Film Boiling Heat Transfer in Superfluid Helium

1.饱和状态下超流氦（He II）中的膜沸腾传热实验研究了在1.8 ~ 2.1K液体温度范围内，超流氦中水平金属丝的膜沸腾传热。导线表面温度高达约300 K，导线上方的液体压头范围为5至30 cm。主要结论如下：1）在本实验范围内，膜态沸腾换热系数对液体压头的依赖性较强，对液体温度的依赖性较弱.本文通过实验研究了在1.85 ~ 2.15K的温度范围内，大气压下过冷Hell中水平方向的薄膜沸腾换热。结果表明：1）过冷条件下的膜沸腾换热系数高于饱和条件下的膜沸腾换热系数; 2）在大气压下过冷条件下，准稳定增加热输入时的丝温在临界热流密度处不跳变，而是连续增加到膜沸腾。Kapitza导热区的临界热流密度与纵列沸腾的最小热流密度基本相同，没有滞后效应.基于气液界面的非平衡动力学效应和用Gorter-Mellink方程的解表示的HeII传热，提出了一种新的水平丝管膜状沸腾模型。证实了该模型能较好地描述作者和其他工作者对直径为0.08 ~ 0.254mm的水平丝上无噪声膜沸腾传热系数的实验数据。

1. Film Boiling Transfer in Superfluid Helium(He II)under Sathrated ConditionFilm boiling heat transfer from a horizontal Wire in super fluid helium under saturated condition was experimentally made clear for liquid temperatures ranging from 1.8 to 2.1 K. wire surface temperatures up to about 300 K and for the liquid heads above the wire ranging from 5 to 30 cm. Major conclusions are as follows :1)Film boiling heat transfer coefficients depend strongly on liquid head but weakly depend on liquid temperature within this experimental range.2. File Boiling Heat Transfer in He]I under Subcooled ConditionFilm boiling heat transfer from a horizontal in subcooled Hell at atmospheric pressure was made clear experimentally for liquid temperatures ranging from 1.85 to 2.15 K. Conclusions are as follows :1)Film boiling heat transfer coefficients under the subcooled conditions are higher than those for saturated conditions.2)Under subcooled conditions at atmospheric pressure, wire temperature for quasi-steadily increasing heat input does not jump at the critical heat flux but continuously increases to film boiling. Critical heat flux of Kapitza conductance regime and minimum heat flux of file boiling are almost same and no hysteresis effect is observed.3. Film Boiling ModelA new model for film boiling on a horizontal wire In Hell based on non-equilibrium kinetic effects at the vapoliquid interface and the HeII heat transport given expressed by the solution for Gorter-Mellink equatons was presented. It was confirmed that his model can describe our and other workers' experimental data of noiseless film boiling heat transfer coefficients on horizontal wires with the diameters ranging from 0.08 to 0.254 mm.