Rectangular and circular microchannels and four kinds of test liquid were used to study the effects of channel geometry and liquid properties on two-phase flow characteristics, i.e., flow regime, bubble length, bubble velocity, void fraction, frictional pressure drop, interfacial friction force. Three types of flow regime were observed, i.e., quasi-homogeneous flow, quasi-separated flow and layered flow. The bubble length data for the quasi-homogeneous flow were well correlated by the scaling law proposed by Garstecki et al (2006). The bubble velocity data and/or the void fraction data were well correlated with the well-known drift flux model (Zuber and Findlay, 1965). The distribution parameter, C0, in the model was found to depend on both the liquid properties and the channel geometries. Thus, C0 correlation was developed with three dimensionless numbers, i.e., Bond number, liquid Reynolds number and gas Weber number. The frictional pressure drop data were also found to depend on both the liquid properties and the channel geometries. And, the pressure drop data were well correlated with Lockhart-Martinelli method with a new two-phase friction multiplier correlation developed also. By substituting these correlations as well as those in literatures into a one-dimensional two-phase two-fluid model, the void fraction was calculated. The calculation with new correlations was found agree with the present data.
