基于COMSOL Multiphysics模型的液态罐头食品热杀菌过程模拟研究

Numerical Simulation of Canned Liquid Food Thermal Sterilization using COMSOL Multiphysics

以水和CMC溶液为研究对象,通过无线实时温度传感器检测热杀菌过程中罐中心温度的变化,并以COMSOL Multiphysics软件为基础建立传热模型。对比模拟结果与实际数据发现模型能很好地模拟罐中心点温度的变化。在此基础上,进一步用COMSOL Multiphysics软件模拟整罐空间的温度分布、速度分布及致死率值,得出在50 s与4 000 s时,水的最大流动速度分别为6.36 mm/s和5.05 mm/s,1%CMC溶液的最大流动速度分别为0.394 mm/s与1.124 mm/s,罐内最慢加热区（SHZ）位于罐体高度10%-30%处,与文献一致。杀菌结束时,水的最大、最小致死率值相差0.6min,而1%CMC与2.5%CMC溶液最大、最小致死率相差分别为12.4 min和18.86 min,这表明对于较高黏度的食品应采用旋转杀菌。

The simulation and validation during thermal processing of model liquids [sodium carboxy-methyl cellulose（CMC） and water] in a still can using COMSOL Multiphysics is the subject of this paper. The COMSOL Multiphysics was used to predict the temperature of centre point in the can. Experiments were run using several metal cans containing water, 1% CMC and 2.5% CMC solution respectively and the temperature of centre point was determined by the wireless real-time temperature recorder. Results obtained by COMSOL Multiphysics for temperature profiles were in good agreement with experimentally determined values. After validation of the model, further simulations were carried out for the temperature distribution, the velocity profile and lethality at each second in the can. It was shown that the maximum velocity was 6.36 mm/s and 5.05 mm/s at 50 s and 4 000 s for water, 0.394 mm/s and 1.124 mm/s for 1%CMC solution. The slowest heating zone is located at a height of about 10%-30% of the can height from the bottom. The difference of lethality between maximum and minimum was 0.60 min for water, 12.40 min for 1% CMC solution and 18.86 min for 2.5% CMC solution which suggests the necessity for sterilization in a rotary retort for high viscosity food.