Wicking Enhanced Critical Heat Flux for Highly Wetting Fluids on Structured Surfaces.

The use of micro/nano-scale structures has been shown to enhance critical heat flux (CHF) during pool boiling in recent studies. A correlation between wicking rate and CHF enhancement for structured superhydrophilic surfaces has been reported in prior work of the authors. In that work, a nondimensional correlation was developed and validated using only water as the working fluid. In this study, a highly wetting fluid (FC-72) was used to demonstrate the applicability of this correlation on structured surfaces for nonaqueous liquids. This has been achieved using a simple modification of the experimental procedure for highly wetting fluids. This experimental modification shows no effect on the quantification of the liquid wicking rate. Numerous structured superhydrophilic surfaces have been fabricated and tested, including micro- and nanoscale structures and hierarchical surfaces which showed the highest CHF enhancement (200%). More importantly, this work demonstrates the validity of the nondimensional parameters used in the proposed CHF correlation and its overall applicability to a wide range of nonaqueous liquids.