EXPERIMENTAL INVESTIGATION OF SEAWATER FOULING EFFECT ON THE 90/10 Cu/Ni TUBE

The fouling effect of seawater on a 90/10 Cu/Ni commercial heat exchanger tube is investigated. A fouling monitoring device, designed on the basis of fouling thermal resistance, is used for the current experimental study. First, the seawater samples collected in different times from Hampton, Rye, and Wallis beaches in New Hampshire, USA are vacuum-filtered down to a 10 mu m filter paper to remove suspended solids, micro-organisms, and the majority of biological spores. Then, the filtered seawater samples are circulated through the closed loop experimental setup for two weeks and the fouling thermal resistance is measured continuously. The results show different fouling behavior for the seawater samples confirmed by the different composition of the samples. Analytical microscopy is performed on the tube surface before and after the experiments to see the effect of seawater fouling on the tube surface. The results of fouling monitoring experiments reveal a higher fouling thermal resistance for one of the seawater samples, Hampton seawater, contrary to the results of SEM1\EDS2 analysis which show lower crystallization for Hampton sample. Water decomposition analysis shows the lowest sodium content for Hampton seawater compared to the other samples. Accordingly, accelerated corrosion of the tube surface occurs for Hampton seawater due to the presence of chlorine ions and low concentration of sodium. The high fouling resistance of Hampton seawater can be explained by participation of several fouling mechanisms simultaneously which makes a composite fouling behavior for Hampton seawater sample. The results of the current study are critical for the industries which use seawater as the cooling water source.