Nucleate pool boiling of dilute water silica nanofluid was numerically investigated using the two-fluid model. The effects of improved surface wettability induced by nanoparticle deposition during the boiling process were specially taken into account when developing new closure correlations for the bubble departure parameters. The effects of changed liquid property on boiling heat transfer performance due to the existence of nanoparticles in the liquid were also considered. Comparison of the numerical results against the pool boiling experimental data of pure water and nanofluids demonstrated that the modified liquid property induced by the existence of nanoparticles has a negligible effect on the boiling heat transfer in dilute nanofluids while the improved surface wettability plays an important role. Although the accuracy of the two-fluid model for nanofluids is still not satisfactory due to failing to take into account the surface morphology modification induced by nanoparticle deposition, this study not only demonstrated that the modifications in surface properties and microstructures are the key factors dominating the heat transfer performance in boiling nanofluids, but also gave suggestion for future research. (C) 2013 Elsevier Ltd. All rights reserved.