Aerosol collection efficiency enhancement in HVAC systems through electrical field-Induced filter media polarization

Abstract

Electrically enhanced media filters improve filtration efficiency in heating, ventilation, and air conditioning (HVAC) systems. Enhancement is accomplished by placing a uniquely formulated media material which can be polarized between arrays of wire electrodes. We explore the implementation of an electrically enhanced filtration system to both quantify the level of enhancement in filtration efficiency achievable in conditions representative of HVAC systems, and to determine the mechanism of collection enhancement. Measurements were carried out on a system comprised of a MERV 11 base filter, two arrays of upstream electrodes, and one array of downstream electrodes. Collection efficiency measurements reveal a strong dependency on the applied voltage across all examined face velocities. At a particle diameter of 0.3 μm, the collection efficiencies showed marked increases of 51.6%, 47.2%, and 30.7% from the zero-field level to a voltage of 10 kV at flow rates of 850, 1700, and 2550 m3 hr−1, respectively. Notably, this enhancement in collection efficiency is maintained even after particle loading on the filter. Charge state examinations revealed minimal changes in particle charge levels within the filter unit, demonstrating that the enhancement of filter performance is driven by dielectrophoretic motion and to a lesser extent electrophoretic motion.