“…According to the results presented in Figures 6 and 7, the current simulation results correspond to the numerical findings of the literature in an appropriate way.Figure 4.Verification of current procedure against results of Wen and Ding 67 and Gӧktepe et al 68 Figure 5.Verification of current procedure against results of Mahdavi et al 69 and Pavel and Mohamad. 70 Figure 6.Comparison of current research against results of Rahbarshahlan et al 33 Figure 7.Comparison of current research against results of Rahbarshahlan et al 33 …”
Section: Numerical Solutionmentioning
confidence: 92%
“…Based on the Figure 5, as you see there is a negligible difference between the current simulation and the existing ones. In the last case, to confirm the accuracy of the simulations of heat transmission and fluid flow in a hydrophobic surface, numerical results of Rahbarshahlan et al 33 are employed. For this validation, in a microchannel, a 3D laminar flowing is generated with a hydrophobic surface covering one of its walls.…”
Section: Numerical Solutionmentioning
confidence: 99%
“…A new passive method to improve the hydro-thermal performance of devices that transport heat is the application of hydrophobic surfaces instead of common ones. 33 The contact angle is one of the most important parameters in the classification of hydrophobic and hydrophilic surfaces. The fluid drop and the hydrophobic surface make contact at an angle greater than 90 degrees.…”
The present study provides a 3D numerical research on the hydro-thermal performance of water-Al2O3/CuO nanofluids and water/Al2O3-CuO hybrid nanofluid inside a U-bend tube incorporating a porous medium with both hydrophilic and hydrophobic surfaces. Furthermore, a single-phase flow is adopted to simulate the nanofluid flow. Taking into consideration the equation of the Darcy-Brinkman-Forchheimer, to simulate the flow of fluids in the porous media. The influence of Dean number on hydro-thermal performance in the range of (600–1750) was investigated. And according to the results, Dn = 600 had the best performance. Considering the outcomes, a completely hydrophobic wall has a better hydro-thermal performance than a completely hydrophilic one and other hydrophilicity and hydrophobicity combinations. As well, improvement in heat transfer efficiency is considerably influenced by the Darcy number (10−4–10−1) and the augmentation of the porous thickness ratio. Additionally, average Nusselt number and pressure losses for any and all types of nanofluids show an incremental schema with augmenting volume fraction, while PEC exhibits a reducing pattern. Besides this, structures with permeable porous media or ones with Da = 0.1 and rp = 0.6 present the highest PEC. Also, among the reviewed nanoparticles, Al2O3 with a volume percentage of 1% had the maximum PEC.
“…According to the results presented in Figures 6 and 7, the current simulation results correspond to the numerical findings of the literature in an appropriate way.Figure 4.Verification of current procedure against results of Wen and Ding 67 and Gӧktepe et al 68 Figure 5.Verification of current procedure against results of Mahdavi et al 69 and Pavel and Mohamad. 70 Figure 6.Comparison of current research against results of Rahbarshahlan et al 33 Figure 7.Comparison of current research against results of Rahbarshahlan et al 33 …”
Section: Numerical Solutionmentioning
confidence: 92%
“…Based on the Figure 5, as you see there is a negligible difference between the current simulation and the existing ones. In the last case, to confirm the accuracy of the simulations of heat transmission and fluid flow in a hydrophobic surface, numerical results of Rahbarshahlan et al 33 are employed. For this validation, in a microchannel, a 3D laminar flowing is generated with a hydrophobic surface covering one of its walls.…”
Section: Numerical Solutionmentioning
confidence: 99%
“…A new passive method to improve the hydro-thermal performance of devices that transport heat is the application of hydrophobic surfaces instead of common ones. 33 The contact angle is one of the most important parameters in the classification of hydrophobic and hydrophilic surfaces. The fluid drop and the hydrophobic surface make contact at an angle greater than 90 degrees.…”
