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低温真空电流引线热分析 总被引:1,自引:1,他引:0
对在两级制冷机传导冷却下由高温超导和铜组成的二元电流引线进行热分析.给出了不同运行电流下,在室温温度(300 K)和制冷机一级冷头温度(77 K)间铜电流引线的温度、热流分布.认为大电流运行下,传导热等于焦耳热的一半时,在二元电流连接点的热流最小.给出了在最小热流下电流引线的尺寸优化方法. 相似文献
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CICC超导导体性能测试用50 kA超导变压器由初级线圈和次级线圈组成,初级线圈浸泡在4.2 K液氦低温杜瓦中,次级线圈为CICC导体采用4.2 K/354 637 Pa超临界氦迫流冷却,液氦和超临界氦均由500 W/4.5 K制冷机提供,变压器低温杜瓦的理论液氦蒸发率为1.52 L/h。为减少电流引线漏热,超导变压器采用B i-2223/AgAu高温超导(HTS)二元电流引线,并且在颈管中部设计了一个新型的直接用液氮冷却的热截流装置来截断电流引线高温端的热流;最后对铜电流引线部分进行了尺寸优化计算,得到最佳截面积和直径分别为28 mm2和6 mm。 相似文献
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研制了中国首台高温超导磁储能直接冷却系统,该系统不使用低温液体(液氦、液氮).在10-3Pa的真空度下,高温超导磁体线圈由1台单级GM制冷机从室温293 K冷却到19 K,Bi2223电流引线由另一台制冷机冷却到77 K以下.整个系统在通140 A直流电流的时候产生了4.5 T的磁场.系统连续运行480 h(20 d),磁体和低温系统各参数动态特性良好.实验研究表明,控制系统的漏热,优化磁体内部导冷结构,有效减少热传导部件的接触界面热阻是制冷机直接冷却高温超导磁体的关键技术. 相似文献
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根据高熵合金凝固用高精度低温超导磁体的技术要求,研制1套磁场可达10 T,室温直径为100 mm的高精度传导冷却超导磁体。该超导磁体由1组Nb3Sn和4组Nb Ti线圈组成,同时设计并制造了直径650 mm、高612 mm的杜瓦。为降低磁体运行过程中漏热,采用1对150 A高温超导电流引线为磁体供电。磁体总质量388 kg,通过1台1.5 W@4.2 K的G-M制冷机作为冷源,经过62 h,将超导磁体冷却至2.92 K,磁体正常运行电流119.95 A,工作磁场10.001 T,励磁过程中未发生失超,运行稳定。同时,对强磁场下高熵合金的凝固进行实验研究,详细介绍了该超导磁体装置的设计、制造和测试过程。 相似文献
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This paper describes the cryogenic system of the International Thermonuclear Experimental Reactor (ITER) Correction Coils (CC) test facility, which consists of a 500 W/4.5 K helium refrigerator, a 50 kA superconducting transformer cryostat (STC) and a background field magnet cryostat (BFMC). The 500 W/4.5 K helium refrigerator synchronously produces both the liquid helium (LHe) and supercritical helium (SHe). The background field magnet and the primary coil of the superconducting transformer (PCST) are cooled down by immersing into 4.2 K LHe. The secondary Cable-In-Conduit Conductor (CICC) coil of the superconducting transformer (SCST), superconducting joints and the testing sample of ITER CC are cooled down by forced-flow supercritical helium. During the commissioning experiment, all the superconducting coils were successfully translated into superconducting state. The background field magnet was fully cooled by immersing it into 4.2 K LHe and generated a maximal background magnetic field of 6.96 T; the temperature of transformer coils and current leads was reduced to 4.3 K; the inlet temperature of SHe loop was 5.6 K, which can meet the cooling requirements of CIC-Conductor and joint boxes. It is noted that a novel heat cut-off device for High Temperature Superconducting (HTS) binary current leads was introduced to reduce the heat losses of transformer cryostat. 相似文献
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A new concept of thermal design to optimize the operating temperature of high temperature superconductor (HTS) magnets is presented, aiming simultaneously at small size and low energy consumption. The magnet systems considered here are refrigerated by a closed-cycle cryocooler, and liquid cryogens may or may not be used as a cooling medium. For a specific magnet application, the size of required HTS windings could be smaller at a lower temperature, by taking advantage of a greater critical current density of HTS. As the temperature decreases, however, the power input to the cryocooler increases dramatically because of the heavy cooling load and the poor refrigeration performance. Through a rigorous modeling and analysis incorporating the effect of magnet size into the load calculation, it is demonstrated that there exists an optimum for the operating temperature to minimize the power required. The optimal temperature is strongly dependent upon the magnitude of AC loss in the magnets and the assistance of heat interception. 相似文献
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A 600 kJ HTS SMES is developed and tested in Korea. The HTS SMES consists of 22 double pancake coils wound on each aluminum alloy bobbin. It is cooled by two GM cryocoolers down to around 6 K and current is charged through HTS current leads up to 275 A. Beside the heat penetration from room temperature structures, heat generation in the HTS coil is inevitable because of the joint resistances and the intrinsic property of the HTS tape such as index loss. Moreover, during the charging and discharging operation, AC loss of the HTS conductor and eddy current loss in the coil bobbin and metallic structures are generated. Therefore, the heat generation should be effectively removed by the cryocooler to ensure the stable operation of the coil. In the HTS SMES, aluminum alloy conduction plates outside the each coil are used as thermal paths to the cryocoolers. This paper describes the thermal characteristics of the HTS SMES for the charging and discharge operation. 相似文献
