Direct Cooling of Microsystems Using a Two-Phase Microfluidic Droplet

Droplet-based microfluidics offers a promising approach for enhancing heat transfer in microchannels, which is critical for the thermal management of microsystems. This study presents a two-dimensional numerical investigation of flow and heat transfer characteristics of liquid–liquid two-phase droplet flow in a rectangular flow-focusing microchannel. The phase-field method was employed to capture the interface dynamics between the dispersed (water) and continuous (oil) phases. The effects of total velocity and droplet size on pressure drop and heat transfer performance are systematically analyzed. The results indicate that the heat transfer of two-phase droplet flow was significantly enhanced compared to single-phase oil flow, with its maximum heat transfer coefficient being approximately three times that of single-phase oil flow. The average heat transfer coefficient increases with total velocity and exhibits a non-monotonic dependence on droplet size. These findings provide valuable insights into the design and optimization of rectangular flow-focusing droplet-based microfluidic cooling systems.