MATHEMATICAL MODELING OF THE PROCESS OF DRYING MEDICINAL PLANTS IN A SOLAR DRYER

Abstract

Experiments were made on drying medicinal plants in a solar dryer.
A new type of a solar dryer was used for this purpose. The solar dryer comprises an air collector, a drying chamber and an air circulation system. In course of the drying process, drying temperature, relative humidity, air flow velocity, solar radiation, and mass loss were continuously measured at different levels of the dryer.
Medicinal plants with an initial moisture content of 0.85 dry matter (kg water/kg dry matter) were dried to a final moisture content of 0.13 (kg water/kg dry matter) at different temperatures depending on changes in solar radiation. Drying time was studied as an exponential and polynomial relationship with moisture content. The effective diffusion coefficient varied at different levels of the temperature range.
Of all 11 empirical drying models used, the Midilli – Kucuk and Page models best fit experimental data. Similarly, the performance of the mathematical model was tested by comparing the correlation coefficient (R2), reduced x-square (X2) and root mean square error (RMSE) coefficients