A Diffusional Model with a Moisture-Dependent Diffusion Coefficient

Abstract

Many investigators point out that a more realistic diffusion model is obtained when the effective diffusivity is considered with both temperature and moisture content dependent. Two mathematical models to predict the drying curves of pineapple at different temperatures have been compared. The simulation provided by model I, where the effective diffusion coefficient was considered as a function of the temperature, was unsatisfactory as indicated by the mean relative error (%E) of 19.8 ± 2.4%. The diffusion equation was modified by including both the effect of the temperature and the local moisture content on the effective diffusion coefficient in model II, being the %E of the simulation of 4.5 ± 2.0%.

Keywords:

• Drying
• Modeling
• Moisture dependent diffusion
• Pineapple

ACKNOWLEDGEMENTS

The authors acknowledge the financial support of CICYT (AGL2003–03889) and the Ministry of Education and Science of the Spain Government.