Pure Glycol Research Articles

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.

Numerical Simulation of Nanofluid Flow in a Channel Using Eulerian–Eulerian Two-Phase Model

In this article, laminar forced convection heat transfer in two-dimensional channel is investigated numerically. This investigation provides significant insight into recognizing the key parameters affecting the properties of the second law of thermodynamics, Darcy friction factor, performance evaluation criterion (PEC) and heat transfer. Because changes in the volume fraction of nanoparticles are significant, the Eulerian–Eulerian two-phase model is considered to simulate nanofluid flow. To enhance heat transfer, single jet and twin jets of ethylene glycol–SiO2 nanofluid are used. The pure ethylene glycol flows from the channel inlet and mixes with the flow of single jet or twin jets. The effects of the number of jet injection (single or twin), the concentration of nanoparticles and inlet velocity of jets are assessed using computational fluid dynamics. Jet injection with constant heat flux can lead to decrease in the general thermal and increase in the frictional entropy generation rates. With jet injection into the ethylene glycol flow, Nusselt number, Darcy friction factor and PEC increase. The nanoparticles’ addition to ethylene glycol increases the heat transfer from the target surface.

Free radical degradation in aqueous solution by blowing hydrogen and carbon dioxide nanobubbles

The main findings are the hydroxyl radical scavenging and the superoxide anion diminishing by mixing the carbon dioxide (CO2) nanobubbles after hydrogen nanobubble blowing in water and alcohol aqueous solution. The nanobubbles produce the hydroxyl radical by ultrasonic waves, changing the pH and catalyst and so on, while the nanobubble is very reactive to scavenge free radicals. In this research especially hydrogen (4% H2 in argon) and CO2 nanobubbles have been blown into hydrogen peroxide (H2O2) added pure water, ethanol, and ethylene glycol aqueous solution through a porous ceramic sparger from the gas cylinder. The aqueous solutions with H2O2 are irradiated by ultraviolet (UV) light and the produced hydroxyl radical amount is measured with spin trapping reagent and electron spin resonance (ESR). The CO2 nanobubble blowing extremely has reduced the hydroxyl radical in water, ethanol, and ethylene glycol aqueous solution. On the other hand, when H2 nanobubbles are brown after CO2 nanobubble blowing, the hydroxyl radical amount has increased. For the disinfection test, the increase of hydroxyl radicals is useful to reduce the bacteria by the observation in the agar medium. Next, when the superoxide anion solution is mixed with nanobubble containing water, ethanol, and ethylene glycol aqueous solution, H2 nanobubble has reduced the superoxide anion slightly. The water containing both CO2 and H2 nanobubble reduces the superoxide anion. The less than 20% ethanol and the 30% ethylene glycol aqueous solution containing CO2 nanobubbles generated after H2 nanobubble blowing can diminish the superoxide anion much more. While the H2 nanobubble blowing after CO2 nanobubble blowing scavenges the superoxide anion slightly. The experimental results have been considered using a chemical reaction formula.

Free Convection Heat Transfer from Horizontal Cylinders

The results of experimental investigation of free convection heat transfer in a rectangular container are presented. The ability of the commonly accepted correlation equations to reproduce present experimental data was tested as well. It was assumed that the examined geometry fulfils the requirement of no-interaction between heated cylinder and bounded surfaces. In order to check this assumption recently published correlation equations that jointly describe the dependence of the average Nusselt number on Rayleigh number and confinement ratios were examined. As a heat source served electrically heated horizontal tube immersed in an ambient fluid. Experiments were performed with pure ethylene glycol (EG), distilled water (W), and a mixture of EG and water at 50%/50% by volume. A set of empirical correlation equations for the prediction of Nu numbers for Rayleigh number range 3.6 × 104 &lt; Ra &lt; 9.2 × 105 or 3.6 × 105 &lt; Raq &lt; 14.8 × 106 and Pr number range 4.5 ≤ Pr ≤ 160 has been developed. The proposed correlation equations are based on two characteristic lengths, i.e., cylinder diameter and boundary layer length.

