Method of thermal calculation of a heat exchanger with a dense layer of granulated material

Abstract

The aim of the work is to develop a methodology for calculating the heat exchanger for the utilization of low-potential heat fluxes from industrial enterprises and its approbation. Methods of solution included the analysis of existing heat recovery devices, the identification of existing problems of creating efficient heat exchangers and the creation of an algorithm for calculating heat exchangers with a dense layer of granulated material. The possibility of using low-potential thermal secondary energy resources in the form of exhaust gases from industrial enterprises of low energy capacity, in particular, food, is considered. Heat exchangers with a fixed dense layer of granular materials are analyzed, providing direct heat exchange of gas (air) with particles. There is a shortage of developed efficient heat exchangers for low-potential heat fluxes and information on rational thermal modes of their operation. The effectiveness of the use of granular materials in heat and power engineering is noted from the standpoint of intensifying the processes of heat and mass transfer is shown. The method of thermal calculation of the contact heat exchanger to determine its geometric characteristics and the main process parameters is described. The proposed method takes into account the change in the coefficient of intercomponent heat transfer over time. The results of calculations of the main characteristics of an industrial heat exchanger with fixed filler are presented. In the regenerator with fixed filler there is no need to organize the movement of a layer of granular material, which greatly simplifies the operation and design of the heat exchanger. The results of the calculation of a fixed bed heat exchanger designed for space heating, located directly next to the ventilation channels of the enterprise, are presented. In the proposed heat exchanger in the heating period, the heat is transferred by direct contact of the gas flow with the material particles, and in the cooling period the heat is transferred from the outer surface of the heat exchanger to the environment. To obtain a smoothed heating characteristic of the room, it is advisable to duplicate the working channels of the heat utilizer filled with granular material and turn them on alternately. The calculated heat exchangers are characterized by a relatively high efficiency and the ability to work without direct contact of the particles with the air of the heated room. Designed for low-potential heat flux of regenerator designs are offered for use in food production plants