scholarly journals Electrical Conductivity of New Nanoparticle Enhanced Fluids: An Experimental Study

Nanomaterials ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1228 ◽  
Author(s):  
Chereches ◽  
Minea
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Base Fluid ◽  
Volume Concentration ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Sio2 Nanoparticles ◽  
Theoretical Models ◽  
Conductivity Ratio ◽  
Hybrid Nanofluids

In this research, the electrical conductivity of simple and hybrid nanofluids containing Al2O3, TiO2 and SiO2 nanoparticles and water as the base fluid was experimentally studied at ambient temperature and with temperature variation in the range of 20–60 °C. A comparison of the experimental data with existing theoretical models demonstrated that the theoretical models under-predict the experimental data. Consequently, several correlations were developed for nanofluid electrical conductivity estimation in relation to temperature and volume concentration. The electrical conductivity of both simple and hybrid nanofluids increased linearly with both volume concentration and temperature upsurge. More precisely, by adding nanoparticles to water, the electrical conductivity increased from 11 times up to 58 times for both simple and hybrid nanofluids, with the maximum values being attained for the 3% volume concentration. Plus, a three-dimensional regression analysis was performed to correlate the electrical conductivity with temperature and volume fraction of the titania and silica nanofluids. The thermo-electrical conductivity ratio has been calculated based on electrical conductivity experimental results and previously determined thermal conductivity. Very low figures were noticed. Concluding, one may affirm that further experimental work is needed to completely elucidate the behavior of nanofluids in terms of electrical conductivity.

Experimental Measurement of Thermophysical Properties of Alumina- MWCNTs/Salt–Water Hybrid Nanofluids

2020 ◽  
Vol 16 (5) ◽  
pp. 734-747 ◽  
Author(s):  
Amir Hossein Sharifi ◽  
Iman Zahmatkesh ◽  
Fatemeh F. Bamoharram ◽  
Amir Hossein Shokouhi Tabrizi ◽  
Safieh Fazel Razavi ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Salt Concentration ◽  
Thermophysical Properties ◽  
Base Fluid ◽  
Volume Fraction ◽  
Ph Value ◽  
Nanoparticle Volume Fraction ◽  
Optimal Conditions ◽  
Hybrid Nanofluids

Background: Hybrid nanofluids are considered as an extension of conventional nanofluids which are prepared through suspending two or more nanoparticles in the base fluids. Previous studies on hybrid nanofluids have measured their thermal conductivity overlooking other thermophysical properties such as viscosity and electrical conductivity. Objective: An experimental investigation is undertaken to measure thermal conductivity, viscosity, and electrical conductivity of a hybrid nanofluid prepared through dispersing alumina nanoparticles and multiwall carbon nanotubes in saltwater. These properties are the main important factors that must be assessed before performance analysis for industrial applications. Methods: The experimental data were collected for different values of the nanoparticle volume fraction, temperature, salt concentration, and pH value. Attention was paid to explore the consequences of these parameters on the nanofluid’s properties and to find optimal conditions to achieve the highest value of the thermal conductivity and the lowest values of the electrical conductivity and the viscosity. Results: The results demonstrate that although the impacts of the pH value and the nanoparticle volume fraction on the nanofluid’s thermophysical properties are not monotonic, optimal conditions for each of the properties are reachable. It is found that the inclusion of the salt in the base fluid may not change the thermal conductivity noticeably. However, a considerable reduction in the viscosity and substantial elevation in the electrical conductivity occur with an increase in the salt concentration. Conclusion: With the addition of salt to a base fluid, the thermophysical properties of a nanofluid can be controlled.

scholarly journals Experimental studies on the viscosity of Fe nanoparticles dispersed in ethylene glycol and water mixture

2016 ◽  
Vol 20 (5) ◽  
pp. 1661-1670 ◽  
Author(s):  
Amir Karimi ◽  
Sadatlu Abdolahi ◽  
Mehdi Ashjaee
Keyword(s):  
Ethylene Glycol ◽  
Base Fluid ◽  
Volume Concentration ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Experimental Results ◽  
Water Mixture ◽  
Fe Nanoparticles

