have been considered and the strength and the effective range of the potential are changed to consider a wide variety of materials. Our results reveal that the...
Determination of Parabolic Trough Solar Collector Efficiency Using Al2O3/Synthetic Oil Nanofluid: A Comprehensive Numerical Study with The Effect of Wind Velocity
, Ph.D. Dissertation Sharif University of Technology ; Shamloo, Amir (Supervisor) ; Kazemzadeh Hannani, Siamak (Supervisor)
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 collectors (PTC). Several parameters have effect on the overall efficiency of the PTC’s.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 detailed...
Two-phase, Two-component Simulation of Nanofluids in Natural Convection Applying Lattice Boltzmann Method
, Ph.D. Dissertation Sharif University of Technology ; Saeedi, Mohammad Hassan (Supervisor)
Abstract
The advances of technology of microelectrical devices and their computational capacity and so, their heat rates, make the thermal control of them more complex. Utilizing nanopfluids is one of proposing options. The current research investigates the effectiveness of using nanoparticles on the heat transfer rate of fluids in the natural convection. A two-component two-phase lattice Boltzmann method (LBM) has been implemented for this purpose. A wide range of Rayleigh number (Ra), namely 103 to 109, 0 to 0.05 volume fraction s of nanoparticles and nanoparticle diameters below 100 nm has been investigated in this research. The method is optimized for complex geometries. Two and three dimensional...
Improving the Cooling Performance of Automobile Radiator
, M.Sc. Thesis Sharif University of Technology ; Afshin, Hossein (Supervisor)
Abstract
Inhencemant of automobile radiator heat performance is the purpose of this study. Radiator fin shape, coolant fluid properties and influence of nanofluid studied in this research. Plain fin, louvered fin and vortex generator fin is choosen and design. With flow simulation influence of fin shape on heat performance is studied. After that, with considering radiator coolant fluid, the effect of antifreezing on fin heat transfer is evaluated. Then by addin nanoparticles to water and antifreezing solution, effect of nanofluid on heat transfer is evaluated. Results show that with increasing the air velocity for all geometries in the study , heat transfer and pressure drop is increased. But heat...
Mixed Convection of Nanofluids in Channels Partially Filled with a Porous Medium
, Ph.D. Dissertation Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
In the present study, mixed-convective heat transfer of nanofluids in a vertical rectangular channel partially filled with open-cell metal foam has been investigated experimentally and numerically. Al2O3–H2O nanofluids with different concentrations were synthesized and their stability was inspected with UV-Vis spectroscopy. The outlet temperature and pressure drop were measured for different nanofluid flow rates (i.e., Reynolds number values). In the numerical section, a two-dimensional volume-averaged form of the governing equations was used. The velocity and temperature profiles were obtained using finite difference method. The Brinkman–Forchheimer extended Darcy model and the...
Investigation of Micro Heat Pipe Performance Using Nano-Fluid as Working Fluid
, M.Sc. Thesis Sharif University of Technology ; shafii, Mohammad Behshad (Supervisor) ; Saboohi, Yadollah (Co-Advisor)
Abstract
Thermal management of micro-electronic devices is a contemporary issue which is increasingly gaining importance in line with the advances in packaging technology. Immediate and consistent multi-disciplinary research is needed to cater to the prevailing trends of net power and flux levels of upcoming micro-electronics products. Material science, packaging concepts, fabrication technology and novel cooling strategies are some of the key areas requiring synchronal research for successful thermal management. Focusing on the latter area, this thesis presents an experimental study on thermal performance of Micro-Closed Loop Pulsating Heat Pipes (MCLPHPs) which are new entrants in the family of...
Experimental Investigation of Pulsating Heat Pipe
, M.Sc. Thesis Sharif University of Technology ; Shafiee, Mohammad Behshad (Supervisor)
Abstract
Pulsating heat pipes (PHP) are complex heat transfer devices which unlike conventional heat pipes do not contain any wick in their structure. The effective parameters consist of; working fluid, volumetric filling ratio, operational orientation and input heat power have been investigated here. The experimental set-up we have contemplated, fabricated and tested included five turns, made of copper tube coupled with two glass tube of internal diameter 1.8 mm. The height of evaporator, condenser and adiabatic section was 60, 60 and 150 mm, respectively. The evaporator was heated with electrical element connected to an AC variant power supply and the condenser was connected to a constant...
