Study on Prevention of Ice Adhesion to Cooling Wall due to Action of Electric Charge in Ice Storage

作者研究了一种新型冰浆，它是由搅拌冷却水油混合物形成的冰浆，用于冰蓄冷系统。在该系统中，解决冷却壁的冰粘附是必不可少的。当混合物在容器中搅拌时，油由于摩擦而带静电。如果容器壁能够吸引充入的油，则可以实现防止冰附着到冷却壁。首先，为了知道仅通过搅拌产生的油的带电量，讨论了油的带电特性。进行了实验，改变旋转数，搅拌翼的大小和容器的地面状态。此外，在搅拌停止后，测量带电量的时间依赖性。从实验结果中，明确了最佳条件。在搅拌开始后20~25分钟，带电量达到最大，搅拌停止后5分钟，带电量为0。为了用高速摄影机或摄像机观察带电油-水液滴或混合物在电场中的行为，进行了两种类型的实验。一个是冲过来的那滴油水。使静电在有电场或无电场的两个电极之间垂直落下，改变液滴的含水量。另一种方法是在装有含油量为50体积%的油水混合物的容器上施加200 V的电压，同时搅拌。根据观察，确认了带电壁（电极）和带电油之间的吸引力起作用，壁处的油含量变为约70%。此外，可以通过改变电压来控制壁处的油含量。结果表明，这一结果可防止冰粘附到冷却壁上。

One of authors has studied new ice slurry formed by cooling water-oil mixture with stirring for ice storage system. In the system, solution of ice adhesion to cooling wall is essential. When the mixture is stirred in a vessel, oil is charged by static electricity due to friction. If the vessel wall can attract charged oil, prevention of ice adhesion to the cooling wall may be realized. At first, in order to know an amount of electrification of only oil generated by stirring, characteristics of electrification for oil were discussed. Experiments were carried out, varying the number of rotations, size of stir wing and state of ground of the vessel. Moreover, after the stop of stirring, time-dependency of amount of electrification was measured. From, experimental results, optimal conditions were clarified. And an amount of electrification became about maximum at 20~25 minutes after the beginning of stirring, and that of electrification became about 0 at 5 minutes after the stop of stirring. In order to observe behavior of charged oil-water droplet or mixture in an electric field by a high speed camera or video camera, two types of experiments were carried out. One was that oil-water droplet charged by. static electricity was made to fall plumb down between two electrodes with electric field or without electric field, varying the water content of droplet. The other was that voltage of 200 V was applied on the vessel filled with oil-water mixture of 5Qvol% oil content with stirring. From the observations, it was confirmed that attracting force between the charged wall(electrode) and charged oil acted, oil content at the wall became about 70%. Moreover, oil content at the wall could be controlled by varying the voltage. And, it was shown that this result led to prevention of ice adhesion to cooling wall.