Study of helically- coiled tube once- through steam generator

Abstract

Heat transfer, dry- out, pressure drop, stability, transient and control characteristics of a water- heated helically- coiled tube once- through steam generator designed for a nuclear merchant ship were examined. Local heat transfer coefficient of convection boiling was little affected by steam quality, mass flow, pressure and location of the coiled tube section. Dry- out generally appeared at lower steam quality on the covex side of the coiled tube than on the concave side, and when mass flow rate was high, it appeared at further lower steam quality on the upper and lower side. Pressure drop was greaterhan that of straight tube. Sharp operation of the inlet valve caused a temporary movement of the superheat boundary in the exit direction.