Experiment on using modified annular jet pump to deliver different fruits and vegetables

Abstract: With the development of agricultural industry, the requirement of fruits and vegetables conveying is increasing, the traditional way of gradually conveying fruits and vegetables cannot satisfy demand. As a result, the improvement or innovation of the way of fruits and vegetables conveying is particularly important. Compared with the traditional way of fruits and vegetables conveying, the use of annular jet pump (AJP) for fruit and vegetable conveying have the advantages of nondestructive, reliable, fast and strong adaptability, etc. In this study, we conducted experiments to search the performance of annular jet pump with the throat diameter of 60 mm and area ratio in 1.75 and 3 to measure its transmission capacity for transporting different fruits and vegetables (potato, carrot, cherry tomato and kumquat) under different conditions. We also analyzed the effect of various factors (flow, head, and fruit and vegetable species) on the transmission capacity, recorded and analyzed the damage in the process of conveying fruits and vegetables. Considering the characteristics of the fruits and vegetables conveying, a conical net tube was used to centralize fruits and vegetables with extremely low possibility of mechanical damage and the lift of AJP was used to control the outlet pressure instead of the outlet tube valve, which avoided potential mechanical damage on fruits and vegetables. Based on the experiments, we demonstrated the impacts of flow ratio and the lift of AJP, as well as different fruits and vegetables on the capacity in fruits and vegetables conveying. The experimental results show that: 1) the maximum transmission capacity of potato, carrot, cherry tomato and kumquat were 3 038.13, 2 158.83, 2 302.92, 1 949.50 kg/h, respectively. The performance of transmission capacity of four fruits and vegetables changes with flow ratio was similar. The transmission capacity increased with the increase of flow ratio under the same area ratio and lift of AJP because the secondary flow rate increased and pressure decreased. Energy consumption per unit mass changed little under small flow ratio but increased sharply under big flow ratio when the hydraulic power continuously increased; 2) the transmission capacity decreased with the increase of lift of AJP under the same flow ratio and area ratio because the secondary flow rate decreased and pressure increased; 3) conveying fruits and vegetables with ellipsoid shape was easier than fruits and vegetables with elongated shape, conveying fruits and vegetables with large density was easier than fruits and vegetables with low density; 4) there was no damage in the process of conveying cherry tomatoes and tomatoes when there were scratches on the surface of the potatoes and carrots. The maximum mass loss rates were 0.13% and 0.21% and the maximum surface loss rates were 0.68% and 1.20% for potatoes and carrots, respectively. Consequently, the main contribution of our work was to demonstrate the influence of flow ratio, H, and different fruits and vegetables on the transportation of fruits and vegetables and to discuss the potential damage risks caused by operation conditions for fruits and vegetables in the AJP. More importantly, the present paper proves the potential of AJP for fruits and vegetables conveying and provides references for the optimization of AJP, which aims to minimize the fruits and vegetables damage rate and improve the transportation capacity of fruits and vegetables.