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

研究了一种新型的冰浆，它是由冷却水-油混合物搅拌形成的冰浆。在系统中，解决冰与冷却壁的粘着是至关重要的。当混合物在容器中搅拌时，由于摩擦，油被静电带电。如果容器壁可以吸引带电荷的油，就可以实现防止冰附着在冷却壁上。首先，为了了解搅拌产生的油的起电量，讨论了油的起电特性。在不同的旋转次数、搅拌翼的大小和船舶的地面状态下进行了实验。并且，在停止搅拌后，测量了通电量的时间依赖性。通过实验结果，明确了最佳工艺条件。在开始搅拌后20~25分钟，电气化量达到最大值，在停止搅拌后5分钟，电气化量达到0左右。为了用高速摄像机或摄像机观察带电油水滴或混合物在电场中的行为，进行了两种实验。一个是油-水的水滴。使静电垂直落在有电场或无电场的两个电极之间，改变液滴的含水量。另一种是在装有含油量为5Qvol%的油水混合物的容器上施加200 V的电压并搅拌。通过观察，证实了带电壁（电极）与带电油之间的引力作用，使壁面含油量达到70%左右。此外，可以通过改变电压来控制壁面的含油量。结果表明，这一结果可以防止冰对冷却壁的粘附。

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.