具有初始孔隙物料冷冻干燥过程的模拟与验证
发布时间：2018-08-14 11:44
【摘要】：在当今的生产生活中,冷冻干燥技术占据着极其重要的地位,在食品、药品、生物制品等领域中应用极其广泛。在现有各种各样的干燥技术中,经过冷冻干燥过程所处理的样品质量最好。但是,冷冻干燥技术高能耗的弊端一直制约着其更深层次的发展。因此,如何提高过程的经济性,降低过程能耗就成了研究的重中之重。本文主要对具有订制孔隙的物料的冷冻干燥过程进行模拟计算,建立了二维冷冻干燥过程的数学模型,并将其嵌入到多物理场仿真软件COMSOL Multiphysics 4.3a中进行数值求解。提出了两种新的吸附-解吸平衡关系,并分析了其适用条件。在保证与实验过程操作条件以及物料量一致的条件下,对比了不同订制孔隙物料的模拟数据和实验数据。分析了多孔介质物质内部的质量、热量的传递机理。探究了环境辐射温度、操作室压力以及物料的预冷冻温度对冷冻干燥过程的影响。结果表明：具有订制孔隙的物料可以显著缩短干燥时间,模拟结果与实验数据吻合良好；在低初始饱和度条件下,Kelvin形式的吸附关系优于Readhead吸附关系。在高初始饱和度的条件下,Readhead吸附关系优于Kelvin形式的吸附关系。通过分析物料温度、饱和度的分布得知：升华界面也随着干燥过程的进行逐渐向物料内部转移。升华过程不只是发生在物料表面,同时也发生在物料内部的冰冻区域。考察操作条件发现：适当升高环境辐射温度,降低干燥室内的压力可以提高冷冻干燥速率,缩短冷冻干燥时间,降低过程能耗,提高整个冻干过程经济性。
[Abstract]:Freeze-drying technology occupies an extremely important position in the production and life of today, and is widely used in food, medicine, biological products and other fields. Among the various drying techniques available, the quality of samples treated by freeze-drying process is the best. However, the drawback of high energy consumption in freeze-drying technology has been restricting its further development. Therefore, how to improve the process economy, reduce process energy consumption has become the most important research. In this paper, the freeze-drying process of materials with custom pores is simulated and calculated, and the mathematical model of two-dimensional freeze-drying process is established. The mathematical model is embedded in the multi-physical field simulation software COMSOL Multiphysics 4.3a for numerical solution. Two new adsorption-desorption equilibrium relationships are proposed and their applicable conditions are analyzed. The simulation data and experimental data of different customized porous materials are compared under the same conditions as the operating conditions of the experimental process and the quantity of materials. The mass and heat transfer mechanism in porous media were analyzed. The effects of ambient radiation temperature, operating room pressure and material pre-freezing temperature on the freeze-drying process were investigated. The results show that the drying time of the materials with customized pores can be significantly shortened, and the simulated results are in good agreement with the experimental data, and the adsorption relationship in the form of Kelvin is better than that of Readhead at low initial saturation. Under the condition of high initial saturation, the adsorption relationship of Readhead is better than that of Kelvin. By analyzing the distribution of material temperature and saturation, it is known that the sublimation interface is gradually transferred to the material with the drying process. Sublimation occurs not only on the surface of the material, but also in the frozen area inside the material. It is found that raising the ambient radiation temperature and reducing the pressure in the drying room can increase the freeze-drying rate, shorten the freeze-drying time, reduce the energy consumption and improve the economy of the whole freeze-drying process.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ028
本文编号：2182756
[Abstract]:Freeze-drying technology occupies an extremely important position in the production and life of today, and is widely used in food, medicine, biological products and other fields. Among the various drying techniques available, the quality of samples treated by freeze-drying process is the best. However, the drawback of high energy consumption in freeze-drying technology has been restricting its further development. Therefore, how to improve the process economy, reduce process energy consumption has become the most important research. In this paper, the freeze-drying process of materials with custom pores is simulated and calculated, and the mathematical model of two-dimensional freeze-drying process is established. The mathematical model is embedded in the multi-physical field simulation software COMSOL Multiphysics 4.3a for numerical solution. Two new adsorption-desorption equilibrium relationships are proposed and their applicable conditions are analyzed. The simulation data and experimental data of different customized porous materials are compared under the same conditions as the operating conditions of the experimental process and the quantity of materials. The mass and heat transfer mechanism in porous media were analyzed. The effects of ambient radiation temperature, operating room pressure and material pre-freezing temperature on the freeze-drying process were investigated. The results show that the drying time of the materials with customized pores can be significantly shortened, and the simulated results are in good agreement with the experimental data, and the adsorption relationship in the form of Kelvin is better than that of Readhead at low initial saturation. Under the condition of high initial saturation, the adsorption relationship of Readhead is better than that of Kelvin. By analyzing the distribution of material temperature and saturation, it is known that the sublimation interface is gradually transferred to the material with the drying process. Sublimation occurs not only on the surface of the material, but also in the frozen area inside the material. It is found that raising the ambient radiation temperature and reducing the pressure in the drying room can increase the freeze-drying rate, shorten the freeze-drying time, reduce the energy consumption and improve the economy of the whole freeze-drying process.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ028
【参考文献】
相关博士学位论文 前1条
1 郭树国;人参真空冷冻干燥工艺参数试验研究[D];沈阳农业大学;2012年
相关硕士学位论文 前1条
1 苏杭;多孔介质干燥过程传热传质的理论分析与实验研究[D];华北电力大学（河北）;2008年
，本文编号：2182756
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