Research on surface characteristics and heat transfer performance of nanocoatings for heat exchange surfaces

Abstract

This paper experimentally investigates the heat transfer performance of finned heat exchangers with nanocoating surfaces under varying curing temperatures and humidity. The nanostructured coating enhances the fin’s hydrophilicity, promoting condensation and improving cooling efficiency, crucial for optimizing heat exchanger design and fabrication. Specimens cured at 250 °C exhibited superior heat transfer performance, approximately 7% higher than uncoated specimens. Lower curing temperatures yield thicker films, with surface processing improving film formation and heat transfer. Film morphology transitions from sheet-like at lower curing temperatures to stripe at higher temperatures, with unprocessed surfaces exhibiting clustered film cores that become more isolated at higher temperatures. Curing at 250 °C optimizes heat transfer performance due to improved surface properties, while higher curing temperatures diminish performance due to reduced film area and thickness. Curing at 250 °C strikes a balance between heat transfer enhancement and wind resistance due to increased surface roughness, whereas higher curing temperatures compromise performance. Coating and curing at 600 °C with a TiO₂ nanocoating optimizes heat transfer performance, particularly at high humidity, due to increased surface roughness and hydroxyl groups.