Effect of corrosion on performance of fin-and-tube heat exchangers with different fin materials

Corrosion on heat exchangers, which have been used long-term, could deteriorate the performance of air conditioning system. In the present study, standard salt spray tests (48 and 96 h) were carried out on evaporators with aluminum (Al) fins and copper (Cu) fins to accelerate corrosion. The micrographs of the Al fins and Cu fins before and after corrosion were obtained. The performances of the samples before and after the corrosion were tested in a psychrometric calorimeter test facility. After the 96 h salt spray test, the cooling capacity decay rate of the sample with Al fins was 12%, whereas that of the sample with Cu fins was only 2%. The average overall heat transfer coefficients of the sample with Cu fins were 55.8%, 67.4% and 69.4% larger than those of the sample with Al fins before corrosion and after the 48 and 96 h salt spray test, respectively. The corrosion factor in the thermal resistance of the evaporator after the salt spray was also investigated. After the 96 h salt spray corrosion test, the proportion of corrosion factor was 27% of the overall thermal resistance of the evaporator with Al fins. For the evaporator with Cu fins, the proportion was 19.1% at its maximum. The effects of corrosion to the air side pressure drop of the different samples were also studied. The change of the air side pressure drop was within 5 Pa for each sample after the salt spray test.

► Effects of corrosion to the performance of fin-and-tube evaporators were investigated.
► The fin materials of different samples were aluminum and copper.
► 48 h and 96 h standard salt spray test was carried out on each sample.
► The performances of each sample before and after salt spray were compared.
► The changing of thermal resistance after salt spray was investigated.