高温超导制冷机直接冷却中界面热阻的辨识与实验研究  

IDENTIFICATION AND EXPERIMENTAL INVESTIGATION ON THERMAL INTERFACE RESISTANCE FOR CRYOCOOLER COOLED HIGH-T_c SUPERCONDUCTOR

作　　者：饶荣水[1] 王惠龄[1] 

机构地区：[1]华中科技大学能源与动力工程学院制冷与低温工程教研室,武汉430074

出　　处：《低温物理学报》2003年第3期209-214,共6页Low Temperature Physical Letters

基　　金：国家自然科学基金 (No .:5 10 76 0 13)资助项目~~

摘　　要：本文给出了三种提高YBCO块材在外磁场中悬浮力的方法 .第一种方法是增强外磁场 ,对于此方法 ,本文研究了一块直径为 30mm的圆柱状YBCO块材分别在圆柱状NdFeB永磁体和NdFeB永磁导轨上的悬浮力 .测量结果表明在 77K温度下YBCO块在圆柱状NdFeB永磁体上的最大悬浮力为 5 0N ,在NdFeB永磁导轨上的最大悬浮力为 10 3.0N .第二种方法是提高YBCO块材自身的性能 ,包括临界电流密度、俘获磁通和块材尺寸 ,对于此方法 ,本文仅研究了块材尺寸对悬浮力的影响 .三块直径分别为 30mm、35mm、4 0mm的圆柱状YBCO块材在NdFeB永磁导轨上的悬浮力被测量 ,77K温度下 5mm悬浮间距时的悬浮力分别为 10 3.0N、134.5N、175 .0N .第三方法是将YBCO块材变成准永久磁体 ,此种情况下 ,直径为 4 0mm的圆柱状YBCO块材在 77K温度下 5mm悬浮间距时的悬浮力高达 2 18.3N .高温超导材料和低温技术的发展 ,促进了制冷机直接冷却高温超导磁体的发展 .在高温超导直接冷却系统中 ,减小和控制界面热阻成了实现超导直接冷却的关键 .界面热阻机制相当复杂 ,虽然可以用公式进行预测 ,但是最可靠的还是通过实验进行测量 .本文介绍了界面热阻测量的基本原理和实验装置 ,提出一种基于导热反问题的参数辩识方法 ,并用这种方法处理了氮化铝 (AlN)The application of high-T-c superconductor magnetic system was promoted by the development of high-T-c superconductor material and low temperature technology. Reducing thermal interface resistance is one of the key technologies for a cryocooler cooled high-T-c superconductor system. The principle and experimental apparatus of measuring thermal interface resistance is introduced, and the parameter identification method is presented to analyse the measured data of the thermal interface resistance across Bi-2223 and AlN contact. It is shown that heat flow direction and the process of increasing and decreasing temperature did not affect the thermal interface resistance, however, thermal interface resistance decreases with the increasing contact pressure and interface temperature within the contact pressure range from 0.15 to 0.55MPa. The thermal interface resistance is decreased from 0.02868 to 0.01109m2·K·W{-1} when the contact pressure is increased from 0.23 to 0.55MPa and the temperature maintains 55K, which means the thermal interface resistance is decreased 61.3%. It is reasonable to increase the contact pressure within the permitted stress range to reduce thermal interface resistance. The results of this study is of great importance for the application of cryocooler cooled high-T-c superconductor system.

关 键 词：高温超导制冷机 直接冷却 界面热阻 实验研究 参数辨识 高温超导材料 

分 类 号：TB61[一般工业技术—制冷工程]