Kinetics of drying of Mint Leaves and Energy Consumption in Thermal Dryers Equipped with Nano-Adsorbents: Examination and Analysis

This study evaluated the performance of a thermal dryer with a closed air circulation system equipped with a metal-organic framework (MOF) system. Dryer sections included: product drying chamber, the MOF containing chamber nano-absorbents, measurement and control systems. Dryer yield on mint was compared at three temperature levels (40, 50, and 60 °C). Finally, the energy consumption and drying mint leaves was evaluated. The results showed that the closed air circulation system reduces the dry time by 27% to 50%, the penetration coefficient of mint leaves increased with increasing temperature. Its values in cases of not using and using nano-absorbent plates were determined respectively (4.05690×10-11) and (2.8215×10-10) m2/s. The activation energy in two methods of not using and using the nano-absorbents was 45.72 and 51.96 kJ/mol, respectively, which is consistent with the researchers' results. Also, the coefficient of performance, the rate of moisture evaporation, and the rate of specific moisture evaporation showed the effectiveness of using nano-absorbent in the dryer system and reducing energy consumption. The total color index (ΔE) did not change much with increasing temperature from 40 to 50 °C, but from 50 to 60 °C, the increased total color index. There wasn't a clear difference in total color index between the two methods of using and not using nano-adsorbent.