Viscosity Of Nanofluids Research Articles

Modeling and Prediction of the Dynamic Viscosity of Nanofluids by a Homogenization Method

Modeling and Prediction of the Dynamic Viscosity of Nanofluids by a Homogenization Method

Numerical investigation on natural convection of hybrid nanofluid Al2O3 – MWCNT/water inside a vertical annulus

A numerical inspection on natural convection inside a vertical annulus interior of which water based (Al2O3 + MWCNT) (7:3) hybrid nanofluid has presently been carried out using CFD solver Ansys Fluent. Finite volume method (FVM) is used to perform the numerical simulations at constant heat flux of 3kW/m2 and various volume fraction (0-0.04) of nanoparticle. The thermal conductivity and viscosity of hybrid nanofluid is computed by modified Maxwell model and Batchelor model respectively. The paper carried explicit analysis on effect of nanoparticle concentration, Nu number and heat transfer coefficient. The maximum enhancement in average heat transfer coefficient found to be 73.67% when gauged on volume fraction of 0.04.

Heat transfer properties of metal, metal oxides, and carbon water-based nanofluids in the ethanol condensation process

This work investigates the convective heat transfer enhancement of water-based nanofluids in pipe heat exchanger used for the ethanol condensation process. The nanofluids were produced with different nature of nanoparticles, Cu, Fe3O4, MWCNT, and graphene, in the volume concentration 0.01–0.1%, using different surfactants. These nanoparticles are characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), specific surface area (BET), and Dynamic light scattering (DLS). Density, thermal conductivity, and viscosity of base fluids and nanofluids were experimentally determined at a relevant temperature of 20 °C. Convective heat transfer enhancement under laminar regime was evaluated from a well-designed experimental setup. As the main results, the thermal conductivity of nanofluids increases up to 3–5% and the viscosity can increase or decrease with nanoparticle concentration, showing a lubricating effect of nanoparticles coupled with respective surfactant. It was shown that the heat transfer properties, heat transfer coefficient, and Nusselt number, are increased with nanofluids compared to water and base-fluids, up to 20%, in the range of Pe 2000–10000. Experimental heat transfer properties are shown to be greater than theoretical ones. Finally, copper nanofluid at low concentration appear to be the best candidate for the application and pipe flow geometry considered.

Particle size-dependent rheological behavior and mechanism of Al2O3-Cu/W hybrid nanofluids

In order to investigate complicated interactions between nanoparticles of different sizes on the rheological characteristics of hybrid nanofluids, Al2O3-Cu/W hybrid nanofluids with volume fractions of 0.3–1.5 vol% were studied in the present study. Moreover, 50 nm Cu nanoparticles and different sizes of Al2O3 nanoparticles, including 20, 30 and 50 nm particles, were utilized in the experiments. Obtained experimental results showed that as the volume fraction increases, the viscosity increases too. When the volume fraction reaches 0.3 vol%, the viscosity increases as the nanoparticle size increases. Moreover, it was found that 20 nm-Al2O3-Cu/W has the lowest viscosity at room temperature. When the volume fraction is higher than 0.3 vol%, the viscosities of 30 nm-Al2O3-Cu/W and 50 nm-Al2O3-Cu/W are low. Moreover, 20 nm-Al2O3-Cu/W hybrid nanofluid shows Newtonian behavior only at low concentrations (<0.3 vol%) and low shear rates (<100 s−1). However, 30 nm-Al2O3-Cu/W and 50 nm-Al2O3-Cu/W are all non-Newtonian fluids. Analysis of variance (ANOVA) indicates that the volume fraction significantly affects the viscosity, contributing to more than 45% in studied temperatures, while the influence of the nanoparticle size is 25%. Finally, it is found that the synergistic effect in hybrid nanofluids affects the nanoparticle arrangement. Accordingly, low-viscosity nanofluids can be achieved by adding nanoparticles of small size at low volume fractions, while large-size nanoparticles are achieved in high volume fractions. The present article is expected to broaden the understanding of the nanoparticle size on the viscosity of hybrid nanofluids.

