An Evaluation of Correlations for Predicting Pressure Drop of Air-Water Flow in Narrow Rectangular Duct

Aiming at developing a more common method for predicting two-phase flow pressure drop for small channels, experiments on frictional pressure drop of air-water flow in a vertical narrow rectangular duct with a cross-section of 40 mm by 1.6 mm were conducted at atmospheric pressure. The mass flow rates of air and water covered the ranges from 0.03 to 12.5 kg/h and from 19 to 903 kg/h, respectively. It was found that the two-phase flow can be divided into three regions according to the liquid only Reynolds number, by which a modified Chisholm two-phase multiplier was proposed for predicting frictional pressure drop. Some leading correlations for predicting two-phase flow pressure drop were compared with the new correlation against current experimental data, the latter had and a mean deviation of 7.2%, showing a better agreement with the experimental results.