Effect of Nanoparticles and Base Fluid Types on Natural Convection in a Three-Dimensional Cubic Enclosure

Convective heat transfer using nanofluids play an important role in thermal applications such as heat exchangers, automotive industries, and power generation. In this work, a numerical analysis is conducted to examine the heat transfer of nanofluid in three-dimensional differentially heated cavity. The finite volume method-based SIMPLEC algorithm is used to solve the system of the mass, momentum, and energy transfer governing equations. The left and the right vertical side walls of the cube are maintained at constant temperatures T C and T H , respectively. The remaining walls of the cube are insulated. Effective thermal conductivity and viscosity of the nanofluid are determined using Brinkman and Maxwell models, respectively. Studies are carried out for three types of nanoparticles and volume fractions of nanoparticles ( 0 – 5 % ). The effects of two binary liquid mixtures as a base fluid (propylene glycol-water and ethylene glycol-water) are also examined. Results show an enhancement of 13 % for Al2O3-EG in comparison to pure ethylene glycol in the case of Ra = 10 3 . In addition, heat transfer enhancement was increased with the rise of nanoparticle volume fractions.

Measurement of thermo-optic coefficient of vanadium dioxide nanofluids using an interferometer

The change in refractive index with respect to temperature (dn/dT) is defined as the thermo-optic coefficient. It varies according to the light wavelength and temperature, so it is a very important physical quantity that influences light propagation. In this study, we observed the metal-insulator transition (MIT) effect of VO2 on the optical properties of VO2 nanofluid and the thermo-optic coefficient of pure ethylene glycol (EG). We prepared two concentrations (1 × 10–3 mol% and 1 × 10–2 mol%) of EG + VO2 nanofluids by dispersing 50-nm VO2 nano-spheres and injecting them into a cubic glass cell (1 × 1 × 4 cm3). The thermo-optic coefficient was measured by counting the number of interference fringe movements with a Michelson interferometer. The thermo-optic coefficient obtained for pure EG agreed with the literature value within 13.3%. Below 60˚C, the thermo-optic coefficients of EG + VO2 were smaller than that of pure EG, but they increased rapidly as the temperature increased. Above 60˚C, the thermo-optic coefficients of both EG + VO2 nanofluids rapidly changed and showed a peak and valley near 62˚C and 67˚C, respectively. We used the maximum value of the derivative of the thermo-optic coefficient (d2n/dT2) to obtain the phase transition temperatures of the VO2 nanofluids, which were 64.6˚C and 65.0˚C in the samples with 1 × 10–3 mol% and 1 × 10–2 mol%, respectively.

Solution thermodynamics and preferential solvation of sulfamethazine in ethylene glycol + water mixtures

The solubility of sulfamethazine (SMT) in ethylene glycol (EG) + water (W) cosolvent mixtures was determined at nine temperatures (278.15, 283.15, 288.15, 293.15, 298.15, 303.15, 308.15, 313.15 and 318.15 K) by means of the stirring method. From the solubility data, the thermodynamic functions of solution, transfer and mixing were calculated using the Gibbs and van´t Hoff equations. On the other hand, the preferential solvation parameters of SMT were determined by means of the method of the inverse integrals of Kirkwood-Buff (IKBI). In general terms, the solubility of SMT is favored by the increase in temperature and the decrease in the polarity of the cosolvent system, thus the maximum solubility is reached in pure EG at 318.15 K and the minimum in pure water at 278.15 K. Gibbs energy is positive in all cases, with a higher contribution from the energy component (enthalpy of solution). Regarding enthalpy-entropic compensation, the process is driven in all cases by the enthalpy of solution. Finally, SMT is preferentially solvated by water in mixtures with higher polarity and by EG in less polar mixtures.

