Assessment and experimental validation of the new wall boiling heat transfer model under different boundary conditions

Abstract

Flow boiling widely exists in industrial systems because of its high heat transfer capability. In the previous study, we proposed a new heat transfer model for wall boiling through mechanism analysis (Zhang et al., 2024). As a newly developed model, it is quite important to explore the impact of different boundary conditions on model performance to provide potential directions for further improvement. In this paper, a series of flow boiling experiments for R134a within a wide range of boundary conditions (q_w = 80–260 kW/m², G = 1000–2000 kg/(m²·s), P = 11–17 bar, $\Delta$ T_in,sub = 19–38 K) were carried out in a 10 mm-diameter vertical tube, providing more than 900 data points. The developed wall boiling model was validated using these experimental data for R134a boiling, as well as referenced water boiling and n-Perfluorohexane boiling experimental data in both pipes and rectangle channels. According to the results, the mean relative error of the wall superheat between our experimental data and the model predictions is ±31.5 %. In addition, an analysis was conducted to examine the influence of different boundary conditions on the accuracy of the developed model. The reasons for the discrepancy of the calculated results were analyzed and further improvements should be considered in the model.