Human exposure to ultrafine particles (UFP, < 100 nm) has been shown to have adverse health effects such as respiratory impacts and cardiovascular mortality. UFP concentrations can be elevated in occupied buildings due to prevalence of UFP sources within buildings such as combustion, heating elements, and electric motors. In-duct electrostatic air filters (ESP) have been shown to be an energy-efficient particulate control device for reducing UFP concentrations (10 nm - 100 nm) in buildings, although they may increase indoor ozone concentrations due to corona discharge. The objective of the present study is to investigate the reduction of ultrafine particles, especially particle sizes < 10 nm, and the increase in ozone level due to the use of residential ESP filters. Experiments monitored size-resolved UFP levels ranging from 3 nm to 100 nm and ozone concentrations in a manufactured test house. An in-duct air cleaner was installed and operated in the central air handling unit of the house. The experiments involved two filter operating modes: ESP on and ESP off. The results indicate that particle removal with the ESP operating in the house was higher for larger particles. The UFP removal efficiency was lowest for the particles less than 10 nm, possibly due to decreased charging efficiency. Operation of the ESP raised indoor ozone concentrations up to six times higher than outdoor concentrations. When using commercial filters containing activated-carbon downstream of the installed ESP, the indoor ozone concentration was reduced by a maximum 50 % for one filter brand and not reduced by two other filter brands.
Proceedings Title: ASHRAE IAQ 2013
Conference Dates: October 15-18, 2013
Conference Location: Vancouver, -1
Pub Type: Conferences
electrostatic precipitator, filtration, indoor air quality, nanoparticles, ultrafine particles