Experimental performance of glass based synthetic dye sensitized solar cell

Owing to the depletion of fossil energy sources, the research concentrates over accretion of power from nonconventional sources of energy. The growth rate of utilizing of abundantly available solar energy lead research in area of solar cell which is cost effective, higher performance, long life. The technology of die sensitized solar cell has been explored with synthetic dye and electrolytes. The die sensitized solar cell has been manufactured in house with fully automatic special purpose machine in order to achieve accuracy of dye application, heating, electrolyte bath etc. Titanium Dioxide (TiO2) being tested as dye for the solar cell. The electrolytic solution which is mixture of pure iodine ethylene glycol and potassium iodide. The graphite-based powder as catalyst being used as liquid conductor. The performance of this die sensitized solar cell being observed with exhaustive experimentations. The performance criteria include varying light intensity throughout the day, varying current densities, varying tilting angles of cell. It was found that the cell is producing output of 30 to 122 mV with current density of 3.85 to 6.33 mA/cm2. The efficiency of cell range between 0.07 and 0.36%. This output is much lower in comparison to that of photo-voltaic cell. But owing to numerous advantages such as window, design glass over building as solar cell panel will make the difference with that of PV cell.

Electrodeposition of ZnNi Alloys from Choline Chloride/Ethylene Glycol Deep Eutectic Solvent and Pure Ethylene Glycol for Corrosion Protection.

The present work follows the trend to develop non-aqueous electrolytes for the deposition of corrosion resistant ZnNi alloys. It investigates the use of the choline chloride/ethylene glycol (1:2 molar ratio) eutectic mixture and of pure ethylene glycol as solvents for ZnNi electroplating. The electrochemical behavior of Zn and Ni is investigated via cyclic voltammetry, and potentiostatic ZnNi deposition is performed. Ni content is found to be precisely tunable in the 10–20% wt range, which presents the highest industrial interest for corrosion protection. ZnNi coatings obtained are characterized from the morphological and phase composition point of view. Evidence of the formation of a metastable γ ZnNi phase is observed for both choline chloride/ethylene glycol and pure ethylene glycol. Finally, potentiodynamic corrosion tests are performed to assess their corrosion properties.

Dynamics of Marangoni convection in hybrid nanofluid flow submerged in ethylene glycol and water base fluids

This research article communicates with the study of hybrid base fluids with suspension of copper nanoparticles. Additionally effects of mixed convection and MHD are also considered. Here ethylene glycol and water are used as a base fluid and nanoparticles of copper are suspended in it. Usually H2O, C2H6O2 or Ethylene glycol are used as a single base fluids when we do a mixture of base fluid and nanoparticles. But here we have used the ethylene glycol+water as base fluids which combines the properties of both fluids and we get much better result as compared to by using single base fluid. Because when we used the mixture of both we get higher thermal conductivity than pure ethylene glycol and lower freezing point as water. Glycoled water have many applications in transfer medium in solar heating installation and as a antifreezer in cars. Governing equations are formed after applying order of approximation. Transformations are utilized for non-dimensionalization of governing equations and NDSolve method is used to construct the physical results. For different values of pertinent parameters the results of velocity, temperature and Nusselt number are seen through graphs.

Molecular Dynamics Simulations Suggest a Possible Role for NO in the Polyol Synthesis of Silver Nanostructures

Polyol synthesis allows the preparation of silver nanostructures with different well-controlled morphologies and opens a window to explore their potential in various emerging applications. Despite their success in controlling the size and shape of many noble-metal nanostructures, some fundamental aspects of this control during the synthesis remain unclear. In this paper, we used molecular dynamics (MD) simulations (three replications 1550 ns long) to represent a possible adsorption structure of poly(vinylpyrrolidone) (PVP) with an average molecular weight of 55,000 Da (PVP55) on an Ag(100) surface on ethylene glycol (EG) medium. The conditions employed in the simulations reproduce the PVP chain length and density reported experimentally. We found that the adsorbed PVP55 layer has a first polymer contact, with some degree of order, where interactions are mediated by carbonyl groups close to the Ag(100) face. In order to study the effects of the presence of AgNO3 and NO in the medium on PVP55, three sets of simulations were run comprising (i) one PVP55 molecule in pure EG and with (ii) 0.25 M AgNO3 or (iii) NO. These simulations showed that the PVP55 compacts in pure EG and in the presence of AgNO3 but expands in the presence of NO. This points at new insights into the roles of the PVP adsorption layer and PVP/AgNO3 ratio in polyol synthesis.

