(331d) Pool Boiling Heat Transport: A Controlled Process to Form Reduced GO Surfaces from GO with Tunable Surface Chemistry and Morphology

Phase change heat transfer is crucial to various engineering applications. Some prominent examples include distillation reboiler, nuclear reactor, high-powered electronic systems, and refrigeration. Boiling is a heat transfer process accompanied by phase change from liquid to vapor, subsequently, pool boiling involves the boiling of a stagnant liquid over a heated surface. For various manifestations, the pool boiling performance of a surface is dictated by higher critical heat fluxes and heat transfer coefficients. In this work, we used repetitive pool boiling to test the durability of graphene oxide-copper (GO-Cu) coated surfaces and studied subsequent changes in surface chemistry and morphology. We observed the transformation of GO-Cu to reduced GO-copper (rGO-Cu) coating that led to improved boiling performance. This improvement is attributed to a) transition of hydrophilic GO to hydrophobic rGO due to the repetitive pool boiling, and b) increased surface roughness as a result of hydrophobic surfaces. The durability of the GO-Cu coatings was found to be higher than pristine-copper and just-copper coated surfaces. A higher performance demonstrated by GO-Cu coatings indicates its increased sustainability and practicability in numerous engineering applications.