Modeling and experimental study on combination of foam and variable density multilayer insulation for cryogen storage.

A combination of polyurethane foam and multilayer insulation is adaptive and qualified for cryogenic propellant storage application, both on orbit for long-duration mission and on earth before and during launching. A generalized layer by layer model has been proposed to predict the thermal performance of the “Foam - Variable Density Multilayer Insulation combination” (FMLI) at different vacuum levels. A cryogen boil-off calorimeter system was designed and fabricated to measure the temperature profile and the apparent thermal conductivity of FMLI samples over a wide range of vacuum level (10 −3 - 10 5 Pa). The experimental data verified the validity of the model and indicated that the heat fluxes through the FMLI and the single VDMLI almost made no difference in vacuum of 10 −3 Pa, which were both equal to 0.23 W·m −2 with the boundary temperatures of 77 and 293 K, respectively. However, at the atmosphere level of 10 5 Pa, the heat fluxes through the FMLI and the single VDMLI significantly differed from each other and exacerbated to 45.2 and 147.8 W·m −2 , respectively. In addition, a comparison between FMLI and Aerogel-MLI was also conducted for the same thickness and weight of VDMLI and at the same boundary temperatures and vacuum levels. [ABSTRACT FROM AUTHOR]