In this paper, experimental studies are conducted in order to measure the viscosity of Fe nanoparticles dispersed in various weight concentration (25/75%, 45/55% and 55/45%) of ethylene glycol and water (EG-water) mixture. The experimental measurements are performed at various volume concentrations up to 2% and temperature ranging from 10?C to 60?C. The experimental results disclose that the viscosity of nanofluids increases with increase in Fe particle volume fraction, and decreases with increase in temperature. Maximum enhancement in viscosity of nanofluids is 2.14 times for 55/45% EG-water based nanofluid at 2% volume concentration compared to the base fluid. Moreover, some comparisons between experimental results and theoretical models are drawn. It is also observed that the prior theoretical models do not estimate the viscosity of nanofluid accurately. Finally, a new empirical correlation is proposed to predict the viscosity of nanofluids as a function of volume concentration, temperature, and the viscosity of base fluid.

scholarly journals Experimental Investigation on Stability, Viscosity, and Electrical Conductivity of Water-Based Hybrid Nanofluid of MWCNT-Fe2O3

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 136
Author(s):  
Solomon O. Giwa ◽  
Mohsen Sharifpur ◽  
Mohammad H. Ahmadi ◽  
S. M. Sohel Murshed ◽  
Josua P. Meyer
Keyword(s):  
Electrical Conductivity ◽  
Visual Inspection ◽  
Volume Concentration ◽  
Working Fluid ◽  
Hybrid Nanofluid ◽  
Multiwalled Carbon ◽  
Transmission Electron ◽  
Hybrid Nanofluids ◽  
Uv Visible ◽  
The Stability

The superiority of nanofluid over conventional working fluid has been well researched and proven. Newest on the horizon is the hybrid nanofluid currently being examined due to its improved thermal properties. This paper examined the viscosity and electrical conductivity of deionized water (DIW)-based multiwalled carbon nanotube (MWCNT)-Fe2O3 (20:80) nanofluids at temperatures and volume concentrations ranging from 15 °C to 55 °C and 0.1–1.5%, respectively. The morphology of the suspended hybrid nanofluids was characterized using a transmission electron microscope, and the stability was monitored using visual inspection, UV–visible, and viscosity-checking techniques. With the aid of a viscometer and electrical conductivity meter, the viscosity and electrical conductivity of the hybrid nanofluids were determined, respectively. The MWCNT-Fe2O3/DIW nanofluids were found to be stable and well suspended. Both the electrical conductivity and viscosity of the hybrid nanofluids were augmented with respect to increasing volume concentration. In contrast, the temperature rise was noticed to diminish the viscosity of the nanofluids, but it enhanced electrical conductivity. Maximum increments of 35.7% and 1676.4% were obtained for the viscosity and electrical conductivity of the hybrid nanofluids, respectively, when compared with the base fluid. The obtained results were observed to agree with previous studies in the literature. After fitting the obtained experimental data, high accuracy was achieved with the formulated correlations for estimating the electrical conductivity and viscosity. The examined hybrid nanofluid was noticed to possess a lesser viscosity in comparison with the mono-particle nanofluid of Fe2O3/water, which was good for engineering applications as the pumping power would be reduced.

Using Theoretical and Computational Models to Understand How Metals Function as Temperature Sensors

2016 ◽  
pp. 668-702
Author(s):  
Fred Lacy
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Electrical Resistivity ◽  
Computational Models ◽  
Theoretical Models ◽  
Temperature Sensors ◽  
Atomic Level ◽  
Atomic Motion ◽  
Temperature Changes ◽  
Theoretical And Computational Models

Electrical conductivity is a basic property of materials that determines how well the material conducts electricity. However, models are needed that help explain how conductors function as their size and temperature changes. This research demonstrates and explains how important atomic motion is in understanding electrical conductivity for conductors (and thus the ability of metals to function as temperature sensors). A derivation is performed (on an atomic level) that provides a theoretical relationship between electrical resistivity, temperature, and material thickness. Subsequently, computational models are used to determine the optimal parameters for the theoretical models as well as the conditions under which they are accurate. Comparisons are performed using experimental data showing that the models are valid and accurate.

