Heat transfer at film condensation of moving vapor with nanoparticles over a flat surface

摘要

Fluid mechanics, heat and mass transfer taking place at condensation of moving vapor with nanoparticles near a flat plate were simulated analytically. An approximate analytical model was employed for simulation of the transport phenomena in the film of condensate, which takes into consideration mechanisms of the Brownian and thermophoretic diffusion. An important novelty of this model is that it suggested five major dimensionless parameters, which are included in the functional dependence of the heat transfer and fluid flow parameters in the condensate film of the nanoparticle concentration and physical properties: (ⅰ) parameter A, i.e. the relation between the thermophoretic and Brownian diffusion; (ⅱ) the nanoparticle concentration in the vapor φ_∞; (ⅲ) the density R of the nanoparticles normalized by that of the fluid; (ⅳ) the thermal conductivity of nanoparticles K normalized by that of the fluid; (ⅴ) and the parameter m describing the properties of the nanofluid viscosity. Consequently, novel analytical solutions were deduced for the velocity profiles, the mass flow rate, the thickness of the condensate film and the Nusselt number was obtained as a function of the aforementioned dimensionless parameters. It can be concluded that an increase in the nanoparticles concentration favors augmentation of the processes of momentum and heat transfer.