Flow and Heat Transfer in Two-Phase Flow Immiscible Droplets in Microchannels

Abstract

ABSTRACT The enhancement of heat transfer in microchannels without phase change is a significant area of study, primarily driven by the internal fluid recirculation in two-phase flows. This investigation focuses on a circular microchannel, 100 μm in diameter, where mineral oil droplets are introduced into a water flow. The study utilizes the conservative level set method for precise interface tracking and liquid film thickness measurement. This research introduces a modified Nusselt number, specifically tailored to describe the heat transfer characteristics of multiphase flows. The study delves into the effects of varying droplet sizes, from small spheres to a slug. The findings indicate that the most significant heat transfer enhancement occurs with droplets whose volume closely matches that of a sphere fitting within the channel. Moreover, the investigation explores the impact of parameters like inlet velocity, primary-phase slug length, and contact angle. Notably, higher inlet velocities lead to improved heat transfer, resulting in a substantial increase in the Nusselt number compared to single-phase flows. The study underscores the delicate balance between recirculation intensity and droplet heat capacity concerning slug length, as excessive variations can harm thermal performance. It also highlights the pivotal role of surface wettability, showing improved thermal performance on hydrophobic surfaces.