Effects of Gold Nanoparticles Shapes on Magnetohydrodynamic Flow and Heat Transfer in the Presence of Thermal Radiation

The objective of present study is to examine the effects of nanoparticles shapes on magnetohydrodynamic (MHD) boundary layer flow and heat transfer of nanofluid over a flat plate in the presences of thermal radiation. Three categories of fluids such as pure water, ethylene glycol and engine oil with Prandtl number (Pr) = 7.8 containing three different shapes of Gold (Au) nanoparticles i.e. sphere, platelet and lamina have used in this study. By using unique similarity transformation, the governing partial differential equations (PDEs) are converted into a system of non-linear ordinary differential equations (ODEs) which have tackled numerically by bvp4c program. The behaviours of several pertinent parameters i.e. solid volume fraction (φ), magnetic field (M) and thermal radiation (Rd) for different shapes of nanoparticles also elucidated in detail. The results indicated that all selected parameters have a significant impact on the thermal boundary layer. The Nusselt number is presented in graphically form. The nanoparticles of sphere shape in Au-Ethylene glycol are more significant for temperature disturbance. The heat transfer rate has found greater for lamina shapes in Au-Engine oil.

Ethylene glycol assisted solvo-hydrothermal synthesis of NGr-Co3O4 nanostructures for ethanol electrooxidation

Different morphologies of Co3O4 nanostructures grown on nanographitic flakes have been synthesized based on the decomposition of cobalt acetate precursor in water, ethylene glycol and water (50%)-ethylene (50%) solution at 180 °C for 18 h via a solvo-hydrothermal process. A subsequent electrophoretic deposition process is used to form composite layers on stainless steel plates. The composite layer fabricated in the water (50%)-ethylene (50%) solution is found to have the best electrocatalytic performance for ethanol electrooxidation due to the hierarchical nanoporous microstructures of Co3O4 exhibiting the lowest onset voltage for ethanol electrooxidation (around −0.3 V vs. Ag/AgCl) among the fabricated electrocatalyst layers. Moreover, the ethanol electrooxidation current for the electrode fabricated in the water (50%)-ethylene glycol (50%) reaches roughly 6.6 mA/cm2, while it is about 3.3 mA/cm2 at 0.5 V (vs. Ag/AgCl) for the electrode fabricated in pure ethylene glycol (values obtained after 1-h stability tests). The electrode fabricated in pure water is confirmed to not exhibit significant ethanol electrooxidation.

Simultaneous Prediction of the Density and Viscosity of the Ternary System Water-Ethanol-Ethylene Glycol Using Support Vector Machine

Ethylene glycol is an organic solvent used in extractive distillation to separate water-ethanol mixtures. An appropriate process description requires accurate physical property data. In this paper, experimental liquid densities and dynamic viscosities of pure ethylene glycol as well as the ternary system water-ethanol-ethylene glycol are presented over a wide temperature range (298.15 to 328.15 K) at atmospheric pressure. Density and viscosity data of the ternary system of water-ethanol-ethylene glycol solutions were obtained from the literature and a support vector machine model was used to predict the density and viscosity of this system. The determination coefficients for density and viscosity of the ternary system of water-ethanol-ethylene glycol are 0.9854 and 0.9892, respectively. The mean square errors of density and viscosity are obtained 4.6572×10-4 and 3.4920×10-4, respectively. The results confirmed that the proposed method can predict the density and viscosity of the ternary system of water-ethanol-ethylene glycol as a function of temperature, using a support vector machine.

