Теплообмін щільного шару сипучого матеріалу з зануреними поверхнями

Abstract

The paper presents the results of experimental studies conducted with the aim of determining the characteristics of the heat exchange of a dense layer of bulk material with surfaces and obtaining empirical dependences for average and local heat transfer coefficients during transverse flow through a dense layer of a submerged cylinder. Empirical dependences are valid in a wide range of changes in geometric and regime parameters within a satisfactory experimental error. The need for research in this area is due to the fact that most of the known literature data on heat exchange between dispersed material and the surface describes heat exchange with flows at a low concentration of dispersed material (dusty flows, gas suspension, fluidized beds). The heat exchange of a dense layer with a surface is devoted to a rather limited number of works carried out in the seventies and eighties, but even in these works there are contradictions not only of a quantitative, but also of a qualitative nature. In the presented work, the research was carried out on an experimental installation, made in the form of a rectangular vertical mine, in which, under the action of gravity, bulk material enters in the form of a dense layer. Determination of heat transfer coefficients was performed using the methods of stationary and regular thermal regimes. As a result of the generalization of experimental data, criterial dependences were obtained, which allow thermal calculation of tubular heat exchangers for heating (cooling) bulk materials moving in the form of a dense layer. The resulting dependencies are important for the chemical industry, at non-ferrous metallurgy enterprises, during heat treatment of materials and in other industries where there is a need to heat (cool) bulk materials in the relevant technological processes or for the purpose of heat utilization