Patterns of direct contact condensation bubbles based on dynamic behaviors and oscillations

Abstract

The occurrence of periodic pressure oscillations caused by direct contact condensation (DCC) bubbles holds great significance in engineering. To investigate and control these oscillations associated with different bubble behaviors through experimental means, a steam flow with a mass flux ranging from 0.06–0.9 kg/h is introduced into a water bath at temperatures ranging from 40–85 °C through nozzles with diameters of 3, 4, and 5 mm. In this study, apart from the internal chugging (IC) behavior, both pressure oscillation and bubble behaviors are simultaneously studied and categorized into three distinct patterns: Bubble detachment type I (BD I), bubble detachment type II (BD II), and condensation oscillation. By considering bubble dynamics and employing dimensional analysis, we establish the dimensionless criteria RenPrJa for differentiating BD I from IC, as well as the critical Reynolds number Ren for distinguishing BD I from BD II. Subsequently, a dimensionless regime diagram is constructed to predict and evaluate the bubble behavior patterns with respect to oscillation under various test conditions. This regime diagram serves as a valuable tool for predicting and assessing the bubble behavior patterns associated with pressure oscillation in different operating scenarios.