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A variable turbulent Prandtl number model for simulating supercritical pressure CO_2 heat transfer

机译：模拟超临界CO_2传热的可变湍流Prandtl数模型

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摘要

In order to predict heat transfer deterioration (HTD) of supercritical pressure fluid correctly and to investigate the HTD mechanism, the effect of turbulent Prandtl number (P_(T_t)) on numerical simulation was theoretically analyzed. Based on such analysis, a new turbulent P_(T_t) model (TWL model) was proposed. Numerical simulations of the supercritical pressure CO_2 heat transfer in vertical heated tubes were conducted with the proposed P_(T_t) model as well as two other previous P_(T_t) models and two constant P_(T_t) numbers. The performance of the new P_(T_t) model was validated by comparing with 14 reported heat-transfer experimental data, especially for the HTD cases. The comparison showed that a better prediction of wall temperature can be achieved with the proposed P_(T_t) model in most of the validations, especially for the HTD cases. When HTD occurs, turbulent mixing was restrained in the buffer layer since an "M" shape of velocity profile is formed under the buoyancy effect. The maximum predicted P_(T_t) value with TWL model also appears in the buffer layer, while the maximum predicted P_(T_t) value with other models appear in the viscous sub-layer. Such P_(T_t) profile restrains the turbulent mixing contribution to heat transfer further. Although the turbulent mixing contribution is still several times higher than molecular conduction contribution in the buffer layer when HTD occurs, it's not strong enough to diffuse energy from near wall region to the bulk region.
机译：为了正确预测超临界压力流体的传热退化（HTD）并研究HTD机理，从理论上分析了湍流普朗特数（P_（T_t））对数值模拟的影响。在此基础上，提出了一种新的湍流P_（T_t）模型（TWL模型）。利用提出的P_（T_t）模型以及其他两个先前的P_（T_t）模型和两个恒定的P_（T_t）数，对垂直加热管中超临界压力CO_2传热进行了数值模拟。新P_（T_t）模型的性能通过与14个已报道的传热实验数据进行了比较，特别是在HTD情况下，得到了验证。比较表明，在大多数验证中，特别是对于HTD情况，使用建议的P_（T_t）模型可以更好地预测壁温。当发生HTD时，由于在浮力作用下形成了速度分布的“ M”形，因此在缓冲层中的湍流混合受到了限制。 TWL模型的最大预测P_（T_t）值也出现在缓冲层中，而其他模型的最大预测P_（T_t）值出现在粘性子层中。这种P_（T_t）轮廓进一步限制了湍流混合对热传递的贡献。尽管发生HTD时，湍流混合贡献仍比缓冲层中分子传导贡献高出几倍，但它的强度不足以将能量从壁附近区域扩散到主体区域。

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  • 来源
    《International Journal of Heat and Mass Transfer》 |2016年第11期|1082-1092|共11页
  • 作者

    Guoli Tang; Hang Shi; Yuxin Wu; Junfu Lu; Zhouhang Li; Qing Liu; Hai Zhang;

  • 作者单位

    Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China;

    Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China;

    Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China;

    Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China;

    State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, No. 68 Wenchang Road, Kunming, Yunnan 650093, China,Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, No. 68 Wenchang Road, Kunming, Yunnan 650093, China;

    Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China;

    Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Supercritical pressure CO_2; Heat transfer deterioration; Turbulent Prandtl number; Mixed convection;

    机译：超临界压力CO_2;传热恶化;湍流普朗特数混合对流;

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