真空失效对低温容器绝热性能的影响

Influence of Vacuum Failure on Heat-Insulating Property of Cryogenic Vessels

针对高真空多层绝热低温容器真空失效问题,建立不同真空度下的传热计算数学模型并搭建相应试验平台,使用干燥氮气作为破空介质开展真空失效试验研究。对几何容积120 L、初始充满率为50%的低温容器,分析其夹层真空度分别为10^(-3)、1、10^(2)、103 Pa时的排放量、压力及温度变化,并与理论计算结果进行验证。结果表明:低温容器压升率、排放量及气相温度随着夹层真空度的降低而升高;夹层真空度为103 Pa时低温容器热流密度分别为10^(2)、1及10^(-3)Pa时的1.32、12.96及122.21倍,最大排放量分别为10^(2)、1及10^(-3)Pa的2.15、9.69、13.77倍;随着夹层真空度的降低,低温容器的安全隐患逐渐加剧。

Aiming at the vacuum failure of high-vacuum multilayer insulated cryogenic vessel,this paper established a mathematical model for calculating the heat transfer of the annular space with different vacuum failure degrees.A test platform on the vacuum failure insulation performance of cryogenic vessels was built up.The experiment used dry nitrogen as leaking gas to fill the annular space of a 120 L cryogenic vessel with 50%initial filling rate.The boil-off gas,pressure and temperature variations were analyzed when the vacuum degrees of annular space were 10^(-3),1,10^(2),and 103 Pa.The results were verified by theoretical calculation.The result shows that the pressure rise rate,boil-off gas and the temperature of ullage in the inner vessels increase with the decrease of vacuum degree of annular space.When the vacuum degree is 103 Pa,the heat flow density of the cryogenic vessel is 1.32,12.96,and 122.21 times of that in 10^(2),1 and 10^(-3)Pa,respectively.The maximum boil-off gas is 2.15,9.69 and 13.77 times of that in 10^(2),1 and 10^(-3)Pa,respectively.With the decrease of the annular space of vacuum degree,the potential safety hazards of cryogenic vessels are gradually aggravated.