Isothermal Air-Water Two-Phase Up- and Downward Flows in a Vertical Capillary Tube. 2nd Report. Pressure Loss.

Abstract

Pressure drop was measured for air-water two-phase flow in a vertical capillary tube. Inner diameters of pipes used were 1mm, 2.4mm and 4.9mm. The directions of flow were both vertically upward and downward. Several correlations of pressure loss in two-phase flow, which have been proposed so far, were examined to determine whether or not they are useful for a capillary tube. As a result, it was clarified that those correlations cannot predict the data with high accuracy, especially in the intermittent flow region. Thus we proposed a new. correlation in which the expansion loss of water flow from water film around a large gas bubble to a water slug is taken into consideration. It shows better agreement with the experimental data.