Dinzhos R. Thermophysical properties of polymer micro- and nanocomposite materials and analysis of the efficiency of their application for heat and power engineering equipment

The thesis is devoted to the thermophysical substantiation of the effectiveness of the use of polymeric micro- and nanocomposite materials for heat-and-power equipment of various purposes. A set of experimental and theoretical studies of the thermophysical properties of these composites with respect to their high- and low-heat-conducting modifications for a wide class of polymer matrices and fillers is performed. For polymer composite materials oriented to the production of heat exchange surfaces, crystallization mechanisms have been established for two stages of structure formation over a wide range of changes in the mass fraction of the filler and the cooling velocity of composites from the melt. The efficiency of the methods for obtaining polymeric composite materials based on the mixing of the components in dry form and polymer melt is compared. Series of polymer micro- and nanocomposite with a maximum operating temperature of 390 ... 470 K and thermal conductivity coefficients reaching a value of 57,5 W/(m•K) have been developed for heat exchange surfaces of various purposes. The researches concerning the efficiency analysis of application of the developed polymer micro- and nanocomposites have been performed for the creation of the main heat exchange equipment of the systems of deep utilization of the waste gases heat of boiler plants, namely, systems with water-heating heat utilizers for heating the return heating system water, with air-heating - for heating of the blown air and combined heat-utilization systems with water-heating and air-heating heat recovery units. Based on the results of the study of the temperature regimes of heat recovery equipment under considered, depending on the temperature of the exhaust gases, the choice of the appropriate micro- and nanocomposite materials is substantiated. A comparative analysis of the heat recovery equipment from traditionally used materials and these composites has been carried out and it is shown that the latter one has significant advantages in terms of basic heat engineering characteristics. The choice of polymeric micro- and nanocomposites for elements of auxiliary equipment of boiler plants with systems of deep utilization of heat of off-gases is substantiated.