A RESEARCH ON RAPID EVAPORATION OF THE MICRO BUBBLE AND ITS INJECTION-COLLAPSE BEHAVIOR

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The purpose of this study is to clarify the miniaturization phenomenon in which large number of minute droplets intensely scatters to the atmosphere, when the droplet collided on the heating surface. Especially, the generation behavior of the minute bubble(micro bubble), which arose, when the liquid-solid contact occurred by a collapse of the thin vapor film formed between the heating surface and the droplet, was caught for the elucidation of the minituarization mechanism. In quartz heating surface used until now, the nucleate boiling behavior continued to the high-temperature range, and the dispersion phenomena of the intense and minute droplets could not be remarkably recognized. Then, sapphire disk of which thermal conductivity is good, ITO(Indium Tin Oxide)film plane which thinly spattered conductive film to the glass plane and the plane which thinly spattered chromium coating on the quartz plane were used as a heating surface. Boiling behavior on each plane was caught by high-speed camera from each back surface, and it was compared with the quartz plane. Evaporation lifetime property of the nucleate boiling condition(boiling of the condition in which heating surface and liquid film sufficiently got wet)on the ITO film plane and the chromium coating plane is similar to the data in the quartz plane. The lifetime property on the sapphire closs to the lifetime for metal surface. The part of divided droplet would contact with heating surface through the thin vapor film, when the temperature of the chromium coating plane exceeds 450°C.At this time, it could be confirmed that the dispersion of the explosive minute liquid particle was generated. It was proven that the result of inducing this explosive dispersion was a micro bubble.