Numerical Study of Heat Transfer in Film Condensation of Nanofluid on an Inclined Plate

In this paper, the heat transfer enhancement by the nanoparticles in the film condensation of nanofluid over a cooled plate is studied numerically. Shooting method and modified-Euler scheme are employed to solve the condensation boundary layer equations. The effect of changes in the plate angle, nanofluid type, volume fraction of nanoparticles and Jacob number, on the velocity and temperature profiles and Nusselt number are investigated. Resulting graphs are compared and validated with the available theoretical results for the base fluid and nanofluid. The results show that the presence of nanoparticles in the liquid film of condensation increases the heat transfer from it. As the plate distances from the vertical position, the temperature change across the boundary layer is close to linear and thus, the heat transfer descends. Also it can be found that the average Nusselt number is almost constant up to the angle of 20o, and then reduces in a gradual manner, so that for instant, for water-TiO2nanofluid, by increasing the angle up to 60o, the temperature gradient is reduced by about 20 percent. Furthermore, it is seen that the relationship between the ratio of nanofluid to pure water Nusselt number and the nanoparticles volume fraction is linear, while the slope of the line for water-Cu and water-Ag is more than other studied nanofluids, i.e., these two nanofluids are more effective in heat transfer enhancement. The obtained results also confirm the fact that the Nusselt theory is only applicable in low Jacob numbers.