吸波材料辅助的液体物料微波冷冻干燥多物理场耦合模型  

Multiphysics conjugated model for freeze-drying of liquid solution assisted by wave-absorbing material

作　　者：杨菁 王维[1] 张朔 宋春芳 唐宇佳 YANG Jing;WANG Wei;ZHANG Shuo;SONG Chunfang;TANG Yujia(School of Chemical Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China;School of Mechanical Engineering,Jiangnan University,Wuxi 214122,Jiangsu,China)

机构地区：[1]大连理工大学化工学院,辽宁大连116024 [2]江南大学机械工程学院,江苏无锡214122

出　　处：《化工学报》2019年第9期3307-3319,共13页CIESC Journal

基　　金：国家自然科学基金项目(21676042);辽宁省自然科学基金项目(201602167)

摘　　要：为了研究吸波材料辅助微波加热对传统冷冻干燥过程的强化作用,建立了多孔介质温度、浓度和电磁场耦合的多相传递模型;以烧结的碳化硅(SiC)为吸波材料、以甘露醇水溶液为待干料液进行了微波冷冻干燥实验,并测定了甘露醇固体的介电特性。模拟和实验结果均表明,吸波材料对初始非饱和多孔物料微波冷冻干燥具有显著的强化作用。初始非饱和样品微波冷冻干燥时间比传统冷冻干燥缩短了18%,比常规饱和样品传统冷冻干燥缩短了30%。模拟结果与实验数据吻合良好。这表明提出的新型干燥方法确实能够实现过程传热传质的同时强化。通过考察样品内部温度、饱和度和电场强度的实时分布,分析了微波冷冻干燥过程的传热传质和电磁波传播与耗散机理。在微波冷冻干燥过程中,初始非饱和样品累计吸收的辐射能和微波能的总和与传统冷冻干燥相当。这说明,该干燥方法只是提高了能量效率,从而大幅缩短了冷冻干燥时间。To investigate the enhanced effect of wave-absorbing material assisted microwave heating on traditional freeze-drying,a multiphase transport mathematical model conjugating temperature field,concentration field and electromagnetic field was developed and numerically solved.The sintered silicon carbide(SiC)was used as the absorbing material and the mannitol aqueous solution was used.Microwave freeze-drying experiments of mannitol aqueous solution were carried out,and dielectric properties of mannitol solid powder were measured.Both numerical and experimental results show that using wave-absorbing material as the supporting pad of sample can effectively enhance the microwave freeze-drying process.Under the typical operating conditions,microwave freezedrying time of the initially unsaturated material can be 18%and 30%,respectively,shorter than the traditional freeze-drying process of the initially unsaturated and conventionally saturated samples.Excellent agreements were received between experimental measurements and model predictions.This indicates that the proposed freeze-drying method can achieve the simultaneous enhancement of heat and mass transfer.Based on the profiles of temperature,ice saturation and electrical field strength,mechanisms of heat and mass transfer,as well as electromagnetic wavepropagation and dissipation inside a sample were analyzed during drying.The accumulatively absorbed energy ofradiation and microwave during drying was almost the same as those of traditional freeze-drying of the initiallysaturated and unsaturated samples.This demonstrates that the proposed method only increases the energyutilization so as to largely reduce the freeze-drying time.

关 键 词：微波 吸波材料 损耗因子 饱和度 干燥 传热 传质 

分 类 号：TQ028.5[化学工程] TQ026.6