胡萝卜片微波真空干燥动力学数值拟合

Numerical Simulation of Microwave Vacuum Drying Kinetics of Carrot Chips

为了探索微波功率密度对产品微波真空干燥(MVD)的影响,本文在干燥特性的基础上,进行了胡萝卜微波真空干燥动力学方程的数值模拟,然后利用遗传算法进行胡萝卜多功率组合的微波真空干燥优化研究。结果表明,单一微波功率密度干燥下,微波功率密度越大,胡萝卜片干燥速率越大,干燥时间越短,产品越易焦糊;在4种常见的薄层干燥及其延伸模型的数值拟合对比研究中,发现基于wang延伸模型1(即MR=aexp(-kt^n)+c)能很好的表征不同功率密度下胡萝卜片微波真空干燥过程的脱水情况。进一步以三条(分别为20、5和0.6 W/g)不同微波功率密度下的胡萝卜干燥动力学方程为对象,通过遗传算法优化并获得了多功率密度连续微波真空干燥组合工艺参数;经验证,该工艺加工的胡萝卜片干基水分含量(0.078±0.005) g/g,没有焦糊;相比0.6 W/g单一微波功率的干燥结果,不但产品减少了收缩和焦糊现象,而且干燥效率提高了4.77倍。采用计算机遗传算法可以达到优化多功率组合的微波真空干燥加工工艺的目的,减少实验工作量,还可以获得计算机数值模拟模型,为实现微波干燥加工过程信息化提供技术支撑。

In order to explore the effect of microwave power density on microwave vacuum drying(MVD)of products,based on the experimental analysis of drying characteristics,the dynamics equation of microwave vacuum drying of carrot was simulated numerically,and then the optimization of microwave vacuum drying of multi-power combination of carrot was studied by genetic algorithm.The results showed that the higher the microwave power density was,the higher the drying rate was,the shorter the drying time was and the easier the product was to be burnt.In the comparative study on the numerical fitting of four common thin-layer drying models and their extension models,it was found that the dehydration of carrot slices during microwave vacuum drying under different power could be well represented based on the wang extension model 1(MR=aexp(-kt n)+c).Furthermore,the kinetic equations of carrot drying under three different microwave power densities(20,5 and 0.6 W/g,)were taken as the object.It was verified that the dry base moisture content of carrot slices processed by this process was 0.078±0.005 g/g without coke paste.Compared with the drying results of 0.6 W/g single microwave power,the product not only reduced shrinkage and coking phenomenon,but also improved the drying efficiency by 4.77 times.The application of computer genetic algorithm can optimize the microwave vacuum drying process of multi-power combination,reduce the experimental workload,and obtain the computer numerical simulation model,which can provide technical support for realizing the informatization of microwave drying process.