Heat transfer between wall and packed bed crossed by low velocity airflow

Abstract Heat transfer between wall and packed bed (spheres, diameter 3.8 cm) crossed by low velocity airflow was studied. An approach, which distinguishes local temperature for fluid and solid phases, was used to characterize the heat transfer between wall and air and between wall and adjacent particles. It was found that the air velocity and the position along the wall are of great influence on the convective heat transfer between the cavity wall and air. A dimensionless correlation was proposed to predict the convective heat transfer coefficient. The conduction between products was quantified experimentally and an extrapolation of the results was proposed to estimate the conductive exchange between wall and product. The results obtained in this study (heat transfers between wall/packed bed) and that obtained in the preceding one (heat transfers within packed bed) were applied to modelling of heat transfer in a stack of food during air cooling in order to predict the product and air temperature change and the variation due to the position in the stack.

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