Correlation of heat transfer coefficient for two-component two-phase slug flow in a vertical pipe

The prediction of heat transfer coefficient for gas–liquid two-phase flows in vertical pipes is important for designing many industrial and engineering apparatuses such as nuclear power plants, solar collectors and petroleum pipelines. The mechanism of two-component two-phase heat transfer is more complicated than that of single-phase heat transfer. This study aims at developing a robust correlation of heat transfer coefficient for two-component two-phase slug flows in vertical pipes. The theoretical framework for the correlation development is inspired by considering classic Reynolds and Chilton–Colburn analogies. The framework demonstrates that the functional dependence of the two-component two-phase heat transfer coefficient on a void fraction or a two-phase multiplier is expressed by the Reynolds and Chilton–Colburn analogies. The correlation for the heat transfer coefficient of two-component two-phase slug flows in vertical pipes has been developed and validated by more than 200 existing data. The newly developed correlation predicts 95.1% of the collected two-phase heat transfer data within ± 30% error and the mean absolute relative deviation of the correlation is estimated to be 14.2%. The extended applicability of the newly developed correlation to other flow regimes such as bubbly, churn and annular flow regimes has been verified by the existing experimental data. The possible application of the newly developed correlation to large pipes is also discussed. In summary, it is expected that the newly developed correlation can predict the heat transfer coefficient of two-component two-phase flows under various conditions such as vertical upward and downward flows, developing and fully developed flows, laminar and turbulent flows and all two-phase flow regimes. The application of the correlation to vertical large pipes is also considered to be reasonable.