The thermal insulation performance of variable metal coating multilayer insulation materials.

Multi-layer insulation (MLI), recognized for its superior thermal performance, is commonly known as 'super insulation'. Traditional MLI designing utilizes one single metallic coating as the reflective layer, neglecting the impact of temperature variations on metal emissivity. This paper proposes a novel approach, variable metalcoating multilayer insulation (VM-MLI), employing aluminum, gold, and copper as reflective layer materials. By adopting an enhanced layer-by-layer model, theoretical analysis of VM-MLI is conducted within the temperature range of 20–300 K, comparing its thermal insulation performance to that of conventional MLI under the same conditions. Additionally, this study examines the influence of layer density, area ratio f, vacuum pressure, and hot boundary temperature on VM-MLI's heat leakage. The results reveal significant reduction in total heat leakage with VM-MLI. Under the conditions investigated, the heat leakage of MLI is 0.6027 W/m2, while that of VM-MLI is 0.3936 W/m2 This represents a reduction in total heat leakage of 0.2091 W/m2,demonstrating approximately 35% better thermal insulation performance than that of the conventional MLI.