MATHEMATICAL MODELING OF FLUIDIZED BED HEAT REGENERATORS

Based on the two-phase theory of fluidization, a fairly rigorous model is developed to describe the dynamic behavior of fluidized-bed heat regenerators. This model takes into account the major hydrodynamic aspects of bubbling fluid beds. Based on the assumption that the gas leaves the bed in thermal equilibrium with the solids, a rather simplified model is presented. Exact analytical solutions are obtained for both models. The predictions of the more rigorous model are found to be in good agreement with many experimental observations. On the other hand, the simplified model gives satisfactory results only when the value of the parameter m₁is relatively large. Using the rigorous model, it has been shown that the bed thermal efficiency can be improved by reducing the time of operation, increasing the mass of solids or decreasing the bed aspect ratio. Also it has been found that when the gas flow-rate is increased, the amount of heat transferred to the solids displays a non-monotonic behavior and passes through a maximum.