Air-side particulate fouling of microchannel heat exchangers: Experimental comparison of air-side pressure drop and heat transfer with plate-fin heat exchanger

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 dust and Arizona Road Test Dust. The ASHRAE 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 267g (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 with fin pitch below 2.0 mm were significantly more prone to fouling than louvered heat exchangers with larger fin pitch. Particulate fouling of the wavy-plate-fin heat exchanger resulted in significantly lower reductions in heat transfer and increase in air-side pressure drop than for the microchannel heat exchanger.