In this study, the air-side pressure drop and heat transfer performance of plate-fin and microchannel coils were tested under clean and fouled conditions. The heat exchangers were tested with two different types of dust, ASHRAE Standard Dust and Arizona Road Test Dust. The ASHRAE Standard Dust was found to have a very significant impact on the pressure drop of the microchannel heat exchanger, increasing the air-side pressure drop of the microchannel heat exchanger over 200% for a dust injection of 267 g (1612.5 g/m2). Fouling of the microchannel heat exchanger with Arizona Road Test Dust was not found to increase the air-side pressure drop of the microchannel heat exchanger but was found to decrease the heat transfer rate by more than 10%. In addition, from studies of the evolution of the air-side pressure drop during the fouling process, it is seen that microchannel coils with louvered fins and fin pitches below 2.0 mm were significantly more prone to fouling than louvered heat exchangers with larger fin pitches. The wavy-plate-fin heat exchanger was significantly less sensitive to fouling with both types of dust. Furthermore, detailed macro photographs were obtained under all conditions tested to more fully characterize the particulate deposition.
heat exchanger, particulate fouling, pressure drop, heat transfer
High Performance Buildings, Thermal Systems and Air Quality
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