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Z. Deng J. Zheng J. Li G. Ma Y. Lu Y. Zhang S. Wang J. Wang 《Materials Science and Engineering: B》2008,151(1):117
High-temperature superconducting (HTS) maglev vehicle is well known as one of the most potential applications of bulk high-temperature superconductors (HTSCs) in transported levitation system. Many efforts have promoted the practice of the HTS maglev vehicle in people's life by enhancing the load capability and stability. Besides improving the material performance of bulk HTSC and optimizing permanent magnet guideway (PMG), magnetization method of bulk HTSC is also very effective for more stable levitation. Up to now, applied onboard bulk HTSCs are directly magnetized by field cooling above the PMG for the present HTS maglev test vehicles or prototypes in China, Germany, Russia, Brazil, and Japan. By the direct-field-cooling-magnetization (DFCM) over PMG, maglev performances of the bulk HTSCs are mainly depended on the PMG's magnetic field. However, introducing HTS bulk magnet into the HTS maglev system breaks this dependence, which is magnetized by other non-PMG magnetic field. The feasibility of this HTS bulk magnet for maglev vehicle is investigated in the paper. The HTS bulk magnet is field-cooling magnetized by a Field Control Electromagnets Workbench (FCEW), which produces a constant magnetic field up to 1 T. The levitation and guidance forces of the HTS bulk magnet over PMG with different trapped flux at 15 mm working height (WH) were measured and compared with that by DFCM in the same applied PMG magnetic field at optimal field-cooling height (FCH) 30 mm, WH 15 mm. It is found that HTS bulk magnet can also realize a stable levitation above PMG. The trapped flux of HTS bulk magnet is easily controllable by the charging current of FCEW, which implies the maglev performances of HTS bulk magnet above PMG will be adjustable according to the practical requirement. The more trapped flux HTS bulk magnet will lead to bigger guidance force and smaller repulsion levitation force above PMG. In the case of saturated trapped flux for experimental HTS bulk magnet, it is not effective to improve its maglev performances by increasing of charging magnetic field, when the guidance force at WH 15 mm is 5.7 times larger than that by DFCM of FCH 30 mm. So introducing HTS bulk magnet into the present maglev system is feasible and more controllable to realize stable levitation above applied PMG, which is an important alternative for the present HTS maglev vehicle. 相似文献
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Hua Jing Suyu Wang Ming Jiang Jiasu Wang 《Journal of Superconductivity and Novel Magnetism》2010,23(8):1455-1459
The levitation performance of a high temperature superconducting (HTS) Maglev system was investigated at different temperatures
for HTS Maglev vehicle application. Using a cryogenic measurement system, we studied the effects of the HTS’s temperatures
and the HTS’s field-cooling heights (FCHs) on the levitation force and its force density by applying a two-pole Halbach array’s
permanent magnet guideway (PMG) at different temperatures. Results show that the levitation force is not only dependent on
the temperature but also dependent on the original FCH. The effect of the temperature on the levitation force is considerably
minute in low FCH. However, it was confirmed that the levitation force of HTS is larger at a lower temperature than at a higher
temperature in high FCHs. Moreover, by applying the temperature of 60 K, the levitation force density of the system can be
increased by 65% and 57.3% compared to the force density at 77 K in 35 mm and 40 mm FCHs. Hence, more magnetic energy at a
low temperature area and high FCH can be utilized. The advancement of Maglev system’s performance will directly promote the
development of HTS Maglev application and is helpful for the further HTS Maglev vehicle. 相似文献
