Investigation of Heat-humidity Transfer in High-porous Gas-filled Polymers to Calculate Its Heat Conductivity

A method for calculating the effective thermal conductivity of moisture-containing highly porous foamed polymers is proposed. In this method a non-additive scheme for taking into account the effect of steam diffusion on heat transfer is used. The sequential binary systems (interstitial substance from a liquid and a vapor- gas mixture, as well as a polymer skeleton and an intra-porous substance) are described by models of structures with interpenetrating components and isolated inclusions. The conditions for the transition from one model of structure to another are defined and there is not necessity to define empirical coefficients. A geometric model of wet foamed polymer has been developed, that allows us to find a way to determine the value of the boundary moisture content of pores or wetting angle at which the transition from partial wetting of the surface of the pores with liquid to full wetting and vice versa occurs. A mathematical description of the process of heat transfer in the model structure of a wet foamed polymer has been made, taking into account the diffusion of water vapor in the pore space.