Drying: principles and equipment calculation

This article is the first in a series devoted to the principles and calculations of industrial dryers, consisting of :

and "Hot-air convection drying" (parts 1 and 2).

"Other drying methods than hot air".

It is completed by three diagrams of humid air , , .

For practical aspects and dryer selection, please refer to the dossier written by Patricia ARLABOSSE (ENSTIMAC).

This first article describes the physical laws associated with the various drying principles, which can lead to quite different "hydrothermal histories" followed by the product, with consequences for the transformation of the product during the process, and therefore for its final quality. We'll provide you with the bases for calculating dryers, concerning heat and material balances, and the transfers that determine the duration of treatment and the size of installations. The appearance of porosity, the texture of the final product and/or its deformation during the process are also drying parameters to be considered.