红外联合热风干燥白萝卜片的耦合建模与热质传递分析  

Coupled modeling and heat and mass transfer analysis of white radish slices dried by infrared radiation combined hot air drying

作　　者：姜大龙 王文杰 王善钰[1,2] 雷登文 刘嫣红 肖红伟[1] 吴敏[1] 高振江[1] 郑志安[1,2] Jiang Dalong;Wang Wenjie;Wang Shanyu;Lei Dengwen;Liu Yanhong;Xiao Hongwei;Wu Min;Gao Zhenjiang;Zheng Zhian(College of Engineering,China Agricultural University,Beijing 100083,China;China Research Center for Agricultural Mechanization Development,China Agricultural University,Beijing 100083,China)

机构地区：[1]中国农业大学工学院,北京100083 [2]中国农业大学中国农业机械化发展研究中心,北京100083

出　　处：《农业工程学报》2022年第1期314-323,共10页Transactions of the Chinese Society of Agricultural Engineering

基　　金：财政部和农业农村部:国家现代农业产业技术体系资助(CARS 21)。

摘　　要：为寻求红外联合热风干燥过程中物料内部热量传递的物理解释,克服水分输运现象不能直观获取的问题,该研究建立白萝卜片红外联合热风干燥过程中水分和温度分布的数值模型。考虑到干燥过程中物料扩散系数动态变化,对实现精准模拟产生干扰,该研究对比考虑温度、收缩相关扩散系数两种方式下单独热风干燥及红外联合热风干燥过程中的热质传递情况并进行试验验证。考虑到二维轴对称几何结构,采用COMSOL Multiphysics 5.2a对该系统的传热传质模型进行求解。结果表明:基于收缩相关有效扩散系数能够准确描述白萝卜片在单独热风及联合干燥过程中的热质传递情况,单独热风和红外联合热风干燥模拟值与试验值的决定系数(R;)分别为0.893和0.911。红外辐射是影响传热传质速率的主导因素。具体表现为恒定干燥温度60℃条件下,红外联合热风干燥比单独热风干燥物料至安全含水率(10%)有效缩短21.4%时间(90 min),红外联合热风干燥样品比单独热风干燥物料达到设定温度值(60℃)缩短36.0%时间。进一步研究表明有效水分扩散系数随红外辐射温度的升高而升高,传热、传质系数对物料升温及水分脱除影响显著。该模型为其他物料在联合干燥技术的模拟研究提供有益借鉴。This study aims to clarify the heat transfer inside the material during the combined infrared and hot air drying. A numerical model was also established for the moisture and temperature distribution during the drying process of white radish slices. The heat and mass transfer was compared in the process of single hot air drying and the infrared combined hot air drying under two shrinkage-related diffusion coefficients. The dynamic change of material diffusion coefficient during drying was considered to interfere with the realization of accurate simulation. A COMSOL Multiphysics 5.2a was used to establish a two-dimensional heat and mass transfer model, where the material and physical field were two-dimensional axisymmetric,particularly for the less solving time, computational cost, and memory. The results showed that the effective diffusivity of shrinkage was enabled to accurately describe the heat and mass transfer of radish slices in the process of single hot air drying and infrared combined hot air drying, where the coefficient of determination(R;) between simulated and experimental values were 0.893 and 0.911, respectively. The infrared radiation was the dominant factor affecting the rate of heat and mass transfer.Optimal performance was achieved under the condition of constant drying temperature of 60 ℃, where the infrared combined hot air drying effectively shortened the time(90 min) by 21.4%, compared with the single hot air drying material to the safe moisture content(10%), whereas, the infrared combined hot air drying sample reached the set temperature(60℃) when shortening the time by 36.0%, compared with the single. The temperature change of the material center was more sensitive to the heat transfer coefficient, and then the heat transfer coefficient led to the rapid change of white radish slices center temperature. The mass transfer coefficient posed a strong influence on the material moisture content, but there was a weak sensitivity of the material center temperature to the mass transfer coefficie

关 键 词：干燥 模型 红外联合热风 数值模型 热质传递 辐射 收缩 

分 类 号：TS222.1[轻工技术与工程—粮食、油脂及植物蛋白工程]