Integrated and load responsive multilayer insulation

Abstract

Multilayer insulation (MLI) is used to reduce heat leak into cryogenic systems such as tanks, dewars and instruments, and used to control spacecraft heat leak. MLI is typically used in a high vacuum (<10-3Pa) where its performance usually exceeds other insulations by 10-fold. Conventional MLI consists of layers of low thermal emissivity metalized polymer sheets separated by low conductance netting spacers. We report on an improved MLI in which the spacer netting is replaced by micro-molded polymer parts with low thermal conductance that provide controlled layer spacing. Integrated MLI (IMLI) is a precisely engineered insulation system with advantages over conventional MLI, including higher performance, more predictable performance, more robust, lower particulate contamination, optional electrical conduction and lower cost. A second novel insulation, Load Responsive MLI (LRMLI) is described which uses polymer spacers that dynamically respond to load, compressing to support a thin, lightweight vacuum shell under one atmosphere external pressure, and decompressing under reduced atmospheric pressure or vacuum for lower heat leak. Structural and thermal analysis and testing results are presented. IMLI and LRMLI performance are compared to conventional MLI and polymer Spray On Foam Insulation (SOFI). © 2010 American Institute of Physics.