Pool Boiling Heat Transfer Inside the Inclined Bottom Closed Annulus

This experimental study explores the pool boiling heat transfer characteristics of an inclined annular tube immersed in saturated water at atmospheric pressure. The internally heated tube, with an outer diameter of 19.1mm and a length of 540mm, was positioned within an annular gap of 17.95mm, with the lower fluid passageway sealed. By varying the inclination angle from horizontal to vertical, it was observed that the heat transfer improvement coefficient initially increased up to 45 degrees, after which it declined as the inclination angle increased further. This behavior is primarily attributed to variations in liquid agitation intensity and bubble coalescence caused by the outer tube’s enclosure. To better represent the findings, a new empirical correlation has been proposed, integrating the experimental data with existing literature.