溶液类样品冻干过程中搁板预冻特性分析  

STUDY ON THE SOLUTION FREEZING ON THE COOLING SHELF DURING LYOPHILIZATION

作　　者：苏树强[1] 丁志华[1] 肖洪海[1] 华泽钊[1] 

机构地区：[1]上海理工大学低温生物与食品工程研究所,上海200093

出　　处：《低温工程》2004年第1期39-43,共5页Cryogenics

基　　金：国家自然科学基金(50376040);上海市教委重点学科建设项目资助

摘　　要：搁板预冻式冻干机在对溶液类样品预冻过程中,样品内存在较大的温度梯度,溶质自下而上的迁移量较大,易形成高浓度表层,在冻干过程中形成相对致密的“硬壳”。三步预冻法较适用于溶液类样品搁板预冻过程,三步法中的第二步温度扯平有效消除了冷却过程的温度梯度,相当于降低了预冻初温,加快了溶液上表面冰晶的形成与冰晶生长的速度,致使冰晶的参差生长方式,降低了溶质自下而上的迁移速度,防止了高浓度表层问题的产生。During the process of solution freezing on the cooling shelf in freeze-drier, the mass transfer is usually smart in longitudinal direction due to the high temperature gradient and slow freezing speed , and a higher concentration layer on the top of solution tends to be formed, which will become a compact dried layer during the drying process. Three steps freezing method is of great benefit to solution freeze-drying on shelf, the second step of which can lower the temperature gradient in solution, that' s to say lowering the initial temperature of freezing, accelerating the form of the ice crystal on the surface and the speed of growth of the ice crystal, lead to the growth of ice crystal irregularly, decreasing the transfer speed of solution from subordinate to aspect, and preventing the production of the higher concentration layer.

关 键 词：溶液类样品 搁板预冻特性 温度梯度 冰晶生长 冷冻干燥 

分 类 号：TB65[一般工业技术—制冷工程]