RADIAL HEAT TRANSPORT IN PACKED BEDS-II: MATHEMATICAL MODELING OF HEAT TRANSFER THROUGH PACKED BEDS AT ELEVATED PRESSURE

Packed bed reactors are often used in the applications in the process which need for the removal or supplying of heat. Modeling of fluid flow, heat transfer and reaction in packed beds is an essential part of their designs, there is especially for endothermic or exothermic reactions that occur at high pressure. Heat transfer in packed beds with fluid flow is important, whereas in these systems both reactor selectivity and velocity of reactions depend largely on bed temperature. Knowledge of temperature profile within the bed and the heat removal rate or which has been added is essential to achieve reactor productivity and product homogeneity. A mathematical model is developed to investigate the adequacy of the conventional equation used to describe the parameters which influences the temperature profile and wall heat transfer of a packed bed heat exchanger under high pressure up to 20 bars. The model equation provides comprehensive relation for predicting the wall heat transfer coefficient through the boundary layer that appears in the voidage between the wall and the random packing of solid particles in the bed and the effective radial thermal conductivity through the bed at elevated pressure. Predicted model equation have been compared with the experimental data of the temperature profile at different tube-particle diameter ratios for cylindrical pellets, inside the reactor tubes in which the only flow is air at high pressure