Pool boiling inversion and secondary boiling effect on CNTs-Cu nanoparticles-coated porous surfaces

In this study, pool boiling experiments were conducted using carbon nanotubes (CNTs)-Cu nanoparticle-coated porous surfaces. Applying a layer of CNTs-Cu nanoparticles on boiling surfaces resulted in the formation of porous structures, which led to a rise in the quantity of active nucleation sites. We fabricated three coated boiling test sections, namely 0.1CNTs-99.9Cu, 0.2CNTs-99.8Cu, and 0.3CNTs-99.7Cu in weight percentages. A bare copper surface and a surface coated only with Cu particles were tested as benchmarks. Distilled water was used in the pool boiling experiments. To investigate the bubble dynamics, a high-speed camera was employed, while scanning electron microscopy was utilized to analyze the morphologies of the surfaces that were coated. The objective of this research was to elucidate the impact of varying CNTs content on boiling inversion and pool boiling efficiency. Findings indicated that an increased content of CNTs improved the boiling heat transfer coefficient, with boiling inversions observed on the porous coated surfaces.