Recent Progress in Experimental Techniques for Thin Liquid Film Evaporation

Thin liquid film evaporation leverages latent heat and low thermal resistance to achieve superior heat transfer capabilities, making it pivotal for next-generation high-heat-flux thermal management systems. This paper presents a systematic review of the fundamental mechanisms, interfacial transport behaviors, and experimental techniques associated with static thin films and falling liquid films. This work elucidates the complex coupling of Marangoni convection, van der Waals disjoining pressure, and contact line dynamics. These mechanisms collectively govern film stability and the intensity of non-equilibrium phase change in the micro-region. The influence of surface wettability and dynamic contact angle hysteresis on hydraulic replenishment and dry spot formation is critically analyzed, offering insights into optimizing surface engineering strategies. In addition, the review categorizes advanced non-intrusive diagnostics, including optical interferometry, laser-induced fluorescence (LIF), and infrared thermography, evaluating their capacity to resolve spatiotemporal variations in film thickness (ranging from 10 nm to several μm) and temperature under complex boundary conditions. Special attention is directed toward falling film evaporation over horizontal tubes, addressing flow regime transitions and the impact of interfacial shear from external airflow. The work concludes by identifying key challenges in multi-physics coupling and proposing future directions for synchronized diagnostics and adaptive surface design.