Micro/Nanoscale surface modifications to combat heat exchanger fouling

Fouling is a ubiquitous phenomenon occurring in heat transfer devices that inhibits the effective passage of thermal energy, leading to energy and economic losses. In recent years, micro/nanoscale surface modifications have emerged as promising pathways to mitigate the adverse effects of fouling. This review examines micro/nanoscale surface modification methods to mitigate heat exchanger fouling. Various coatings based on titanium, silicon, polymers, amorphous carbon (a-C), electroless nickel-phosphorus (Ni-P), and polyethylene glycol (PEG) are detailed. The coating characteristics in terms of surface chemical and mechanical stability are discussed, and limitations in their commercial utilization are identified. Further, the review outlines the effect of micro/nanoscale surface topographies and novel surface designs on the adhesion and removal of foulants. For instance, laser surface texturing, EDM, anodization, and sandblasting are discussed for generating micro/nanoscale surface topographies. These micro/nanoscale surface topographies play a crucial role in determining surface-foulant interactions and coating durability. It is concluded that the surface energy component is a critical parameter in reducing fouling effects, with low surface energy being favorable for early foulant removal under shear force. Several studies attempting to minimize changes in surface energy components under harsh fouling conditions are discussed in detail.