Thermal Performance of Multilayer Insulation Down to 4.2 K

Abstract

The thermal performance of different types of multilayer insulation (MLI) down to 4.2 K is presented. A double guarded cylindrical boil-off calorimeter has been designed and fabricated to evaluate thermal performance of multilayer insulations between 300–77 K and 77–4.2 K. Studies on steady state heat flux between 300–77 K and 77–4.2 K of multilayer insulations as a function of number of layers and that of aluminum foil adhesive taped cold boundary (with no MLI) surfaces have been carried out. Use of aluminum foil adhesive tape over the bare copper surface has reduced the heat flux by a factor of ≅ 3 for both temperature ranges. Application of a few layers of MLI on the aluminum foil adhesive taped surface resulted in the decrease of heat flux for the 300–77 K range. On the contrary, it increased the heat flux for the 77–4.2 K range. The comparative performance of different types of insulations for both temperature ranges are discussed.