Theoretical Study of the Film Boiling Heat Transfer of Different Nanofluids on the Vertical Heated Surface

Abstract

The use of boiling nanofluids for cooling high-temperature perorating surfaces allows intensifying considerably the process of cooling by increasing the heat transfer coefficient nanofluid compared to the pure base fluid. A significant influence on the intensity of heat transfer during the boiling of nanofluid will turn out properties of nanoparticles and their concentration in the base fluid, under heating of base fluid to saturation temperature. In this study, the mathematical model of the numerical solution and the results of the simulation calculation of characteristics of film boiling of Al2O3, CuO, ZnO, TiO2, ZrO2 and SiO2 water nanofluid for various nanoparticles concentration φ∞ of (0.1, 0.2, 0.3, 0.4, and 0.5) Water nanofluid on the vertical heated wall were presented. The theoretical results obtained allow us to estimate the influence of physical properties of nanofluids on heat and mass transfer during cooling low-temperature surfaces. It is shown that the greatest impact on the processes heat and mass transfer during film boiling nanofluids overheating of the wall depended upon the ratio of temperatures, Brownian diffusion, and concentration of nanoparticles in a base fluid. Also, the results showed that the use of nanofluids as coolants for heat exchange equipment in the mode of supercritical heat exchange increases the heat transfer and accelerate the process of cooling high-temperature surfaces. Increasing the concentration of nanoparticles in the nanofluids will contribute to a greater increase in heat transfer in the supercritical heat transfer due to the low thermal capacity of steam compared to that fluid conductivity. While increasing the nanoparticle concentration will lead to an increase in the effective viscosity of the nanofluids.