Modeling the Effect of Dryer Configurations on the Thin-Layer Solar Drying Kinetics of Ogbono Seeds (Irvingea Gabonensis)

Abstract

This paper aimed at modeling the effect of dryer configurations on the thin-layer solar drying kinetics of ogbono seeds. Ogbono seeds were dried using a solar drying system, which was a forced convection distributed type solar collector, equipped with a sun-tracking mechanism. The seeds were dried at four different tilt angles of 0, 5, 10, and 15°; two absorber plate thicknesses of 1.5 mm and 2.7mm; and a constant air velocity of 2 ms^-1. The drying data obtained from the experiment was fitted to six thin-layer drying predictive models. The effective moisture diffusivities at varying treatments as well as the activation energy of the ogbono seeds were determined. Results from the experiment revealed that the drying kinetics of the seeds varied with the different tilt angles and plate thicknesses. All the six drying models fitted fairly accurately with the drying data of ogbono seeds. However, the Wang and Singh model with the highest coefficient of determination (R²) value of 0.9994 and least Root Mean Squared Error (RMSE) value of 0.007 was the best-fitted model for the thin-layer solar drying of ogbono seeds. The effective moisture diffusivities determined for the seeds ranged from 2.03 x 10^-11 to 3.24 x 10^-11 m²s^-1. The research results revealed that these values increased with the absorber plate thickness of the dryer. The activation energy of 59.724 kJ/mol was determined for the ogbono seeds. The results obtained from this research showed that a solar drying system in alliance with a good predictive model could be employed in food processing industries for better dryer designs and more efficient product drying.

Keywords: Drying kinetics, forced convection, ogbono seeds, effective moisture diffusivity,

activation energy