低温容器在水蒸气膜态凝结前后的绝热效果分析

绝热失效严重影响了低温容器的经济和安全运行。膜态凝结的出现是绝热失效最直接的表现。提出了用低温容器表面温度与空气露点温度的比较来判别低温容器的绝热是否失效的方法。理论上,分析了低温容器表面水蒸气膜态凝结出现前后的换热机理。在一个高真空多层绝热低温容器上进行了实验,测量并分析了水蒸气膜态凝结前后低温容器表面温度和液氮蒸发速度的变化。理论分析和实验均验证该方法对于判别绝热效果的有效性和可行性。

ANALYSIS OF THE INSULATION EFFECT OF CRYOGENIC VESSELS BEFORE AFTER THE FORMATION OF FILM CONDENSATION OF WATER VAPOR

The insulation failure seriously affects the economic and safe operation of cryostats. The formation of the film condensation is the direct representation of the insulation failure. A method using the comparison of the temperature of the cryogenic vessel outer surface with the drew\|point temperature of the air to judge the effectiveness of the cryogenic vessel vacuum is proposed. The heat transfer mechanics before and after the film condensation formation was analyzed theoretically. Experiments were carried out on a high vacuum and multiliayer insulation cryogenic vessel. The surface temperature and evaporation rates of liquid nitrogen before and after the film condensation formation were measued and analyzed. The validity and practicability of this method in judging the insulation effect is proved by results of the theoretical analysis and experimental study.