BI-2212超导圆筒热学特性测试及有限元分析

The Thermal Characteristic Test and Finite Element Analysis of Bi-2212 High-temperature Superconductive Tube

感应屏蔽型高温超导故障电流限制器的动态测试实验中,在故障期间,Bi-2212超导圆筒处于磁通流动状态并出现电阻,处于交变磁场中的超导圆筒的内部,有大量的感应电流产生,焦耳热引起超导圆筒温升,使限流器的阻抗不断上升,进行超导圆筒的热学性能测试和分析,对研究限流器故障阶段阻抗的变化及故障后限流器的恢复具有重要的意义。该文通过对有银皮包套的超导圆筒和没有银皮包套的超导圆筒在通过大电流(大于临界电流Ic)时温度变化的测试及有限元分析计算,得到了样品分别在液氮和77K氮气中温度的变化和分布。结果表明,银皮包套对超导圆筒的温升有很大影响,超导圆筒的中心温度高于边界温度,超导圆筒温度的恢复时间大约为3s,与限流器动态测试中的恢复时间相同。

In the dynamic test of inductive hightemperature Superconductive fault current limiter （HSFCL）, the Bi-2212 HTS tubes are in the magnetic flux state during the fault period, and the resistance arises. Because the HTS tubes are placed in the alternating magnetic field, so there is a large inductive electric current in the HTS tubes. When the resistance appears in the tubes, the Joule heat will generate and the temperature of the tubes will rise, which makes the impedance of HSFCL increase constantly. So it has an important meaning to carry on the thermal characteristic test and analysis on the HTS tubes for studying the impedance during the fault period and recovery time after fault of HSFCL. In this paper, we present the experimental results and the finite element analysis calculation results of the HTS tubes with a large DC current greater than the critical electric current Ic of tubes, flowing in them when placed in liquid nitrogen and 77K nitrogen, respectively. The results indicate that the silver cladding has an important influence to the HTS tube＇s temperature during the test. The temperature of HTS tube＇s centre is higher than the border＇s. The temperature recovery time of the HTS tubes in liquid nitrogen is probably 3s, similarly to the recovery time of the inductive HSFCL in the dynamic test.