Pengaruh Penambahan Surfaktan Gum Arabic Terhadap Sifat Fisik dan Stabilitas Fluida Nano Titania (TiO2)

This study aims to examine the physical properties of titania (TiO2) by adding arabic gum surfactants to obtain stable nanofluid. Nano titania fluid preparation was carried out by dispersing titania nanoparticles and arabic gum in a homogenizer for 3 hours with particle variations in fraction volume and arabic gum surfactant concentration. The study was carried out by varying the volume of the particle fraction at 0.1%; 0.2%; 0.3%; 0.4% and 0.5% and arabic gum surfactant concentrations at 1%; 2%; 3%; 4%; and 5%. Measurements are also made at a temperature variation of 30 OC; 40 OC; and 50 OC. Measurement of physical properties is carried out by measuring the properties of electrical conductivity, density, viscosity, and stability of titania nanofluid. The measurement results indicate that the higher the concentration of surfactant and the volume fraction of particles, the electrical conductivity, density, and viscosity of nano titania fluid is increasing. Increased temperature will reduce the viscosity of titania nanofluid.

Squeezed flow of water-based nanofluid having temperature dependent viscosity and thermal conductivity

Subjected to the numerous applications of squeezed flows of nanofluids, this article provides the analysis of squeezed flow of water-based nanofluids. Viscosity and thermal conductivity of nanofluid is considered to vary with temperature. Appropriate modifications in the Brinkman’s viscosity and Hamilton-Crosser’s thermal conductivity model have been made for the present analysis. Heat generation/absorption has been also considered. Analysis is presented by considering the various nanoparticles (i.e. copper, silver, alumina etc). Physical analysis of numerical results is facilitated via graphs and tables. Comparison for cylindrical and spherical nanoparticles is also provided. Results indicate that the velocity profile shows a decreasing behavior with an increase in squeeze number and decays against incrementing thermal conductivity parameter for both spherical and cylindrical nanoparticles.

Experimental Investigation of Thermo-Physical Properties of Tri-Hybrid Nanoparticles in Water-Ethylene Glycol Mixture

In recent years, research has focused on enhancing the thermo-physical properties of a single component nanofluid. Therefore, hybrid or composite nanofluids have been developed to improve heat transfer performance. The thermo-physical properties of the Al2O3-TiO2-SiO2 nanoparticles suspended in a base of water (W) and ethylene glycol (EG) at constant volume ratio of 60:40 and different volume concentrations were investigated. The experiment was conducted for the volume concentrations of 0.05, 0.1, 0.2, and 0.3% of Al2O3-TiO2-SiO2 nanofluids at different temperatures of 30, 40, 50, 60, and 70 °C. Thermal conductivity and dynamic viscosity measurements were carried out at temperatures ranging from 30 to 70 °C by using KD2 Pro Thermal Properties Analyzer and Brookfield LVDV III Ultra Rheometer, respectively. The highest thermal conductivity for tri-hybrid nanofluids was obtained at 0.3% volume concentration, and the maximum enhancement was increased up to 9% higher than the base fluid (EG/W). Tri-hybrid nanofluids with a volume concentration of 0.05% gave the lowest effective thermal conductivity of 4.8 % at 70 °C temperature. Meanwhile, the dynamic viscosity of the tri-hybrid nanofluids was influenced by volume concentration and temperature. Furthermore, tri-hybrid nanofluids behaved as a Newtonian fluid for volume concentrations from 0.05 to 3.0%. The properties enhancement ratio (PER) estimated that the tri-hybrid nanofluids will aid in heat transfer for all samples in the present. The new correlations for thermal conductivity and dynamic viscosity of tri-hybrid nanofluids were developed with minimum deviation. As a conclusion, the combination of the enhancement in thermal conductivity and dynamic viscosity for tri-hybrid at 0.3% volume concentration was found the optimum condition with more advantage for heat transfer than other concentrations.

