Droplet formation in oval microchannels with a double T junction: a CFD and experimental study

The use of microfluidics can improve the process of droplet formation while reducing energy consumption. In the present work, a microreactor system with a double T junction and oval microchannel reactor 2509 mm long was analyzed. The stream was composed of styrene, water, and an emulsifier. The concentration of water in the emulsion and the flow rates of water and styrene were evaluated. Droplets were observed at styrene/water flow rate ratios (Qd/Qc) ranging from 1:10 to 1:80. The simulations in the double T junction were carried out with laminar flow and the Volume Of Fluids model was selected for the phase interactions. Experiments with four flow rates of styrene and water were carried out. A simple optical system was used for in-line observation of droplets formed in the microreactor. For the flow ratio 1:1, there was no drop formation. For the other rates, droplets were observed from 59 to 200 μm. The droplets moved along the reactor maintaining shape and size. This fact indicated that the micro reaction system is suitable for developing a system that requires stability, such as emulsion polymerizations. The comparison between model and experimental results pointed out that these were reasonably represented by the model.