The objective of this research was to study of rotary drying of high-moisture long pepper by using a combined hot air and infrared radiation. The experiment was carried out at the drying temperatures of 80 90 and 100 °C infrared power level of 500 W hot air velocity of 2.5 m/s and rotary revolution of 3 6 and 9 rpm. In this study two patterns were examined by the different drying conditions namely 1) hot air drying and 2) combined hot air and infrared radiation drying. The effects of above drying parameters on the change in moisture content of long pepper and specific energy consumption (SEC) of the drying system were investigated. The results showed that the combined hot air and infrared radiation drying was shorter drying time than hot air drying. The lowest total SEC during drying process of 26.77 MJ/kg water when the drying temperatures of 80 °C infrared power level of 500 W hot air velocity of 2.5 m/s and rotary revolution of 3 rpm were used.

This research is the study of microwave distribution in the drying chamber to develop the belt-conveyor microwave dryer. The dimensions of the drying chamber are 90 cm width 3 cm length and 30 cm height. Two 800 W magnetrons were installed at the top of the chamber. It was found that the uniform of microwave distribution was observed at the center area of drying chamber. The uniform microwave distribution in the drying chamber at 400 W is achieved. A microwave leakage from the prototype is within the microwave oven safety standard of the US Department of Health and Human Services. This study can be used as a guideline for an industrial design for belt-conveyor microwave dryer.