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Forced Convection Heat Transfer in Superfluid Helium at Pressures up to Supercritical

超流氦在超临界压力下的强制对流换热

基本信息

批准号：
15360109
负责人：
SHIOTSU Masahiro
金额：
$ 7.04万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15360109/
关键词：
Supercritical Pressure He II He I Laminar Flow Heat Transfer Turbulent Flow Heat Transfer Critical Heat Flux 層流乱流熱伝達常流動ヘリウミ臨界熱流速

项目摘要

Major Results of this study are as follows.Critical Heat Fluxes (CHFs) in He II under subcritical and supercritical pressures are higher for higher flow velocity and lower liquid temperature. Under supercritical pressures, there exists a heat transfer region similar to film boiling for the heat flux higher than the CHF.In He I under supercritical pressures, the heat transfer curve for lower heat flux range has a steeper gradient and the curve for higher heat flux has a lower gradient. The peak heat fluxes of the former curves are treated as the pseudo-critical heat fluxes in this study. The pseudo-CHFs for T_<in>=2.2 K at 2.3 atm and 2.8 atm are nearly the same for each flow velocity and are about 2.2 times of those for the same temperature liquid at 2.0 atm. At the flow velocity of 2.1 m/s, they reach the value for He II under supercritical pressure (2.0 K, 2.8 atm). The pseudo-CHFs become significantly lower with the increase in T_<in>.CHFs in He I under subcritical pressures are significantly dependent on pressure in the low flow velocity range : they are lower for higher pressures. The CHFs increase with the increase in flow velocity in such a way that the pressure dependence becoming smaller. The pressure dependence is almost negligible for the flow velocities higher than 1.2 m/s.

主要研究结果如下：He Ⅱ在亚临界和超临界压力下的临界热流密度（CHFs）随流速的增加和液体温度的降低而增大。在超临界压力下，当热流密度高于临界热流密度时，存在一个类似于膜沸腾的传热区域，在He I中，在超临界压力下，低热流密度区的传热曲线具有较陡的梯度，而高热流密度区的传热曲线具有较低的梯度。在本研究中，将前述曲线的峰值热通量视为拟临界热通量。在<in>2.3atm和2.8atm下，T = 2.2K时的赝CHF值几乎相同，约为2.0atm下相同温度液体赝CHF值的2.2倍。在2.1 m/s的流速下，它们达到超临界压力（2.0 K，2.8 atm）下He II的值。亚<in>临界压力下He I中的CHF与低流速范围内的压力有显著的依赖关系：压力越高，CHF越低。CHF随流速的增加而增加，使得压力依赖性变小。对于高于1.2 m/s的流速，压力依赖性几乎可以忽略不计。