An Experimental Determination of the Viscosity of Propylene Glycol/Water Based Nanofluids and Development of New Correlations

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Ravikanth S. Vajjha ◽  
Debendra K. Das ◽  
Godwin A. Chukwu
Keyword(s):  
Experimental Data ◽  
Carbon Nanotubes ◽  
Propylene Glycol ◽  
Base Fluid ◽  
Volume Concentration ◽  
Plastic Behavior ◽  
Average Particle ◽  
Particle Volume ◽  
Temperature Range ◽  
Newtonian Behavior

Measurements have been carried out for determining the viscosity of several nanofluids, in which different nanoparticles were dispersed in a base fluid of 60% propylene glycol (PG) and 40% water by mass. The nanoparticles were aluminum oxide (Al2O3), copper oxide (CuO), silicon dioxide (SiO2), titanium oxide (TiO2), and zinc oxide (ZnO) with different average particle diameters. Measurements were conducted for particle volume concentrations of up to 6% and over a temperature range of 243 K–363 K. All the nanofluids exhibited a Bingham plastic behavior at lower temperatures of 243 K–273 K and a Newtonian behavior in the temperature range of 273 K–363 K. Comparisons of the experimental data with several existing models show that they do not exhibit good agreement. Therefore, a new model has been developed for the viscosity of nanofluids as a function of temperature, particle volume concentration, particle diameter, the properties of nanoparticles, and those of the base fluid. Measurements were also conducted for single walled, bamboolike structured, and hollow structured multiwalled carbon nanotubes (MWCNT) dispersed in a base fluid of 20% PG and 80% water by mass. Measurements of these carbon nanotubes (CNT) nanofluids were conducted for a particle volume concentration of 0.229% and over a temperature range of 273 K–363 K, which exhibited a non-Newtonian behavior. The effect of ultrasonication time on the viscosity of CNT nanofluids was investigated. From the experimental data of CNT nanofluids, a new correlation was developed which relates the viscosity to temperature and the Péclet number.

scholarly journals Interactive, visual simulation of a spatio-temporal model of gas exchange in the human alveolus

2021 ◽  
Author(s):  
Kerstin Schmid ◽  
Andreas Knote ◽  
Alexander Mueck ◽  
Keram Pfeiffer ◽  
Sebastian von Mammen ◽  
...  
Keyword(s):  
Experimental Data ◽  
Gas Exchange ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Simulation Software ◽  
Visual Simulation ◽  
Model Parameters ◽  
Interactive Simulation ◽  
Temporal Model ◽  
Spatio Temporal

In interdisciplinary fields such as systems biology, close collaboration between experimentalists and theorists is crucial for the success of a project. Theoretical modeling in physiology usually describes complex systems with many interdependencies. On one hand, these models have to be grounded on experimental data. On the other hand, experimenters must be able to penetrate the model in its dependencies in order to correctly interpret the results in the physiological context. When theorists and experimenters collaborate, communicating results and ideas is sometimes challenging. We promote interactive, visual simulations as an engaging way to communicate theoretical models in physiology and to thereby advance our understanding of the process of interest. We defined a new spatio-temporal model for gas exchange in the human alveolus and implemented it in an interactive simulation software named Alvin. In Alvin, the course of the simulation can be traced in a three-dimensional rendering of an alveolus and dynamic plots. The user can interact by configuring essential model parameters. Alvin allows to run and compare multiple simulation instances simultaneously. The mathematical model was developed with the aim of visualization and the simulation software was engineered based on a requirements analysis. Our work resulted in an integrative gas exchange model and an interactive application that exceed the current standards. We exemplified the use of Alvin for research by identifying unknown dependencies in published experimental data. Employing a detailed questionnaire, we showed the benefits of Alvin for education. We postulate that interactive, visual simulation of theoretical models, as we have implemented with Alvin on respiratory processes in the alveolus, can be of great help for communication between specialists and thereby advancing research.

scholarly journals Numerical modeling of the porosity influence on strength of structural materials

