高濃度マイクロバブル水を用いた 気泡含有氷の生成

抄録

In this paper, ice layer containing many bubbles was formed by freezing high density micro-bubble water on a copper plate, which was tilted downward. We observed the ice layer and obtained its closed-porosity by measuring volume of the ice layer. From the results, it was found that larger bubbles due to coalescence of micro-bubbles were trapped in the ice layer and caused reduction of closed-porosity and of freezing rate. The larger bubbles, however, reduced with tilting the cooling plate because they could not hold on the tilted surface of the ice layer. We show that the cooling plate tilted at 30 degrees angle to horizontal formed a high closed-porosity ice layer with keeping freezing rate. In addition, a heat transfer analysis of the process was carried out and was validated by comparison with the experimental results. The analysis results revealed a relation between velocity of ice layer surface and porosity. And finally, the analysis results of constant cooling rates provide optimum cooling conditions for forming gas-containing ice, in which amount of contained gas is maximum.