Mathematical Description of the Heat Exchange Process between Gas Flows and Disperse Material

Heat exchangers of contact type have a number of undoubted benefits in comparison with heat exchangers of surface type. Features of contact heat exchangers is the transfer of heat through direct contact of working bodies. The main advantages are the high intensity of heat transfer processes due to the developed heat exchange surface, the absence of the separation wall, the simplicity of design. The subject of the study is a heat recovery exchanger, in which heat exchange is carried out between gas flow and dispersed material. The importance of knowledge about the influence of individual factors and conditions on the temperatures distribution and heat exchange efficiency determine the need to construct the appropriate mathematical models. A two-component model describing heat exchange between gas and particle flows in a differential form is presented. As a result of its solution, analytical dependencies for calculating the temperatures of gas and solid components in the conditions of the steady-state regime for a direct-flow and countercurrent motion scheme were obtained. The results of calculations of component temperatures for two types of dispersed materials, gravel and expanded clay are presented. The obtained dependencies make it possible to study the processes of heat exchange analytically and can be proposed to assess the effect of geometric and physical characteristics on the efficiency of heat recovery exchangers, in which flows of gas and dispersible material interact.