共查询到18条相似文献,搜索用时 78 毫秒
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对近年来国内外从贫氦天然气中回收氦的技术发展动态和氦的利用作了介绍,对He/CH_4的分离新技术与合成氨尾气提氦技术的优缺点作了简要评述,论述了利用钛基合金可逆贮氢特性进行H_2/He变温吸附分离的可能性。 相似文献
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给出了氦放电色谱法测定高纯氢中微量氧、氮杂质的工作原理、气路流程和色谱图,考查了仪器鉴定性能,并同其它分析方法进行了比对,证明此方法可行。 相似文献
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改革开放极大地促进我国科学技术的飞跃发展同时不断推动航天技术进步,使我国火箭技术已跻身世界先进国家行列中,低温液体发挥的作用功不可没,低温液体在国民经济、国防建设起着重要作用。 相似文献
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改革开放极大地促进我国科学技术的飞跃发展同时不断推动航天技术进步,使我国火箭技术已跻身世界先进国家行列中,低温液体发挥的作用功不可没,低温液体在国民经济、国防建设起着重要作用,它们广泛用于宇宙空间技术、激光、 相似文献
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分别推导和分析了环境大气氦分压对压氦法的影响,地球干洁大气氦分压对预充氦法和预充氦密封器件压氦法复检的影响.证明对于压氦法,不需要考虑地球干洁大气氦分压的影响.但是如果候检室环境大气氦分压显著升高,对于内腔有效容积大,且等效标准漏率小的密封器件,会加大测量漏率值,所以压氦后,被检器件应尽快离开压氦设备所在的房间.对于预充氦法,地球干洁大气氦分压会使测量漏率通过极大值后出现极小值,且当候检时间与内腔有效容积之比大于100 h/cm3时,极小值点的气流仍处于分子流状态,不能靠粗检鉴别,所以需压氦法复检加粗检,才能防止漏检.另外,地球干洁大气氦分压会使预充氦法候检时间的第一特征点变大,从而扩大了需压氦法复检加粗检的范围,但第二特征点不变,也不影响压氦法复检加粗检的结果. 相似文献
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It is shown that the maximum superheat temperature ΔTmax in liquid helium I, determined under steady-state peak nucleate boiling conditions, cannot be realistically estimated from the thermodynamic limit of superheat (spinodal), as has been previously claimed. It is suggested that a more meaningful estimate of ΔTmax can be obtained from the kinetic limit of super-heat (homogeneous nucleation temperature). Experimental data on the homogeneous nucleation superheat temperature, ΔTh, in liquid helium I over an extended temperature range are presented and compared with the ΔTmax measurements of several investigators. It is pointed out that in any quantitative predictions of ΔTmax, a knowledge of ΔTh alone is not sufficient. In fact, the measured value of ΔTmax can lie either below or even above ΔTh depending on the bath temperature, conditions of the surface, and the thermophysical properties of both heater and liquid. 相似文献
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The flow of saturated liquid helium at 4.2 K was studied in a unique weir flowmeter mounted inside a duct. The objective was to develop a calibration for helium flow rate in the weir, and thereby, making it a viable flowmeter. The weir flowmeter was tested in a liquid helium system at Fermi National Laboratory used for cooling the superconducting magnets in the experimental areas of the site. Unlike for open channel weir devices, the calibration of this flowmeter was influenced by both the liquid flow through the weir notch and the vapor flow over it. The results of this study and the calibration are presented taking into account effects of both liquid and vapor. 相似文献
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A technique is described for calculating the shape of the surface tension meniscus at a vertical wall, in the presence of Van der Waals forces. The method of analytic continuation is used to compute a solution of the relevant differential equation. Results (believed accurate to better than 0.5%) are presented for He3 and for He4 at a variety of film flow rates. It is found that the shape of the classical meniscus remains unaltered over most of its length, but it is displaced horizontally relative to the wall by a flow dependent amount. The results are contrasted with those from a previous calculation. 相似文献
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An automatic LHe transfer system for use with small (~50 l) research dewars is described. The system is simple and is designed to be safe and reliable. 相似文献
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R.C. Longsworth 《低温学》1984,24(4):175-178
Several different means of connecting small closed cycle refrigerators to liquid helium cryostats for the purpose of reliquefying the boiloff or reducing the boiloff rate are described. Interface principles which enhance the reliability and serviceability are presented. Most of the interfaces which are described permit the refrigerator to be serviced while maintaining liquid helium in the cryostat. 相似文献
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Two units to measure the level of liquid helium in a superconducting magnet and in a storage dewar are described. 相似文献
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The experimental results of a new method to measure a vacuum in an environment at liquid helium temperatures are presented. The method uses a thin superconducting wire suspended in the vacuum vessel, the wire is heated by a current pulse > lc. The cool down time, which depends on the heat transfer into the rest gas and on the axial heat conductance of the wire, is a measure of the vacuum and it is detected by the recovery of the wire to superconductivity. The results exhibit good resolution in the range of pressures from 5 × 10?3 to 5 Pa (5 × 10?5 to 5 × 10?2 mbar). 相似文献