Research on heat transfer capability of liquid film in three-phase contact line area

Abstract

• Heat transfer studies were carried out in the three-phase contact line region using the TDTR method with high spatial and temporal resolution. • The experimentally measured results of the overall heat transfer coefficient of the n-octane liquid film in the evaporating thin-film region can reach 439 kW/(m 2 ·K). • A bidirectional heat transfer model for the TDTR experiment was built during data processing. • The usability of the TDTR method in microscopic liquid film heat transfer studies is demonstrated by numerical calculation. The three-phase contact line area plays a vital role in the heat dissipation of micro-devices due to its intense heat transfer capacity. However, the scale of the three-phase contact line area is small, and experimental studies are mainly used to observe the film profile. Few experiments can characterize this area with high spatial resolution, making it a well-known challenge to make a quantitative assessment of the limit of heat transfer capacity. In this work, we use the time-domain thermoreflectance system to measure the liquid film heat transfer capacity in the contact line region. The effective thermal conductivity of the liquid film obtained from the experiment can well reflect the heat transfer capacity of the liquid film at different positions and can be used to calculate the evaporating heat flux and the overall heat transfer coefficient of the liquid film. We also established a theoretical model and performed numerical calculations compared with the experimental results. The results show that the liquid film has the most vital heat transfer capacity in the evaporating thin-film region. The overall heat transfer coefficient can reach ∼439 kW/(m 2 ·K), and the evaporating heat flux of the liquid film can reach ∼1.8 × 10 6 W/m 2 . This work provides a new idea for the experimental study of the three-phase contact line area, offers experimental support for theoretical research, and lays a foundation for revealing the heat and mass transport mechanism in the three-phase contact line area.