Nanofluid Boiling on Micro/Nano-engineered Surfaces.

This work characterizes the impact of boiling aqueous nanofluids on engineered surfaces designed for boiling enhancement with pure water. Although micro/nano-engineered surfaces have been shown to enhance boiling, these achievements are typically demonstrated using deionized water or other purified fluids. In parallel, particulate-laden fluids, also known as nanofluids, have been shown to enhance boiling as well. In this study, we investigate a variety of engineered surfaces and the boiling degradation due to the addition of SiO ₂ particles at a fixed concentration of 0.2% by volume but varying sizes from 7 nm to 10 μm. Although the addition of SiO ₂ particles is shown to moderately improve critical heat flux (CHF) on all the surfaces considered, the heat transfer coefficient (HTC) is seen to deteriorate with the addition of particles of any size. The bare copper surface and a nanostructured surface show particle size-dependent degradation of the HTC due to clogging. Bi-conductive surfaces also show a degradation of the HTC, but it was shown to be independent of the particle size. This work has shown specific and unique degradation mechanisms for each of the surfaces considered including the reduction of nucleation sites and thermal insulation. Additionally, the surfaces tested in this work exhibited a partial-CHF condition occurring with the addition of particles.