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首页> 外文期刊>International Journal of Heat and Mass Transfer >The effect of an ideal fluid mixture on the evaporator performance of a heat pipe in microgravity
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The effect of an ideal fluid mixture on the evaporator performance of a heat pipe in microgravity

机译：理想流体混合物对微重力下热管蒸发器性能的影响

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摘要

Previous studies on wickless heat pipes showed that a temperature induced "Marangoni flow" prevents liquid from recirculating to the heater end, and therefore reduces the effectiveness of the heat pipe. Recently, several research groups used a water and alcohol mixture, with a low concentration of alcohol, resulting in better performance of the heat pipe. The alcohol/water combinations were peculiar in that for a certain composition range, the surface tension increases with increasing temperature thereby driving liquid toward the hotter end. It was believed that changing the direction of the Marangoni stress or reducing its magnitude by differential evaporation of an ideal binary mixture would also improve the performance of the heat pipe. For the first time, an ideal fluid mixture of 94 vol%-pentane and 6 vol%-isohexane was used as the working fluid in the Constrained Vapor Bubble (CVB) heat pipe experiment on the International Space Station (ISS). Using a simple heat transfer model developed in our laboratory, an internal heat transfer coefficient in the evaporator section was determined and shown to be almost twice that of the case where pure pentane was used under the same conditions. The Marangoni stress in the mixture was five times lower. Interestingly, reducing the Marangoni stress led to less liquid accumulation near the heater end and surveillance images of the device, taken at the steady state, showed that the bubble gets much closer to the heater end in the mixture case instead of being isolated from the heater by a thick liquid pool as in the pure pentane case. The proximity of the bubble to the heater wall led to more evaporation at the heater end in the mixture case, and therefore a higher heat transfer coefficient. The pressure profile calculated from the Young-Laplace equation supports the observations made from the surveillance images.
机译：先前对无芯热管的研究表明，温度引起的“马兰戈尼流”会阻止液体再循环到加热器端，因此降低了热管的效率。最近，几个研究小组使用了酒精浓度低的水和酒精的混合物，从而提高了热管的性能。醇/水组合的独特之处在于，在一定的组成范围内，表面张力会随着温度的升高而增加，从而将液体推向较热的一端。可以相信，通过理想二元混合物的差异蒸发来改变Marangoni应力的方向或减小其大小，也会改善热管的性能。在国际空间站（ISS）上的“约束蒸汽泡”（CVB）热管实验中，首次将94％（体积）戊烷和6％（体积）异己烷的理想流体混合物用作工作流体。使用我们实验室开发的简单传热模型，确定了蒸发器部分的内部传热系数，表明该系数几乎是在相同条件下使用纯戊烷的情况下的两倍。混合物中的马兰戈尼应力降低了五倍。有趣的是，降低Marangoni应力导致加热器端附近的液体积聚减少，并且在稳定状态下拍摄的设备监控图像显示，气泡在混合情况下更靠近加热器端，而不是与加热器隔离像纯戊烷的情况一样，通过浓稠的液体池。气泡与加热器壁的接近导致在混合情况下加热器端的蒸发更多，因此传热系数更高。根据Young-Laplace方程计算出的压力曲线支持了从监视图像中获得的观察结果。

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  • 作者

    Thao T.T. Nguyen; Akshay Kundan; Peter C. Wayner Jr.; Joel L. Plawsky; David F. Chao; Ronald J. Sicker;

  • 作者单位

    The Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA;

    The Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA;

    The Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA;

    The Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA;

    NASA Glenn Research Center, Cleveland, OH 44135, USA;

    NASA Glenn Research Center, Cleveland, OH 44135, USA;

  • 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

    Ideal liquid mixture; Marangoni stress; Interfacial heat transfer; Capillarity; Heat pipe;

    机译：理想的液体混合物;马兰戈尼（Marangoni）压力;界面传热;毛细作用热管;

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