Effect of Al2O3/water nanofluid on performance of parallel flow heat exchangers
01 Jan 2019-Journal of Thermal Analysis and Calorimetry (Springer International Publishing)-Vol. 135, Iss: 1, pp 625-643
TL;DR: In this paper, a comprehensive experimental investigation is intended to survey consequence of nanofluid on performance of parallel flow heat exchangers with the same heat transfer surface area, including one double-pipe heat exchanger, two shell-and-tube heat exchiners with different tube passes, and one plate heat exchinator.
Abstract: A comprehensive experimental investigation is intended to survey consequence of nanofluid on performance of sundry parallel flow heat exchangers with the same heat transfer surface area. An experimental setup including one double-pipe heat exchanger, two shell-and-tube heat exchangers with different tube passes, and one plate heat exchanger is designed and built to carry out the experiments. The experiments are performed under turbulent flow conditions using distilled water and Al2O3/water nanofluid with 0.2, 0.5, and 1% particle volume concentrations. Based on the results from this study, the double-pipe heat exchanger reflected the best outcomes in the heat transfer coefficient with a maximum enhancement of 26%, while only a 7% increment in the heat transfer coefficient is observed for the plate heat exchanger. On the other hand, minimum punishment for pressure drop of the working fluids due to adding the nanoparticles is observed in the plate heat exchanger at 1% volume concentration with a maximum value of 10%.
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TL;DR: A review of the progress made in the area of nanofluids preparation and applications in various heat transfer devices such as solar collectors, heat exchangers, refrigeration systems, radiators, thermal storage systems and electronic cooling is presented in this paper.
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TL;DR: In this article, the heat transfer development with the turbulent flow of novel metal oxide-based ternary composite nanofluids of ZnO+Al2O3+TiO3 +TiO2/DW at varying wt.% concentrations was discussed.
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48 citations
References
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Journal Article•
7,568 citations
"Effect of Al2O3/water nanofluid on ..." refers methods in this paper
...Uncertainty analysis for the experiments is performed Kline and McClintock method [33]....
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TL;DR: In this article, the authors considered seven slip mechanisms that can produce a relative velocity between the nanoparticles and the base fluid and concluded that only Brownian diffusion and thermophoresis are important slip mechanisms in nanofluids.
Abstract: Nanofluids are engineered colloids made of a base fluid and nanoparticles (1-100 nm) Nanofluids have higher thermal conductivity' and single-phase heat transfer coefficients than their base fluids In particular the heat transfer coefficient increases appear to go beyond the mere thermal-conductivity effect, and cannot be predicted by traditional pure-fluid correlations such as Dittus-Boelter's In the nanofluid literature this behavior is generally attributed to thermal dispersion and intensified turbulence, brought about by nanoparticle motion To test the validity of this assumption, we have considered seven slip mechanisms that can produce a relative velocity between the nanoparticles and the base fluid These are inertia, Brownian diffusion, thermophoresis, diffusioplwresis, Magnus effect, fluid drainage, and gravity We concluded that, of these seven, only Brownian diffusion and thermophoresis are important slip mechanisms in nanofluids Based on this finding, we developed a two-component four-equation nonhomogeneous equilibrium model for mass, momentum, and heat transport in nanofluids A nondimensional analysis of the equations suggests that energy transfer by nanoparticle dispersion is negligible, and thus cannot explain the abnormal heat transfer coefficient increases Furthermore, a comparison of the nanoparticle and turbulent eddy time and length scales clearly indicates that the nanoparticles move homogeneously with the fluid in the presence of turbulent eddies so an effect on turbulence intensity is also doubtful Thus, we propose an alternative explanation for the abnormal heat transfer coefficient increases: the nanofluid properties may vary significantly within the boundary layer because of the effect of the temperature gradient and thermophoresis For a heated fluid, these effects can result in a significant decrease of viscosity within the boundary layer, thus leading to heat transfer enhancement A correlation structure that captures these effects is proposed
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"Effect of Al2O3/water nanofluid on ..." refers result in this paper
...(24), while there is a 89% agreement between the present results and the Gnielinski correlation [35], Eq....
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...Present data Gnielinsji [35] Dittus-Boelter [34] Naphon et al....
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...Nusselt number for single phase flow was calculated from the Gnielinski correlation [35] as shown: Nu 1⁄4 ðf =8ÞðRe 1000ÞPr 1þ 12:7ðf=8ÞðPr2=3 1Þ ð22Þ...
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