A theoretical evaluation on the HNO3 artifact of the annular denuder system due to evaporation and diffusional deposition of NH4NO3-containing aerosols

A mathematical model was developed to evaluate HNO3 artifact of the annular denuder system due to evaporation and diffusional deposition of nitrate-containing aerosols. The model performance was validated by comparing its numerical solutions with laboratory and numerical data available in the literature for evaporation and diffusional deposition of monodisperse and polydisperse NH4NO3 aerosols. Measurement artifacts were evaluated by varying typical sampling ranges of ambient temperature, HNO3 gas concentration, aerosol number concentration, aerosol mass median diameter, and nitrate mass fraction of <2.5 μm aerosols to see their respective effects. Potential application of the present model on estimating HNO3 artifacts was demonstrated using literature data sampled in USA, Taiwan, Netherlands, Korea and Japan. Significant measurement artifact could be found in Taiwan and Netherlands due either to low HNO3 gas concentration and high nitrate concentration in <2.5 μm aerosols or to high ambient temperature.