Validation of a General Heat Transfer Correlation for Non-Boiling Two-Phase Flow With Different Flow Patterns and Pipe Inclination Angles Available to Purchase

A general heat transfer correlation for non-boiling gas-liquid two-phase flow with different flow patterns and inclination angles was developed. To verify the correlation, local heat transfer coefficients and flow parameters were measured for air-water flow in a pipe for the horizontal and slightly upward inclined (2°, 5°, and 7°) positions, and all the flow patterns in the entire flow map. The test section was a 27.9 mm stainless steel pipe with a length to diameter ratio of 95. A total of 763 data points were collected for horizontal and slightly upward inclined positions by carefully coordinating the liquid and gas superficial Reynolds number combinations. The heat transfer data were collected under a uniform wall heat flux boundary condition ranging from about 1800 to 10900 W/m². The superficial Reynolds numbers ranged from about 740 to 26000 for water and from about 560 to 48000 for air. The general heat transfer correlation was validated with the 763 data points that were experimentally collected. The validation confirmed the robustness of the general two-phase heat transfer correlation to adequately predict heat transfer data for various flow patterns and inclination angles. The accuracy of the correlation to correlate the experimental data was further explored by applying various available void fraction correlations. The performance of the correlation when applied with the different void fraction correlations were compared and appropriate recommendations are made.