Heat Transfer Between Gas-Solid Phases Within Packed Particle Beds

Abstract

A new method is presented to determine the internal heat convection coefficients for air flowing steadily through a bed of spherical particles. In this technique, a series of step change experiments are carried out on beds of glass beads of different diameters that are subjected to a temperature step change in the inlet airflow at different flow rates. Thermocouples are arranged along the particle bed height to record the particle temperature distribution and inlet/outlet air temperatures at any time. A theoretical energy analysis of particle beds to determine the convective heat transfer coefficients is performed for the short time duration when the experimental data show that temperature distribution along the airflow direction at any time is almost spatially linear and the temperature at any specific position is almost temporally linear. The energy change of the particle beds within this time duration is shown to be a function of the heat convection coefficient. Therefore, a new correlation, in terms of Nusselt number versus Reynolds number (, with uncertainty limits at 95% confidence level, is developed and found to be in good agreement with most other correlations developed by other researchers for beds of similar spherical particles.