Study on Calculation Method of Soluble Aerosol Removal Efficiency Under High Humidity Condition

Abstract

Pool scrubbing is a potential method to remove aerosol particles under accident conditions of nuclear power plants. The relative humidity of aerosol laden gas will increase significantly when passing through the water pool, which will most likely induce hygroscopic growth of soluble aerosol. The hygroscopic growth of soluble aerosol can lead to the deviation of the size distribution of aerosol at the outlet of the water pool, resulting in a large evaluation error of the removal efficiency. In order to solve this problem, the size distributions of sodium chloride at the upstream and downstream of bubble column were measured at a gas flow rate of 4 lpm and a liquid height of 80 cm, respectively. Two methods of calculating aerosol actual size-dependency removal efficiency were proposed and compared. One method is directly calculating the removal efficiency by adding a diffusion drying tube installed at the upstream of Scanning Mobility Particle Sizer (SMPS) to reduce the relative humidity of sample gas below the efflorescence point. Another method is modifying the aerosol size distribution and concentration curve by using the hygroscopic growth theory of soluble aerosols. The experiment results obtained by the two methods are in good agreement.

Computational Modeling of Multiscale Air Filter Media Consisting of Nano- and Microfibers

“…For the filtration test, NaCl particles (mass median aerodynamic diameter, MMAD 347 nm with a density of 2130 kg/m 3 ) were generated using an aerosol generator (Model 8118A in TSI 8130) . The particle charges were neutralized to have a zero mean charge according to the Boltzmann charge distribution, where the fractions of the particles with positive and negative charges are identical.…”

“…For the filtration test, NaCl particles (mass median aerodynamic diameter, MMAD 347 nm with a density of 2130 kg/m 3 ) 34 were generated using an aerosol generator (Model 8118A in TSI 8130). 35 The particle charges were neutralized to have a zero mean charge according to the Boltzmann charge distribution, 36 where the fractions of the particles with positive and negative charges are identical. A NaCl mass concentration of 15 ± 5 mg/m 3 was passed through the filter web (surface area 0.01 m 2 ) at face velocities of 71 and 142 mm/ s. These face velocities correspond to flow rates of 42.5 and 85 L/min for the filter web with a surface area of 0.01 m 2 .…”

Sequential Multiscale Simulation of a Filtering Facepiece for Prediction of Filtration Efficiency and Resistance in Varied Particulate Scenarios

“…41 After IPA immersion for 10 min, the sample was dried at 23 ± 2 °C and a RH of 50 ± 5% for at least 24 h. As challenge particles, NaCl particles (count median diameter, CMD, 0.075 ± 0.020 μm; mass median aerodynamic diameter, MMAD, 0.347 μm with a density of 2130 kg/m 3 ) 2 were generated using an aerosol generator (model 8118A in TSI 8130). 46 The particle charges were neutralized to have zero mean charge in the Boltzmann distribution. 3 NaCl mass concentration of 15 ± 5 mg/m 3 was passed through the filtering facepiece (surface area ∼170 cm 2 ) or filter media (surface area ∼28 cm 2 ) at a face velocity of 83 mm/s at 23 ± 2 °C and a RH of 50 ± 5%.…”

“…As challenge particles, NaCl particles (count median diameter, CMD, 0.075 ± 0.020 μm; mass median aerodynamic diameter, MMAD, 0.347 μm with a density of 2130 kg/m 3 ) were generated using an aerosol generator (model 8118A in TSI 8130) . The particle charges were neutralized to have zero mean charge in the Boltzmann distribution .…”