Abstract:This study established differential pressure pre-cooling models for different grape varieties and analyzed the differential pressure pre-cooling processes.According to the heat transfer theory，a spherical analogy model and a porous medium model of grapes were established via the computational fluid dynamics（CFD）simulation software.The effects of air supply velocity，air supply temperature，packaging method，and fruit diameter on the pre-cooling effect and energy consumption of grapes during differential pressure pre-cooling were studied by combining single-factor experiments with orthogonal experiments.The results showed that the spherical analogy model could fully reflect the differential pressure pre-cooling process of the three varieties of grapes，and the maximum difference between the average temperature of the model and the experimental value was about 2.5 ℃.As the air supply velocity increased，the pre-cooling of grapes became faster，and the uniformity was higher.After normalization of processing time and energy consumption，the optimal air supply velocity was 1.3-1.5 m/s.As the air supply temperature increased，the time for grapes to reach 7/8 pre-cooling remained unchanged，while the uniformity at the end of pre-cooling became higher.According to the influences on pre-cooling time，pre-cooling non-uniformity，and fan energy consumption，plastic mesh boxes were selected for packaging.As the fruit diameter increased，the pre-cooling of grapes became slower，and the nonuniformity at the time reaching 7/8 pre-cooling became higher.On the basis of orthogonal experiments，the influences of factors on pre-cooling speed followed the trend of air supply velocity >packaging box >fruit diameter >air supply temperature，and those on pre-cooling non-uniformity were in the order of packaging box >air supply velocity >air supply temperature >fruit diameter.