To investigate the effect of deposited dust particles on the long-term performance degradation of outdoor air-conditioner units

acceleration experiments on dust deposition were carried out in the present study. An acceleration-experiment method for short-term dust deposition with high dust concentration was proposed to simulate the actual long-term dust deposition with low dust concentration

and an experimental rig was established to perform the accelerating-dust test. Acceleration experiments for 2–10 h were carried out on three types of heat-exchanger samples with different fin structures and tube row numbers

and the test results were used to predict the long-term performance degradation of outdoor heat exchangers operated for one to five years. The results show that after five years of operation

the air-side pressure drops of a one-tube wavy fin-and-tube heat exchanger

a two-tube wavy fin-and-tube heat exchanger

and a two-tube plate fin-and-tube heat exchanger were increased by 21.8%

29.5%

and 25.0%

respectively. Meanwhile

the air-side heat-transfer capacity was reduced by 11.2%

19.3%

and 18.0%

respectively.