A boundary element method for evaluation of the effective thermal conductivity of packed beds

The problem of evaluating the effective thermal conductivity of random packed beds is of great interest to a wide-range of engineers and scientists. This study presents a boundary element model (BEM) for the prediction of the effective thermal conductivity of a two dimensional packed bed. The model accounts for four heat transfer mechanisms: (1) conduction through the solid; (2) conduction through the contact area between particles; (3) radiation between solid surfaces; and (4) conduction through the fluid phase. The radiation heat exchange between solid surfaces is simulated by the net-radiation method. Two regular packing configurations, square array and hexagonal array, are chosen as illustrative examples. The comparison between the results obtained by the present model and the existing predictions are made and the agreement is very good. The proposed BEM model provides a new tool for evaluating the effective thermal conductivity of the packed beds.