Shorting drying time of Hami-melon slice using infrared radiation combined with air impingement drying

Abstract: In order to reduce the drying time, the middle short-wave infrared radiation combined with air impingement drying was used to dry Hami-melon slices in this study. The effects of drying temperature of 50, 60, 65, 70, 75, and 80℃, radiation distance of 80, 120, and 160 mm, and sample thickness with 3, 5, 7, 9, and 11 mm, moisture effective diffusivity, and drying activation energy of Hami-melon slices were investigated through a series of experiments. Results indicated that the drying time of Hami-melon slices by infrared combined with air impingement drying was about 2-3.5 h. The drying time was decreased when compared with other drying technologies. The whole drying process occurred in the falling rate drying stage. The moisture effective diffusivity determined by Fick's second law varied from 10.65×10-10 to 33.76×10-10m2/s and from 8.06×10-10 to 39.97×10-10m2/s with increasing drying temperature and sample thickness, respectively. The drying activation energy was 7.788kJ/mol calculated based on Arrhenius equation. The energy needed to trigger drying is very small, drying can be operable easily using the middle short wave radiation combined with air impingement drying technology. The kinetics of surface temperature changes indicated that it increased quickly in the initial and middle drying stages and the drying process was accelerated due to the energy directly combined with water. This paper provides theoretical background and technical information for applying the middle short wave infrared combined with air impingement drying on Hami-melon slices.