HOT AIR DRYING, IMPACT OF INFRARED DRYING, AND COMBINED HOT AIR- INFRARED DRYING ON ALFALFA DRYING QUALITY AND PERFORMANCE

This study analyzes the drying of alfalfa using hot air, infrared and combined drying techniques at different temperatures, irradiation heights and radiant powers. Different temperatures, radiation heights, radiation power and wind speed are used as control factors, and drying time, color, crude protein and specific energy consumption are used as evaluation indicators. After assigning weights to each indicator, the comprehensive evaluation index is calculated. Test results and data analysis show that the drying performance is optimal when the hot air flow velocity is 1.5 m/s, the hot air temperature is 62.1 degrees C, the radiation distance is 10 cm, the radiation power is 1200 w, and the material thickness is 20 mm, it has the best drying performance; its coefficient of determination R2 is 0.9995. The comprehensive evaluation index of alfalfa drying after combined drying is between 1.00 and 1.30, which is overall higher than hot air drying and infrared drying. Combined drying technology can effectively improve the efficiency and quality of the alfalfa drying process.