AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Ultrafine Particle Removal by Central Heating and Air-Conditioning Filters in a Test House
BRENT STEPHENS, Jeffrey Siegel, Illinois Institute of Technology
Abstract Number: 325 Working Group: Indoor Aerosols
Abstract Much of human exposure to ultrafine particles (UFPs: particles less than 100 nm in diameter) often occurs indoors, particularly in residences. Central heating and air-conditioning (HAC) filters can be a primary removal mechanism for particles in indoor environments, depending on particle size, HAC system runtime, and filtration efficiency. Unfortunately, most filter test standards do not incorporate the measurement of UFP removal efficiency. Additionally, laboratory tests involve particle concentrations, compositions, face velocities, pressure drops, and climate conditions that do not necessarily reflect real indoor environments. Therefore, there remains a need to improve knowledge of UFP removal by HAC filters, particularly in residential environments.
This work utilizes a whole-house filter test method to measure the UFP removal efficiency of a range of commercially-available HAC filters in a test house. Size-resolved UFP measurements were made using a scanning mobility particle sizer. UFP concentrations were elevated by burning sticks of incense in the well-mixed house and the subsequent first-order decay of UFP concentrations was measured during three experimental conditions: 1) with the HAC system off, 2) with the HAC system on without a filter installed, and 3) with the HAC system on with a filter installed. HAC system airflow rates were measured, the building volume was estimated, and filtration efficiency was calculated using differences in loss rates between system and filter conditions. Three 1-inch depth filters (MERV 4, 6, and 11) and three 5-inch depth filters (MERV 10, 13, and 16) were tested. UFP removal efficiency ranged from less than 20% for MERV 4, 6, 10 and 11 filters to 50-80% for MERV 16 filters for most particle sizes. These results can help standards organizations adopt adequate filtration requirements for UFP removal.