Boiling heat transfer characteristics of steam generator U-tube fouling

Abstract

The boiling heat transfer characteristics of steam generator u-tube fouling deposits were identified by developing a boiling heat transfer model and determining its accuracy through the comparison of calculated and experimental results. Magnetite deposits were fabricated in the laboratory and were characterized using a variety of techniques. Heat transfer measurements were then taken, so that the effect of deposit parameters, including pore size distribution, porosity, permeability and thickness, as well as the effect of mass flux, heat flux and steam quality were investigated. The model predictions were consistent with the experimental results, differing by an average of ±17.5%. Over the range of parameters studied, pore size distribution dominated the deposit heat transfer. It was found that some fabricated deposits improved the heat transfer of the u-tubes, whereas others hindered it. The data were consistent with that of fouled u-tubes pulled from CANDU steam generators. The conditions of the heat transfer measurements and the fabricated deposits were similar to those of US and Canadian steam generators. Therefore, the conclusions drawn in this study are presumed to apply to the steam generators used in the Canadian and US industries.