Interfacial area concentration correlation for boiling steam-water two-phase flows in annulus flow channels

Abstract

The investigation of boiling two-phase flows in annulus flow channels has garnered increasing significance given its extensive utilization in various heating devices and its crucial contribution as a fundamental basis for comprehending boiling two-phase flow behavior in intricate flow channels, such as rod bundle flow channels. Accurate modeling of Interfacial Area Concentration (IAC) in boiling steam-water two-phase flows is essential for enhancing the predictive performance of the two-fluid model in simulating complex two-phase behaviors in a diverse range of practical boiling systems. The present study evaluates the predictive performance of seven representative IAC correlations using available typical experimental IAC data from boiling steam-water two-phase flows in annulus flow channels. Although some representative IAC correlations exhibit favorable predictive performance for specific experimental databases, none of the reviewed existing correlations consistently maintain acceptable predictive performance across all collected experimental data. In order to enhance the accuracy and reliability of IAC predictions under boiling flow conditions, a novel IAC correlation has been proposed grounded in physical-based considerations to effectively model the IAC contributions of small (group-1) and large (group-2) bubbles in boiling steam-water two-phase flows in annulus flow channels. The newly proposed two-group bubble IAC correlation has been validated through the examination of 303 boiling steam-water data obtained from annulus flow channels, demonstrating satisfactory predictive performance with the mean relative error of 0.216. Moreover, the applicability of the newly proposed IAC correlation to rod bundle flow channels has been evaluated using 53 boiling steam-water data taken from a 3 × 3 rod bundle flow channel, yielding a favorable prediction result with a mean relative error of 0.173. The anticipated improvement in the accuracy of predicting IAC for steam-water two-phase flows through the newly proposed correlation is expected to provide a scientific foundation for enhancing the performance and safety of thermal systems.