Experimental investigation on the cooling performance of polystyrene encapsulated n-Docosane based nanofluid in mini channel heat sink

The present work focusses on the comparative study of cooling performance of nano encapsulated phase change material (nanoPCM) based heat transfer fluid (PCM nanofluid) and deionized water in a minichannel heat sink (MCHS) with a hydraulic diameter of 2.6 mm. Polystyrene encapsulated n-Docosane was synthesised by mini emulsion polymerisation. The melting point and latent heat of nanoPCM was found to be 42.6 °C and 180.6 J/g respectively. PCM nanofluid with concentrations ranging from 0.6 to 1.5 vol.% was prepared by dispersing nanoPCM in deionized water. High zeta potential values indicated excellent suspension stability of PCM nanofluid. Viscosity of PCM nanofluid increased slightly, whereas thermal conductivity and density were comparable to deionized water. Experiments were conducted at different flow rates (75–450 mL/min) in the laminar flow regime under uniform heat flux of 2.6 W/cm2. Even though, PCM nanofluid at 0.7 vol.% showed an enhancement in heat transferup to 44% at 225 mL/min, as compared to water, pumping power increased up to 17%. However, the Figure of Merit values greater than unity shows the insignificance of increase in pumping power over heat transfer enhancement obtained for PCM nanofluid. The improved cooling performance at low flow rates makes PCM nanofluid a propitious coolant over conventional fluids for electronics cooling.

The enhanced heat transfer of diathermic oil-based alumina-doped zinc oxide nanofluids for domestic solar heating systems

Doped material-based nanofluids, as an extension of single-phase nanofluids, expand the performance of heat transfer fluids. In this study, a new type of diathermic oil (DO)-based alumina-doped zinc oxide (AZO) nanofluids was prepared, and the thermophysical characteristics of nanofluids were analyzed. It could be found that the addition of new doped nanoparticles made up for the deficiency in the performance of DO as heat transfer fluid (HTF). Compared with the pure DO, the thermal conductivity of the AZO nanofluids (0.08 mass%) was increased by 8.125%. And the viscosity of nanofluids was decreased by 70% as the temperature increased. So as to further determine the application of nanofluids in the domestic heating system, the parameters of forced convection heat transfer in the tube were analyzed in this article. The convective heat transfer coefficient of AZO nanofluids increased with the increase in temperature. At 50 ℃, the convective heat transfer coefficient of 0.08 mass% AZO nanofluid reached the maximum of 5.49% compared with pure DO. More importantly, this research investigated the heat transfer benefits of using nanofluids in domestic solar heating systems. These promising results indicated that AZO nanofluids showed excellent properties at higher temperatures. It shows DO-based AZO nanofluids application potential in domestic solar heating systems.

Low Temperature rheological characterization of single-step silica nanofluids: An additive in refrigeration and gas hydrate drilling applications

Silica nanofluids are novel interdisciplinary solutions that have found several industrial applications on account of their superior rheological, chemical, and mass/heat transfer properties. However, their use in low-temperature applications (primarily drilling through gas hydrate reserves) is constrained due to the lack of understanding of their rheological behavior under low-temperature and high-pressure conditions. Hence, in this study, the viscosity, and the stability of novel single-step silica nanofluids of varying composition (0.1–1 wt%, synthesized via the Stober sol-gel method) were investigated under 2–30 °C. Following a comprehensive analysis, it was observed that while increasing the concentration of silica NPs in the aqueous solution and reducing the temperature caused a slight increase in the viscosity of the solution, increasing pressure (till 50 bar) was found to have no appreciable effect on the viscosity of the solution. The silica nanofluids showed a characteristically vicious nature (higher values of G″ than G′). The nanofluids were also able to maintain their dispersion stability and did not show any sedimentation after repeated heating and cooling between 2 and 30 °C. Finally, the silica nanofluids were used as additives in water-based drilling fluids for drilling through gas hydrate reservoirs which are prone to having high gas influxes. The presence of silica NPs was able to stabilize the absorbed gas bubbles, reducing the likelihood of them affecting the mud returns and causing a runaway gas blowout, though the duration of gas bubble retention reduced significantly at a higher temperature. The observations of the study indicate the superior viability of formulated single-step silica nanofluids for low-temperature applications like refrigeration and gas hydrate drilling mud additives. • Nanofluid exhibited stable viscoelastic response at low temperature and high pressure. • Reducing temperature increased nanofluid viscosity but pressure had no appreciable effect. • Nanofluid exhibited dispersion stability after 300 heating-cooling cycles. • Nanofluid inclusion in drilling mud controlled rate of gas invasion for wellbore stability. • Proposal of using silica nanofluids in refrigeration and gas hydrate drilling applications.

