低温绝热气瓶定期检验探讨

根据低温绝热气瓶结构特点,讨论了在低温绝热气瓶定期检验过程中,对低温绝热容器定期检验的关健项目、技术要点进行了具体分析,解决了在缺少具体检验标准、规范的情况下该类气瓶的定期检验问题.     

低温绝热气瓶定期检验中抽真空技术的探讨

本文以低温绝热气瓶为主要研究对象,重点介绍了一套适合低温绝热气瓶定期检验的新的抽真空工艺,通过理论分析和实验研究相结合的方法,分析其抽空效果,可为国内低温绝热气瓶的定期检验机构提供参考。     

关于低温绝热气瓶定期检验与评定方法的探讨

低温绝热气瓶因其使用方便、充装率高和可重复冲装等特点在很多场所都具有广泛的应用。当低温绝热气瓶的真空出现一定程度的丧失后,内胆压力升高导致气体外溢而容易发生危险。本文针对此种情况指出了对低温绝热气瓶进行定期检验的必要性并提出了一套用于低温绝热气瓶定期检验及评定的方法。     

低温绝热气瓶自升压值与静态蒸发率关系

对低温绝热气瓶的特点及应用现状进行了分析,指出了其在定期检验中存在的问题,进而提出利用自升压值来表征低温绝热气瓶绝热性能。静态蒸发率测试过程复杂、周期长,使得大量气瓶超期未检,而24h自升压法测试过程简单、周期短。首先通过理论计算其可行性,再经试验对比得出,24h实测自升压值与计算自升压值接近,而随着时间延长,差值逐渐变大。因此在实际检验过程中,可尝试通过实测其24h自升压值来表征焊接气瓶的绝热性能。     

车载液化天然气气瓶定期检验问题论述

针对大量安装在各类城市公交和运输重卡上的液化天然气(LNG)低温绝热钢瓶的定期检验问题进行探讨。随着使用年限的增长,现各省市都有已超过3年的LNG气瓶,而至今只有少数几省市开展了相关的检验工作,那么是什么原因导致此类气瓶的定期检验工作难以开展。参照相关的规程规范要求,对此类气瓶从检验标准、制造要求、检验指标、气瓶系统结构等方面进行浅显分析,对限制气瓶开展定期检验的因素就其特殊性进行总结。     

真空-检漏技术在低温绝热压力容器制造中的应用

通过介绍真空-氦质谱检漏技术在夹套式真空低温绝热压力容器制造中的应用情况,简单讲解了真空与检漏的基本概念,及真空检漏技术在本公司系列产品制造中的使用方法、必要性以及所产生的效果。     

焊接绝热气瓶定期检验问题的探讨

本文主要针对焊接绝热气瓶定期检验问题进行讨论,将气瓶的定期检验项目分为一般检验和专项检查,更准确的得出检验结论。     

真空绝热低温移动式压力容器检验问题探讨

探讨了真空绝热低温移动式压力容器的定义及其作用,阐述了压力容器定期检验的意义,最后详细分析了真空绝热低温移动式压力容器定期检验中的常见问题,不同缺陷的产生原因及处理措施,以期为真空绝热低温移动式压力容器的检验提供一定的参考。     

静置时间和充满率对静态蒸发率的影响

静态蒸发率受环境温度、压力、静置时间和充满率的影响。实验研究了静置时间对卧式低温绝热气瓶的影响,及充满率对立式低温绝热气瓶和卧式低温绝热气瓶的影响,并基于不同的充满率对卧式低温绝热气瓶静态蒸发率进行修正。研究表明:当静置时间大于12 h,静态蒸发率随静置时间的增大而减小;静置时间小于12 h,静态蒸发率随静置时间的增大无规律变化。静态蒸发率随着充满率的减小而减小。     

氦检漏工艺在低温储罐制造中的应用

本文简述了低温压力容器建造过程中氦质谱检漏原理、检漏方法、工艺过程及操作过程中注意事项。     

关于车用气瓶定期检验中进口瓶阀更换的探讨

依据国家相关法规,车用气瓶实行强制定期检验制度,在定期检验中,瓶阀检验是其中的重要项目,对于不合格的瓶阀必须进行更换,以保证气瓶能安全使用到下一检验周期。文章针对志俊车型的气瓶瓶阀在检验中遇到的问题进行分析,并找到解决的办法。     

浅析真空粉末绝热运输车罐体的检修工艺

根据真空粉末绝热运输车罐体的结构和故障的特点,在罐体发生泄漏时,就夹层泄漏气体的分析以及根据夹层抽真空的速度等来判断出罐体的污漏情况,同时综合分析氢质谱仪检测的各种数据,能准确地判断出漏点的位置,并采取相应处理措施,能大大地提高真空粉末绝热罐车的检修效率。     

焊接绝热气瓶定期检验与评定问题

对焊接绝热气瓶的蒸发率和漏热量检测以及内胆材料的热冲击损伤进行试验研究,开发了焊接绝热气瓶绝热性能自动检测与信息系统.     

