Comprehensive analysis of scalable anti-frosting and anti-corrosion heat exchanger coatings

Frosting and corrosion are two key degradation mechanisms limiting the performance and durability of heat exchangers. Previous studies have typically investigated anti-frosting or anti-corrosion strategies separately under idealized laboratory conditions, with limited consideration of their combined performance in practical operating environments. Here, we systematically investigate twelve flat aluminum-based surfaces spanning hydrophilic (HPL) to superhydrophobic (SHPB) wettabilities by separately evaluating their anti-frosting and anti-corrosion performance and comprehensively comparing their overall performance. Among the superhydrophobic coatings, the best-performing surface (SHPB-1), fabricated by HCl etching, hydrothermal treatment, and heptadecafluorotetrahydrodecyltrimethoxysilane coating, prolonged the anti-frosting duration by approximately 3470% relative to the bare surface and by 460–1350% relative to conventional hydrophobic coatings under ambient conditions. Under forced-convection, low-temperature conditions, the corresponding improvements reached at least 600% and 140–820%, respectively. Microscale analysis shows this surface exhibits fewer but longer inter-droplet ice bridges and greater cumulative bridge length. Combined with the effect of ice bridge suspension, the ice bridging speed is reduced to approximately one-eighth of that on a hydrophilic surface. Despite the absence of a direct correlation between corrosion resistance and wettability, SHPB-1 exhibits a considerably low corrosion current density and the fifth-lowest mass loss among all tested coatings across two corrosion evaluation methods. Cost analysis further shows that SHPB-1 possesses the lowest material cost (∼2.9 $/kg) among the hydrophobic and superhydrophobic coating candidates. By comprehensively considering anti-frosting performance, corrosion resistance, fabrication cost, and processing complexity, SHPB-1 provides a well-balanced combination of anti-frosting capability and corrosion resistance, making it a promising coating for practical heat-exchanger applications. Rather than identifying a universally optimal coating, this study establishes a practical framework for balancing anti-frosting performance, corrosion durability, and fabrication cost in the design of heat exchanger coatings.