Numerical investigation of heat resistances in uniform dense granular flows along a vertical plate

Moving bed heat exchangers have been the economic alternatives for the granular flow in industries. To predict the heat transfer coefficients, a better understanding is required of the contact resistance (1/h(ws)) and the penetration resistance (1/h(so)). In this work, the heat transfer coefficients were simulated using the finite volume method to investigate these resistances in both ordered and random packing sphere particles. It was found that, the 1/h(ws) is determined by the effective thermal conductivity in the wall region, of which the thickness is around 3/22 particle diameters. Moreover, the 1/h(so) is affected by the heat capacity, thermal conductivities and particulate structures. The effect is reflected by two modified equivalent heat absorption coefficients (1/p(1) and 1/p(3)) in granular flows. Generally, p(1) is smaller in the ordered structure because the peak local solid fraction is higher, while p(3) is smaller in the random structure due to the lower average porosity. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, the heat transfer coefficients in ordered and random packing sphere particles were simulated using the finite volume method to investigate contact resistance and penetration resistance. It was found that contact resistance is mainly determined by the effective thermal conductivity in the wall region, while penetration resistance is affected by heat capacity, thermal conductivities, and particulate structures. The impact is reflected in the modified equivalent heat absorption coefficients in granular flows.