Liquid holdup in vertical airwater multiphase flow with surfactant

Liquid holdup for air-water flow was measured in a 0.0508 m-id vertical clear PVC pipe both with and without surfactant using two electrical capacitance sensors. Experimental results were compared to five predictive models and estimated from the measured pressure drop. The measured, estimated and predicted holdup in the two cases considered (with and without surfactant) decreases as the superficial gas velocity increases. None of the models accurately predicted the measured holdup for either case. The value of the holdup estimated from pressure drop was similar to the values predicted from the models. It is believed that the deviation is a result of both inaccuracies of holdup measurement and poor performance of the models. Hasan and Kabir and Aziz gave the best of holdup. Observations from the plots revealed that the measured holdup had an uncertainty of ± 0.07 due to a non-linearity