In this study, the drying of mint was investigated under solar drying conditions with natural and forced convection modes. Solar drying of mint with both natural and forced convection modes occurred in the falling rate period; where no constant rate period of drying was observed. The drying rate of mint under forced convection was higher than that of mint under natural convection, especially during first hours of drying (first day). For forced convection, the rate of drying was the same in both direct and indirect drying, since the temperatures and the air velocity above the trays were almost the same.
To explain the drying behavior of mint, ten thin layer drying models were applied. The results showed that for natural convection runs, Diffusion approach and Verma et al. models were the best models able to describe thin layer solar drying of mint for both direct and indirect drying, respectively. For forced convection, Verma et al. model was the best model for thin layer solar drying of mint for both direct and indirect drying.
The values of the effective diffusion coefficients for the drying of mint (as a whole plant) ranged between 1.2 · 1011 and
1.33 · 1011 m2 s1.
Conflict of interest
The authors have declared no conflict of interest.
Compliance with Ethics Requirements
This article does not contain any studies with human or animal subjects.
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