Microscale Phase Separation Through Nanoporous Membranes

Abstract

This paper presents an experimental study on bubbles extraction from a two-phase flow in microchannels. The bubbles were extracted through a hydrophobic porous membrane covering the microchannels. The two-phase flow was generated through mixing water and air at a T-junction positioned before a microchannel on a microfabricated device. To study the effect of different parameters on the extraction rate, an extensive parametric study was conducted. The parametric space included variations of the channel depth, pressure difference across the membrane, and water and air flow rates. Differential pressure across the membrane was found to be the most critical factor impacting the bubbles extraction rate. Also, the effect of flow quality on the extraction rate was determined to be insignificant. Furthermore, it was found that at a critical velocity a liquid layer forms between the bubbles and the membrane and consequently the bubbles cease to extract.