Experimental investigations into thermophysical, wettability and tribological characteristics of ionic liquid based metal cutting fluids

In the present study, a novel cutting fluid has been prepared by using the combination of Ionic Liquids (ILs) and Nano-Particles (NPs) as lubricant additives in Jatropha Oil (JO) based vegetable oil. For this, six different ILs (i.e., immidazolium and ammonium-based) of 1 wt. % concentration were added with JO, and its thermo-physical properties (rheological, thermal, and wettability) were measured. Tetrabutyl ammonium bromide ionic liquid (IL4) has been found to result in the best lubricant additive out of all six ILs considered for the present work. Afterward, the effect of different NPs was investigated by adding Al2O3, ZrO2, and both NPs (i.e., Al2O3+ZrO2) in the JO + IL4 solution, and the experimental results show further improvement in the thermo-physical properties. The hybrid nanofluid's viscosity containing 1 wt.% concentration of Al2O3+ZrO2 NPs in the JO + IL4 is the highest compared to other samples. Thermal conductivity and wettability of hybrid nanofluid with 0.75 wt. % of Al2O3+ZrO2 NPs are improved by 14.03 % and 28.5 %, respectively, as compared to JO + IL4. Further, the tribological test results show the JO + IL4 + 0.5 % Al2O3 gives the least friction force among the prepared cutting fluids.

An Analytical Study to Compare the Heat Transfer Performances of Water-Based TiO2, SiO2, TiC and SiC Nanofluids

The thermophysical properties as well as the thermal performance of a nanofluid can be altered upon varying the nanoparticle type and/or nanoparticle volume concentration. Herein, the effects of variable nanoparticle concentration on water-based TiO2, SiO2, TiC, and SiC nanofluids have been studied analytically. The dispersion effects of 1-4% nanoparticle on the single-phase forced convection heat transfer performance of the nanofluids have been investigated. The effective thermophysical properties of the nanofluids are determined adopting the general correlations. The flow velocities of the nanofluids relative to their base fluids are assumed to be constant. Mouromtseff number has been employed as a convenient figure of merit to compare the nanofluids under fully developed internal laminar and turbulent flow conditions. The results indicate an increase in effective density, thermal conductivity, and dynamic viscosity of the nanofluids. Nanofluids containing carbide suspensions exhibit superior heat transfer properties compared to those having oxide suspensions.

Examining rheological behavior of MWCNT-TiO2/5W40 hybrid nanofluid based on experiments and RSM/ANN modeling

In this study, the rheological behavior of MWCNT-TiO2/5W40 hybrid nanofluid was examined experimentally and then the results were compared with regression-based methodologies. Performing FESEM and DLS, the molecular structure, nanoparticle size distribution of the samples were inspected. To examine the effect of nanoparticles, the viscosity of the base fluid and the nanofluid were measured and compared at 20–60 °C and 0.05–1 vol% using Brookfield viscometer. The results showed that 5 W40 and MWCNT-TiO2/5W40 conform to Newtonian and non-Newtonian fluid classification. The nanofluid viscosity intensified with decreasing shear rate as well as temperature and increasing volume fraction. The presence of nanoparticles amplified the nanofluid viscosity up to 790%. In the numerical section, the neural network capability was challenged and it was observed that the maximum error was below 5% and considering of R2 = 0.999, the viscosity ratio forecasting was acceptable.

THERMOELECTRIC GENERATION AND THERMOPHYSICAL PROPERTIES OF METAL OXIDE NANOFLUIDS

This study describes the comprehensive characterization of the diverse water-based nanofluids involving aluminum oxide, titanium dioxide, and zinc oxide nanoparticles, which were prepared through the two-step synthesis method assisted by a microemulsion ultrasound skill with effects of both weight-percent concentration (wt.%) in the range of 1.0% and 5.0% and between 20 °C to 40 °C. The mean cluster size, zeta potential, pH value, viscosity, thermal conductivity, absorbance, light absorption, and electrical charge density of the various nanofluids were surveyed by relative experiments. The results showed that the 2 wt.% Al_2O_3, 2 wt.% TiO_2, and 1 wt.% ZnO nanofluids were preferentially prepared with a good suspension stability through four weeks. The thermal conductivity and the power generation increased with an increase in temperature. The present synthesis method is suitable for fabricating the metal oxide nanofluids at a temperature between 20 °C and 40 °C and a concentration of 1 wt.% to 5 wt.%.

