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首页> 外文会议>6th international conference on nanochannels, microchannels and minichannels 2008 >FLOW AND HEAT TRANSFER IN 0.0196MM QUARZ MICROTUBE
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FLOW AND HEAT TRANSFER IN 0.0196MM QUARZ MICROTUBE

机译：0.0196毫米Quarz微管中的流动和传热

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摘要

The flow and the heat transfer characteristics in quartz microtube with inner diameter of 0.0196mm are investigated experimentally. By measuring the pressure drop between the inlet and outlet of microtube with different working fluid and the average temperature of microtube wall heated by steam, the corresponding friction factors and Nusselt number are obtained. The experimental results show the friction factors in microtubes exceeds the prediction of Hagen-Poiseulle due to the predominance of the electrical double layer effect (EDL effect) when the working fluid is distilled water, and the experimental Nusselt number is less than the classical laminar at Reynolds number<500 due to the effects of the variation of the thermophysical properties with temperature and the conjugate heat transfer. However, the effect of viscous dissipation results in temperature rise of the working fluid, due to which the friction factors are less than the prediction of Hagen-Poiseulle with the working fluid of tetrachloromethane. Using nitrogen gas as the working fluid, the rarefaction effect still brings on that the friction factor is less than the classical laminar solution, though gas density and viscosity increases resulted from the stagnant velocity between gas and inner wall and the viscous heating lead to the increase of friction factor.
机译：实验研究了内径为0.0196mm的石英微管的流动和传热特性。通过测量不同工作流体的微管进出口之间的压降和蒸汽加热的微管壁的平均温度，得到相应的摩擦系数和努塞尔数。实验结果表明，由于工作流体为蒸馏水时电双层效应（EDL效应）的优势，微管中的摩擦系数超过了Hagen-Poiseulle的预测，并且实验时的Nusselt值小于经典层流。由于热物理性质随温度和共轭传热的变化的影响，雷诺数＜500。然而，粘性耗散的作用导致工作流体的温度升高，由于该摩擦因子小于用四氯甲烷工作流体的Hagen-Poiseulle的预测。使用氮气作为工作流体，尽管气体密度和粘度由于气体和内壁之间的停滞速度以及粘性加热导致的增加而增加，但稀疏效应仍然带来了摩擦系数小于经典层流解决方案的结果。摩擦系数。

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