The HVAC system can be both a sink and a source of contaminants; however, being a source of contamination is a direct product of being a sink of pollutants. In order to understand the HVAC system as a pollution source, one must first understand the HVAC system as a sink of contaminants. Characteristics of contaminant aerosol deposition on the fin and tube surfaces for typical air-conditioning evaporator coils were examined, and numerical methods were used to provide an understanding of the deposition of aerosols on fin and tube surfaces of an evaporator coil. A combination of two airflow rates (1.5 m/s or 4.9 ft/s and 2.3 m/s or 7.6 ft/s), two coil orientations (horizontal and vertical), three fin spacing (3.9 fins/cm or 10 fins/in., 4.7 fins/cm or 12 fins/in., and 5.5 fins/cm or 14 fins/in.), and particle size (ranging from 1 to 100 µm aerodynamic diameter) were examined. Particle sizes chosen are representative of microbiological and other contaminants that can affect actual and perceived indoor air quality. Results indicate that the evaporator coil will collect significant amounts of aerosol in the particle size range of 5-100 µm AD.

Authors: Arnoldo Muyshondt, Ph.D., P.E., Darin W. Nutter, Ph.D., P.E., Matthew H. Gordon, Ph.D., P.E.
Citation: IAQ and Energy 98: Using ASHRAE Standards 62 and 90.1 Conference Papers
Keywords: October, Louisiana, 1998