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Cryogenic quenching enhancement of a nanoporous surface

机译：纳米多孔表面的低温淬火增强

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摘要

Quenching heat transfer is of fundamental interest in cryogenic chilldown applications. Surface configuration can improve quenching heat transfer and clear understanding of the effect of different surface characteristics is necessary. In the present study, the effect of anodic aluminum oxide (AAO) surface on pool quenching is investigated. The AAO surface and other four types of surfaces are quenched in liquid nitrogen and a theoretical model is applied to further investigate the effect of surface thermal resistance. It is shown that the total chilldown time is decreased from 63.8 s on electropolishing surface to 33.4 s on the AAO surface. By comparisons with other surfaces, it is found that the effect of the MO surface results from two aspects: surface thermal resistance and nanopore structure. For surface thermal resistance, it is indicated by the consistence of numerical and experimental results that the end of film boiling is resulted from the decrease of local surface temperature that is not high enough to sustain the local vapor film, even though the bulk temperature is still high. For the nanopore structure, it is theoretically estimated that the nanopores will be kept filled with vapor at the surface temperature higher than the critical pinning state temperature (94.4 K). This phenomenon of vapor-filled nanopores reduces the liquid-solid contact area and local vapor generation rate, resulting in a higher temperature of the Leidenfrost point (LFP) and lower heat flux in partial nucleate boiling regime. When the surface temperature drops below the critical pinning state temperature, liquid nitrogen infiltrates into the nanopores and a heat flux jump appears. (C) 2019 Elsevier Ltd. All rights reserved.
机译：淬火传热在低温冷却应用中具有根本的意义。表面配置可改善淬火的热传递，因此必须清楚了解不同表面特性的影响。在本研究中，研究了阳极氧化铝（AAO）表面对熔池淬火的影响。在液氮中对AAO表面和其他四种类型的表面进行淬火，并应用理论模型进一步研究表面热阻的影响。结果表明，总的冷却时间从电抛光表面上的63.8 s减少到AAO表面上的33.4 s。通过与其他表面的比较，发现MO表面的作用来自两个方面：表面热阻和纳米孔结构。对于表面热阻，数值和实验结果的一致性表明，薄膜沸腾的结束是由于局部表面温度的降低而导致的，尽管表面温度仍然很高，但局部表面温度仍不足以维持局部蒸汽膜。高。对于纳米孔结构，理论上估计在高于临界钉扎状态温度（94.4 K）的表面温度下，纳米孔将保持充满蒸汽。这种充满蒸汽的纳米孔现象会降低液固接触面积和局部蒸汽产生速率，从而导致莱顿弗罗斯特点（LFP）的温度更高，并且在部分成核沸腾状态下热通量较低。当表面温度下降到临界钉扎状态温度以下时，液氮渗透到纳米孔中，并且出现热通量跳跃。 （C）2019 Elsevier Ltd.保留所有权利。

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  • 来源
    《International Journal of Heat and Mass Transfer》 |2019年第5期|1061-1072|共12页
  • 作者

    He Dongjiao; Zhang Peng; Lv Fengyong; Wang Shubin; Shu Da;

  • 作者单位

    Shanghai Jiao Tong Univ, Inst Refrigerat & Cryogen, Shanghai 200240, Peoples R China;

    Shanghai Jiao Tong Univ, Inst Refrigerat & Cryogen, Shanghai 200240, Peoples R China|State Key Lab Technol Space Cryogen Propellants, Beijing 100028, Peoples R China;

    Shanghai Jiao Tong Univ, Inst Refrigerat & Cryogen, Shanghai 200240, Peoples R China|Donghua Univ, Sch Environm Sci & Engn, Shanghai 201620, Peoples R China;

    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, Shanghai Key Lab Adv High Temp Mat & Precis Formi, Shanghai 200240, Peoples R China;

    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, Shanghai Key Lab Adv High Temp Mat & Precis Formi, Shanghai 200240, Peoples R 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

    Thermal resistance; Nanopore; Cryogenic quenching; Heat transfer;

    机译：耐热性;纳米孔;低温淬火;传热;

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