Effect of Cathodic Protection Design for Galvanic-Coupled Components on Localized Corrosion Resistance of Aluminum Heat Exchanger

This study investigates the impact of cathodic protection design on the corrosion resistance of heat exchangers (HE1, HE2). Two distinct heat exchanger assemblies underwent a 720-h cyclic corrosion test, revealing higher corrosion resistance in HE2 compared to HE1. The difference in cathodic protection design was observed at the fin-tube junction, where variations in the filler metal composition played a crucial role. Corrosion resistance was primarily influenced by the cathodic protection design at this junction rather than by the header-tube junction or the inherent corrosion susceptibility of the tube. Boundary element method simulations quantitatively confirmed that the tube’s corrosion resistance was supported by the current provided at the fin-tube junction, particularly across the fin-free zone. Optimization of the cathodic protection design was achieved by adjusting the Zn content in the filler metal at the fin-tube junction. These findings provide valuable insights for enhancing corrosion resistance in practical heat exchanger applications.