不同送风方式下樱桃压差预冷的数值模拟

Numerical Simulation of Pressure Difference Pre-cooling of Cherry in Different Air Supply Modes

预冷时间对樱桃的贮藏期有着重要的影响,故合适的压差预冷方式成为预冷的研究重点。本文建立了水平送风与垂直送风的樱桃压差预冷数学模型,分析了两种不同送风方式下不同风速下包装箱内部的压力损失、预冷时间、均匀程度的变化情况。模拟结果表明:樱桃的预冷时间随送风速度的增加而减小,压力损失随风速的增加而增大,两者与送风速度的拟合关系均为幂函数;同时樱桃的不均匀度也受送风速度的影响,两者呈正相关;在送风速度6~16 m/s范围内的垂直送风的不均匀度仅为水平送风的75%左右。综合预冷时间、压力损失和均匀程度可以得到水平送风与垂直送风的最佳送风风速分别为9.3 m/s与12.7 m/s,压力损失分别为94.8 Pa与87.9 Pa,预冷时间分别为48.10 min与45.89 min,不均匀度分别为0.412与0.330。即垂直送风的预冷方式在樱桃压差预冷方面有一定的优势。

The pre-cooling time of cherries has an important influence on the storage period of cherries,so the appropriate differential pressure pre-cooling mode has become the focus of pre-cooling research.This paper established a mathematical model for the differential pressure pre-cooling of cherries in horizontal and vertical air supply,analyzed changes of pressure loss,precooling time and evenness inside the packing box at different wind speeds in two different air supply modes.The simulation results showed that the pre-cooling time of cherries decreased and the pressure loss increased with the increase of air supply velocity.The fitting relationship between the above two factors and the air supply velocity was a power function.At the same time,the unevenness of the cherry was also affected by the air supply velocity with a positive correlation.The unevenness of the vertical air supply in the range of wind speed of 6~16 m/s was only about 75%of the vertical air supply.Comprehensively considering the above three factors,for horizontal and vertical air supply modes,the optimum air supply velocity were 9.3 m/s and 12.7 m/s,pressure loss was 94.8 Pa and 87.9 Pa,pre-cooling time was 48.10 min and 45.89 min,and unevenness was 0.412 and 0.330,respectively.So the pre-cooling method of vertical air supply had certain advantages in cherry differential pressure pre-cooling.