Reproductive accuracy of two-phase flow pressure loss correlations for vertical 90° bends

The method proposed by Sookprasong underpredicts, while the Chisholm B-equation still overpredicts the pressure loss in vertical upward air-water flow through a 90∘ Plexiglass bend with an internal diameter of 30 mm and a curvature radius of 120, 180, 240 and 300 mm. The scatter of the logarithmic ratios between the experimental and the predicted values exhibited by both models is about 40%. The Chisholm model, on the other hand, is physically consistent and, therefore, recommended for use, resp., suitable for extrapolations.