Esmaeel Seyedabadi; Mehdi Aran; Abdolrahman Rahimian Boogar
Abstract
The drying characteristics of mallow (Malva sylvestris L.) in a microwave dryer were examined at different microwave power levels. To dry 30 g of mallow leaves, microwave power levels of 360, 450, 540, 720, and 900 W were used. The initial moisture content of samples was 6.31±0.01 g water/ g dry ...
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The drying characteristics of mallow (Malva sylvestris L.) in a microwave dryer were examined at different microwave power levels. To dry 30 g of mallow leaves, microwave power levels of 360, 450, 540, 720, and 900 W were used. The initial moisture content of samples was 6.31±0.01 g water/ g dry base. To determine the kinetic parameters, which were calculated by comparing the ratio of the difference between the initial and final moisture contents to the equilibrium moisture content, experimental data were fitted to seven distinct models. At various microwave power levels, the moisture diffusivity and energy consumption were measured. Based on the results, increasing microwave power from 360 to 900 W resulted in a drying time reduction between 14 and 5 minutes. A comparison of the proposed models demonstrated that the logarithmic model (MR= a.exp(-k.t)+b) provided the best fit because it had the highest coefficient of determination (R2), the lowest sum of squared errors (SSE), and the lowest root mean square error (RMSE). This model can therefore be used to estimate the moisture content of mallow leaves during microwave drying. Also, the maximum and minimum energy consumptions for drying with 360 W and 720 W microwaves were 84.0 and 67.5 W.h, respectively. Moreover, the effective diffusivity of mallow leaves varied from 1.098×10−10 to 3.532×10−10 m2/s for different microwave powers.
