A DEM-based heat transfer model for the evaluation of effective thermal conductivity of packed beds filled with stagnant fluid: Thermal contact theory and numerical simulation

Author(s)
C. Wang, L. Chen, M. Kamlah, M. Moscardini, S. Liu
Publisher
Elsevier
Source
International Journal of Heat and Mass Transfer
Keywords
Discrete element method, Effective Thermal Conductivity, Fluid-filled packed bed, radical, Thermal contact theory, Voronoi tessellation
Year
2019

The Effective thermal conductivity (keff) is one of the key thermal properties for packed beds in the presence of a stagnant fluid. In this study, a thermal discrete element model (DEM) based on the original Cheng-Yu-Zulli analytical model for mono-sized packed beds has been improved and implemented especially for mixed beds of different particle sizes or materials. In order to perform the DEM simulation for packed beds, a thermal contact theory considering three heat transfer mechanisms (solid contact conduction, solid-fluid-solid conduction and radiation) was derived and applied in the network of Voronoi cells obtained by radical Voronoi tessellation of the relevant beds. The numerical model was validated through a comparison with experimental results already reported in literature and a good prediction for the effective thermal conductivity was obtained for both mono-sized and multi-sized packed beds in a wide range of solid-to-fluid conductivity ratio. The model also showed a good performance to study the heat flow distribution as well as the coupled thermo-mechanical behavior of packed beds.

Keywords: Fluid-filled packed bed, Effective thermal conductivity, Discrete element method, Thermal contact theory, Radical,  Voronoi tessellation, 

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