RADIATIVE TRANSFER IN VACUUM THERMAL INSULATION OF SPACE VEHICLES

An improved radiative transfer model for vacuum thermal insulations of space vehicles is developed. The effects of both the fibrous spacer between the metal foils and thin oxide layer on the foil surface are taken into account in the calculations of the integral radiative flux through the insulation. Parametric calculations at realistic values of the problem parameters indicate that absorption and scattering of thermal radiation by fibers do not lead to a significant decrease in the radiative flux. At the same time, even very thin oxide films on the surfaces of aluminum foils should be taken into account in engineering calculations. Theoretical estimates show that not even a very dense spacer made of metalized glass fibers with aluminum coating about 50 nm thick may lead to almost a twofold decrease in the integral radiative flux.