Effect of a plasma-assisted self-cleaning filter on the performance of PWT coil for the mitigation of mineral fouling in a heat exchanger

The present study investigated the effect of a plasma-assisted self-cleaning filter on the performance of physical water treatment (PWT) solenoid coil for the mitigation of mineral fouling in a concentric counterflow heat exchanger. The self-cleaning filter utilized shockwaves produced by pulse-spark discharges in water to continuously remove deposits from the surface of the filter, thus keeping the pressure drop across the filter at a relatively low value. Artificial hard water with hardness ranging from 250 to 1000 ppm was used with zero blowdown in the present fouling experiments for three different cases: no-treatment, PWT coil only, and PWT coil plus the self-cleaning filter. Fouling resistances decreased by 59-72% for the combined case of PWT coil plus filter compared with the values for no-treatment cases. SEM photographs showed much smaller particle sizes for the combined case as larger particles were continuously removed from circulating water by the filter. The X-ray diffraction data showed calcite crystal structures for all three cases. (C) 2009 Elsevier Ltd. All rights reserved.