Heat transfer and frictional characteristics of rifled tube in a 1000MW supercritical lignite-fired boiler

Water wall design is a key issue for supercritical lignite-fired boiler. On account of the excellent heat transfer performance, rifled tube is applied in water wall design of a 1000MW supercritical lignite-fired boiler in China. In order to investigate the heat transfer and friction characteristics of the vertical rifled tube, an in-depth experiment was conducted in the range of pressure from 11 to 30MPa, mass flux from 300 to 1900kg/(m²s), and inner wall heat flux from 200 to 600kW/m². The wall temperature and pressure drop data of the rifled tube were obtained from the experiment. In this paper, the effects of pressure, inner wall heat flux and mass flux on heat transfer characteristics are analyzed, the heat transfer deterioration mechanism and the frictional pressure drop performance are discussed, and the corresponding empirical correlations are also presented.