气冷屏复合绝热结构传热分析及屏位优化

Heat transfer analysis of vapor cooled shield compounded insulation and optimization of shield's position

由气冷屏、聚氨酯泡沫和变密度多层绝热组成的气冷屏复合绝热结构是一种新型的高效热防护绝热结构,通过对不同环境条件下低温贮箱气冷屏复合绝热结构的传热机理分析,推导了气冷屏复合绝热结构中屏温与屏位的数值计算关系,并在此基础上根据漏热量最小原则对气冷屏复合绝热结构中的屏位进行了优化。结果表明,随着环境条件的不同,气冷屏复合绝热机理不同,气冷屏最优位置也不同。常温常压的地面环境,气冷屏置于SOFI与VD-MLI之间时,低温贮箱漏热量最小,绝热效果最优;真空且温度变化剧烈的空间环境,气冷屏置于VD-MLI最中间时,低温贮箱漏热量最小,绝热效果最优。气冷屏复合绝热结构可进一步降低空间低温贮箱的漏热量,同时能满足地面及空间环境使用要求。

The compounded insulation, which consists of vapor cooled shield insulation and SOFI/VD - MLI, is a r/ew and efficient thermal insulation technology of cryogenic storage tank. Through the analysis of the heat leakage at different arrangement of insulation configuration for cryogenic storage tank under various environmental temperature, a numerical calculation relation- ship between the temperature and the position of vapor cooled shield was established, and for a given compounded insulation, the position of vapor cooled shield was optimized on the basis of the numerical calculation relationship and the principle of minimum heat leakage. The result shows that the mechanism of heat insulation and optimal position of shield changes with the various envi- ronmental temperature. Under the ground stage condition of ambient temperature and pressure, when the vapor cooled shield is placed in the position between SOFI and VD - MLI, the heat insulation effect of the vapor cooled shield compounded insulation is the best, and in the space stage where is vacuum and temperature changes constantly, when the vapor cooled shield is placed in the middle position of VD - MLI, the heat insulation effect of the vapor cooled shield compounded insulation is optimal. There- fore, the vapor cooled shield compounded insulation can further reduce the heat leakage of storage tank to meet the use require- ments in both ground and space environment.