基于CFD技术的预冷参数对盒装荔枝微环境温湿度的影响

Effect of CFD Technology Based Pre-cooling Parameters on Temperature and Humidity of Micro-environment for Litchi with Packages

中文关键词: 荔枝  预冷  数值模拟

英文关键词: litchi  pre-cooling  numerical simulation

中文摘要:

      目的 深入研究外环境参数对荔枝包装盒内环境的影响，获得荔枝包装盒内外环境温度湿度规律。方法 建立盒装荔枝果实和外流场的三维模型。结合荔枝果实和包装物理特性，对预冷过程中包装荔枝果实内外环境温湿度变化进行数值分析，获得包装内流场的分布情况。结果 在达到二分之一冷却时间之前，提高风速可以缩短预冷时间，并且能够加快荔枝果实的传热;在达到二分之一冷却时间之后，风速超过6 m/s后，荔枝果实温度变化不显著，相邻风速间果实温度标准差的差值较小，标准差趋于稳定;包装内相对湿度主要受荔枝果实温度的影响;预冷初始阶段选择较低环境温度，有利于加快荔枝果实与空气的传热，促进果实温度的降低，但是荔枝果实间的温度差异随着环境温度降低而增大。结论 在预冷期间，外环境参数温度和风速对包装内环境温湿度有较大的影响。

英文摘要:

      The work aims to study the effect of environmental parameters on the environment inside the litchi packaging box in depth to obtain the temperature and humidity pattern of the environment inside and outside the packages. A three-dimensional model of the litchi fruit in the box and the external flow field was established. Combining the physical characteristics of the litchi fruit and the package, the numerical analysis of the temperature changes inside and outside the packaged litchi fruit during the pre-cooling process was carried out, and the distribution of the flow field in the package was obtained. Before one-half the cooling time, increasing the wind speed shortened the pre-cooling time and accelerated the heat transfer to the litchi fruit. After reaching one-half of the cooling time and wind speeds above 6 m/s, the variation of litchi fruit temperature was not significant. The difference in standard deviation of fruit temperature between adjacent wind speeds was small and the standard deviation tended to stabilize. The relative humidity inside the package was mainly affected by the temperature of the litchi fruit. Selection of low ambient temperature in the initial stage of pre-cooling was conducive to accelerating the heat transfer between litchi fruit and air, and promoting the reduction of fruit temperature. But the temperature difference between litchi fruit increased as the ambient temperature decreased. During pre-cooling, the external ambient parameters temperature and wind speed have a large effect on the ambient temperature and humidity inside the package.