Influence of T-semi attached rib on turbulent flow and heat transfer parameters of a silver-water nanofluid with different volume fractions in a three-dimensional trapezoidal microchannel
TL;DR: In this paper, the influence of T-semi attached rib on the turbulent flow and heat transfer parameters of a silver-water nanofluid with different volume fractions in a three-dimensional trapezoidal microchannel was explored.
Abstract: This study aimed at exploring influence of T-semi attached rib on the turbulent flow and heat transfer parameters of a silver-water nanofluid with different volume fractions in a three-dimensional trapezoidal microchannel. For this purpose, convection heat transfer of the silver-water nanofluid in a ribbed microchannel was numerically studied under a constant heat flux on upper and lower walls as well as isolated side walls. Calculations were done for a range of Reynolds numbers between 10,000 and 16,000, and in four different sorts of serrations with proportion of rib width to hole of serration width (R/W). The results of this research are presented as the coefficient of friction, Nusselt number, heat transfer coefficient and thermal efficiency, four different R/W microchannels. The results of numerical modeling showed that the fluid's convection heat transfer coefficient is increased as the Reynolds number and volume fraction of solid nanoparticle are increased. For R/W=0.5, it was also maximum for all the volume fractions of nanoparticle and different Reynolds numbers in comparison to other similar R/W situations. That's while friction coefficient, pressure drop and pumping power is maximum for serration with R/W=0 compared to other serration ratios which lead to decreased fluid-heat transfer performance.
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TL;DR: In this paper, the authors evaluated the heat transfer efficiency of Al2O3-MWCNT/thermal oil hybrid nanofluid over different temperatures (25-50°C) and solid concentrations (0.125% −1.5%).
249 citations
TL;DR: In this paper, the effects of nanoparticles volume fraction, flow direction and Reynolds number on base fluid, nanofluid and wall temperatures, thermal efficiency, Nusselt number and convection heat transfer coefficient have been studied.
209 citations
TL;DR: In this article, double layered micro-channel heat sink (MCHS) was used to transfer heat from nanofluid water/single-wall carbon nanotubes.
205 citations
TL;DR: In this paper, the effect of volume fraction (0.125-2%) and temperature (25-50°C) on thermal conductivity of a hybrid nanofluid was examined.
193 citations
TL;DR: In this paper, the enhancement of thermal conductivities of water in the presence of copper oxide and multiwalled carbon nanotubes is investigated for the first time, and the results show that the thermal conductivity of the nanofluid increases at more solid concentration.
Abstract: The enhancement of thermal conductivities of water in the presence of copper oxide and multiwalled carbon nanotubes is investigated for the first time. Hybrid nanofluid is a homogenous mixture of multiwalled carbon nanotubes-CuO particles suspended in water as the base fluid. The thermal conductivity of mixture is measured by KD2 Pro instrument. All thermal conductivity measurements are repeated three times in the range of 25–50 °C. A hot water bath is used to stabilize the temperature at 25, 30, 35, 40, 45 and 50 °C during the measurements. The results show that the thermal conductivity of the nanofluid increases at more solid concentration. Furthermore, the thermal conductivity of the nanofluid increases with the temperature; however, this increase is by far more noticeable in higher solid concentrations compared with the lower ones. Moreover, it is tried to propose a new correlation for predicting the thermal conductivity of the present nanofluid at different temperatures and volume fractions. The highest enhancement percentage was observed as 30.38% for the state of T = 50 °C and φ = 0.6%. However, the enhancement percentages were achieved as 25.57–30.38 for the state of φ = 0.6% at T = 25–50 °C, respectively.
190 citations
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01 Jan 1980
TL;DR: In this article, the authors focus on heat and mass transfer, fluid flow, chemical reaction, and other related processes that occur in engineering equipment, the natural environment, and living organisms.
Abstract: This book focuses on heat and mass transfer, fluid flow, chemical reaction, and other related processes that occur in engineering equipment, the natural environment, and living organisms. Using simple algebra and elementary calculus, the author develops numerical methods for predicting these processes mainly based on physical considerations. Through this approach, readers will develop a deeper understanding of the underlying physical aspects of heat transfer and fluid flow as well as improve their ability to analyze and interpret computed results.
21,858 citations
TL;DR: In this paper, two new two-equation eddy-viscosity turbulence models are presented, which combine different elements of existing models that are considered superior to their alternatives.
Abstract: Two new two-equation eddy-viscosity turbulence models will be presented. They combine different elements of existing models that are considered superior to their alternatives. The first model, referred to as the baseline (BSL) model, utilizes the original k-ω model of Wilcox in the inner region of the boundary layer and switches to the standard k-e model in the outer region and in free shear flows. It has a performance similar to the Wilcox model, but avoids that model's strong freestream sensitivity
15,459 citations
Additional excerpts
...The transfer equation for k- ω shear stress transfer model is as shown below [34]: ⎛ ⎝ ⎜⎜ ⎞ ⎠ ⎟⎟ X ρ k u X Γ k X G Y S ∂ ∂ ( ) = ∂ ∂ ∂ ∂ + − + ∼...
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TL;DR: In this article, the authors used a Brookfield rotating viscometer to measure the viscosities of the dispersed fluids with γ-alumina (Al2O3) and titanium dioxide (TiO2) particles at a 10% volume concentration.
Abstract: Turbulent friction and heat transfer behaviors of dispersed fluids (i.e., uttrafine metallic oxide particles suspended in water) in a circular pipe were investigated experimentally. Viscosity measurements were also conducted using a Brookfield rotating viscometer. Two different metallic oxide particles, γ-alumina (Al2O3) and titanium dioxide (TiO2), with mean diameters of 13 and 27 nm, respectively, were used as suspended particles. The Reynolds and Prandtl numbers varied in the ranges l04-I05 and 6.5-12.3, respectively. The viscosities of the dispersed fluids with γ-Al2O3 and TiO2 particles at a 10% volume concentration were approximately 200 and 3 times greater than that of water, respectively. These viscosity results were significantly larger than the predictions from the classical theory of suspension rheology. Darcy friction factors for the dispersed fluids of the volume concentration ranging from 1% to 3% coincided well with Kays' correlation for turbulent flow of a single-phase fluid. The Nusselt n...
3,730 citations
"Influence of T-semi attached rib on..." refers background in this paper
...Park and Cho [9] studied effect of friction on the turbulent flow and heat transfer behavior of nanofluids made by TiO2 and Al2O3 particles....
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...For the first time, Choi suggested adding metal materials of nanometer size into http://dx.doi.org/10.1016/j.physe.2016.11.021 Received 14 September 2016; Received in revised form 31 October 2016; Accepted 16 November 2016 ⁎ Corresponding author....
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TL;DR: In this paper, the authors proposed a new algorithm called Al2O3, which is based on the SiO2-2-SiO3 algorithm, and showed that it is more efficient than SiO3 and TiO2.
Abstract: 超微粒子を少量, 液体に分散させることによって, 母液の熱伝導率をどれだけ変えられるかが実験的に試みられた. 超微粒子としてAl2O3, SiO2およびTiO2超微粉末を, 液体として水を用い, 安定な分散系を生成した. 非定常細線加熱法で分散系の有効熱伝導率を測定し, 超微粒子の種類, 粒子濃度, 温度による熱伝導率の変化傾向を明らかにした. またそれら分散媒体の粘性率も測定し, その増加傾向を検討した.
1,960 citations