Nano-coated surfaces to mitigate fouling in thermal water services

Abstract: In thermal water services, the overwhelming proportion of losses by fouling is compensated by additional consumption of fossil energy carriers. This comes, not surprisingly, with an enormous energy price-tag as well as considerable green-house gas emissions, acidification of water resources and release of fouling chemical inhibitors. In the present paper, the performances of innovative nano-modified surfaces are discussed when subjected to CaSO₄ scale deposition during convective heat transfer. Two types of non-structured and structured nano-modified surfaces were experimentally examined. The experimental results demonstrated that such coatings would increase the induction time before fouling starts and also reduce the subsequent fouling rate, in comparison with untreated stainless steel surfaces. After laboratory runs, the coatings that performed best in laboratory were utilized in a desalination plant in a plate heat exchanger. The field findings resulted in applying thinner thickness of the attempted coatings with no sign of fouling. Considering these promising results, the paper continues to assess the requirements for better thermal and mechanical stabilities that such coatings would have to satisfy.