摘要
用有限差分方法计算的数值求解一个微波冷冻干燥质、热传递数学模型,以考察介电物质对微波冷冻干燥的影响。被干燥物料水溶液的溶质选用乳糖(Lactose)——一种典型的药物赋形剂。介电物质为烧结的碳化硅(SiC)。数值计算结果表明,介电物质能够有效地强化微波冷冻干燥过程,干燥时间大为缩短。在典型操作条件下,干燥时间为179.1min,比普通微波冷冻干燥节省43.4%。通过考察温度、冰饱和度、蒸汽质量浓度和压力分布,分析传质传热机理,确定了干燥速率控制因素。
The finite-deference technique was used to numerically solve a mathematic model of simultaneous heat and mass transfer for the dielectric material assisted microwave freeze-drying.Lactose,one of typical pharmaceutical exeipients,was chosen as the representative solid material in the aqueous solution to be freeze-dried.The silicon carbide(SiC) was selected as the dielectric material.Numerical results show that the microwave freeze-drying process can be significantly enhanced by using the dielectric material.Drying time is greatly reduced compared to the ease without the aid of the dielectric material.Under typical operating conditions,the drying time is 179.1 min,43.4% shorter than that of ordinary microwave freeze-drying.Profiles of the temperature,ice saturation,vapor concentration and pressure during freeze-drying were presented.Mechanisms of the heat and mass transfer inside the material cylinder were analyzed.The drying rate controlling factor was determined.
关键词
介电物质
微波冷冻干燥
药物赋形剂
数学模型
传质
传热
Microwave freeze-drying
Pharmaceutical excipient
Dielectric material
Mathematical model
Heat and mass transfer
