微波辅助生物柴油生产的一体化计算

Integrative calculation for microwave process of biodiesel production

多物理场仿真动态计算对于优化微波化学加热反应体系的生产工艺,避免高功率微波带来的安全问题起到极其重要的作用.然而目前大多数微波加热化学反应的多物理场模型仅引入电磁和热传模块进行分析,且将电磁、热力学等物性参数视为常量而忽视了反应体系中各组分和温度变化对物性参数的影响,从而影响到模型的可靠性和准确性.本工作在以往模型的基础上,利用最近提出的简化且精度更高的介电系数表达式,通过引入化学反应工程和传质的计算来对电磁、热力学等物性参数随着反应体系浓度和温度的变化进行自适应实时更新,同时考虑了自然对流对传热和传质的影响.新模型避免了以往模型需要手动更新参数、介电系数表达公式复杂、热力学参数仅根据反应组分变化更新而无法获得更多化学反应模块信息、忽略液体自然对流对温度扩散的影响的弊端,实现了微波促进生物柴油生产的一体化计算.通过实验测量的温度分布验证了模型的合理性和准确性.

The multiphysics simulations for the microwave heating on the chemical reaction have been deemed as an efficient way to optimize the microwave treating process and avoid the safety problems coursed by the high-power microwave energy applied. Unfortunately, most of the multiphysics simula- tions for the microwave heating on the chemical reaction only involve the Electromagnetics and Heat transfer modules and treat the physical properties as constant values~ ignoring the influent of variation of the chemical reaction status. Compared to the previous model, Chemical Reaction Engineering and Mass Transfer have been added and a simplified bivariate characterization for effective permittivity was em- ployed in the new model. Therefore, all properties are automatically updated by the reaction solution^s component and temperature. Meanwhile, the influence of the nature convection for heat and mass trans- fer is discussed. The problems such as manual update for the properties~ complex characterization function for effective permittivity; thermal properties only updated by the chemical components; ignore the influence of nature convection for the temperature diffusion and less information about chemical reaction system in previous model can be avoided. The temperature diffusion coursed by nature convection has also been discussed. Integrative calculation for microwave process of biodiesel production is done in this study. Good agreement can been seen between the experimental and simulated results.