Determination of Optimum Performance Characteristics of Combined Infrared- Convectional Dryer in Drying of Banana Slices

 Producing any dried product with acceptable quality is one of the main processes in the postharvest engineering. Several researchers reported the high quality of the product dried with new drying methods such as combined infrared-convectional drying methods compared with ones dried with convectional dryers. Evaluation of drying method and their effects on dried product could increase the quality of the final product and be used in designing and engineering of dryers. In this research, a constructed combined infrared-convectional dryer was evaluated at the various drying temperatures for banana slices with various thicknesses at the constant air temperature. The experiments were performed to calculate the values for effective moisture diffusivity, shrinkage percentage, and rehydration ability of banana slices. The drying duration of the slices with a thickness of 4 mm was 83 min at the infrared drying temperature of 75 °C, the air velocity of 0.7 ms-1 and the air temperature of 50°C. The effective moisture diffusivity was varied from 5.81×10-10 to 2.14×10-9 m2 s-1; as a function of drying temperature and slices thickness. The results indicated that the effect of slice thickness was significant on the rehydration ability of dried products. The drying temperature and the slice thickness had no significant effect on the shrinkage of the slices. This property was increased linearly as a function of moisture content. Therefore, it is not essential to consider the shrinkage as a function of temperature and thickness during the simulation process.