LAMINAR-FILM CONDENSATION INSIDE A HORIZONTAL ELLIPTIC TUBE WITH VARIABLE WALL TEMPERATURE

An analytical study is performed for a condensation heat transfer with the quiescent or very slow vapor inside a horizontal elliptical tube in which the wall temperature T(w) may vary along the circumferential coordinates. Analytical solutions for local condensate film thickness, local and mean heat-transfer coefficients have been expressed in terms of ellipticity e of the cross section, each of wall temperature variation functions and the reverse Bond numbers. The results show that both surface tension forces and wall temperature variation functions affect the local heat-transfer coefficient and hydrodynamics characteristics inside an elliptical tube; however, the surface tension effect on the mean heat-transfer coefficient is nearly insignificant. The variation of NuBAR with the amplitude of wall temperature variation functions depends on the position forming the liquid level.