Mathematical modeling of the heat transfer process in a dense blown layer of granular material

Abstract

The object of research: a mathematical model of unsteady heat transfer between particles forming a dense layer in a heat exchange channel and an air flow passing through the layer.
 Investigated problem: obtaining a mathematical model adequate to the physical phenomenon will significantly expand the field of research, reduce the time for determining the thermal characteristics of heat transfer and data processing.
 The main scientific results: an explicit analytical dependence is obtained that allows calculating the local temperature of the layer in an arbitrary cross-section of the channel at selected moments of time. The presented analytical dependence was verified by analyzing the calculated data on the material temperatures in the channel obtained by varying the main physical quantities: the effect of the heating duration, heat transfer coefficient, porosity, and density on the temperature distribution was studied. The temperatures along the length of the channel were calculated at different points in time with the following initial data: material - gravel: c=860, ρ=1500, λ=0.6, ε=0.4; aud=800. Based on the results of the calculations for the time τ=60 s, τ=900 s, τ=1800 s, τ=2400 s, τ=1800 s, the graphs shown in the paper are constructed. It is shown that the mathematical model adequately describes the process of heating a layer of granular material in a heat exchange channel and allows obtaining satisfactory data on the temperature distribution along the length at different points in time. The calculated data correlate satisfactorily with the experimental results.
 Innovative technological product is an analytical dependence obtained for the first time, which is necessary for inclusion in the calculation method of regenerative heat exchangers intended for the utilization of low-potential heat flows.
 The area of practical use of the research results is the heat engineering calculations of regenerative heat exchangers with a dense granular packing. The consumers of the developed regenerators are greenhouses and food industry. Such industries are characterized by a low-potential level of thermal emissions, the heat of which is difficult to utilize using existing heat exchange equipment.
 Scope of the innovative product: design bureaus focused on the design of innovative heat exchangers for the utilization of low-potential heat flows, and research laboratories studying the processes of heat exchange between a dense layer of granular material and a through gas (air) flow.