Modelling the thermal resistance of layered structures for blocking infrared radiation

Ensuring high thermal resistance of building, cladding, finishing and other materials helps to solve the problems of energy efficiency of buildings and energy saving in general. Typically, building and cladding structures have several layers. This makes it difficult to predict their heat transfer. To solve these problems, it is proposed to model the thermal resistance of layered structures. The mathematical functions that should be used in modelling are determined. In particular, the mechanisms of heat transfer due to thermal conductivity and radiant heat transfer are separated. The assumptions and simplifications in the calculations that are acceptable in terms of errors are determined. The use of glass fibres for blocking infrared radiation is theoretically substantiated. The thermal resistance of a layered structure with an arbitrary number of layers and different thermal properties of each layer was modelled. The modelling was carried out using COMSOL tools. Changes in the thermal state of the layered structure in space and time were obtained. The modelling results were verified. Samples of materials based on glass fibre were manufactured and tested using a standard thermal imager. It was found that such a three-layer glass fibre material actually completely blocks infrared radiation at an initial temperature of up to 40 °С. Comparison of the results with the efficiency of a standard thermal insulation product shows that the predominant mechanism for blocking infrared radiation in a glass fibre-based product is the scattering of infrared radiation. This opens up the possibility of using glass fibre fabrics both to increase the thermal resistance of building and finishing materials and to produce infrared camouflage.