This paper is concerned with the integration of a heat and mass model with a population balance model of a fluid bed granulation process. The heat/mass model helps to track the liquid and porosity changes that occur within the granulation process due to simultaneous drying in the granulator. A mechanistic kernel proposed by [22] was used to model the aggregation process, which is a function of mechanistic properties such as liquid thickness and particle size. The model takes into account various mechanisms that significantly affect the granulation outcome, such as aggregation, drying/rewetting, and consolidation. Since these rate processes evolve dynamically, the aggregation kernel is updated periodically over time and for the first time, dynamically coupled with the heat/mass model to provide a more accurate qualitative description of granulation dynamics in a fluid-bed granulator. (C) 2012 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.