portable air cleaners; long term performance; HEPA; electrostatic precipitators; particles; ozone
Although there has been many studies conducted on the initial performance of portable air cleaners (PACs), there is little research on the evaluation of their long term performance. This paper quantifies the effects of particle loading on PAC particle removal, airflow rate, power consumption and ozone emissions for a HEPA- and electrostatic precipitator (ESP) - based PAC. Ozone emission rates decreased in a linear fashion for the ESP-based PAC suggesting dust masking on the unit's discharge electrode. Performance in terms of particle clean air delivery rates (CADR), airflow rates and power consumption reduced for both units as dust was loaded up to the filter's half-life. For the HEPA based PAC, particle CADR reductions are due to reduced airflow rates. As a consequence, the particle single pass efficiencies (SPEs) grew indicating dust accumulation on the filter. This phenomenon is not observed on the ESP-based PAC where both particle CADR as well as SPE reduced upon dust loading. This study demonstrates the importance of regular filter maintenance for PAC to ensure optimal performance.