Influence of nanoparticle shapes in nanofluid film boiling on vertical cylinders: A numerical study

Abstract

This research explores how nanoparticle shapes affect the thermal behavior of nanofluid film boiling along a vertical cylinder, utilizing a Continuous-Species-Transfer method embedded in a Computational Multi-Fluid Dynamics framework. By modeling the behavior of nanoparticles in both liquid and vapor phases, with considerations for Brownian motion and thermophoresis, a comprehensive 2D axisymmetric analysis is conducted. The analysis focuses on the effects of various Al2O3 nanoparticle shapes – spheres, bricks, blades, cylinders, and platelets – on boiling heat transfer performance. Results demonstrate that while nanoparticle shape has a minimal impact on deposition dynamics, it significantly affects kinematic viscosity, particularly for platelet-shaped nanoparticles. Blade-shaped nanoparticles stand out for their substantial enhancement of thermal transport, as demonstrated by pronounced temperature gradients and elevated thermal conductivity. Furthermore, these nanoparticles contribute to a notable improvement in the Nusselt Number, suggesting enhanced efficiency in boiling heat transfer. This improvement is particularly significant at higher nanoparticle concentrations, where the effects are more pronounced, though not strictly linear when compared to the effects at lower concentrations. Future work will explore different nanoparticle materials, boiling scenarios, and experimental validation.