Design and Experiment of Tea Fresh Leaf Sorting Equipment Under Double Negative Pressure Airflow Field Based on <scp>CFD</scp> ‐ <scp>RSM</scp> Coupling Optimization

In response to the demand for sorting fresh tea leaves according to the mass gradient, this paper designs a double negative pressure air-suction sorting equipment; this equipment is composed of a double negative pressure fan unit, a multi-hole turntable adsorption system, a tea dropping cabin system and a conveyor belt system. Based on Computational Fluid Dynamics (CFD), the airflow field in the equipment was simulated, and the flow field characteristics under different combinations of negative pressure values (Group A: 380/380 Pa, Group B: 320/320 Pa, Group C: 380/320 Pa, Group D: 320/380 Pa) were analyzed. It was found that the velocity gradient distribution of the flow field in Group A was uniform, which was suitable for the sorting of fresh tea leaves at multiple scales. Through single-factor experiments, the influences of the rotational speed of the multi-hole turntable (20, 30, 40, 50 r/min), the initial lateral distance of the blade drop from the negative pressure port (30, 40, 50 mm), and the combination of the pressure values of the double negative pressure ports on the separation rate were studied. The results show that: The separation effect is better when the rotational speed is 30 r/min, the distance is 40 mm, and the pressure is 380/380 Pa. The Box-Benhnken response surface method was further adopted to optimize the parameters, and a regression model of the sorting rate (<i>R</i> ² = 0.9980) was established. The optimal parameters were determined as follows: the rotational speed of the turntable was 30 r/min, the horizontal falling distance was 35 mm, and both the upper and lower negative pressure ports were 380 Pa. The verification test score selection rate was 77.5%. This study provides a theoretical and experimental basis for the development of efficient sorting equipment for fresh tea leaves. Subsequently, the influence of factors such as the position of the negative pressure port and the vertical distance on the sorting rate can be further explored.