Aggregation and adsorption properties of benzyldimethylhexadecylammonium tetrachloromanganate(II) metallosurfactant in water–ethylene glycol medium

The aggregation and adsorption properties of metallosurfactant, benzyldimethylhexadecylammonium tetrachloromanganate(II) (BDHA2[MnCl4], where BDHA represents benzyldimethylhexadecylammonium group) in binary aqueous mixtures of ethylene glycol (EG) were investigated by tensiometric, conductometric, dynamic light scattering (DLS) and transmission electron microscopy (TEM) methods at 298.15 K. The percentage of EG (by weight) was varied between 0 and 100%. The physicochemical properties determined and discussed include critical micelle concentration (cmc), counterion binding constant (β), Gibbs free energy of micellization (), surface excess at cmc (), minimum area per surfactant molecule (), surface pressure (πcmc), minimum free energies (G min) and size of aggregates. This study revealed that with increase in percentage of EG the cmc of BDHA2[MnCl4] metallosurfactant increases and the cmc of BDHA2[MnCl4] in EG is about 158 times higher than that in water. The counterion binding constant values increase with increase in percentage of EG from 10% to 70% and thereafter decrease. The adsorption of metallosurfactant at the air–solution interface decreases as the EG content in the bulk increases. The values were found to be negative and the negative value decreases with increase in percentage of EG. Gordon parameter and ratio of surface tension of medium to that of the metallosurfactant solution at cmc are used to represent solvophobicity of the medium. DLS measurements revealed that the hydrodynamic diameters (d H) of the micelles increase with increase in percentage of EG (in pure EG, d H = 28.3 nm). TEM measurements showed the presence of spherical micelles.

Effects of novel hybrid nanofluid (TiO2–Cu/EG) and geometrical parameters of triangular rib mounted in a duct on heat transfer and flow characteristics

Heat transfer and flow characteristics have been numerically analyzed by using four different fluids [pure ethylene glycol (EG), TiO2/EG and Cu/EG nanofluids and 50%:50% TiO2–Cu/EG hybrid nanofluid] and changing the position, length and height of a triangular rib placed in a two-dimensional duct under forced convection and turbulent flow conditions using RNG k-epsilon turbulence model. While forming the hybrid nanofluid, all nanoparticles are added at 50–50%. A constant heat flux of 500 W m−2 is applied to the bottom wall of the duct. The Reynolds number is considered in the range of 50,000 and 100,000. Two different nanoparticle volume fractions, 1.0% and 4.0%, are used. The parameters of the rib are dimensionlized, and three different rib positions (X/H = 1, 3 and 5), lengths (S/H = 0.5, 1 and 1.5) and heights (h/H = 0.1, 0.2 and 0.3) are used. Governing equations are determined with the finite volume method. In the study, analysis of Nusselt number, Darcy friction factor (f), PEC number and velocity streamlines is performed in detail. Generally, heat transfer performance increases with increasing Reynolds number and nanoparticle volume fraction, but the increase in nanoparticle volume fraction also increases the Darcy friction factor. TiO2–Cu/EG hybrid nanofluid having the 4.0% nanoparticle volume fraction is the best heat transfer fluid. When using TiO2–Cu/EG hybrid nanofluid, the increase in the PEC number varies between 8 and 30% in the smooth duct. From the results obtained by using hybrid nanofluid in the duct with the triangular rib, it is understood that the rate of heat transfer enhances with increasing dimensionless rib position, length and height. But the most effective parameter of these is change in the rib height. The most suitable fluid for the study is TiO2–Cu/EG hybrid nanofluid with 4.0% nanoparticle volume fraction, and the most favorable rib parameters are rib height of h/H = 0.3, rib length of S/H = 1.5 and rib position of X/H = 5.

Experimental study of nanofluids flow and heat transfer over a backward-facing step channel

The forced convective heat transfer and friction factor of nanofluids flow over a backward-facing step (BFS) in a channel with the base wall dissipating a uniform heat flux are experimentally investigated in this paper. Nanoparticles such as CuO and MgO dispersed in pure ethylene glycol (EG) with average diameters of 40 nm, and volume concentrations of 0, 1, 3, and 5% are considered as the working nanofluids. The results indicate that the heat transfer rate increases as the volume concentration of nanoparticles increased. The Nusselt number is enhanced up to 11% at 0.05 volume concentration compared to pure EG. The friction factor increases up to approximately 15% at Reynolds number (Re) of 5000 and volume concentrations of 0.01 and 0.03. The maximum value of the PEC in a BFS channel is 1.5 for the CuO-EG and 1.2 for the MgO-EG at a volume concentrations of 0.03 and Re = 20,000.

