Abstract
In order to clarify the effect of bottom configuration on pool film boiling heat transfer from a vertical finite-length cylinder with a length comparable to the diameter, three kinds of silver cylinder with flat, hemispherical and conical bottoms were tested by quenching in saturated and subcooled water. For saturated water, the wall heat flux averaged over the entire surface of a finite-length cylinder takes a higher value for the cylinder with a conical bottom than those for the other two types as the wall superheat decreases. For highly subcooled bulk water, the average wall heat flux for the cylinder with a flat bottom becomes larger than those for the cylinders with hemispherical and conical bottoms. This is attributed that the cylinder with a flat bottom has quite a thin vapor film at the lower end of the vertical cylinder due to the edge effect. The wall superheat (ΔT_<min>) corresponding to the vapor-film-collapse is constant at about 133K for three kinds of test cylinder in saturated bulk water. However, for highly subcooled bulk water(ΔT_<sub> =20K), ΔT_<min> with the cylinder with a flat bottom surface is about 60K larger than those with hemispherical and conical bottom surfaces.
