Thermal Conductivity of TiO 2 Nanoparticles Based Aqueous Nanofluids with an Addition of a Modified Silver Particle (original) (raw)
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International Communications in Heat and Mass Transfer, 2021
The paper presents the experimental investigation of thermal conductivity enhancement of a newly developed nanocompositefluid (TiO 2-Ag/water) and compares the enhancement with mono nanofluid (TiO 2 /water). The experiments are carried out for 0.1, 0.2, 0.3 and 0.4 volumetric concentrations and at fluid temperatures 35, 40, 50 and 60 °C. The results show that the thermal conductivity enhancement of the nanocompositefluid is higher than the mono nanofluid. The maximum enhancement is 18.47% for 0.4 vol% at 60 °C relative to the TiO 2 /water nanofluid. From the results, it is understood that 0.1 vol% of TiO 2-Ag/water has almost the same thermal conductivity as that of 0.4 vol% TiO 2 /water nanofluid. Thus, for the same enhancement, a lower vol% of TiO 2-Ag nanocomposite particles is required as compared to the TiO 2 nanoparticle only in water. Based on the experimental data, regression analysis, thermal conductivity ratio models are developed for the two nanofluids and the best model is selected based on maximum R 2 values.
Dispersion and thermal conductivity of TiO2/water nanofluid
Journal of Thermal Analysis and Calorimetry
Stability of nanofluids is one of the major challenges for their real-world applications and benefits. Although ultrasonication and addition of surfactant are commonly used to obtain better stability of nanofluids, there is a lack of adequate knowledge on the effects of various parameters and duration of ultrasonication as well as some other influences of surfactant. The effect of ultrasonication on the dispersion of nanoparticles and agitation as well as temperature on the thermal conductivity measurements of aqueous TiO 2 nanofluids was experimentally studied. An UV-Vis absorbance analysis was performed to identify the degree of dispersion of nanoparticles (stability) and also to determine the right amplitude as well as the duration of the ultrasonication. In addition, agitation of nanofluids during the measurement of thermal conductivity showed a serious adverse effect as significant fraction of nanoparticles adhered to both the probe and the wall of the sample container. Furthermore, present results showed that the enhanced thermal conductivity of this nanofluid further increases noticeably with increasing temperature.
Analysis of shape dependency of thermal conductivity of silver-based nanofluids
Journal of Thermal Analysis and Calorimetry, 2022
Nanofluids are a class of fluids prepared by dispersing nanoparticles in conventional base fluids. Owing to their excellent thermo-physical properties, nanofluids find potential applications in manufacturing industries. They are introduced to overcome the limitation with using traditional base fluids like water having low thermal conductivity (~ 0.612 W/mK at room temperature). The thermal conductivity of a base fluid is considerably increased by adding a modest number of nanoparticles to it. In the present work, we have prepared silver nanoparticles and nanorods using the simple chemical reduction method. UV-Visible spectroscopy and field emission scanning electron microscopy were used to investigate the optical characteristics and morphology of the produced nanomaterials. Furthermore, the effect of volume loadings of produced nanomaterials (0, 2%, 4%, 6%), as well as temperature on the thermal conductivity of the base fluids was investigated. The results are compared to different silver nanoparticles (AgNPs) loadings in the base fluid. Both silver nanoparticles and nanorods have optimal heat conductivity at 2 vol%. It is interesting to note that fluids with silver nanorods (AgNRs) portrayed better results compared to nanoparticles and the maximum enhancement observed of 78.4% for AgNRs-based nanofluids at temperature 323 K, which is very high when compared to most of the previously reported values.
The effect of silver and aluminum oxide nanoparticles on thermophysical properties of nanofluids
Journal of Nanostructure in Chemistry, 2013
The present paper describes experimental and theoretical aspects of the effective thermal conductivity, electrical conductivity, and viscosity of nanofluids. The thermal conductivity, electrical conductivity, and viscosity of nanofluids increase with the nanoparticle volume fraction. The nanofluid was prepared by synthesizing Al 2 O 3 and Ag nanoparticles using microwave-assisted chemical precipitation method and then dispersed in distilled water using a sonicator. Water nanofluid with nominal diameters of 20 and 40 nm at various volume concentrations (0.25% to 5%) at a temperature of 15°C was used for the investigation. The thermal conductivity, electrical conductivity, and viscosity of nanofluids were measured, and it was found that the viscosity and electrical conductivity increase is substantially higher than the increase in thermal conductivity. The pure base fluid thermal conductivity displayed a Newtonian behavior at 15°C; it transformed to a non-Newtonian fluid with the addition of a small amount of nanoparticles φ > 3%.
Thermal Conductivity and Viscosity Measurements of Water-Based TiO2 Nanofluids
International Journal of Thermophysics, 2009
The dispersion and stability of nanofluids obtained by dispersing Al 2 O 3 nanoparticles in ethylene glycol have been analyzed at several concentrations up to 25% in mass fraction. The thermal conductivity and viscosity were experimentally determined at temperatures ranging from 283.15 K to 323.15 K using an apparatus based on the hot-wire method and a rotational viscometer, respectively. It has been found that both thermal conductivity and viscosity increase with the concentration of nanoparticles, whereas when the temperature increases the viscosity diminishes and the thermal conductivity rises. Measured enhancements on thermal conductivity (up to 19%) compare well with literature values when available. New viscosity experimental data yield values more than twice larger than the base fluid. The influence of particle size on viscosity has been also studied, finding large differences that must be taken into account for any practical application. These experimental results were compared with some theoretical models, as those of Maxwell-Hamilton and Crosser for thermal conductivity and Krieger and Dougherty for viscosity.