Integrated experimental investigation of seawater composite fouling effect on the 90/10 Cu/Ni tube

The fouling effect of seawater samples collected from three New Hampshire beaches on a 90/10 Cu/Ni commercial heat exchanger tube was investigated. A fouling monitoring device, designed on the basis of fouling thermal resistance, was used for this experimental study. The filtered seawater samples were circulated through the closed loop experimental setup for durations of seven and 14 days and the fouling thermal resistance was measured continuously. Analytical microscopy was performed on the tube surface before and after the experiments to see the effect of seawater fouling on the tube surface. The results show different fouling behavior for the seawater samples. This different behavior is confirmed by the different composition of the samples. Fouling monitoring experiments reveal a higher fouling thermal resistance for one of the seawater samples, Hampton seawater, contrary to the results of SEM analysis which show a lower crystallization rate for Hampton sample. Water decomposition analysis shows the lowest sodium content for Hampton seawater compared to the other samples. Accordingly, corrosion of the tube surface occurs with a higher rate for Hampton seawater due to the presence of chlorine ions and a lower concentration of sodium. The high fouling resistance of Hampton seawater can be explained as the result of several simultaneous fouling mechanisms, corrosion and crystallization indicating composite fouling behavior. The results of the current study are critical for the industries which use seawater as the cooling water source.