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火龙果真空冷冻干燥的模拟分析和实验研究
张彤,余克志,张得正
0
(上海海洋大学食品学院;农业部冷库及制冷质量监督检验测试中心(上海);上海冷链装备性能与节能评价专业技术服务平台)
摘要:
为了准确预测冷冻干燥时间,本文基于传热传质理论,利用COMSOL软件对厚度为12 mm、半径为4 cm的红心火龙果片进行建模,模拟升华干燥阶段火龙果内部水蒸气流动耦合热质传递、火龙果温度分布特性、升华界面位移以及冰升华过程,预测升华周期,并通过实验验证模型的可靠性。结果表明:模拟值与实测值相吻合且误差较小,火龙果中心点温度模拟值与实测值绝对误差为0.9 ℃,火龙果含水率模拟值与实测值相对误差为1.2%,脱水速率模拟值与实测值相对误差为6.63%。本模型可以准确模拟升华干燥过程热质传递动态变化。通过模拟对比不同厚度火龙果片升华周期,同时考虑到冻干制品质量和产量,12 mm为红心火龙果片冻干最佳厚度。
关键词:  真空冷冻干燥  传热传质  脱水速率  火龙果
DOI:
投稿时间:2021-09-09修订日期:2021-11-03
基金项目:上海市科学技术委员会科技支撑计划(13dz1203002)
Simulation Analysis and Experimental Research on Vacuum Freeze-drying of Pitaya
Zhang Tong,Yu Kezhi,Zhang Dezheng
(College of Food Science & Technology, Shanghai Ocean University;Quality Supervision, Inspection and Testing Center for Cold Storage and Refrigeration Equipment(Shanghai),Ministry of Agriculture;Shanghai Professional Technology Service Platform on Cold Chain Equipment Performance and Energy Saving Evaluation)
Abstract:
To accurately forecast freeze-drying time, COMSOL software was used to simulate the sublimation drying process of pitaya slices based on the theory of heat and mass transfer in this study. The thickness of the red pitaya slices was 12 mm, and the radius was 4 cm. By simulating the water vapor flow coupled with the heat and mass transfer of the sublimation drying stage, the temperature distribution characteristics of pitaya slices, the movement of the sublimation interface, and the condition of ice sublimation, the sublimation cycle was forecast. Experiments were conducted to validate the model. The results show that the errors are low: the absolute error between the simulated and measured pitaya center temperatures is 0.9 ℃, the comparative error between the forecast and measured moisture ratios is only 1.2%, and the relative error between the simulated and measured dehydration rates is 6.63%. It can be concluded that the model can accurately simulate the dynamic changes in heat and mass transfer during the sublimation drying process. By comparing the simulated sublimation cycle of pitaya slices with different thicknesses, and considering the quality and production of freeze-drying products, it is concluded that 12 mm is the best thickness of red pitaya slices for freeze-drying.
Key words:  vacuum freeze-drying  heat and mass transfer  dehydration rate  pitaya

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