Thermoelectric Generation and Thermophysical Properties of Metal Oxide Nanofluids

This study describes the comprehensive characterization of the diverse water-based nanofluids involving aluminum oxide, titanium dioxide, and zinc oxide nanoparticles, which were prepared through the two-step synthesis method assisted by a microemulsion ultrasound skill with effects of both weight-percent concentration (wt.%) in the range of 1.0% and 5.0% and between 20 oC and 40 0C. The mean cluster size, zeta potential, pH value, viscosity, thermal conductivity, absorbance, light absorption, and electrical charge density of the various nanofluids were surveyed by relative experiments. The results showed that the 2 wt.% Al2O3, 2 wt.% TiO2, and 1 wt.% ZnO nanofluids were preferentially prepared with a good suspension stability through four weeks. The thermal conductivity and the power generation increased with an increase in temperature. The present synthesis method is suitable for fabricating the metal oxide nanofluids at a temperature between 20 oC and 40 oC and a concentration of 1 wt.% to 5 wt.%.

Back propagation modeling of shear stress and viscosity of aqueous Ionic-MXene nanofluids

Back-propagation modeling of viscosity and shear stress of Ionic-MXene nanofluid is carried out in this work. The data for Ionic-MXene nanofluid of 0.05, 0.1, and 0.2 mass concentration (mass%) are collected from the experimental analysis. Shear stress and viscosity as a function of shear rate and mass% of MXene nanoparticles is used as input. Additionally, viscosity as a function of temperature and % of MXene nanoparticles is collected separately. Based on the possible combinations, five back-propagation algorithms are developed. In each algorithm, five models depending upon the number of neurons in the hidden layer are used. The training and testing of all the models in each algorithm are performed. Statistical analysis of the network output is done to evaluate the accuracy of models by finding the losses in terms of mean squared error (MAE), root-mean-squared error, mean absolute error, (MAE), and error deviation. Model 1 is found to have lower accuracy than the remaining models as the number of neurons in its hidden layer is only one. The performance evaluation metrices of the back-propagation model show that the error involved is acceptable. The training and testing of the algorithms are satisfactory as the network output is found to be in comfortably good agreement with the desired experimental output.

Study on preparation, stability, thermal conductivity, and viscosity of silver nanoparticles-decorated three-dimensional graphene-like porous carbon hybrid nanofluids

In the present study, a novel silver nanoparticles-decorated three-dimensional graphene-like porous carbon (Ag/3D GPC) nanocomposite has been synthesized via the method of carbonization and reduction of silver ions at the same time. This Ag/3D GPC nanocomposite possess an interconnected network of well crystalized and submicron-sized macropores with thin graphene walls of several nanometers, where silver nanoparticles distributing uniformly. The water based and ethylene glycol based Ag/3D GPC hybrid nanofluids have been prepared without any surfactant. The hybrid nanofluids with low concentration (<0.8 wt%) can be steadily dispersed for more than six months. The thermal conductivity enhancement for the nanofluids with 0.1 wt% can reach 10.3% and 8.8% at 25 °C compared with pure water and ethylene glycol, respectively. The viscosity of nanofluids is investigated, the temperature dependence of the dynamic viscosity obeys an Arrhenius-like behavior. The prepared Ag/3D GPC hybrid nanofluids with good stability and thermal conductivity are promisingly considered to be used in heat transfer field.

