The measurement of liquid holdup in two-phase horizontal slug flow

The horizontal slug flow regime is one of the more important two-phase flow regimes because of its widespread occurrence, particularly in systems where flashing or boiling is occurring. Thus the need for methods of predicting the momentum, heat and mass transfer characteristics for design purposes in such a system is evident. In a study recently carried out a method was presented for predicting the pressure drop across a single liquid slug in the system. However, two of the basic system parameters necessary for the calculations could not be measured. These were the liquid holdup in a slug and in the film zone separating the slugs. The correlations found in the literature for predicting holdup in the slug flow regime all give values of holdup averaged over both the slug and film zones and not the instantaneous values required for these pressure drop equations. Similarly, most of the traditional experimental methods for measuring two-phase holdup are based on some form of averaging. [...]