Abstract:The fruits and vegetables pre-cooling effect and power consumption are greatly influenced by the supply air temperature of pre-cooling process. The heat transfer model of tomato was developed by theory of heat transfer and used to predict tomatoes of different diameters temperature change during the different temperature pre-cooling process. Then pre-cooling experiments of tomato were performed with the developed pre-cooling experiment setup. The relationships between supply air temperature, tomato diameter and temperature change rate of tomato, pre-cooling system power consumption were studied based on theoretical analysis and experimental data. The results show that the mean error between simulated and measured temperatures of tomato center was 0.685 ℃, so that the heat transfer model of tomato can be used to predict pre-cooling time effectively. Besides, pre-cooling time of tomato increases with the increase of supply air temperature and tomato diameter, pre-cooling system power consumption increases with the decrease of supply air temperature. Finally, the optimization pre-cooling scheme of variable supply air temperature is proposed according to the above analysis results. The supply air temperature remains 4 ℃, 2 ℃, 0 ℃ during process of the tomato center temperature dropping from 26 ℃ to 15 ℃, 15 ℃ to 10 ℃ and 10 ℃ to 5 ℃, respectively. The optimized scheme can save energy 9.7% to 14.8%, compared to constant temperature pre-cooling schemes.