To study the impact of different gases and annular space vacuum levels on the thermal performance of multilayer insulation under vacuum failure conditions,an experimental platform was established.For a vessel wrapped with 50 reflective layers of variable density multilayer insulation,vacuum failure experiments were carried out at pressures of 10-1,10,102 and 103 Pa using N2,Air,Ar and CO2.The boil-off rates of cryogenic liquid and the warm boundary temperatures were measured,and the apparent thermal conductivity of the variable density multilayer insulation was obtained.The results indicate that,for the same gas,the apparent thermal conductivity increases with the decrease of vacuum level,especially obvious when the vacuum level is between 10-1 to 102 Pa.For different gases,when the vacuum level is 10-1 Pa,the apparent thermal conductivity of the multilayer insulation is highest when the interlayer atmosphere is air,followed by CO2,N2 and Ar.The magnitude order of apparent thermal conductivity is sequentially N2,Air,CO2 and Ar at the vacuum levels between 10 to 103 Pa.The relationship between the apparent thermal conductivity of different gases at various vacuum levels is inconsistent,which is caused by physical properties of the gases and the different heat transfer mechanisms under varied vacuum levels.This study provides theoretical support and data reference for exploring the mechanism of multilayer insulation under vacuum failure.
关键词
低温容器/真空失效/变密度多层绝热/表观导热系数/绝热性能
Key words
cryogenic vessel/vacuum failure/variable density multilayer insulation/apparent thermal conductivity/thermal insulation performance
维普
万方数据