【摘要】：在當今的生產(chǎn)生活中,冷凍干燥技術(shù)占據(jù)著極其重要的地位,在食品、藥品、生物制品等領(lǐng)域中應用極其廣泛。在現(xiàn)有各種各樣的干燥技術(shù)中,經(jīng)過冷凍干燥過程所處理的樣品質(zhì)量最好。但是,冷凍干燥技術(shù)高能耗的弊端一直制約著其更深層次的發(fā)展。因此,如何提高過程的經(jīng)濟性,降低過程能耗就成了研究的重中之重。本文主要對具有訂制孔隙的物料的冷凍干燥過程進行模擬計算,建立了二維冷凍干燥過程的數(shù)學模型,并將其嵌入到多物理場仿真軟件COMSOL Multiphysics 4.3a中進行數(shù)值求解。提出了兩種新的吸附-解吸平衡關(guān)系,并分析了其適用條件。在保證與實驗過程操作條件以及物料量一致的條件下,對比了不同訂制孔隙物料的模擬數(shù)據(jù)和實驗數(shù)據(jù)。分析了多孔介質(zhì)物質(zhì)內(nèi)部的質(zhì)量、熱量的傳遞機理。探究了環(huán)境輻射溫度、操作室壓力以及物料的預冷凍溫度對冷凍干燥過程的影響。結(jié)果表明：具有訂制孔隙的物料可以顯著縮短干燥時間,模擬結(jié)果與實驗數(shù)據(jù)吻合良好；在低初始飽和度條件下,Kelvin形式的吸附關(guān)系優(yōu)于Readhead吸附關(guān)系。在高初始飽和度的條件下,Readhead吸附關(guān)系優(yōu)于Kelvin形式的吸附關(guān)系。通過分析物料溫度、飽和度的分布得知：升華界面也隨著干燥過程的進行逐漸向物料內(nèi)部轉(zhuǎn)移。升華過程不只是發(fā)生在物料表面,同時也發(fā)生在物料內(nèi)部的冰凍區(qū)域�？疾觳僮鳁l件發(fā)現(xiàn)：適當升高環(huán)境輻射溫度,降低干燥室內(nèi)的壓力可以提高冷凍干燥速率,縮短冷凍干燥時間,降低過程能耗,提高整個凍干過程經(jīng)濟性。
[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.
【學位授予單位】：大連理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TQ028

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本文編號：2182756