Optimizing variable-density configurations: A multi-objective study on multilayer insulation performance

Yao, Shuting

doi:10.1016/j.icheatmasstransfer.2026.112108

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Optimizing variable-density configurations: A multi-objective study on multilayer insulation performance

2026-07-01

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DOI：10.1016/j.icheatmasstransfer.2026.112108

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Abstract

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The number of density regions and the ratio of radiation shields within each density region for variable-density multilayer insulation (VDMLI) is the key to high vacuum insulation technology. To further improve the thermal performance of multilayer insulation (MLI) structure applied to cryogenic vessel, the NSGA-II-LINMAP method is employed in the optimization of VDMLI. The heat flux and the insulation thickness are defined as optimization objectives, and the optimal variable-density configurations under different working conditions are calculated. Additionally, the influences of different operating conditions on the heat flux as well as on the optimal variabledensity configuration are analyzed. The results show that the heat flux decreases with an increase in the number of radiation shields, a decrease in the hot boundary temperature, an increase in the cold boundary temperature, and a higher vacuum level. When the number of radiation shields is fewer than or equal to 50 layers, the MLI structure consists of medium-density region and high-density region, with the medium-density region accounting for 20% of the total radiation shields. When the number of radiation shields is more than 50 layers, the VDMLI transitions to a configuration of low-density region and high-density region, where the low-density radiation shields comprise 10% of the total radiation shields. Furthermore, for identical radiation shields, the heat flux for VDMLI is 12.51% similar to 16.10% lower than UDMLI; whereas for the same thickness, it reduces heat flux by 5.70% similar to 9.00%; for the same thermal insulation performance, the thickness of VDMLI is 5.37% similar to 8.47% thinner than the UDMLI.

Keywords:

Multilayer insulation

Insulation thickness

Optimized density regions

Layout ratio

NSGA-II

LINMAP