Void fractions and pressure drops were measured for gas-liquid flows in five kinds of horizontal narrow flat channels with a width of 10 mm and channel clearances of 0.2∼2.0 mm. Four kinds of aqueous ethanolic solutions were used to examine the influences of surface tension 6 and viscosity μ of liquid on flow characteristics. The void fractions increased with a decrease in σ, μ and channel clearance. Under low liquid velocity conditions, the pressure drops were affected by the surface tension, and it was found that Chisholm's equation for the Lockhart-Martinelli correlation could not be applied to channels with relatively large clearances.
