Theoretical investigation into condensation heat transfer on horizontal elliptical tube in stationary saturated vapor with wall suction

An analytical investigation is performed into the problem of steady filmwise condensation flow over the outer surface of a horizontal elliptical tube with wall suction effects within a stationary saturated vapor. In performing the analysis, the liquid film flow is governed by the combined effects of the gravitational force and the surface tension force. To facilitate the analysis, an effective suction function is introduced to represent the effect of the wall suction on the thickness of the liquid film such that the local condensate film thickness and local Nusselt number can be derived using a simple numerical shooting method. It is found that the tube ellipticity and the wall suction effect have a significant influence on the mean Nusselt number. Moreover, the surface tension force has a significant effect on the local Nusselt number, but a negligible effect on the mean Nusselt number. An analytical solution is derived for the mean Nusselt number in the absence of wall suction effects. Finally, a closed-form correlation is presented for the mean Nusselt number when the effects of wall suction are taken into account. It is shown that the maximum difference between the numerical results and the closed-form correlation results is less than 5%.