Laminar flow and heat transfer in the entrance region of elliptical minichannels

Su, Liangbin; Duan, Zhipeng; He, Boshu; Ma, Hao; Ding, Guangchao

doi:10.1016/j.ijheatmasstransfer.2019.118717

Cited by 19 publications

(6 citation statements)

References 43 publications

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“…Maia et al [28] analyzed the heat transfer of non-Newtonian fluids using the generalized integral transform technique with T boundary and the results of fully developed Nusselt numbers were shown with figures. The above basic data are used to validate the present numerical model in the fully developed condition and the results are shown in our previous work [33]. Good agreement can be observed and the deviations are less than 0.46%.…”

Section: Mathematical Formulationsmentioning

confidence: 74%

“…However, the effect of Reynolds number on Nusselt number is often ignored. Some work about the effect has been done for simultaneously developing flow [33]. While, for thermal developing flow, to the authors’ best knowledge, there is little work about the local Nusselt number and thermal entrance length varying with Reynolds number in elliptical minichannels, which are focused on in this paper.…”

Section: Introductionmentioning

confidence: 99%

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Thermally Developing Flow and Heat Transfer in Elliptical Minichannels with Constant Wall Temperature

Duan

et al. 2019

Micromachines

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Laminar convective heat transfer of elliptical minichannels is investigated for hydrodynamically fully developed but thermal developing flow with no-slip condition. A three-dimensional numerical model is developed in different elliptical geometries with the aspect ratio varying from 0.2 to 1. The effect of Reynolds number (25 ≤ Re ≤ 2000) on the local Nusselt number is examined in detail. The results indicate that the local Nusselt number is a decreasing function of Reynolds number and it is sensitive to Reynolds number especially for Re less than 250. The effect of aspect ratio on local Nusselt number is small when compared with the effect of Reynolds number on local Nusselt number. The local Nusselt number is independent of cross-section geometry at the inlet. The maximum effect of aspect ratio on local Nusselt number arises at the transition section rather than the fully developed region. However, the non-dimensional thermal entrance length is a monotonic decreasing concave function of aspect ratio but a weak function of Reynolds number. Correlations for the local Nusselt number and the thermal developing length for elliptical channels are developed with good accuracy, which may provide guidance for design and optimization of elliptical minichannel heat sinks.

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Section: Mathematical Formulationsmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Thermally Developing Flow and Heat Transfer in Elliptical Minichannels with Constant Wall Temperature

Duan

et al. 2019

Micromachines

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“…Their results found that the transversal elliptical channel has reduced the pressure drop and enhanced the cooling performance. Su et al 17 investigated the local heat transfer coefficient of the elliptical mini channel in laminar flow regime at constant wall temperature. In their analysis, authors used a channel aspect ratio range of 0.2–1 and flow range of Re 25–2000.…”

Section: Introductionmentioning

confidence: 99%

Comparative study of elliptical fin microchannel over oblique micro‐fin heat sinks

Peddigari

Kumar

Balasubramanian

et al. 2022

Asia-Pacific J Chem Eng

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In the present paper, the effect of elliptical fin and its orientation were computationally examined by considering equivalent fin cross-sectional area and height of oblique fin to enhance thermal performance. A total of seven distinctly oriented elliptical fin microchannel models were developed and analyzed using finite volume method for velocity range of 0.2 to 0.9 m/s at constant heat flux of 65 W/cm 2 . The results showed that the elliptical fin microchannel model reduced pressure drop significantly and consumed less pumping power than the oblique fin microchannel model. It was also found that the average Nusselt number initially increases with decreasing elliptical fin orientation angle and then it rapidly decreases on further reduction of orientation angle beyond 4 . The optimal performance factor for a 4 elliptical fin was 1.21, with only a 6.5% penalty in wall temperature at Re 436.Furthermore, the maximum pumping power reduction of 41.4% was found for the 4 elliptical fin microchannel model with a 2.3% increase in Nusselt number. Hence, for the same pumping power, the 4 elliptical fin microchannel model performs better than oblique fin microchannel.

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“…Their findings revealed that the cooling performance of the transversal EFMC was better than the SFMC. Liangbin et al 30 investigated the local heat transfer coefficient of the elliptical cross-sectional channel at constant wall temperature under laminar flow region. They considered a range of channel aspect ratio 0.2-1 and Re range of 25-2000.…”

Section: Introductionmentioning

confidence: 99%

Heat transfer enhancement using elliptical fin microchannel

Peddigari

Kupireddi

Balasubramanian

et al. 2021

Asia-Pacific J Chem Eng

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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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Laminar flow and heat transfer in the entrance region of elliptical minichannels

Cited by 19 publications

References 43 publications

Thermally Developing Flow and Heat Transfer in Elliptical Minichannels with Constant Wall Temperature

Thermally Developing Flow and Heat Transfer in Elliptical Minichannels with Constant Wall Temperature

Comparative study of elliptical fin microchannel over oblique micro‐fin heat sinks

Heat transfer enhancement using elliptical fin microchannel

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