Filter evaluation and selection for heating, ventilation, and air conditioning systems during and beyond the COVID-19 pandemic

Abstract

Particle size removal efficiencies for 0.1-1.0 μm ( ${\mathrm{PSE}}_{0.1-1.0}$ ) and 0.3-1.0 μm ( ${\mathrm{PSE}}_{0.3-1.0}$ ) diameter of Minimum Efficiency Reporting Value (MERV) filters, an electrostatic enhanced air filter (EEAF), and their two-stage filtration systems were evaluated. Considering the most penetrating particle size was 0.1-0.4 μm particulate matter (PM), the ${\mathrm{PSE}}_{0.1-1.0}$ as an evaluation parameter deserves more attention during the COVID-19 pandemic, compared to the ${\mathrm{PSE}}_{0.3-1.0}$ . The MERV 13 filters were recommended for a single-stage filtration system because of their superior quality factor (QF) compared to MERV 6, MERV 8, MERV 11 filters, and the EEAF. Combined MERV 8 + MERV 11 filters have the highest QF compared to MERV 6 + MERV 11 filters and EEAF + MERV 11 filters; regarding 50% of ${\mathrm{PSE}}_{0.1-1.0}$ as the filtration requirements of two-stage filtration systems, the MERV 8 + MERV 11 filtration system can achieve this value at 1.0 m/s air velocity, while ${\mathrm{PSE}}_{0.1-1.0}$ values were lower than 50% at 1.5 m/s and 2.0 m/s. EEAF obtained a better ${\mathrm{PSE}}_{0.3-1.0}$ in the full-recirculated test rig than in the single-pass mode owing to active ionization effects when EEAF was charged by alternating current.

Keywords: HVAC; electrostatic filters; filtration performances; minimum efficiency reporting value; particulate matter; recirculation.