This seminar presentation defines Galvanic Corrosion and what causes this form of corrosion. It also offers insight into distinguishing the modes of degradation in All-Aluminum micro channel heat exchangers.

Condensation and corrosion can be major problems when surfaces are exposed to environmental conditions. Because of geometry it may be difficult to drain condensate, leading to increased corrosion or frosting at lower temperatures. Superhydrophobic (SH) materials can minimize anti-condensation and corrosion. SH coatings can be tailored for micro-channel heat exchangers, fin tube coils, and internally enhanced shell-tube heat exchangers. The impact of SH coatings on heat transfer performance needs to be considered along with the overall energy efficiency improvement resulting from SH coatings. SH coatings can help reduce performance degradation from corrosion by 50% and therefore improve the operational efficiency.

Round tubing is used in non-brazed, mechanically assembled in form of U-Bend hairpins. Aluminum hairpins provide requisite formicary corrosion protection and have the majority market share for indoor application. Outdoor application requires more stringent corrosion protection, smaller diameter tubing and larger coils. This makes applying this tubing in outdoor environment an engineering challenge. Developments in long life 3000 series alloys, hairpin lubrication, processing and coil fabrication may open up a limited outdoor market, and make the indoor market more attractive. Alloy development has focused on refinements/composition that alter failure mode from pitting to general lateral corrosion, increasing tubing’s corrosion performance.

After this presentation, attendees will understand and distinguish the three inter-related design factors that influence corrosion durability of an aluminum heat exchanger. They will also be able to apply fundamental learnings to future HEX designs.