In this study, a numerical model for heat and mass transfer in the differential pressure precooling of peaches stored in layered packaging under different precooling conditions was constructed based on computational fluid dynamics. Through the analysis of experimental and simulation data, it was found that the maximum root mean square error (RMSE) between the constructed numerical model and the experimental group was 0.7967 ℃, and the mean absolute percentage error (MAPE) was 6.74%, which demonstrated the feasibility and authenticity of the modeling method. The precooling efficiencies of two air supply velocity modes were compared, demonstrating that compared with the constant velocity mode, the variable velocity mode ΔP₁ + ΔP₂ improved the uniformity of precooling and shortened the cooling time, and there was a sevenfold threshold relationship between ΔP₂ and ΔP₁. When ΔP₂ was more than seven times as high as ΔP₁ (ΔP₁ < 35 Pa), the uniformity of precooling was improved by about 10%–20%, and the precooling time was shortened by 50%-75%; however, the energy consumption cost increased by at least 8 times, and it increased exponentially with ΔP₂. Therefore, the variable velocity mode should be selected when priority is given to the precooling quality and the transfer time to cold storage; in which (15 + 105) Pa is the optimal environmental parameter combination for peach precooling, while the constant velocity mode should be selected to achieve energy savings in precooling. This study provides a theoretical reference for small and medium-sized orchards to reasonably select air supply modes and accurately control the precooling efficiency of fruits.

The objective of this study was to explore the effect of the vent mode of corrugated boxes universally used in the market on the precooling performance of layered peaches and to determine the functional relationship between the precooling environmental parameters and the precooling efficiency and the optimal vent mode under different differential pressure precooling working conditions in order to realize the rapid energy-saving precooling of peaches after harvest. A numerical model of heat and mass transfer during differential pressure precooling with circular and rectangular vents (abbreviated as CV and RV, respectively) was established based on computational fluid dynamics. By comparing and analyzing the experimental and simulated data, it was found that the maximum root mean square error and mean absolute percentage error between the two vent designs were 0.799 ℃ and 6.6%, respectively, which fully verified that this numerical model had high prediction accuracy. Through in-depth exploration of the temperature and flow field distribution in different vent modes, it was found that CV exhibited inferior precooling uniformity when compared with RV. Nevertheless, CV demonstrated a notable reduction in precooling time by 30%—40% and a decrease in fan energy consumption by 50%. Additionally, their relationships with differential pressure were described by. Based on these obtained results, the precooling quality of peaches could be improved by using RV, and the precooling cost could be reduced by using CV. To simultaneously achieve these two goals, the diameter of CV should be greater than 35 mm. This study provides a theoretical reference for the reasonable selection of vent parameters and accurate monitoring of fruit precooling performance in small and medium-sized orchards.