PERFORMANCE PREDICTION OF MULTILAYER INSULATION

Multilayer insulation (MLI), using alternate layers of shield and spacer material, is the most effective insulation developed so far for cryogenic applications. The effective thermal conductivity of MLI is a function of various parameters, such as shield and spacer materials, number of layers and layer density, contact pressure, vacuum maintained and interstitial pressure. This paper presents an analysis involving fabric spacer material. The model considers the heat transfer by various modes such as solid conduction, conduction through contact surfaces, radiation through the exposed area between adjacent shields and radiation through the fibrous spacer. Gas conduction has also been considered, taking into account the estimated interstitial pressure. Results are presented for the radiation mode alone, as well as for radiation, conduction and gas conduction considered collectively. © 1990.