The present study provides a 3D numerical research on the hydro-thermal performance of water-Al2O3/CuO nanofluids and water/Al2O3-CuO hybrid nanofluid inside a U-bend tube incorporating a porous medium with both hydrophilic and hydrophobic surfaces. Furthermore, a single-phase flow is adopted to simulate the nanofluid flow. Taking into consideration the equation of the Darcy-Brinkman-Forchheimer, to simulate the flow of fluids in the porous media. The influence of Dean number on hydro-thermal performance in the range of (600–1750) was investigated. And according to the results, Dn = 600 had the best performance. Considering the outcomes, a completely hydrophobic wall has a better hydro-thermal performance than a completely hydrophilic one and other hydrophilicity and hydrophobicity combinations. As well, improvement in heat transfer efficiency is considerably influenced by the Darcy number (10−4–10−1) and the augmentation of the porous thickness ratio. Additionally, average Nusselt number and pressure losses for any and all types of nanofluids show an incremental schema with augmenting volume fraction, while PEC exhibits a reducing pattern. Besides this, structures with permeable porous media or ones with Da = 0.1 and rp = 0.6 present the highest PEC. Also, among the reviewed nanoparticles, Al2O3 with a volume percentage of 1% had the maximum PEC.
“…Alizadeh et al [8] studied the convective heat transfer in a cavity, and made a comparison of the enhancement in heat transfer for different heat source patterns. Rostamzadeh et al [9,10] discussed the influence of hydrophobic and hydrophilic surfaces on heat and mass transfer.…”
Heat-transfer enhancement in microchannel heat sinks (MCHS) has been a hot topic in the last decade. However, most published works did not focus on the heat sources that are discrete, as in most microelectronic devices, and the enhancement of heat and mass transfer (HMT) due to the Soret and Dufour effects being ignored. Based on a heterogeneous two-phase model that takes into consideration the Soret and Dufour effects, numerical simulations have been performed for various geometries and heat sources. The numerical results demonstrate that the vortices induced by a heat source(s) can enhance the heat transfer efficiency up to 2665 W/m2·K from 2618 W/m2·K for a discrete heat source with a heat flux q = 106 W/m2. The Soret effect can affect the heat transfer much more than the Duffour effect. The integrated results for heat transfer due to the Soret and Dufour effects are not sampled superpositions. Discrete heat sources (DHS) arranged in microchannels can enhance heat transfer, especially when the inlet velocity of the forced flow is less than 0.01 m/s. This can provide a beneficial reference for the design of MCHS with DHS.
“…Later, many researchers attempted various techniques to boost thermo-hydraulic performance of conventional SFMC by varying geometrical parameter 5,6 (aspect ratio and channel length), surface texture, 7 two-phase fluid, 8,9 and using hydrophilic and hydrophobic surfaces. 10,11 However, cooling performance of conventional SFMC is limited due to inefficient fluid mixing and incremental boundary layer thickness along the stream. As a result, there were significant temperature variations within the heat sink from the channel inlet to the outlet.…”
Thermal performance and fluid flow characteristics of elliptical fin microchannel are numerically investigated by varying fin orientation in the laminar flow region. Six distinctly oriented elliptical fins ranging 0 -12 along channel length are numerically examined for inlet Reynolds number (Re) ranging 174-748. The same is compared with the conventional straight fin microchannel. It is found that continuous straight fin when replaced with a series of short length elliptical fins leads to re-establishment of the thermal boundary layer and results in thinning of boundary layer thickness. By varying the fin angle, fluid is directed from primary channel to secondary channel which finally flows into the primary channel. These secondary flows disrupt the boundary layer and show better fluid mixing in the channel. Among all the orientations considered, elliptical fin oriented at 2 yields better cooling performance ensuing an optimum average Nusselt number enhancement of 116% (7.68-16.64) with a very less pressure penalty (15%). Besides this, the rise in wall temperature is reduced by 25.39% in comparison to straight fin microchannel.
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