Wall boiling of Al2O3-water nanofluid: Effect of nanoparticle concentration

Highlights: • Numerical studies of low flow rates convection boiling of Al2O3 water nanofluid in a partially heated vertical annulus. • Validation of model with previous and present experimental data and previous numerical data. • For maximum heat transfer the volumetric concentration of nanoparticles should be 0.5%. • The maximum enhancement in heat transfer coefficient is 42.1%. Numerical studies on the effects of volumetric concentration of Al₂O₃-water nanofluid during low flow rates convection boiling in a vertical annulus is carried out. The aspect ratio of the vertical annulus is 352 while the annular gap is 3.5 mm. The Fluent code is developed using the RPI wall boiling model. The Fluent code is verified with the results available in the literature and also with the results on a similar experimental set-up which shows excellent agreement. The results show that for maximum heat transfer the volumetric concentration of nanoparticles should be 0.5%. It is also inferred that to achieve maximum heat transfer there should be an optimum concentration of nanoparticles. The maximum enhancement in heat transfer coefficient is 42.1%.