PARAMETRIC IDENTIFICATION OF THERMAL CONDUCTIVITY OF HIGHLY POROUS MATERIALS
UNDER THE INFLUENCE OF SPACE FACTORS 

Nikita O. Borshchev, Candidate of technical sciences, leading engineer, Astro Space Center Institutions of the Russian Academy of Sciences P.N. Lebedev Institute of Physics (53 Leninsky avenue, Moscow, Russia), E-mail: moriarty93@mail.ru 

Background. In this paper, a method for determining the thermal conductivity of a highly porous material for operating conditions during orbital flight is considered. This method is based on the classical approach of minimizing the standard deviation between the theoretical and experimental temperature field in the zones of installation of temperature sensors. Materials and methods. To do this, the "direct" heat transfer problem for a porous sample is first solved under orbital initial boundary conditions with preliminary spline construction taking into account the dependence of thermal conductivity on temperature. The heat exchange process inside the pores will be accompanied by radiant-conductive heat transfer. Next, the problem of minimizing the target root-mean-square error is solved. To do this, it is first necessary to find the components of the gradient of the target functional of the descent step, since this optimization problem is solved by the conjugate directions method, which allows achieving the required convergence in the minimum number of iterative approximations. Results and conclusions. The results showed that at this temperature level, the thermal conductivity coefficient will vary between 0,26–0,28 W/mK. The developed method and calculation results can be used in the design of heat-protective coatings. 

highly porous insulation, inverse thermal conductivity problem, conjugate directions method, thermal regime assurance system, radiation-conductive heat exchange 

Borshchev N.O. Parametric identification of thermal conductivity of highly porous materials under the influence of space factors. Nadezhnost' i kachestvo slozhnykh sistem = Reliability and quality of complex systems. 2022;(4):98–109. (In Russ.). doi:10.21685/2307-4205-2022-4-11