AbstractsEngineering

Water and supercritical carbon dioxide have different wetting angles to a glass surface, where water has a lower angle. In a microfluidic channel, the lower wetting angle draws the water to surround the supercritical carbon dioxide and the supercritical carbon dioxide therefore easily form droplets or segments if the flow rate is low. In this study, the flow of supercritical carbon dioxide and water has been studied in a microfluidic system with a double Y-channel. The micro channels have been built in borofloat glass to withstand high mechanical and chemical forces, still enabling in situ characterization. The aim has been to analyze flow changes in the water and supercritical carbon dioxide in structured channels with and without surface modification.             The result shows that the flow regime of supercritical carbon dioxide and water can be controlled by changing flow rates, adding walls, or coating a channel as well as any combination of these three. If adding a large enough wall in a channel, the flow will be segmented only in half the channel at moderate flow rates from both sources, and parallel if the flow rate of supercritical carbon dioxide is high enough. A non-polar coating of half a channel will make the supercritical carbon dioxide flow along the coated side and supercritical carbon dioxide can by that way be forced to only take one of the outlets. However, still water exit at both outlets.