Selection and evaluation of thin-layer drying models for describing drying kinetics of garlic slices in an infrared dryer

To improving energy efficiency and increasing quality of dried product, a infrared dryer was constructed that can be used to dry fruits and vegetables. In this study, drying kinetics modeling of garlic in an infrared dryer was investigated. The effect of samples distance from the radiation lamp in three levels of 5, 7.5 and 10 cm and the effect of garlic slices thickness in the in three levels of 3, 6 and 9 mm on the mass transfer rate and effective moisture diffusivity coefficient during the dry process of garlic was investigated. To determine the appropriate kinetics model in the drying process, the drying curves can be analyzed under the defined conditions. Therefore, in this research, to investigate on the drying kinetics of garlic slices, the standard models were fitted to the experimental data. By increasing the distance of the samples from the heat source from 5 to 10 cm, the average drying time of garlic increased from 35.8 minutes to 37.3 minutes. By increasing the thickness of the samples from 3 to 9 mm, the average drying time of garlic increased from 22.7 minutes and 50.9 minutes. The effect of sample distance from infrared heat lamp and sample thickness on changes in effective moisture diffusivity coefficient of garlic was investigated and results showed that this coefficient values were increased with decreasing in distance and increasing samples thickness. By reducing sample distance from the lamp from 10 to 5 cm, it was observed that the effective moisture diffusivity coefficient increased from 2.71×10-9 m2s-1 to 3.63×10-9 m2s-1. The average effective moisture diffusivity coefficient of garlic slices for thicknesses of 3, 6, and 9 mm were 0.94×10-9 m2s-1, 2.72×10-9 m2s-1, and 5.54×10-9 m2s-1, respectively. In drying process modeling of garlic, the Midilli model with the highest coefficient of determination and the lowest