球形果蔬差压预冷过程中质量损失分析

果蔬预冷过程中的质量损失是一个在传热影响下发生的传质过程，分析不同的影响因素对于减少预冷过程的质量损失具有重要意义。结合球形果蔬的集总参数传热方程，通过分析果蔬预冷时水分损失过程，推导了果蔬水分损失的热质耦合方程，包括了果蔬物性和预冷环境参数。在这基础上，分别分析了果蔬内部水分扩散率、预冷空气风速、预冷空气相对湿度对水分损失的影响。结果表明果蔬结构是决定因素，风速的影响对预冷时间明显，水分损失则受果蔬结构影响更大，并且随风速增大而减小。并通过苹果的差压预冷试验进行了验证，试验结果与理论分析结果具有相同的结果。

Analysis of weight loss of fruits and vegetables in forced air precooling

The water loss of fruits and vegetables in precooling is a mass transferring process affected by the heat transfer, it is important for reducing the weight loss of fruits and vegetables to analyze the affecting factors in forced air precooling. Combining with the integrate heat transferring equation of spherical fruits and vegetables, the coupling equation of heat and mass transfer of water loss was derived by analyzing the process of water loss of fruits and vegetables in precooling, including the factors of the parameters of fruits and vegetables and precooling conditions. The effects of the internal water diffusion coefficient, precooling air velocity and precooling air relative humidity on water loss were analyzed. The results show that the structure parameter is the key factor and the effect of the air velocity on the precooling time is significant. The water loss is mainly affected by the structure parameters of fruits and vegetables and decreases with the increase of air velocity. The result was verified by the experiment with apple, which had a similar result with the theoretical analysis.