Heat and Mass Transfer Modeling of Recirculating Flows During Air Drying of Moist Objects for Various Dryer Configurations

Abstract

Heat and mass transfer during air drying of a rectangular moist object in a rectangular cavity is studied numerically through an implicit finite difference method for various configurations and aspect ratios. A number of geometrical orientations for various inlet and outlet stations of the drying air are considered for the cavity at different aspect ratios of 0.6, 1.0, and 1.66, respectively. Initially, the recirculating flow in the cavity is numerically predicted using the Fluent CFD package. Using these distributions, the local variations of the convective heat transfer coefficients around the moist object are determined. Subsequently, the temperature and moisture distributions inside the moist object are predicted for different periods of time through the present model using the code developed. It is found that the convective heat transfer coefficient varies from 0.48 to 17.82 W/m²K and 2.95 to 22.32 W/m²K, while the convective mass transfer coefficient ranges between 4.64 × 10⁻⁴ and 1.66 × 10⁻² m/s and 2.78 × 10⁻³ and 2.07 × 10⁻² m/s for various configurations and aspect ratios.

ACKNOWLEDGEMENTS

The authors acknowledge the financial support provided by Karadeniz Technical University Research Fund under grant no. 2004.112.003.01 and the Turkish Republic Prime Ministry State Planning Organization (DPT) under grant no. 2003K120750.