Ultrasonic Properties of Nanoparticles-liquid Suspensions (original) (raw)
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Synthesis and Ultrasonic Characterization of Cu/PVP Nanoparticles-Polymer Suspensions
Open Journal of Acoustics, 2011
A polymer colloidal solution having dispersed nanoparticles of Cu metal has been developed using a novel chemical method. Colloidal solutions of representative concentrations of 0.2 to 2.0 wt% Cu-nanoparticles contents in the primary solutions were prepared to study the modified ultrasonic attenuation and ultrasonic velocity in polyvinyl pyrrolidone (PVP) polymer molecules on incorporating the Cu-nanoparticles. The synthesized copper metal nanoparticles dispersed in the polymer solutions were characterized by UV-Visible absorption spectroscopy, X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The nanofluid sample showed a symmetrical peak at 592 nm due to the surface plasmon resonance of the copper nanoparticles. XRD results confirmed that copper nanoparticles were crystalline in the colloidal solution. The TEM micrograph revealed spherical copper nanoparticles having diameter in the range 10-40 nm. A characteristic behaviour of the ultrasonic velocity and the attenuation are observed at the particular temperature/particle concentration. It reveals that the colloidal suspension occurs in divided groups in the small micelles. The results are discussed in correlation with the thermophysical properties predicting the enhanced thermal conductivity of the samples.
Dispersions of CuO Nanoparticles in Paraffin Prepared by Ultrasonication : A Potential Coolant
In this study, CuO nanoparticles of rod shape were synthesized with sol gel method, the thermal conductivity of CuO nanoparticles in paraffin were investigated up to a volume fraction of 7.5 % of particles. The nanofluid was prepared by dispersing CuO nanoparticles in paraffin by using high intensity ultrasonic equipment. The mean diameter and shape of CuO nanoparticles was confirmed with TEM and XRD and it was rod shape 25 nm. While the thermal conductivity of nanofluids has been measured with KD2 pro analyzer based on transient hot wire methods. The effective thermal conductivity of CuO nanoparticles in paraffin was measured at room temperatures The experimental results showed that the thermal conductivity increases with an increase of particle volume fraction, and the enhancement was observed to be 20 % over the base fluid for a nanofluid with 3% volume fraction of CuO nanoparticles.
Synthesis and Ultrasonic Investigations of CuO-PVA Nanofluid
Materials Sciences and Applications, 2012
Study of nanofluids is important for different types of heat transfer management systems. Cupric oxide nanoparticles (CuO NPs) were prepared by the chemical route and different nanofluid samples of CuO NPs dispersed in PVA in different concentrations were prepared using ultrasonication. The apparatus acoustic particle sizer (APS-100) was used to make high precision measurements of the ultrasonic attenuation depending upon different frequencies in the frequency range 48 to 99 MHz. The ultrasonic attenuation data are inverted to particle size distribution (PSD) and are used for particle size determination of CuO NPs. Temperature dependent ultrasonic velocity in the samples is also measured. The results of ultrasonic spectroscopy are compared with the microscopic measurements such as transmission electron microscopy (TEM) and X-ray diffraction (XRD). There is good agreement between data produced by ultrasonic spectroscopy and the microscopic measurements.
2015
Nanofluids are colloidal suspensions obtained by dispersing nanoparticles in any base fluid. These new type of fluids have attracted wide interest in recent years as nanofluids have significantly higher thermal conductivity than the base fluids. In this work nanofluids containing copper nanoparticles have been developed using a novel chemical method in our laboratory. Nanofluids soprepared were characterized by UV-Visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The measurements of ultrasonic velocity and ultrasonic attenuation in the prepared samples were made as function of temperature and concentration of the copper nanoparticles in the PVA. The obtained results were analyzed taking into account the ultrasonic and thermal behavior of matrix and particles. The thermal conductivity of synthesized nanofluids was measured with Hot Disk Thermal Constant Analyser and 20-35% enhancement was found in the thermal conductivity of Cu-PVA nanofluids h...
