where C, is a constant. The value of C = 0.66 was given by Mishima
and Hibiki [27]. We found that C = 0.24 was best fit the two-phase
pressure drop measured by Kawahara et al. [3] in a circular tube
of d = 100 lm.
A comparison of the two-phase frictional pressure gradient data
with the predictions of the Lockhart–Martinelli correlation using
different C-values is shown in Fig. 8a,b, including C = 0.24 and
C = 0.66. A good agreement (within ±10%) was obtained with the
use of the value of C = 0.24. As can be seen (Fig. 8b) agreement with
he use of the value of C = 0.66 is not good.