热流逸效应的抽真空特性分析

发布时间：2018-05-02 01:48

  本文选题：微通道 + 净质量流量　； 参考：《真空科学与技术学报》2017年09期

【摘要】：热流逸效应可输送气体并产生压力差,可利用其抽真空。本文建立了描述热流逸效应及其抽真空泵送特性的数学模型,以空气为例探讨了气体流态(努森数)、微通道特征尺寸和径长比以及温差等参数对压力比、净质量流量、抽速和无量纲抽气时间的影响。结果表明,压力比、净质量流量、抽速和无量纲抽气时间均随温差的增大而增大,但过大的温差对提高流量不明显且使抽真空达到稳态过程变得相对缓慢,应根据实际条件确定适宜温差。净质量流量和抽速随努森数增大而减小,且在过渡流区域还受径长比的影响;压力比和无量纲抽气时间在过渡流区域随努森数增大而增大,但在自由分子流区域与努森数无关;故应根据实际需求权衡净质量流量与压力比以确定适宜的热流逸发生条件、并控制气体流态来调整抽气特性。
[Abstract]:Heat flux effect can transport gas and produce pressure difference, which can be used to pump vacuum. In this paper, a mathematical model is established to describe the heat flux effect and the characteristics of vacuum pumping. Taking air as an example, the pressure ratio and net mass flow rate of the gas flow state (Knudsen number, characteristic dimension and diameter ratio of microchannel, temperature difference, etc.) are discussed. Effects of pumping speed and dimensionless pumping time. The results show that the pressure ratio, the net mass flow rate, the pumping speed and the dimensionless pumping time increase with the increase of the temperature difference, but the excessive temperature difference is not obvious to increase the flow rate and make the vacuum to reach the steady state process becomes relatively slow. The appropriate temperature difference should be determined according to the actual conditions. The net mass flow rate and pumping speed decrease with the increase of Knudsen number, and are also affected by the ratio of diameter to length in the transition flow region, and the pressure ratio and dimensionless pumping time increase with the increase of Knudsen number in the transitional flow region, but they are independent of the Knudsen number in the free molecular flow region. Therefore, the ratio of net mass flow to pressure should be weighed according to the actual demand to determine the appropriate conditions for heat flux to occur and to control the gas flow state to adjust the pumping characteristics.
【作者单位】： 广西大学化学化工学院;
【基金】：广西自然科学基金资助项目(2016GXNSFAA380232) 国家自然科学基金资助项目(51366001) 广西研究生教育创新计划资助项目(YCSW2017035)
【分类号】：TB71
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本文编号：1831891