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. (April 2019)

• Record Type: Journal Article
• Authors: Chen, Lei; Wang, Cong; Moscardini, Marigrazia; Kamlah, Marc; Liu, Songlin
• Is Part Of: International journal of heat and mass transfer. Volume 132(2019)
• Page Start: 331
• Page End: 346
• Publication Date: 2019-04
• Subjects: Fluid-filled packed bed -- Effective thermal conductivity -- Discrete element method -- Thermal contact theory -- Radical Voronoi tessellation; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2018.12.005
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: A thermal contact theory was derived and implemented into a DEM model. Effective thermal conductivity (ETC) tensor was derived. The model predicted the ETC consistent with experiments in a wide range. Heat flow distribution in pebble beds were investigated. Influence of packing structure and mechanical load on ETC were studied. Abstract: The Effective thermal conductivity ( k eff ) 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.