Non-chemical biofouling control in heat exchangers and seawater piping systems using acoustic pulses generated by an electrical discharge.

Acoustic pulses generated by an electrical discharge (pulsed acoustics) were investigated as a means for biofouling control in two test formats, viz. a 5/8" outside diameter titanium tube and a mockup heat exchanger. The pulsed acoustic device, when operated at 17 kV, demonstrated 95% inhibition of microfouling over a 20 ft length of titanium tube over a 4-week period, comparable to chlorination in combination with a high-velocity flush. The pulsed acoustic device inhibited microfouling over a downstream distance of 15 ft, therefore, a single pulsed acoustic device is theoretically capable of protecting at least 30 ft of tube from microfouling (15 ft on either side of the device). A correlation between acoustic intensity in the frequency range 0.01-1 MHz and the level of biofouling inhibition was observed. The threshold acoustic intensity for microfouling inhibition was determined for this frequency range. It was also observed that the orientation of the device is critical to obtaining microfouling inhibition.