| Research Abstract |
To improve the performance of the ice thermal energy storage, basic researches were performed concerning a few subtopics. That is, (1) the statistical condition to freeze the supercooled water through the non-homogeneous nucleation, (2) the method to initiate the instantaneous freezing of supercooled water by supplying an electric trigger and (3) the transient thermal and fluid mechanical process of the freezing of supercooled water flowing through a pipe.
In the research of the first subtopic, a physical parameter particular to the individual surfaces, which control the freezing of the supercooled water, was discussed for the case of a non-homogenous nucleation, using the experimental relation among the temperature of the ice appearance, the cooling rate, the surface properties of the solid, the surface area and the surface conditions. From the results, initiation of the freezing was confirmed to be expressed by a general formula, using the above parameter.
In the research of the second
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subtopic, experiments to freeze the supercooled water instantaneously were performed varying the voltage supplied, the distance between the electrodes, the shape of the electrode and the degree of the supercooling. From a series of experiments, the electrical trigger was proved having an effect to freeze the supercooled water. At the same time, the condition of the initiation of the freezing was clarified by introducing a statistical concept concerning the relation of the degree of the supercooling, the electrical current and the time.
In the research of the third topic, the processes of the dendrite growth and the development of the solid ice after the appearance of the ice nucleation in a pipe flow of the supercooled water was investigated through precise observations and measurements. Based on the experimental and analytical results, a general physical relation deciding the propagation velocity of a solid ice was shown. And the mechanism of the relaxation process of a flowing supercooled water, where the distribution of the degree of the supercooling, the development of the solid ice, the growth and the disappearance of the dendrite effect each other. Less
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