In order to obtain the frictional characteristics of fully developed Taylor flow in the vertical capillary tube

numerical simulations of the flow in the capillary tube with diameter of 2 mm were conducted by using the moving frame reference method. The shape

rising velocity of Taylor bubble

liquid film thickness and pressure drop were obtained using two different working fluids and analyzed. Simulation results showed that the length of Taylor bubble and the radius of curvature increased with increasing two-phase superficial velocity Vtp. The length of Taylor bubble also increased with increasing gas void ξg

while the nose and tail of Taylor bubble were independent of ξg. Dimensionless thickness of liquid film and rising velocity of Taylor bubbles were proportional to capillary number Ca. Friction factor fc decreased with increasing Vtp and ξg. The fc of Taylor flow with N2/ (CH2OH)2 as working fluid was lower than that of single phase with the same Vtp

while the fc for N2/H2O was higher than that of single phase. The model proposed by Lockhart and Martinelli

and the flow pattern dependent model proposed by Kreutzer et al. could predict the pressure drop obtained from simulation with an error of ±10%. The Chisholm number C 5 which was recommended for conventional tube when both phases were laminar was also reasonable for the capillary tube in the simulation work.