Heat transfer in stable film boiling of a nanofluid over a vertical surface

The paper focuses on modeling of heat, momentum and concentration transport in stable film boiling of a nanofluid over a vertical surface. An approximate analytical model of the transport processes in the vapor film was employed in simulations. The model takes into account effects of the Brownian and thermophoretic diffusion. The novelty of the model consists in pinpointing six major non-dimensional parameters, which describe effects of the nanoparticles on heat transfer and fluid flow in the vapor film. They include: (i) parameter A that accounts for the relation between the thermophoretic and Brownian diffusion; (ii) the nanoparticle concentration φ∞ in the vapor; (iii and iv) the normalized densities of the nanoparticles Rpυ and Rpf; (v) the relative thermal conductivity of the nanoparticles K; and (vi) parameter m that characterizes the viscosity of nanofluids. Novel analytical solutions resulting from this model characterize velocity profiles, the mass flow rate, the thickness of the vapor film and the Nusselt number as the functions of the aforementioned parameters. It was demonstrated that an increase in the nanoparticles concentration fosters the processes of momentum, mass and heat transfer.