Synthetic Study on the Techniques for Storage/Conveyance/Utilization of Cold Energy using Phase-Change Phenomena

众所周知，利用相变现象的热存储系统是非常有效的，但是效率由于相变材料（PCM）中发生的过冷现象而降低。同时，为了提供储存在PCM中的冷能，应解决输送技术问题，因为冷量储存在冷冻的（即固体）PCM中，不易移动。因此，本研究涉及冷的存储/传输技术以及相变现象本身。与此同时，具有相变现象的冷能的新应用，即，电子设备的冷却和生物体的冷冻保存也进行了研究。主要研究结果如下：（1）采用分子动力学模拟方法，对包括过冷度在内的液固相变现象进行了数值模拟。通过数值模拟，研究了过冷水的热物性以及电场对过冷水冻结过程的影响 ...更多信息 讨论了过冷水的稳定性。(2)对裸冰块的气力输送特性进行了实验研究，并与球形胶囊内冰块的气力输送特性进行了比较。结果表明，裸冰输运过程中的冷量损失比无冰输运过程中的冷量损失大，但对泵功率的影响不大。(3)对水平管内盐水-冰混合物的熔化传热进行了实验研究。从结果中，它是得到的在下游区域的传热系数增加的盐水-冰的混合物的流速的增加，和局部的传热减少与盐水浓度的增加。(4)为了将微通道内液固两相流的传热应用于电子器件的冷却，对微通道内液固两相流的传热特性进行了研究。对0.5 ~ 3 mm高的通道内的传热和压降进行了测量，并从强化传热的角度对测量结果进行了讨论。(5)通过实验研究了小麦原生质体的冻结特性和渗透压，并从微观角度讨论了冰晶的产生对细胞损伤的影响。利用这些结果，得到了冷却速率与有机细胞生物学条件之间的关系。少

It is known that the thermal storage system utilizing the phase-change phenomena is quite effective, but that the efficiency is reduced by the supercooling phenomenon occurring in the Phase-Change Materials (PCMs). At the same time, in order to supply the cold energy stored in PCMs, conveying technique should be settled since the cold is stored in frozen, i.e.solid, PCMs, which can not be easily moved. This study therefore dealt with the storage/conveyance techniques of cold as well as the phase-change phenomenon itself. At the same time, new applications of cold energy with phase-change phenomena, i.e., cooling of electronic devices and freezing preservation of organisms, were also examined. The results can be summarized as follows :(1) Liquid-to-solid Phase-change phenomenon including the supercooling was numerically examined by using molecular dynamics simulation method. From the simulation, thermal properties of supercooled water and the effect of electric field on the freezing pro … More bability of supercooled water were discussed.(2) Pneumatic conveying characteristics of the cold using bare-ice cubes were experimentally examined so as to compare the results with the ones of the system using ice enclosed in spherical capsules. The results showed that the cold loss during conveyance with bare-ices is larger than that in encapsuled case, but that the pumping power is little affected.(3) melting heat transfer of a brine-ice mixture flowing inside a horizontal tube was experimentally examined. From the results, it was obtained that the heat transfer coefficient in the downstream region increases with increase in flow velocity of the brine-ice mixture, and that the local heat transfer decreases with increasing the concentration of brine.(4) Heat transfer characteristics of the liquid-solid two-phase flow within micro-channels were examined so as to apply the heat transfer to the cooling of electronic devices. Heat transfer and pressure drop within a channel of 0.5-3mm height were measured, and the results were discussed from the viewpoint of heat transfer enhancement.(5) Freezing characteristics and osmotic pressure of a protoplast of wheat were experimentally examined, and the effects of ice-crystal generation within a cell on the damage to the cell were discussed from the microscale view point. Using the results, relation between the cooling rate and biological condition of the organic cells was obtained. Less