Influence of Opening Size and Position on the Performance of Forced-Air Precooling of Apples

Abstract

In this article, to investigate the comprehensive influence of the opening size and location of the packing box on precooling performance, a simulation model of precooling with 20 opening parameters is established based on computational fluid dynamics. There are six openings on one side of the box, 12 in total, with 5 opening positions (Cases 1–5) and 4 opening sizes, each with an opening size and corresponding total opening area of 15 mm (2120 mm²), 30 mm (8482 mm²), 45 mm (19,085 mm²), and 60 mm (33,929 mm²). The results show that when the diameter of the opening is 15–60 mm, increasing the opening increases the precooling time, and Case 4, which moves the position of the openings on both sides to the left and right, reduces the precooling time. Increasing the opening does not necessarily improve precooling uniformity at different opening positions. Case 5, with the position of the two side openings moved toward the center, had the worst precooling uniformity for each opening size. The larger the opening, the lower the precooling energy consumption for a given opening position. This is because the reduction in power at increased opening is much greater than the increase in precooling time. When the opening size is certain, the reasonable opening position can reduce the precooling energy consumption. Case 4, 30 mm is more balanced overall. Therefore, the opening parameter has a large impact on the precooling performance, and it is necessary to select the opening parameter reasonably for different requirements.