多层绝热材料抽真空阻力测试研究

Impact Factorson Effective Pumping Speed of Multi-Layered Insulation Structures in Cryogenic Containers

主要对真空绝热夹层抽空阻力的原因进行汇总分析,在综合考虑夹层抽真空过程处理工艺的基础上,制定出实验方案并设计制造一套多层绝热材料抽真空阻力性能测试装置,通过对比不同缠绕层数、不同层密度、有无打孔等因素对抽真空阻力的影响,分析阻力产生的机理及变化规律,研究表明:①随着测试厚度的增加,内、外部的真空度差值逐渐增大,动态平衡时间增长,内部压强平衡值逐渐增大,抽空阻力随之增大;②打孔纸的动态平衡值略低于无孔纸,层间气体的抽出路径主要是沿层间形成的纵向流道散出,层间少许气体可以通过反射屏打孔排出;③层密度过大或者过小都会增加抽气阻力以及使绝热层表观导热系数增大。

The effective pumping speed,of the multi-layered insulation materials of cryogenic container after baking at^100℃,was experimentally evaluated with the lab-built test platform.The influence of the properties of the sandwiched multilayer materials,including,but not limited to the thermal-conductivity/gap-width/number/perforation of the glass-fiber-paper/Al-foil bilayers,and surface cleanliness,on the effective pumping speed of desorbed gas was investigated.The results show that the perforation and bilayer number had a major impact.For instance,as the bilayer-number increased,the effective pumping speed decreased;the longitudinal interlayer gaps were the dominant gas-paths;the apparent thermal conductivity changed in a decrease-increase mode;the perforation promoted interlayer gases diffusion,significantly reducing the axial heat-leakage and weakly affecting the effective pumping speed.We suggest that our preliminary results be of some technological interest in design optimization of cryogenic container.