Effect of Ultrasonication Duration on Colloidal Structure and Viscosity of Alumina−Water Nanofluid
Industrial & Engineering Chemistry Research, 2014
Nanofluids are promising fluids for heat-transfer applications. Low stability and high viscosity are two important drawbacks for practical applications of nanofluids. The aggregation and sedimentation of nanoparticles are related to the colloidal structure of nanofluids, which directly affects the stability and viscosity. An ultrasonic homogenizer can break the aggregation of particles. The aim of this work was to study the effect of the duration of ultrasonic treatment on colloidal structure, including the stability and temperature-dependent viscosity of a nanofluid. Specifically, a 0.5 vol % Al2O3−water nanofluid was prepared using an ultrasonic homogenizer for various durations from 0 to 180 min. The microstructure, colloid and particle sizes, precipitation, and zeta (ζ) potential were analyzed to investigate the aggregation and sedimentation of the nanofluid. The viscosities of nanofluids subjected to ultrasonic treatment for different durations were also measured at different temperatures from 15 to 45°C. Better particle dispersion, lower particle sizes, smaller colloid sizes, less precipitation, and higher ζ potentials were observed with increasing sonication time. The viscosity of Al2O3−water nanofluid was found to increase with the sonication time up to 60 min and then subsequently decreased. In addition, the viscosity decreased with increasing temperature. The research concluded that more stabler and lower-viscosity nanofluids can be obtained by applying ultrasonic treatment for durations of 90 min or longer.
Ultrasonic Properties in Au Nanoparticles Reinforced PVA Solution
The present investigation is focused on the influence of the nanocrystalline structure of pure iron metal on the ultrasonic properties in the temperature range 100 -300 K. The ultrasonic attenuation due to phononphonon interaction and thermoelastic relaxation phenomena has been evaluated for longitudinal and shear waves along <100>, <110> and <111> crystallographic directions. The second-and third-order elastic constants, ultrasonic velocities, thermal relaxation, anisotropy and acoustic coupling constants were also computed for the evaluation of ultrasonic attenuation in this temperature scale. The direction <111> is most appropriate to study longitudinal sound waves, while <100>, <110> direction are best to propagate shear waves due to lowest values of attenuation in these directions. Other physical properties correlated with obtained results have been discussed.
Ultrasonic and Thermal conductivity Study of Binary mixtures of CuO nanofluid aB
Ultrasonic and thermal conductivity study of the binary mixtures of Butyl acetate and Diethyl amine with CuO nano particle were studied for various concentration. From these data the various acoustical parameters such as compressibility (β), Inter molecular free length (L f ), Wada's constant(W), Molar sound fraction(R) and acoustic impedance (Z) and thermal conductivity (K) have been measured. The acoustical parameters with composition of the mixture helps us to understand the interaction between the unlike molecules and thermal conductivity study gives us the heat transfer behavior of CuO nano fluid
Study of Ultrasonic velocity of Nanofluid of Silver
As scientific inquires in nano science progress, the opportunity for nanotechnology breakthroughs continue to expand. Nano materials hold the key to significant future advances in a wide range of miniaturized consumer product such as miniaturized computer chips, nano scale sensors, and devices for sorting DNA molecules, including products that are reliant on synthesized nano materials and their integration with micro systems and biotechnology. Nano fluids are stable suspensions of nano particles in a liquid. In order to avoid coagulation of the particles, the particles must be coated with a second distance holder phase which in most cases, consist of surfactants that are stable in the liquid. An important application of Nano fluids containing nano particles is as a coolant, since the addition of only a few volume percent of nano particles to a liquid coolant and significantly improves its thermal conductivity. Ultrasonic velocity is the speed in which sound propagates in a certain m...
Ultrasonic Properties of Composites of Polymers and Inorganic Nanoparticles
Phys. Status Solidi A , 2013
The temperature dependencies of ultrasonic velocity and attenuation were measured in composites of inorganic nano-particles with two types of polymers, poly(urea) elastomer with inorganic Mo6S4I6nanowires and poly(e-caprolactone) (PCL)with Mo6S3I6nanowires. Below room temperature large ultrasonic relaxation attenuation maxima and velocity dispersion were observed. It was found that the attenuation peak in the elastomer shifted to higher temperatures after doping with nanoparticles and this behavior was related to the shift of glass transition temperature. The ultrasonic attenuation data were fitted to a relaxation equation with single temperature-dependent relaxation time. The thermal activation energy of the relaxation process, which was calculated from ultrasonic data, was found to increase in the poly(urea) elastomer doped with MoSI nanowires. The low-temperature ultrasonic velocity increased in the poly(urea) with nanowires added and is determined by the increase in elastic modulus. Similarultrasonic behavior was obtained for PCL composites with inorganic MoSI nanowires. In this case, the increase in elastic modulus was smaller in comparison to the composites of poly(urea) and nanowires. Therefore, the reinforcement of PCL was less pronounced.