Surface Coating with Nanofluids: The Effects on Pool Boiling Heat Transfer

Recent research has confirmed a buildup of a thin layer of nanoparticles on the heated surface during nucleate boiling in nanofluids. Most of these studies report no change of heat transfer and, even worse, the presence of heat transfer deterioration. However, a few others report a heat transfer enhancement. In order to understand these controversial results, experiments were performed to explore the mechanism of surface coating during nucleate boiling in nanofluids. The thickness of the nanoparticle layer was observed to depend on the nanoparticles concentration and the experiment duration. Compared to a clean surface, the wettability of the surfaces with a TiO2 nanoparticle layer has been significantly improved. However, up to 50% of heat transfer coefficient deterioration was observed with TiO2-coated surfaces in water pool boiling. An explanation is proposed that involves the role of adhesion energy on heat transfer.