AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
HVAC Filter Loading Characterization by Ammonium Sulfate and Ammonium Nitrate Sub-micron Particles
CHENXING PEI, Qisheng Ou, David Y. H. Pui, University of Minnesota
Abstract Number: 378 Working Group: Control and Mitigation Technology
Abstract Sodium chloride and potassium chloride are typical salt aerosols used in laboratory for filter loading test, and they are also recommended in ASHRAE52.2 as challenging particles for HVAC filter test. While in the atmospheric aerosol, the most common ions are ammonium, sulfate and nitrate, hence the ammonium sulfate and ammonium nitrate particles may be better salt particles to challenge HVAC filter used in ambient environment, especially considering the hydration and dehydration processes are different among these hydrophilic salt. It is worthwhile to compare the loading performance of conventional sodium chloride and potassium chloride particles to that of ammonium sulfate and ammonium nitrate.
In this study, the loading characteristics of a HVAC filter media by three salt particles are investigated, including potassium chloride, ammonium sulfate, and ammonium nitrate. Salt particles with very similar size distribution but different concentrations are generated by a home-made Collison-type atomizer with proper solution concentration and dilution. A SMPS system is employed to monitor the size distribution of the upstream and downstream of the filter, while the relative humidity in the system is monitored and recorded. The loading performance is found independent with the salt aerosol concentration within the range from 5 to 21 mg/m3. The KCl and (NH$_4)$_2SO$_4 particles have similar loading characteristics when the RH is below 15%, while the NH$_4NO$_3 needs more loading mass to achieve the same pressure drop. Different dendrite structures are found in loaded filter samples by scanning electron microscopy, and their effect on loading characteristics will be discussed in the presentation.