Abstract
In this study, visual observation of flow pattern by using a high-speed camera and direct measurement of liquid film thickness by using a laser displacement meter for slug flow in microchannels with inner diameter of 0.5 mm, 1 mm and 2 mm were conducted. 5 fluids with different surface tension and viscosity (water, ethanol, FC72, KF-96L-0.65cs, KF-96L-2cs) were selected to investigate the effect of physical properties on the flow pattern and liquid film thickness. Experimental results were compared with several existing correlation to provide better understanding of two phase flow and heat transfer characteristics at a various tube scale and working fluid physical properties. For the flow pattern, the difference between experimental data and flow pattern map in previous studies becomes larger as the tube diameter increases, and liquid surface tension decreases. However, liquid viscosity has relatively small effect on its flow pattern. For the bubble velocity and liquid film thickness, comparing with correlations in previous studies, the error between experimental data and correlations becomes larger when liquid surface tension and viscosity are low relatively. And also in that case, as the tube diameter increases, the error becomes larger.
