Thermal analysis of vacuum-shield multilayer insulation

A method is presented for calculating heat transfer in vacuum-shield multilayer thermal insulation, taking into account the interaction of the radiation and molecules with the heat-sensing surfaces of the system within the framework of a specular-diffuse reflection model. An arbitrary number of coaxial cylindrical (or concentric spherical) bodies is considered, the length of the bodies being much greater than the diameters. The inner and outer cylinders have specified time-invariant temperatures and the radiation and accommodation properties of the surfaces are known. Shields, which have perforations distributed uniformly over the surfaces, are placed between the cylinders. It is assumed that the distance between the cylindrical surfaces is greater than the radiation wavelength corresponding to the Wien displacement law and smaller than the molecular mean free path. Results include: (1) the resultant heat flux in systems with different numbers of shields, (2) the molecular component of the resultant heat flux on the shield, and (3) the temperature distribution of the shields in multilayer insulation systems.