沸騰熱伝達における固液接触現象 : 接触界線長さ密度の概念の提案

概要

論文の詳細を見る
In the present study, the dynamic behavior of liquid-solid contact phenomena in saturated pool boiling is observed from beneath the boiling surface by using a single crystal sapphire plate as the boiling surface. The results indicate that at low wall superheat in the nucleate boiling region, most of the dry areas are the primary dry areas corresponding to the bubble base areas, but secondary dry areas appear through coalescence of the primary dry areas with incresing wall superheat. However, even at wall superheat near the critical heat flux point, the ratio of the total area of primary dry areas to the total dry areas is not so small. This fact indicates that, even at the critical heat flux point, not only secondary dry areas but also primary dry areas contribute to boiling heat transfer. To account for the contribution of all the dry areas equally, the contact-line length density which is the total length of the periphery between liquid-solid contact and dry areas in a unit heat transfer area is measured. The dependence of this new time- and space-averaged quantity on the wall superheat is very similar to the boiling curve measured on the sapphire surface. Using the experimental data of the contact-line length density and the model of evaporation heat flux per unit contact-line length developed by Dhir and liaw, boiling curves are predicted as a function of contact angle. The calculated boiling curve for the contact angle of 30 degrees is in good agreement with the measured boiling curve. The results indicate that the contact-line length density, which represents the ratio of intensively evaporating area to the total heat transfer area, is a more direct measure of boiling heat transfer in high-heat-flux nucleate and transition boiling regions than the liquid-solid contact fraction is.
1997-06-25

沸騰熱伝達における固液接触現象 : 接触界線長さ密度の概念の提案

スポンサーリンク

概要

著者

関連論文

スポンサーリンク