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首页> 外文期刊>International Journal of Heat and Mass Transfer >Experimental and numerical investigation on heat transfer of ultra-supercritical water in vertical upward tube under uniform and non-uniform heating
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Experimental and numerical investigation on heat transfer of ultra-supercritical water in vertical upward tube under uniform and non-uniform heating

机译：均匀和非均匀加热条件下超超临界水在垂直向上管内传热的实验和数值研究

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摘要

Heat transfer of ultra-supercritical water in vertical upward tube under uniform heating was investigated experimentally and numerically. For comparison, similar studies under non-uniform heating were also simulated. The effects of specific heat ratio, buoyancy and acceleration on the heat transfer of ultra-supercritical water were discussed according to the experimental data. Results show that these dimensionless parameters have no single relationship of independence with the heat transfer coefficient which indicates that using them directly to predict heat transfer is inaccurate. The shear stress transport k-co model was used in the numerical simulation. Results concur with the experimental data to a high degree, which proves that the model has strong applicability in predicting heat transfer. The mechanisms of heat transfer enhancement and deterioration were analyzed through simulation results, and the integral of specific heat in the boundary layer and the buoyancy effect were confirmed to be their main factors, respectively. Furthermore, the differences between the uniform and non-uniform heating were also revealed. The wall temperature of smooth tube under non-uniform heating shows a parabola distribution, and the peak value occurs at the midpoint of the heated side. Moreover, the peak value of the wall temperature is higher under non-uniform heating than that under uniform heating; however, the heat flux is higher when heat transfer deterioration occurs. (C) 2018 Elsevier Ltd. All rights reserved.
机译：对超超临界水在均匀加热条件下垂直向上管内的传热进行了实验和数值研究。为了进行比较，还模拟了在非均匀加热下的类似研究。根据实验数据，讨论了比热比，浮力和加速度对超超临界水传热的影响。结果表明，这些无量纲参数与传热系数没有独立性的单一关系，这表明直接使用它们来预测传热是不准确的。在数值模拟中使用了剪切应力传递k-co模型。结果与实验数据高度吻合，证明该模型在预测传热方面具有很强的适用性。通过模拟结果分析了传热增强和劣化的机理，并确认了边界层中比热的积分和浮力效应是它们的主要因素。此外，还揭示了均匀加热和不均匀加热之间的差异。加热不均匀时的光管壁温呈抛物线状分布，峰值出现在受热侧的中点。而且，不均匀加热时的壁温峰值比均匀加热时的高。然而，当发生传热恶化时，热通量更高。 （C）2018 Elsevier Ltd.保留所有权利。

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