2019 ◽  
Vol 51 (4) ◽  
pp. 459-467
Author(s):  
Mohamed Higaeg ◽  
Igor Balac ◽  
Aleksandar Grbovic ◽  
Milorad Milovancevic ◽  
Milos Jelic
Keyword(s):  
Experimental Data ◽  
Structural Material ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Structural Materials ◽  
Material Strength ◽  
Material Microstructure ◽  
Dimensional Unit ◽  
Material Porosity ◽  
Porosity Volume Fraction

The effect of micro-scale structural low-level porosity on strength of structural materials was studied using the three-dimensional Unit Cell Numerical Model - UCNM. A comparison between proposed UCNM and available experimental data in literature was done by comparing obtained values for stress concentration factor - SCF for different sizes and shapes of pore. Results for normalized strength obtained by proposed UCNM model are in agreement with available experimental data published in literature. It was confirmed that material porosity in form of closed pores, regarding pores? size (volume fraction) and shape, has note cable influence on strength of structural material. Less porosity in the material microstructure generally leads to higher values of material strength. For fixed porosity volume fraction, shape of pores has an impact on strength of structural material.

scholarly journals On Experimental Data of the TCR of TFRs and Their Relation to Theoretical Models of Conduction Mechanism

1985 ◽  
Vol 11 (4) ◽  
pp. 255-259 ◽  
Author(s):  
I. Storbeck ◽  
M. Wolf
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Theoretical Model ◽  
Temperature Dependence ◽  
Electrical Conduction ◽  
Conduction Mechanism ◽  
Volume Fraction ◽  
Theoretical Models ◽  
Strain Dependence ◽  
Conducting Component

Any theory of electrical conduction in TFRs encounters mainly two problems: (i) explanation of the dependence of R□on properties of conducting component (volume fraction, grain size, resistivity), (ii) explanation of the temperature dependence of R□taking into account (i). In order to achieve this one has to fit some microscopic parameters to experimental R□-and TCR-values, and to check if they are reasonable or not. The aim of the following discussion is to show, that such a fitting by means of experimental TCR-values is not correct. This is due to the fact that TCR-behaviour, as is well known, is determined also by the dependence of resistivity on strain. But any theoretical model neglects strains, also those who are induced by thermal strains. By means of published experiments concerning the strain dependence of resistance, the magnitude is estimated by which the TCR-values have to be corrected for the described fit.

Robust Conservative Level Set Method for 3D Mixed-Element Meshes — Application to LES of Primary Liquid-Sheet Breakup

2014 ◽  
Vol 16 (2) ◽  
pp. 403-439 ◽  
Author(s):  
Thibault Pringuey ◽  
R. Stewart Cant
Keyword(s):  
Experimental Data ◽  
Level Set ◽  
Multiphase Flows ◽  
Volume Fraction ◽  
Computational Cost ◽  
Three Dimensional ◽  
Liquid Sheet ◽  
Liquid Volume ◽  
Mixed Element ◽  
Conservative Level Set

AbstractIn this article we detail the methodology developed to construct an efficient interface description technique — the robust conservative level set (RCLS) — to simulate multiphase flows on mixed-element unstructured meshes while conserving mass to machine accuracy. The approach is tailored specifically for industry as the three-dimensional unstructured approach allows for the treatment of very complex geometries. In addition, special care has been taken to optimise the trade-off between accuracy and computational cost while maintaining the robustness of the numerical method. This was achieved by solving the transport equations for the liquid volume fraction using a WENO scheme for polyhedral meshes and by adding a flux-limiter algorithm. The performance of the resulting method has been compared against established multiphase numerical methods and its ability to capture the physics of multiphase flows is demonstrated on a range of relevant test cases. Finally, the RCLS method has been applied to the simulation of the primary breakup of a flat liquid sheet of kerosene in co-flowing high-pressure gas. This quasi-DNS/LES computation was performed at relevant aero-engine conditions on a three-dimensional mixed-element unstructured mesh. The numerical results have been validated qualitatively against theoretical predictions and experimental data. In particular, the expected breakup regime was observed in the simulation results. Finally, the computation reproduced faithfully the breakup length predicted by a correlation based on experimental data. This constitutes a first step towards a quantitative validation.

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