Laminar mixed convection heat transfer of SiC-EG nanofluids in a triangular enclosure with a rotating inner cylinder: simulations based on the measured thermal conductivity and viscosity

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Abstract
A numerical study has been carried out for a laminar steady mixed convection flow in a 2D triangular enclosure with an inner rotating coaxial cylinder, with the enclosure filled with ethylene glycol-silicon carbide (SiC-EG). The thermal conductivity and viscosity of the SiC-EG nanofluids were experimentally determined by using a Decagon Devices KD2 Pro thermal property meter and a rotational Brookfield viscometer, respectively. Various pertinent parameters, such as the dimensionless rotation velocity, solid volume fraction, dimensionless radius of the inner cylinder, and Rayleigh numbers, were analyzed to determine their influences on heat transfer and fluid flow. Results clearly show how the direction of rotation of the cylinder affects the thermal performance in a triangular enclosure. It is found that the average Nusselt number increases with rise in the Rayleigh number or as more nanoparticles are added to the base liquid. It was also observed that at constant Rayleigh number, different rotational conditions have remarkable effects on the flow and heat transfer characteristics. 明确在封闭腔内放置旋转柱体时, 柱体尺寸及转速对不同浓度下纳米流体的流动传热的影响。 1. 数值模拟中采用的碳化硅-乙二醇(SiC-EG)纳米流体的重要热物性参数均为实验测量值; 2. 考虑封闭腔内柱体的动态旋转对腔内纳米流体流动传热的影响。 基于对SiC-EG纳米流体导热系数与粘度的实验测量, 采用数值模拟方法探究封闭腔内旋转柱体、 纳米流体浓度以及瑞利数对SiC-EG纳米流体流动传热性能的影响。 1. 在柱体的旋转方向与由自然对流引起的纳米流体流动方向相同的情况下, 置于腔内的旋转柱体可以起到强化传热的效果。 2. 二者旋转方向相反时情况较为复杂, 当柱体尺寸较小且柱体转速较低时削弱传热效果; 当柱体尺寸较大且转速较高而引发的强制对流占主导地位时, 将对腔内传热起到一定的强化效果。
Funding Information
  • National Natural Science Foundation of China (51106144)

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