This paper presents a transient three-dimensional CFD model of heat and mass transfer in porous bulks of particulate foodstuffs. The mass, momentum and energy equations were solved to predict the air flows, temperature and moisture changes of the air and solids. The interaction between the air flows and the porous media were described by the Ergun equation. Moisture diffusion and heat transfer within the solids was predicted assuming the solids to be spheres, and the heat of respiration was included in the model as an empirically derived function of temperature. The predicted and measured temperature profiles across a bed of potatoes with a height of 2.4 m and a diameter of 0.7 m during forced cooling, from 15.5 degrees C to 6 degrees C, show similar spatial and temporal variations with a maximum difference of 1.4 degrees C. Predicted weight loss of the bed in a 4-day test period was within 5% of the measured value.