Surface Wettability Effects on Flow Characteristics in Gas-liquid Two-phase Flow through Rectangular Horizontal Micro-channel

Experiments for gas-liquid two-phase flow in a horizontal rectangular micro-channel were conducted. The channel with rectangular cross-section of 1.0 mm height × 1.0 mm width was used as the test channel. In order to understand the effects of wettability on the two-phase flows in the micro-channel, the channel wall near gas and liquid mixer was coated by a hydrophobic agent. The contact angles were approximately 80°for the non-coating surface (hydrophilic) and 127° for the coating one (hydrophobic). In the experiments, flow pattern, bubble length, bubble velocity, void fraction and pressure drop were measured. From the comparison of the measured parameters between coating and non-coating cases, the hydrophobic surface (coating surface) makes bubble length longer. Then, the longer bubble reduces pressure drop.