Parameter Optimization and Experimental Study of an Apple Postharvest Damage-Reducing Conveyor Device Based on Airflow Cushioning Technology

This study addresses inefficiencies in manual apple harvesting and high damage rates in mechanical methods by developing an airflow-cushioned conveyor to minimize postharvest losses. Analyzing apple dynamics in pipelines and collision mechanics identified three key damage factors: fruit size, conveyor linear velocity, and airflow speed. A Box–Behnken-designed response surface model linked these parameters to damage area and collision force. The results showed optimal settings for small (grade III: 11 m/min, 18.2 m/s; 34.24 mm2, 8.7 N), medium (grade II: 11 m/min, 19.01 m/s; 48.62 mm2, 9.52 N), and large apples (grade I: 11 m/min, 19.3 m/s; 67.01 mm2, 10.34 N). Under the optimal parameters, the damage rate for grade I apples was only 12%, while grade II apples had a 0% damage rate, fully meeting the grade II standards. This damage rate was significantly lower than the over 50% damage rate observed in vibration harvesting. Additionally, the harvesting speed using the optimized device increased by more than twice compared to traditional manual harvesting. The findings provide an engineering case for balancing fruit quality maintenance and harvesting speed improvement.