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Yiyun Lu Xucan Bai Yunwang Ge Jiasu Wang 《Journal of Superconductivity and Novel Magnetism》2011,24(6):1967-1970
Levitation forces of a high temperature superconductor (HTS) bulk with a different thickness over a permanent magnet railway
(PMR) is studied mathematically. Several cylindrical models of HTS bulk with a diameter of 30 mm and a different thickness
over a PMR are researched by the magnetic field vector method (H-method). A 3D-modeling numerical method using finite element
method (FEM) is used to simulate the electromagnetic behavior of the models. The thickness of the HTS bulk increases with
1 mm from 4 mm to 15 mm. The simulation results show that the thickness of the HTS bulk and the minigap between the bottom
surface of the bulk and the top surface of the PMR have much influence on the levitation forces. With a certain applied magnetic
field, there is a certain thickness value of the bulk, which means the levitation force will not increase obviously with the
increase of the thickness while the thickness larges the value. 相似文献
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A practical Bi-2223 superconducting magnet, working in liquid nitrogen (L.N2), was designed and fabricated. Bi-2223 tape with a critical current of 147 A was prepared by a controlled overpressure (CT-OP) process at 77.3 K in self-field. Ten double-pancake coils were resistively connected by copper terminals. The bore diameter was 54 mm?, the magnet outer diameter was 122 mm?, the height of the magnet was 124 mm, and the weight of the magnet was about 3 kg. The maximum magnetic field at the center of the bore was 0.48 T with an operating current of 50 A. The experimental results agree well with design predictions calculated by finite element method. AC operation was also performed, and no distortion of the voltage waveform was observed. Therefore, this Bi-2223 superconducting magnet is a suitable replacement for copper magnets designed for applications in science and technology. 相似文献
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Minxian Liu Yiyun Lu Guangtong Ma Suyu Wang 《Journal of Superconductivity and Novel Magnetism》2011,24(4):1339-1344
In the present High Temperature Superconducting (HTS) maglev vehicle system, the nonuniformity of the magnetic field along
the movement direction above the NdFeB guideway is inevitable due to the assembly error and inhomogeneity of the material
property of the NdFeB magnet. In order to investigate the influence of the nonuniformity on the levitation performance of
the HTS bulk, the experiment involved an electromagnet, which is supplying AC current to simulate the nonuniformity of the
external magnetic field. The levitation force of the HTS bulk is measured when applying AC current on the electromagnet coils.
The results indicate that the levitation force abruptly changes and oscillates after applying AC external magnetic field.
The effect of the amplitude of the AC magnetic field on the levitation force is studied; the result shows that the oscillation
amplitude of the levitation force increases with the amplitude of the AC external magnetic field and is independent of the
Field Cooling Height (FCH) of the bulk. 相似文献
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Minxian Liu Suyu Wang Jiasu Wang Guangtong Ma 《Journal of Low Temperature Physics》2009,155(3-4):169-176
In the present High Temperature Superconducting (HTS) maglev vehicle system, the nonuniformity of the magnetic field along the movement direction above the NdFeB guideway is inevitable due to the assembly error and inhomogeneous of the material property of the NdFeB magnet. In order to investigate the influence of the nonuniformity on the levitation performance of the HTS bulk, an electromagnet supplied by AC current is used to simulate the nonuniformity of the external magnetic field. The levitation force of the HTS bulk is measured when applying AC currents to the electromagnet coils. Experimental results indicate that the levitation force changes abruptly and then oscillates after applying AC external magnetic field, and the levitation force is attenuated by the AC magnetic field after withdrawing the AC field. Moreover, the oscillation amplitude and the attenuation rate of the levitation force increase with the amplitude of the AC external magnetic field. 相似文献