Thermal explosion of an annular layer with boundary conditions of the third kind

An analytical solution of the problem of thermal explosion of an annular layer is obtained for two cases: 1) the inner cylinder is thermally insulated (heat exchange with the environment through the surface of the outer cylinder follows Newton’s law); 2) the outer cylinder is thermally insulated (heat exchange through the surface of the inner cylinder follows the same law). The dependence of the critical value of the Frank-Kamenetskii parameter on the ratio of the radius of the inner cylinder to the radius of the outer cylinder is constructed for various values of the Biot number. The limiting cases where this ratio tends to zero and unity are considered.     

煤油贮箱冷氦鼓泡增压过程数值研究

火箭飞行过程中,约90 K的低温氦气用以加压室温下的煤油贮箱使煤油流出,保障发动机燃料供应。为尽可能减少氦气用量,设计低温氦气从液相中喷入,使得氦气在贮箱内上升过程先和液态煤油充分换热升温,再进入气相空间增压。但该过程可能引起两个不利的结果,首先浸没在煤油中的低温氦气管路表面可能结冰,结冰沉底或可能堵塞发动机滤网;其次氦气可能被煤油携带,从而排出口位置可能出现气液两相流。这两种情况都对火箭发动机稳定运行造成负面影响,因此是不允许的。对低温氦气在贮箱中心喷入和环向多孔喷入两种结构的气液两相流过程进行了数值研究,构建了基于Euler-Euler模型的两相传热非稳态模型,数值结果与地面实验观察到的现象进行了定性对比,定性验证了模型的准确性。重点考察了煤油排出过程两种喷入结构的气液两相流分布以及煤油结冰可能性。研究结果从机理上解释了实验现象,并为煤油贮箱增压排出方案设计提供了参考。     

Experimental study of helium leakage parameters in flexible composite

The helium leakage characterizations of flexible composites are experimentally studied in this article. Three data processing techniques (Defining method, Fourier series method, and Fast series method) are used to evaluate the helium leakage parameters including the diffusion coefficient D, the solubility S, and the permeant rate k. The chamber pressure variation for helium permeation in flexible composite is measured by the differential pressure method. The results indicate that Fast series method is an effective technology in extracting the helium leakage parameters for flexible composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚酯装置的真空系统检漏技术探讨

根据聚酯装置真空系统特点,讨论了在开车前的冷态氮气加压试漏、热态氟利昂加压试漏和热态真空氦检漏技术。结果表明:通过多次检漏并消除聚酯装置漏点,确保真空系统无泄漏,保证在开车和正常运行过程中真空系统的气密性,使装置开车顺利,运行稳定。     

Effect of insulation layer for thermal shock in cryogenic composite laminates

The structural weight of a cryogenic propellant tank for reusable launch vehicles (RLVs) can be effectively reduced by the use of advanced composite materials. However, microscopic damage such as transverse matrix cracks (TMC) and delaminations are prone to develop in composites well below the load levels that would result in mechanical failure. This microscopic damage leads to a leakage path for the fuel. The leakage is influenced by many factors including connectivity of the cracks, residual and service‐induced stresses, and composite stacking sequence. This article is concerned with the effect of thermal gradients due to sudden exposure to a cryogenic temperature with and without insulation layer. An investigation of the insulation layer for sudden exposure to cryogenic temperatures is conducted numerically. The exposure of the harsh environment could make the damages such as delaminations, TMC, and leakage path. The defects from manufacturing could be formed, and they are critical parts under sudden exposure to cryogenic temperature. Therefore, the qualitative analysis for insulation technique is needed. The results from this article are very important because the stress levels which cause damages can be predicted and also controlled using the insulating techniques. The insulation skill which can suppress the stress levels is newly introduced in this article for RLV cryogenic fuel tank. Moreover, the effect of lay‐ups is also investigated in this article. The thermal gradient can be controlled by using different lay‐ups. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Electric Strength of Polymers Under Vacuum at Cryogenic Temperatures

Abstract

The electric strength of solid polymers under high vacuum is investigated at a temperature ranging from 293°K down to that of liquid helium (5°K) under power frequency alternating- and direct-voltages. The electric strength of polymers was found to be very dependent on the pre-breakdown partial discharges when measured in cryogenic medium whether gas or liquid. When helium was used as coolant, discharges may extend very far from the electrodes and thus exerted high electric stresses on large areas of the sample under test. These discharges may produce flash-over and serious troubles. It may also lead to localised breakdown of polymers which may give apparent reduction in dielectric strength.

A large increase in the electric strength of polymers was observed when used at cryogenic temperatures under vacuum; the increase was very significant for polyethylene and polyimide specially under direct voltages.

The results showed promising properties and it is concluded that the high vacuum will offer the solution to many insulation problems at liquid helium temperatures in cryogenic and superconducting equipment.