Suppression of the Leidenfrost Phenomenon by a Superhydrophilic Graphene Nanobush

The Leidenfrost phenomenon considerably reduces heat transfer at high temperatures, but proper micro/nanofabrication can enhance heat transfer by elevating the Leidenfrost temperature. However, the complicated micro- and nanofabrication techniques are difficult to implement in large-scale commercial applications. This paper describes a superhydrophilic graphene nanobush (SGNB) on Cu plates prepared by the PECVD method and subsequent air plasma etching that improves spray cooling heat transfer. The results show that the Leidenfrost temperature of the superhydrophilic graphene nanobush on a Cu plate (SGNB/Cu) is up to 240 °C greater than that of a bare Cu surface. The much higher temperature on the SGNB/Cu surface is due to the fast water wicking and spreading by the nanobush's superhydrophilicity, as well as the increased heat transfer area, increased number of boiling nucleation sites, and robust vapor channels provided by the porous nanobush structure. This study shows the great ability of the nanobush for enhancing boiling heat transfer and a feasible strategy for suppressing the Leidenfrost phenomenon.