Fuzzy modeling and particle swarm optimization of Al2O3/SiO2 nanofluid

This study aims to model and optimize the performance of a shell and helically coiled tube heat exchanger application using Aluminum oxide (Al2O3) and Silicon dioxide (SiO2) nanofluids. An adaptive network-based fuzzy inference system (ANFIS) in MATLAB was used to build the fuzzy logic model for density, viscosity, specific heat, and thermal conductivity properties of nanofluid. The accuracy of the model was evaluated by checking the mean square error (MSE) for training data, testing data, and all data. The particle swarm optimization (PSO) based on the effectiveness of heat exchanger and friction factor as objective functions were used to find the optimum nanofluid properties. The optimum properties can be achieved by minimizing the viscosity and specific heat and maximizing the thermal conductivity; while keeping the density at optimum value for this application. The optimal properties of nanofluids were found at 60 °C using a hybrid nanofluid consisting of 0.3 Al2O3 and 0.1 SiO2. The optimum values of the density, viscosity, specific heat, and thermal conductivity were 985.77 kg/m3, 0.000471 Pa s, 4129.36 J/kg.°K and 0.71069 W/m. °K, respectively. The coupling between the fuzzy model and the PSO method was effective to find the optimum properties of nanofluids under operation.

Experimental investigations of the performance of a flat-plate solar collector using carbon and metal oxides based nanofluids

Covalently functionalized carbon nanoplatelets and non-covalent functionalized metal oxides nanoparticles (surfactant-treated) have been used to synthesize water-based nanofluids in this paper. To prove nanofluid stability, ultraviolet–visible (UV–vis) spectroscopy is used, and the results show that nanofluid is stable for sixty days for carbon and thirty days for metal oxides. The thermophysical properties are evaluated experimentally and validated with theoretical models. Thermal conductivities of f-GNPs, SiO2, and ZnO nanofluids are enhanced by 25.68%, 11.49%, and 15.42%, respectively. Lu-Li and Bruggeman’s thermal conductivity models are correctly matched with the experimental data. Similarly, the viscosity, density, and specific heat capacity of nanofluids are measured and compared with theoretical models. The enhancement in density, specific heat and viscosity of f-GNPs, ZnO, and SiO2 nanofluids are 0.12%, 0.22%, and 0.12%; 1.54%, 0.96%, and 0.73%; 12%, 9.41%, and 24.05% respectively in comparison of distilled water. A flat-plate solar collector is installed, and its thermal performance is evaluated by using carbon and metal oxides based nanofluids, following the ASHRAE standard 93–2003, at different heat flux intensities (597, 775, and 988 W/m2), mass flow rates (0.8, 1.2 and 1.6 kg/min), inlet fluid temperatures (30–50 °C) and the weight concentrations (0.025–0.2%). The thermal efficiency of the flat-plate solar collector is measured for distilled water and compared with the weight concentration (0.025–0.2%) of functionalized carbon and metal oxide-based nanofluids. A comparison of 0.1 wt% water-based nanofluids can be sequenced f-GNPs > ZnO > SiO2 because of a percentage improvement of thermal efficiency of the flat-plate solar collector obtained at a mass flow rate of 1.6 kg/min with values of 17.45% > 13.05% > 12.36%, respectively in comparison to water.

Thermal Conductivity and Viscosity: Review and Optimization of Effects of Nanoparticles.

This review was focused on expressing the effects of base liquid, temperature, possible surfactant, concentration and characteristics of nanoparticles including size, shape and material on thermal conductivity and viscosity of nanofluids. An increase in nanoparticle concentration can lead to an increase in thermal conductivity and viscosity and an increase in nanoparticle size, can increase or decrease thermal conductivity, while an increase in nanoparticle size decreases the viscosity of the nanofluid. The addition of surfactants at low concentrations can increase thermal conductivity, but at high concentrations, surfactants help to reduce thermal conductivity of the nanofluid. The addition of surfactants can decrease the nanofluid viscosity. Increasing the temperature, increased the thermal conductivity of a nanofluid, while decreasing its viscosity. Additionally, the effects of material of nanoparticles on the thermal conductivity and viscosity of a nanofluid need further investigations. In the case of hybrid nanofluids, it was observed that nanofluids with two different particles have the same trend of behavior as nanofluids with single particles in the regard to changes in temperature and concentration. Additionally, the level of accuracy of existing theoretical models for thermal conductivity and viscosity of nanofluids was examined.