液氮冻结食品冻结时间的计算方法及实验验证
Calculating Method and Experimental Verification of Freezing Time of Frozen Food by Liquid Nitrogen

冻结时间是评价冻结食品质量的重要指标，正确计算冻结时间是食品冻结装置优化设计及运行的关键。本文通过建立液氮速冻实验平台，测试了食品的冻结时间，介绍了现有的理论模型，选择了几种典型的计算方法应用于食品冻结，并将各模型的理论结果与实验值进行比较，分析各偏差原因，获得计算食品冻结时间最准确的方法。以有限长圆柱状食品为例，通过研究发现在整个氮气温度场中国际制冷学会模型计算结果与实验值最相近，平均偏差为8.86%，分段计算法次之，平均偏差小于15%。
Freezing time is an important index to evaluate the quality of frozen food, and the correct calculation of freezing time is the key to the optimal design and operation of food freezing equipment. In this paper, the freezing time is tested by the established frozen experiment platform with liquid nitrogen. After introducing existing models, several typical calculation methods are chosen to calculate the food freezing time. By comparing the theoretical results with the experimental results, the most accurate method to calculate the food freezing time is obtained. Taking the finite cyclical foodstuff as an example, the result shows that the International Institute of Refrigeration Model has the smallest difference with the experimental results, and the average deviation is 8.86%, while the Staging Model takes second place with an average deviation less than 15%