MODEL OF THE STRUCTURE OF FIBROUS SYSTEMS FOR THE STUDY OF THERMOPHYSICAL PROPERTIES
The calculated thermal conductivity ratio is obtained for the material under the assumption that the unit cell is represented in the form of a parallelepiped with non-equal edges of the two-phase material. The existence of a minimum function of the dependence of the thermal conductivity coefficient on porosity is also shown, and its numerical evaluation is carried out. The results obtained are of interest when using composite materials as thermal insulation in non-stationary processes. The heating or cooling time of an object with composite thermal insulation will be maximum when the porosity values are in the range from 0.5 to 0.8.