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超导电缆循环过冷液氮温度场模拟 总被引:2,自引:0,他引:2
建立了循环过冷液氮在恒温器内迫流冷却超导电缆的模型,利用Fluent软件模拟了30 m电缆系统内液氮温度场在不同流量、终端漏热、交流损耗等工况条件下的变化情况。仿真结果表明,在终端漏热和交流损耗一定时,液氮出口断面的最高温度随流量的增大而降低;在流量和交流损耗一定时,液氮出口断面的最高温度随终端漏热的增大而升高;在流量和终端漏热一定时,液氮出口断面的最高温度随交流损耗的变化不明显。 相似文献
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本文用沉浸法研究小样品沉浸入过冷液氮的沸腾传热特性。实验发现,沉浸样品的直径减少、液氮过冷度增大,均导致沸腾的热流密度急剧向右上方移动。当小直径足够小,过冷度足够大时,稳定膜态沸腾段消失了,“M”形的沸腾曲线变为“Λ”形。 相似文献
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<正>我车间在一次1000 m3/h空分设备开车过程中,曾发生一起通往液化器管道阀门(即蝶-8)被卡死,使液化器不能工作的故障。如果按常规处理,停机扒搭,修理阀门后再开车,这样将停产5天,影响炼钢生产,经济损失很大。为此,我们采取了用液空过冷器 相似文献
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研制了柱面加载压缩的液氮温区低温靶,该低温靶以液氮为冷源将样品室冷却到所需的温度,并保持该温度,然后对注入的样品气体液化,为柱面等熵压缩提供条件。根据加载方式和保温时间要求确定了低温靶的初步结构和尺寸,在此基础上分析计算了靶体的漏热、样品室的温度分布和保温时间,对结构尺寸进行优化。在自行搭建的实验台上对柱面压缩液氮低温靶的漏热、降温、温度调控及不同环境条件下的保温特性、样品气体(氩气)液化过程的温度变化进行了试验。试验结果表明:柱面压缩液氮低温靶的温度可在一定范围进行调节控制;借助样品室顶部针阀内部的温度计,结合分批充注样品气体的方法可以很好地观测样品室液体充满状况;成功地将氩气液化,充满样品室;断开冷源和真空泵后,样品室温度可以维持93 min。 相似文献
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M.A.A. Moussa 《低温学》2009,49(1):17-20
This paper describes a simple and low-cost experimental setup intended for AC susceptibility measurements between 60 and 300 K. A mutual inductance bridge for measuring the transition temperature of high-Tc superconductor thick films was constructed. The device is based on using liquid nitrogen and subcooled liquid oxygen; it allows temperatures down to 60 K to be achieved. Experimental details are described and illustrative measurements on high-Tc superconductor thick films are included. 相似文献
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This paper studies the influence of secondary heat sources on the convective heat transfer from a vertical cylindrical heater immersed in a LIN pool. Two types of secondary heat source have been used. In the first case, the heat leak through the vessel walls into the pool was varied without causing nucleation, so as to retain convective heat transfer. It was found that the convective flow loops induced in the pool produced a small enhancement of the heat transfer from the cylindrical heater. In the second case, a small horizontal heater loop was introduced into the pool below the cylindrical heater. The secondary heat flux used was such that boiling occurred at the loop to give rising bubbles surrounding the cylindrical heater. This produced a large enhancement of the convective heat transfer from the cylindrical heater. The enhancement ratio is presented as a function of the power supplied to the loop heater. 相似文献
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The design and construction of inner containment tanks for liquid oxygen and liquid nitrogen is discussed. Standards and recommendations by official bodies are cited and potential failure areas are highlighted. 相似文献
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芳纶纤维增强树脂(AFRP)复合材料是一种公认的难加工材料,加工中极易出现毛刺、烧蚀等缺陷,目前缺乏对其有效的加工工艺方法。为提高其加工质量,研究了液氮作为冷却介质的AFRP复合材料钻孔试验。在相同切削参数下进行了干式切削和超低温加工对比试验,测量了切削过程中的轴向切削力和孔临近区域的温度,并计算了孔的进出口毛刺面积和分层因子,分析了AFRP复合材料缺陷的成因,探讨了不同加工条件下缺陷的变化规律。结果表明:与干式切削相比,采用液氮超低温冷却加工的切削力升高了约15.2%,切削温度降低了约141.6℃,毛刺面积减少了约24.7%,因切削热产生的烧蚀现象得到抑制,明显改善了AFRP复合材料的加工质量。 相似文献
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Capacitive devices with active lengths up to 460 mm have been developed for the continuous reading of cryogenic liquid levels without power dissipation. Resolutions of ± 0.7 mm for liquid nitrogen and ± 1 mm for liquid and superfluid helium have been achieved. Sensor construction, an electronic circuit for capacitance measurement using the technique of charging with constant current and an automatic filling unit for LN2 are presented. 相似文献