以0.85%CMC溶液为研究对象,基于COMSOL Multiphysics软件建立三维传热模型来模拟液态罐头食品的热杀菌过程。采用无线温度传感器检测热杀菌过程中罐内CMC溶液中心温度的变化进行验证,发现模型能很好地模拟罐中心点温度的变化。在此基础上,模拟等体积不同高径比与不同倾斜角对热杀菌过程的影响。结果表明,液态圆柱罐头的杀菌时间随高径比与倾斜角的增大先增加后减少,在高径比为0.75~1时,杀菌时间出现大值。当高径比小于0.75时,罐体垂直放置杀菌时间小;当高径比大于0.75时,罐体水平放置杀菌时间小;高径比等于0.75时,罐体垂直放置与水平放置杀菌时间相近。慢加热区(SHZ)达到100℃时,高径比为0.75,倾斜角为0°的罐内流动为激烈,大流速为2.83 mm/s,高径比为0.25,倾斜角为45°时,罐内流动为缓慢,大流速为1.22 mm/s。

A three-dimensional heat transfer model was established to simulate thermal sterilization of model liquids( 0.85% CMC solution) in this paper.Experiments were run with 0.85% CMC solution in can and the temperatures of geometric center weredetermined 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, further simulations were carried out with the same volume of different ratios of height to diameter and orientation angles.The sterilization time increased with ratio of height to diameter and orientation angle and passed through a maximum around an ratio of height to diameter 0.75 ~ 1,then reduced gradually.When ratio of height to diameter was less than 0.75,the sterilization time reduced to a minimum around an orientation angle 0°.When ratio of height to diameter was more than 0.75,the sterilization time reduced to a minimum around an orientation angle 90°.When ratio of height to diameter was equal to 0.75,the sterilization time reduced to a minimum around an orientation angle 0° and 90°.The maximum and minimum velocity were found to be 2.83mm/s and 1.22mm/s with ratio of height to diameter 0.75,orientation angle 0° and ratio of height to diameter 0.25,orientation angle 45° respectively in all of cans for the Slowing Heating Zone( SHZ) to reach the value of 100℃ 。This study was expected to be a significant contribution for further optimization studies.