Hi'/> Confinement and vapour production rate influences in closed two-phase reflux thermosyphons Part A: Flow regimes
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首页> 外文期刊>International Journal of Heat and Mass Transfer >Confinement and vapour production rate influences in closed two-phase reflux thermosyphons Part A: Flow regimes
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Confinement and vapour production rate influences in closed two-phase reflux thermosyphons Part A: Flow regimes

机译：密闭两相回流热虹吸管的限制和蒸汽产生速率的影响A部分：流态

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Highlights•A thermally conductive and fully transparent reflux thermosyphon test apparatus has been constructed.•Two-phase boiling heat transfer within the thermosyphon is investigated for varying levels of confinement and heat fluxes.•Flow regimes are characterized as geyser, bubbly-churn and slug-plug.•Results show that the boiling regimes influence the boiling heat transfer coefficient.AbstractThis work investigates boiling heat transfer for a small scale thermosyphon. Heat transfer results were analysed for three fluids; water, ethanol and HFE-7000. The influence of confinement and vapour mass flux on thermosyphon heat transfer was studied using a fully transparent two-phase closed thermosyphon. By considering the thermal performance of the thermosyphon together with the observed flow regimes, diabatic flow maps were developed. Of particular importance is the reduced pressure of the system which influences the size of the generated vapour bubbles in the evaporator. At low reduced pressures, bubble diameters may be large enough to span the tube diameter and the thermosyphon exhibits confined flow behaviour similar to that of micro-scale convective two-phase flows. Flows of this nature result in oscillatory behaviour and the boiling heat transfer is less effective. The phenomenon can be avoided by increasing the reduced pressure or tube diameter of the system. The most favourable flow regime in the context of thermosyphon heat transfer was found to be churn-type flow. It was found that slug/plug-type flow was not conducive to heat transfer where vapour production rates, and thus latent heat transfer, were relatively low. The flow regime maps relating phase superficial momentum flux the heat transfer coefficient may be used as an aid to the design of thermosyphons for specific applications.
机译： 突出显示 • 已构建了一种导热且完全透明的回流热虹吸测试设备。 • 热虹吸管内的两相沸腾传热是 • 流态的特征是间歇泉，起泡和塞塞。 • 结果表明，沸腾方式会影响沸腾的传热系数。 摘要 此工作研究了小型热虹吸管的沸腾传热。分析了三种流体的传热结果。水，乙醇和HFE-7000。使用完全透明的两相封闭式热虹吸管研究了约束和蒸气质量通量对热虹吸管传热的影响。通过考虑热虹吸管的热性能以及观察到的流态，开发了非绝热流图。特别重要的是系统的压力降低，该压力会影响蒸发器中产生的蒸气气泡的大小。在较低的减压下，气泡直径可能足够大以跨越管直径，并且热虹吸管表现出与微尺度对流两相流相似的受限流动行为。这种性质的流动导致振荡，沸腾的传热效果不佳。可以通过增加系统的减压压力或管道直径来避免该现象。发现在热虹吸传热中最有利的流动方式是搅动型流动。已经发现，团块/塞子式流动不利于热传递，因为蒸汽的产生速率和潜热传递相对较低。有关相表面动量通量，传热系数的流态图可用于特定应用的热虹吸管设计。

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    K. Smith; A.J. Robinson; R. Kempers;

  • 作者单位

    Department of Mechanical & Manufacturing Engineering, Parsons Building, Trinity College Dublin;

    Department of Mechanical & Manufacturing Engineering, Parsons Building, Trinity College Dublin;

    Department of Mechanical & Manufacturing Engineering, Parsons Building, Trinity College Dublin,Department of Mechanical Engineering, York University;

  • 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

    Thermosyphon; Flow maps; Two phase flow; Confinement; Heat transfer;

    机译：热虹吸;流图;两相流;约束;传热;

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