EVAPORATION KINETICS OF Al2O3 NANOFLUID DROPLETS ON BAMBOO AND KALANCHOE BLOSSFELDIANA LEAVES: INFLUENCE OF SURFACE ROUGHNESS AND STRUCTURE

This study focuses on the effects of surface roughness and rough structures of bamboo leaves and Kalanchoe blossfeldiana leaves on the evaporation kinetics of Al<sub>2</sub>O<sub>3</sub> nanofluid droplets. In this paper, the evaporation of Al<sub>2</sub>O<sub>3</sub> nanofluid droplets (2 ± 0.1 μL) on bamboo and Kalanchoe blossfeldiana leaves was investigated using the droplet shape analysis system, focusing on the effects of rough structural morphology and parameters on evaporation characteristics. Kalanchoe blossfeldiana leaves, with dense irregular concave structures, and bamboo leaves, with sparser regular stripes, both exhibit constant contact-radius and mixed evaporation modes for nanofluid droplets. During the evaporation process, the evaporation rate of the droplets was affected by the combined effect of rough structure, roughness, and nanoparticles. In particular, the evaporation rate of droplets demonstrated a tendency to increase and subsequently decline with an increase in roughness. Moreover, the increase in roughness is manifested as an increase in heat transfer area, which promotes the evaporation of nanofluid droplets, while the deposition of nanoparticles hinders the evaporation, and the two show a competitive mechanism. In contrast to the dense concave structure of Kalanchoe blossfeldiana, which is more likely to trap nanoparticles, the regular bamboo leaf structure has a lesser inhibitory effect on the evaporation of nanofluid droplets. This study further reveals the evaporation mechanism of nanofluid droplets on rough biosurfaces and provides a theoretical reference for the nanofluid-enhanced heat transfer process on rough, patterned surfaces.