Experimental Investigation of Nano Particle Effect on Heat Transfer in a Micro Heat Exchanger
, M.Sc. Thesis Sharif University of Technology ; 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...
Experimental Investigation of Pulsating Heat Pipe Using Nano-Fluid
, M.Sc. Thesis Sharif University of Technology ; Saidi, Mohammad Hassan (Supervisor) ; Afshin, Hossain (Supervisor) ; Shafiee, Mohammad Behshad (Supervisor)
Abstract
Considerable increase in speed and decrease in size of electronic devices results in increase of heat flux, so there is a need to enhance efficiency of cooling electronic devices. In the present research two sets of OLPHPs with five turns for two different magnetic nano-fluids were fabricated and the effects of working fluid (water, and two types of magnetic nano-fluids), working pressure, concentration, magnetic field, magnets location, and inclination angle on the thermal performance of OLPHPs have been considered in both startup and steady thermal conditions.
Experimental results show that magnetic nano-fluids can improve thermal performance of the OLPHPs. Application of magnetic...
Experimental results show that magnetic nano-fluids can improve thermal performance of the OLPHPs. Application of magnetic...
Investigation of the Influence of Nanoparticle & Nanofluidic Conduit Geometry on Ionic Transport
, M.Sc. Thesis Sharif University of Technology ; Taghipoor, Mojtaba (Supervisor)
Abstract
Resistive pulse sensing (RPS) has proved to be a viable method for detection and characterization of micro and nano particles. This method works based on ionic current variation inside nanopores. Modern fabrication methods have introduced different nanopore geometries for resistive pulse sensors therefore studing the effects of geometry on sensing performance of nanaopores is important. Numerical simulation has been used to study a wide variation of nanopore’s geometry configurations and study the physics behind this phenomena. Based on the results, numerical simulation could be used as a fast and easy tool for size determination for nanopore. To compare the sensing performance of different...
Preparation of Nanofluid by Using Hybrid Nanostructures and Investigation of Thermal and Rheological Properties and Using it in the Petroleum Fluids
, M.Sc. Thesis Sharif University of Technology ; Rashtchian , Davood (Supervisor) ; Rashidi, Alimorad (Supervisor) ; Lotfi, Roghayeh (Co-Advisor)
Abstract
In this study, thermal and rheological properties of nanofluids of water/carbon nanotubes, water/spherical silica nanoparticles and water/hybrid nanoparticles (hybrid of carbon nanotubes and spherical silica nanoparticles) have been investigated. To do so, carbon nanotubes have been synthesized by CCVD process and spherical silica nanoparticles and hybrid nanoparticles by wet chemical method. After synthesis of nanomaterials, nanofluids have been prepared by using SDBS as a dispersant with the concentration of 1.5 times of concentration of nanomaterials and then thermal conductivity, kinematic viscosity, dynamic viscosity and density of nanofluids have been investigated. As the results show,...
Experimental and Theoretical Investigation on Thermal Conductivity of Combined Nanofluids
, M.Sc. Thesis Sharif University of Technology ; Shafii, Mohammad Behshad (Supervisor)
Abstract
Application of nanotechnology in the field of heat transfer has increased recently. The need to increase heat transfer rate yet decrease the size of cooling equipment, brought about lots of attention to thermal properties of Nanofluids. Nanofluid is the suspension of nanometer-sized solid particles in base liquid. Research on convective heat transfer of nanofluids which is only two decades old, shows great potential in increasing heat transfer rate. Although there is a remarkable research on thermal conductivity of Nanofluids, negligible research was conducted on combined Nanofluids . Developed Theory for thermal conductivity of combined nanofluid can be used to modeling the thermal...