SIMULATION OF SUPERHEATED STEAM DRYING CONSIDERING INITIAL STEAM CONDENSATION

Abstract

A heat and mass transfer model was proposed for the superheated steam drying, focusing on phenomena which occur during the initial stage of drying, i.e., condensation of superheated steam on material surfaces and subsequent shift from condensation to evaporation leading to the beginning of the actual drying (Reverse Process Model). Next, drying equations considering the reverse process were formulated for a shrinking/swelling infinite flat plate to calculate moisture content and temperature distributions in a material, changes in mass of a material with time, and a characteristic drying curve. Then, the influence of the initial thickness of a material and the heat transfer coefficient were investigated. In addition, calculation results were compared with experimental ones with regard to the change in mass of material with time and the characteristic drying curve, and good conformance was obtained for the initial stage of drying.

Keywords:

• Characteristic drying curves
• Phase change
• Reverse process
• Numerical simulation

Acknowledgments