engleski

Influence of airflow velocity on kinetics of convection apple drying

The aim of this experiment was to investigate airflow velocity influence (0.64, 1.00, 1.50, 2.00, 2.50 and 2.75 ms^-1) on kinetics of convection drying of Jonagold apple, heat transfer and effective diffusion average coefficients. Drying was conducted in a convection tray drier at drying temperature of 60 °C using the rectangle-shaped (20x20x5 mm) apple samples. Temperature changes of dried samples, as well as relative humidity and temperature of drying air were measured during the drying process. Rehydratation was used as a parameter for the dried samples quality. Kinetic equations were estimated by using an exponential mathematical model. The results of calculations corresponded well with experimental data. Two well-defined falling rate periods and a very short constant rate period at the lower air rate were observed. With an increase of the airflow velocity an increase of heat transfer coefficient and effective diffusion was found. During rehydratation, around 72% of water removed by drying process was returned.

airflow velocity ; convection apple drying ; exponential drying model ; effective diffusion coefficient ; heat transfer coefficient

nije evidentirano