A Basic Study on Freezing of Food (Freezing Behavior of a Saline Solution Through a Semipermeable Membrane)

众所周知，食品的新鲜度取决于冷冻食品的冷却速度。因此，为了控制食品的新鲜度，研究冷却速率对细胞内冷却和冷冻行为的影响是非常重要的。要做到这一点，不仅需要评估单个细胞内的流量、温度和浓度分布过程，还需要考虑通过细胞膜在细胞内外进行的热量和质量交换。本研究将食物视为细胞聚集物。作为细胞组分，考虑到自由水在细胞组分中凝固点最高的特点，选用质量浓度为5%的氯化钠水溶液（NaCl水溶液）。此外，考虑到功能和强度，采用微孔膜作为细胞膜。本文从热工程的角度研究了NaCl水溶液在微孔膜中的冷却和冻结行为。这些行为是可视化的，并使用实时激光全息干涉测量。作为对比，采用铜板作为隔板，除微孔膜外不采用隔板。除NaCl水溶液外，还采用水作为冷却液。结果得出以下结论：在NaCl水溶液实验中，由于隔板的存在，冷却过程没有明显差异。而在冻结过程中，随着凝固过程的进行，在第一个单元中被凝固拒绝的NaCl通过微孔膜进入第二个单元。因此，在分析食品冷冻过程中，有必要考虑凝固后薄膜传质问题。在用水的实验中，澄清了水本身是通过微孔膜的。然而，在水不能完全通过的情况下，使用薄膜和使用铜板的传热特性差异不大。少

It is well known that the freshness of food depends on the cooling rate in freezing food. Therefore, in order to control the freshness of food, it is important to obtain the effect of cooling rate on the cooling and freezing behaviors in cells. To do it, it is necessary not only to evaluate the processcs of flow, temperature and concentration distributions in a single cell, but also to consider the exchange of heat and mass inside and outside of cells through cell membrance.This study regards food as the cell aggregation. As a cell component, paying attention on free water having the characteristics of the highest freezing point in cell components, an aqueous sodium chloride solution (NaCl aqueous solution) with a concentration of 5% by mass was used. Furthemor, a micro porous film was used as a cell membrane taking account of function and strength.This study deals with the cooling and freezing behaviors of NaCl aqueous solution through a micro porous film from the viewpoint of thermal … More engineering. These behaviors were visualized and measured using a real-time laser holographic interferometry. For comparison, a copper plate and no partitions other than a micro porous film were used as partitions. Water other than NaCl aqueous solution was also used as liquid to be cooled.As a result, following conclusions were obtained.In the experiments using NaCl aqueous solution, there is no significant difference in the cooling process due to partitions. However, in the freezing process, NaCl rejected by solidification in the first cell goes into the second cell passing through a micro porous film with the progress of solidification. Therefore, it is necessary to consider mass transfer through films after solidification in analyzing food freezing.In the experiments using water, it is clarified that water itself passes through the micro porous film. However, there is little difference in heat transfer characteristics between the results using film and those using copper plate where water cannot pass completely. Less