Heat transfer to subcooled Helium II

本研究中，（1）对实验装置的性能进行了改进，（2）对过冷氦Ⅱ进行了稳态传热实验。(1)研制了由热交换器和分隔氦I槽和氦II槽的隔板组成的插入件。自去年以来，人们一直在研究过冷氦II是否可以稳定地生产。在P=0.1044 [Mpa]时，获得了较低的过冷氦Ⅱ浴温Tb=1.72 [K] -1.75 [K]。从开始在饱和氦II浴中排空He I到达到上述过冷氦II的条件需要大约一个小时。(2)本文采用铑-铁温度传感器和铂-铑丝同时作为温度传感器和加热表面，研究了过冷氦Ⅱ的稳态传热特性。获得了Rh-Fe温度传感器在垂直方向上和增大热流密度时对过冷He Ⅱ的传热特性。结果表明，这些传感器的加热表面温度高于Au-Mn [0.25%]丝（直径= 0.25mm）。0.08[mm]，Tb=2 [k]）。还得到了铂铑丝在增、减热流和水平方向上对过冷氦的传热特性。铂铑丝的加热表面温度也高于M.Shiotsu等人的Au-Mn丝和Rh-Fe丝（直径= 1.5 mm）。0.051 [mm]，Tb=1.85 [K]），并且对于较小直径的线，它变得更高。

In this research, (1) the improvement of the performance of experimental apparatus has been attempted and (2) the experiment of steady heat transfer to subcooled Helium II has been performed.Results are as follows.(1) The insert which consists of heat exchangers and the lambda-plate separating the Helium I bath and Helium II bath has been manufactured. It has been investigated since last year if subcooled helium II could be produced steadily. A lower bath-temperature of subcooled helium II of Tb=1.72 [K] -1.75 [K] at P=0.1044 [Mpa] was attained. It took about one hour to attain the condition of the above-mentioned subcooled Helium II from the beginning of evacuating He I in saturated Helium II bath.(2) The steady heat transfer characteristics to subcooled Helium II have been investigated using Rh-Fe temperature sensors and Pt-Rh wire as the temperature sensors and the heating surfaces at the same time. The heat transfer characteristics to subcooled He II in increasing heat flux and vertical orientation was obtained for Rh-Fe temperature sensors. It was found that the temperature of heating surface for these sensors were higher than that of Au-Mn [0.25%] wire (dia.=0.08 [mm], Tb=2 [k]) by M.Shiotsu et al.. The heat transfer characteristics to subcooled He II in increasing/decreasing heat fluxes and horizontal were also obtained for Pt-Rh wire. The temperature of heating surface for Pt-Rh wire was also higher than those using Au-Mn wire by M.Shiotsu et al. and Rh-Fe wire (dia.=0.051 [mm], Tb=1.85 [K]) by I.Arend et al. and it became higher for smaller diameter of the wires.