Dispersion stability and rheological characteristics of water and ethylene glycol based ZnO nanofluids

With advancement of nanoscience, "nanofluids" are becoming quite popular among thermal engineers. High thermal conductivity, relatively less settling speed, and higher surface area of nanoparticles are a few key promoting properties. The last two decades have seen dramatic progress towards using nanoparticles in industrial applications. However, the stability and rheological characteristics of prepared nanofluids have serious effects on their transport characteristics, but unfortunately, this has not found proper attention from researchers. In this study, stability and rheological characteristics of ZnO nanoparticles within deionized water, ethylene glycol, and their blends have been extensively tested. Stability was observed using UV-vis spectroscopy, while the viscosity was measured with the help of a rheometer. The data was collected with 0.011-0.044 wt.% loading of nanoparticles, while experiments were conducted within 15-55?C temperature range. Better stability was recorded when nanofluids were prepared with pure ethylene glycol. Experiments showed that the viscosity increased with particle loading, whereas the effect of surfactants appeared to be insignificant. Research results were used to assess predictions of different viscosity models. Experimental data was overpredicted by Einstein, Brinkman, and Batchelor?s models.

Rheological characteristics of CeO2, Al2O3 and their hybrid mixture in ethylene glycol base fluid in the wide range of temperature and concentration

In the present work, the rheological behaviour of three different categories of nanofluid samples, 25 nm CeO2/EG, 13 nm Al2O3/EG and the hybrid mixture CeO2–Al2O3 (in 50:50 volume)/EG, was experimentally investigated. The rheology experiments on nanofluid samples were conducted over volumetric concentrations 0.05–1 vol% and temperature of 30–90 °C. An approach to obtain base fluid flow behaviour from two distinct mixtures of nanoparticles is explored for the first time in the present work. The prepared hybrid nanofluid rheological characteristics are influenced by both the contributing CeO2 and Al2O3 nanoparticles. The hybrid nanofluid flow behaviour was similar to the pure ethylene glycol (EG), which makes this hybrid nanofluid very useful in anti-freezing applications. CeO2/EG and Al2O3/EG nanofluids show dilatant nature at higher temperatures. This is due to the clustering of nanoparticles, and the mixture of these substances is shown to reduce their nature. Field emission scanning electron microscope (ESEM) and transmission electron microscopy (TEM) confirm details of the morphology of the nanoparticles. The power-law model was found the best-suited method to explore and compare the rheology behaviour of nanofluids over variation in concentration and temperature.

Ethylene glycol based silver nanoparticles synthesized by polyol process: Characterization and thermophysical profile

This study reports the synthesis and the characterization of ethylene glycol silver-based nanofluids produced from the polyol process. This synthesis process is based on the reduction of silver nitrate (AgNO3) with the presence of the aqueous emulsion of latex copolymer, used here for the first time along with ethylene glycol. The influence of latex copolymer content for a fixed amount of AgNO3 for the production of silver-based nanofluids is investigated. The efficiency of the synthesis process is demonstrated from UV–Vis spectrometry, TEM and EDS characterization of the nanofluids. In addition, the dynamic viscosity of both the base fluids and nanofluids is experimentally measured over a wide shear rate and temperature range. While the base fluids behave in a non-Newtonian manner due to the presence of copolymer nanoparticles, it appears that the nanofluids are simply Newtonian without any noticeable viscosity enhancement compared to pure ethylene glycol. The thermal conductivity of the produced ethylene glycol silver-based nanofluids shows an enhancement of about 3% for the higher initial contents in copolymer latex. Such a thermophysical profile of ethylene glycol silver-based nanofluids is promising for their potential applications as circulating heat transfer fluids.