微波加热土豆泥过程中温度和失水量数值模拟

Numerical Simulation of Temperature and Moisture Loss During Microwave Heating of Mashed Potatoes

中文关键词: 多孔介质  加热时长  温度分布  失水量  体积分数

英文关键词: porous media  heating time  temperature distribution  moisture loss  volume fraction

中文摘要:

      目的 探究微波加热不同体积分数的多孔介质食品的温度和失水量变化。方法 本文采用盘装土豆泥为研究对象，在COMSOL Multiphysics 6.0软件中建立耦合电磁场、流场、传热和传质的三维多孔介质有限元模型，通过实验验证该模型的准确性，并预测不同体积分数的土豆泥的温度分布、特征点的瞬态温度变化和失水量变化。结果 600 s内土豆泥上表面温度分布的仿真与实验结果一致，且冷点和热点RMSE值分别为1.23 ℃和1.92 ℃，平均误差分别为3.9%和3.7%。5个特征点的瞬态温度变化仿真与实验结果的RMSE值最大为1.146 ℃，温度均匀系数COVT的RMSE值为0.008 1;仿真失水量变化与实验结果的RMSE值为0.963 1 g，平均误差为3.69%，表明仿真模型具有可靠性。基于此模型，发现随着土豆泥体积分数增大，冷热点的温度呈现非线性升高。不同体积分数下的5个特征点瞬态温度在360 s前均呈现非线性升高，360 s后温度逐渐平稳;失水量在60 s后明显增大，在360 s后呈线性增长。结论 体积分数和加热时长对土豆泥的微波加热过程有明显影响。为食品包装开发人员从空间和时间上了解食品的微波加热过程提供了理论基础，为食品包装材料或结构设计提供了帮助。

英文摘要:

      The work aims to study the changes of temperature and moisture loss of porous media food with different water contents by microwave heating. A three-dimensional porous media finite element model of coupled electromagnetic field, flow field, heat and mass transfer was established in COMSOL Multiphysics 6.0. The accuracy of the model was verified through experiments. The temperature distribution of mashed potatoes with different volume fractions, the transient temperature change of characteristic points and the change of moisture loss were predicted. The results showed that the temperature distribution on the surface of mashed potatoes in 600 s was consistent with the experimental results, and the RMSE of the cold point and hot point were 1.23 ℃ and 1.92 ℃, respectively, with an average error of 3.9% and 3.7%. The RMSE maximum value of the simulation and experimental results of the transient temperature changes of the five feature points was 1.146 ℃, and the RMSE value of the temperature uniformity coefficient COVT was 0.008 1. The RMSE value of simulated moisture loss changes and experimental results was 0.963 1 g, and the average error was 3.69%, which indicated that the simulation model was reliable. Based on this model, it was found that with the increase of mashed potato volume fraction, the temperature of the cold hot spot presented a nonlinear increase. The transient temperature of 5 characteristic points at different volume fractions increased nonlinearly before 360 s, and became stable after 360 s. The moisture loss increased significantly after 60 s and linearly after 360 s. Volume fraction and heating time have obvious influence on the microwave heating process of mashed potatoes. It provides a theoretical basis for food packaging developers to understand the microwave heating process of food from space and time, and provides help for food packaging materials or structural design.