A Review on Corrosion of All Aluminum Microchannel Heat Exchangers

Abstract

All aluminum micro-channel heat exchanger (MCHE) is used in automobiles and HVAC because of their low density and relatively high strength. While exhibiting significant general corrosion resistance, the MCHE or aluminum alloy is susceptible to various forms of localized corrosion, such as crevice and pitting corrosion. Crevice corrosion also occurs on the contact surface of the fin and tube for an all-aluminum microchannel heat exchanger. An electrochemical impedance spectroscopy (EIS) examination was performed on aluminum MCHE in corrosive conditions with varying sodium chloride and ammonium sulfate concentrations. The electrolytes discussed in this book chapter have pH values between 4.0 and 5.8, closer to neutral conditions commonly seen in various atmospheres. This work employs high-fidelity conjugate heat transfer simulations to analyze a microchannel heat exchanger system with fins and tubes in crossflow to investigate the possibility of crevice corrosion in the MCHE alloy. A predicted flow field can identify crevices between fins and tube surfaces. These crevices are typically linked with regions of low velocity.