Evaluating a commercially available in-duct bipolar ionization device for pollutant removal and potential byproduct formation. (15th May 2021)

• Record Type: Journal Article
• Authors: Zeng, Yicheng; Manwatkar, Prashik; Laguerre, Aurélie; Beke, Marina; Kang, Insung; Ali, Akram S.; Farmer, Delphine K.; Gall, Elliott T.; Heidarinejad, Mohammad; Stephens, Brent
• Is Part Of: Building and environment. Volume 195(2021)
• Publication Date: 2021-05-15
• Subjects: Indoor air quality -- Air cleaner -- Ionizer -- Particulate matter -- Volatile organic compounds; Buildings -- Environmental engineering -- Periodicals; Building -- Research -- Periodicals; Constructions -- Technique de l'environnement -- Périodiques; Electronic journals; 696
• DOI: 10.1016/j.buildenv.2021.107750
• Languages: English
• ISSNs: 0360-1323

Abstract

Abstract: We conducted a series of experiments to evaluate the gas and particle removal effectiveness and potential for byproduct formation resulting from the operation of a commercially available in-duct bipolar ionization device. Laboratory tests were conducted with the ionizer installed in a small air handler serving a large semi-furnished chamber. Chamber experiments were conducted under (i) normal operating conditions to characterize the impact of the ionizer on concentrations of particles (0.01–10 μm), ozone (O3 ), nitrogen dioxide (NO2 ), volatile organic compounds (VOCs), and aldehydes, and (ii) particle injection and decay conditions to characterize the impact of the ionizer operation on particle loss rates. The field test involved air sampling of particulates (0.01–10 μm), O3, and VOCs upstream and downstream of an operating ionizer device installed in an air handling unit serving an occupied office building. Both the chamber and field tests suggested that the use of the tested bipolar ionization unit led to a decrease in some hydrocarbons (e.g., xylenes) among the lists of compounds we were able to analyze, but an increase in others, most prominently oxygenated VOCs (e.g., acetone, ethanol) and toluene. Ionizer operation appeared to minimally impact particle, O3, and NO2 concentrations during normal operating conditions. Particle injection and decay experiments in the chamber suggest that operation of the ionizer unit led to a small increase in loss rates for ultrafine particles (<0.15 μm) and a small decrease in loss rates for larger particles (>0.3 μm), but with negligible net changes in estimated PM2.5 loss rates. Highlights: Laboratory and field tests conducted to characterize bipolar ionization device. Evaluated impacts on gas and particle removal and byproduct formation. Ionization decreased some hydrocarbons but increased others. Ionization minimally impacted particles, ozone, and nitrogen dioxide. Ionization shifted particle size distribution but did not impact PM2.5 mass.