Flow Patterns and Frictional Pressure Drop in Gas-Liquid Two-Phase Flow in Vertical Capillary Channels with Rectangular Cross Section.

In a compact heat exchanger, a gas-liquid two phase mixture flows in a noncircular channel with a narrow cross sectional area. Therefore it is necessary to clarify the flow phenomena and the pressure drop in such a small channel. In the present experiment, we used capillary vertical rectangular channels. The shorter side length is constant at 1 mm, and the longer side length of each duct is 1.0, 2.0 or 5.0 mm. The effects of the aspect ratio of the channel on the velocity characteristics, flow patterns and two-phase frictional pressure drop are discussed. The modified correlations for the estimation of frictional pressure drop were obtained by taking the effect of aspect ratio into account. These formulae agree well with the experimental data.