Extraordinary enhancement of nucleate pool boiling on intrinsically biphilic graphene nanostructured surfaces

Abstract

• We use graphene nanoplatelets (GNPs) of varied wettability to enhance nucleate boiling. • Hydrophobic GNPs enhances boiling heat flux up to 219% as compared to uncoated case. • A profound heat transfer coefficient enhancement of 230% is obtained. • A drastic temperature drop of 36.1°C on the heated surface is achieved by using GNPs. • Hydrophobic GNPs manifests as a natural biphilic coating favorable to nucleate boiling. Miniaturized electronics components require effective heat removal to ensure their reliability and long-lifespan. Here, the importance of surface wettability of graphene nanoplatelets (GNPs) coatings in the thermal performance enhancement of subcooled pool boiling is elucidated. The boiling enhancement of superhydrophilic, hydrophobic and superhydrophobic GNPs coatings, is compared and benchmarked with that of the uncoated copper surface. The hydrophobic GNPs case manifests extraordinarily enhanced boiling performance. When compared with the uncoated copper surface, the boiling heat flux and the heat transfer coefficient are enhanced up to 219%, and 230%, respectively. A significant temperature decrease up to 36.1°C and an effectiveness of 3.19 as compared to the uncoated case are obtained. Besides the nanoporosity of GNPs coatings which is favourable to bubble nucleation, the unique nanostructure of the hydrophobic GNPs, which possesses a combination of hydrophilic and hydrophobic characteristics provide synergetic effect on the vapor bubble growth and departure rates. The hydrophobic GNPs is a single coating endowed with biphilicity naturally. This study incorporates facilely fabricated GNPs coatings while showcasing the importance of the wettability of GNPs in nucleate pool boiling. We envisage that the intrinsically biphilic GNPs coating has an immense potential in the highly demanding thermal management of electronics devices.