Experimental Study on the Thin-Film Evaporation of Organic Solvent Droplets on Metal Surfaces

In order to meet the demand for enhanced heat transfer capabilities in practical application areas such as high heat flux density and high stability, the film evaporation heat dissipation method has been widely applied in fields such as microelectronic device cooling, heat pipe technology, solar steam generation, and seawater desalination. In the current study, film evaporation experiments are conducted on droplets of propylene glycol and ethanol using a film evaporation observation platform. The morphological changes and temperature of the droplets are investigated by varying the overheating degree, material, roughness, and wettability of the heating plate. The results indicate that the droplet thickness undergoes three stages of change with variations in overheating degree, and the droplet thickness decreases overall with increasing roughness. The thickness of ethanol droplets is higher than that of propylene glycol droplets in the low overheating degree range but lower in the high overheating degree range. Ethanol droplets are more sensitive to overheating degree than propylene glycol droplets. As the droplets enter the film evaporation state, the surface temperature of the droplets gradually approaches the wall temperature and the rate of change slows down. This trend shows a certain similarity to the change in droplet thickness. Increasing the surface roughness slightly raises the overall temperature, while altering the wettability has minimal impact on the temperature variation.