降压过程对过冷水成核影响的理论和实验研究

发布时间：2018-04-23 06:03

  本文选题：冷冻干燥 + 预冻　； 参考：《制冷学报》2017年02期

【摘要】：控制预冻阶段的过冷度对冷冻干燥制品品质的均一性以及后期干燥速率有重要影响。本文通过实验和理论研究了主动降压诱发过冷水成核过程中降压速率、预冷温度和终压等因素对小瓶内过冷水成核现象的影响。结果表明:常压下解除过冷度范围为9~17℃,而在降压过程中解除过冷度范围为8~11℃;在5~20 k Pa/s内降压速率对成核影响不大;在100~400 Pa内终压越低,检测到的解除过冷度越低。计算分析表明,降压过程中水体表面及附近区域达到的最低温度可能是影响成核的关键因素。
[Abstract]:Controlling the degree of undercooling in the prefreezing stage has an important effect on the uniformity of the quality of freeze-dried products and the drying rate in the later stage. In this paper, the effects of pressure lowering rate, precooling temperature and final pressure on the phenomenon of supercooled water nucleation in a small bottle have been studied experimentally and theoretically. The results show that the range of undercooling at atmospheric pressure is 9 鈩，

本文编号：1790745