Authors

Abstract

To ensure optimum peach quality during precooling, air supply temperature within the precooled facility should be precisely controlled. Three-dimensional unsteady computational fluid dynamics (CFD) model was established in this research, taking air supply temperature as an influencing factor, a dynamic simulation of this model was performed based on Fluent, and its reliability was verified through experiments. Simulation results showed that the decrease of air supply temperature did not affect the 7/8ths cooling time (SECT) significantly, but shortened the cooling time of the fruit which was cooled from the initial temperature to a fixed temperature, especially when air supply temperature dropped below 4℃, its corresponding cooling time showed a trend of steady variation. Meanwhile, respiration rate of 6-8℃ was about twice as high as that of 2-4℃, its corresponding moisture loss was also increased by 34.71-39.74%. Thus, the range of 2-4℃ was more suitable for quick precooling peaches after harvest. Experiments showed that the root mean square error (RMSE) of 0.7 and 2.7 m·s-1 were 0.747 and 0.836℃, respectively. It could be seen that simulation results were in good agreement with experimental results, which fully verified the feasibility and high accuracy of this new modeling method. Finally, this study can provide a reliable reference for establishing an accurate precooling numerical model, and rationally optimizing air supply temperature range of fruits precooling experiment to maintain its high quality.

Abstract in Chinese

为保证蜜桃在预冷过程中的最佳品质，预冷设备内的送风温度须精确控制。本研究建立了三维果品非稳态的CFD数学仿真模型，以送风温度为影响因素，基于Fluent对该模型进行了动力学仿真，并通过实验进一步验证了该模型的可靠性。仿真结果表明：风温的减小并不会显著影响果品的7/8预冷时间，反而会缩短果品从初始温度降温至某一固定温度的冷却时间。当风温减小到低于4℃时，其对应的冷却时间将呈现平稳变化的趋势，而且风温为6-8 ℃时果品的呼吸速率约为2-4 ℃的两倍，其水分损失量也增大了34.71-39.74 %。由此可知，2-4 ℃的风温范围更适合蜜桃采后预冷。此外，模型验证实验表明：该模型在风温为2 ℃时，0.7和2.7 m·s-1的仿真和实验的均方根误差分别为0.747 和 0.836 ℃，模拟与实验结果的高度吻合充分证明了该新型建模方法的可行性和高准确性。该研究为建立高精准度预冷数值模型，合理优化果品预冷实验送风温度范围，保持其高品质提供了可靠的参考依据。