Critical heat flux and boiling behaviors on a horizontal surface in saturated pool boiling at high pressures

摘要

The purpose of this study is to investigate the critical heat flux and bubble behaviors of ethanol, water, and R141b at high pressures. The heating surface was a 7 mm diameter horizontal copper surface. The pressure varied between 0.1 MPa and 1.49 MPa. The measured results showed that Kutateladze-type correlation explained well the variations in the CHF with pressure for ethanol and R141b, however, underestimates the pressure dependence of the CHF for water. This suggests that it is necessary to consider the effect of surface wettability on the CHF for water boiling. The boiling behaviors were observed by the high-speed video. It was found that large vapor masses that cover the heating surface were formed for water, ethanol and R141b at high heat fluxes in the whole range of pressures, and the detachment frequencies of the large vapor masses were little affected by the heat flux and pressure.