Next generation header materials for corrosion resistant heat exchangers

摘要

Today's brazed condensers for the HVAC&R market are typically based on a design which uses extruded microchannel tubes in combination with corrugated fins and header tubes made from rolled aluminium strip. Increasing demands for corrosion lifetime relentlessly expose any inconsistency in the galvanic compatibility of the individual components, which concerns especially the match between rolled and extruded aluminium alloys. Consequently a new header material has been developed which was for the first time optimized for galvanic compatibility with extruded microchannel tubes. Thus the hazard of galvanic corrosion in the header - tube joint region is eliminated and the use of zinc containing filler alloys on the header is no longer necessary. The lower total zinc load also reduces zinc enrichment in brazing joints and helps to prevent premature fin loss.