基于介电特性的狭鳕鱼糜无线电波解冻数值模拟

Numerical simulation of temperature distribution during radio frequency tempering of pollack surimi based on dielectric properties

无线电波加热具有选择加热的特性,随着被解冻物料温度的升高,物料的介电特性随温度的变化会导致热点部位吸收能量多,升温迅速,而相应的较冷部位吸收能量少,致使温度分布差异增大,物料品质大幅下降。提高加热均匀性是无线电波解冻中被最为关注的问题。文章以阿拉斯加狭鳕(Theragra chalcogramma)鱼糜为研究对象,采用同轴探针方法测定了狭鳕鱼糜的介电特性,得出了狭鳕鱼糜介电常数和介电损失随温度变化的回归方程;在此基础上应用COMSOL Multiphysics软件,对无线电波解冻狭鳕鱼糜的物理过程进行动态数值模拟,以有限元方法数值求解电磁波耗散及热传递耦合方程并通过实验测定对温度计算值进行验证。结果表明,基于介电特性的耦合方程可准确地模拟无线电波加热过程的温度变化,从而用于预测物料的温度分布。

Radio frequency tempering has properties of selective heating.As the increase of temperature,the hotter part of the thawed material absorbs more energy;heat increases rapidly with the change of dielectric properties,while the corresponding cooler part absorbs less energy,which leads to the difference of temperature distribution and will reduce the quality of thawed materials.Increasing uniformity of temperature distribution is most concerned during radio frequency.In this paper,the dielectric properties of pollock(Theragra chalcogramma)surimi were determined by open ended coaxial-line probe method.The regression equations of the dielectric constant and dielectric loss were obtained.Based on the dielectric property,a numerical simulation of the temperature distribution during radio frequency tempering of pollack surimi was carried out by COMSOL Multiphysics software.In order to obtain the physical process of radio frequency tempering for dynamic numerical simulation,the finite element method was used to solve the electromagnetic wave dissipation and heat transfer coupling equation,and was experimentally verified by conducting radio frequency tempering on pollack surimi.The results show that the simulation of coupling equation based on dielcetric property can pre-dict the temperature distribution of the samples accurately during radio frequency tempering.