超导磁悬浮列车是高温超导块材最有前景的应用之一.磁悬浮列车系统要求高温超导块材处于超导状态,因此在磁悬浮列车运行过程中,车载高温超导块材始终被浸泡在温度为77K的液氮容器中.当运行一段时间液氮将被耗尽时,,为防止超导块材失超,需要向液氮容器补充液氮.由于受空气中水蒸汽的影响,在补充液氮的过程中很容易在超导块材的外表面形成结冰现象.块材表面的冰层不利于块材和液氮的热交换,甚至有可能对交流磁场下块材的导向力性能产生影响.在本论文中,实验研究了块材表面覆盖的冰层对高温超导磁悬浮列车系统中到向力性能的影响情况.实验结果表明:和未被冰层覆盖的块材相比,在相同交流磁场影响下的磁悬浮列车系统中,覆盖有冰层的超导块材的导向力衰减更明显.因此,在高温超导磁悬浮列车系统中,为防止导向力的急剧衰减,应该尽量避免车载高温超导块材外表面被冰层覆盖.
Superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a sys-tem, the HTS bulks are required to keep in the superconducting state all the time, so they are always placed in ves-sel which is filled with liquid nitrogen at 77K. In the running process of HTS maglev vehicle system, it is necessary to add liquid nitrogen constantly to the vessel so as to keep the bulks out of the normal sate. In this process, owe to the effect of the water vapors in the air, it is easily for the surface of the bulks to be covered with ice crystals, which may be disadvantageous to heat transfer between the bulks and the liquid nitrogen and influence the guidance force of the bulks exposed to AC magnetic field in the maglev vehicle system. In this paper, we experimentally studied the influence of ice-cover on guidance force of bulk exposed to AC magnetic field in the maglev vehicle system. From the experiment results, it was found that the guidance force of the bulk covered with the ice crystals was greatly attenu-ated compared with the one was not covered with the ice crystals. Therefore, in order to avoid the guidance force be-ing attenuated greatly, we should make effort to keep the bulk onboard from being covered with the ice crystals in the HTS maglev vehicle system.
参考文献
| [1] | K. B. Ma;Y. V. Postrekhin;W. K. Chu .Superconductor and magnet levitation devices[J].Review of Scientific Instruments,2003(12):4989-5017. |
| [2] | Quan-Sheng Shu;Guangfeng Cheng;Joseph T. Susta .Magnetic levitation technology and its applications in exploration projects[J].Cryogenics,2006(2/3):105-110. |
| [3] | Y. Zushi;I. Asaba;J. Ogawa .AC losses in HTS bulk and their influence on trapped magnetic field[J].Cryogenics,2005(1):17-22. |
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