Experimental study on the overall heat transfer capability of the thin liquid film at different positions in the three-phase contact line area

With the miniaturization and integration of electronic devices, the power density in electronic devices has increased significantly, putting forward higher requirements on the service life and stability of electronic devices. The micro-scale liquid cooling systems have played an essential role in the heat dissipation of microelectronic devices. In the micro-scale liquid cooling systems, when solid, liquid, and gas are in contact, a three-phase contact line area is formed. At the micro-nano scale, heat transfer in this area cannot be ignored. However, because of the small size of the three-phase contact line area, the experimental researches are mainly focused on the profile of the liquid thin film. Few experimental methods can easily measure the heat transfer capacity of the three-phase contact line area. In this study, we used the transient time-domain thermoreflectance (TDTR) technique, which has a satisfactory spatial and temporal resolution, to characterize the heat transfer capacity of the thin liquid film at different positions in the three-phase contact line area and established a heat transfer model for TDTR to measure the overall heat transfer coefficient of the thin liquid film. In addition, we used Wayner’s evaporation model of wetting film to verify the experimental results. The experimental results show that the overall heat transfer coefficient of the liquid film in the middle of the microgroove is much smaller than that at the edge, which has the same law as the theoretical calculation. The evaporating thin-film region’s measured overall heat transfer coefficient can reach ~ 650 kW/(m2·K). This study provides an idea for the experimental study of micro-nano-scale liquid film heat transfer and laid the foundation for revealing the heat and mass transport mechanism in the three-phase contact line area.