直接接触式蒸発器の伝熱過程に関する研究 : 第3報,流下水膜上に滴下したR113液の挙動と蒸発特性

To explain the negative temperature dependence of heat-transfer coefficient in a column-like boiling regime, where a vapor column is formed just behind a nozzle outlet, simplified model experiments were carried out. Optical observation of R113 liquid behavior floating on a flowing water surface gave the following results. R113 liquid on the water surface alternatively could take three states, such as spheroidal drop, lens and continuous thin film. When the temperature difference between water and saturation temperature of R113 was raised, the appearance time of the spheroidal drop state became longer and the average thickness of the lens or continuous thin film states with shorter appearance time increased. Heat transfer to evaporating R113 liquid was enhanced in this order of three states. These results lead to a lower heat-transfer coefficient at a higher temperature difference.