Numerical Study on the Effect of Indoor Air Condition on Particle Growth in Water Condensation-Based Sampling Devices
WONYOUNG JEON, Junbeom Jang, Jaesung Jang, Ulsan National Institute of Science and Technology, Korea
Abstract Number: 664
Working Group: Bioaerosols
Abstract
The coronavirus, with a size range of 60-140 nm, is challenging to collect using inertia-based sampling devices. These viruses can be effectively collected using a water condensation-based sampling device known as a growth tube collector (GTC).
The GTC employs the temperature difference between wetted walls, referred to as the conditioner and the initiator, to grow particles. The air passing through the conditioner is cooled, increasing its humidity. When this cooled air then passes through the initiator, the supersaturated vapor causes water to condense on the surface of the aerosol particles, leading to particle growth. Due to the limited length of the conditioner, if the incoming air is not fully conditioned before entering the initiator, the particles may not grow properly.
Therefore, this study utilized numerical methods to assess the feasibility of using the GTC in various indoor environments by altering the conditions of the incoming air in the growth tube and observing the final size of the grown droplets. When the inlet air temperature is 25 °C and the growth tube operates at 6 LPM, particles with an initial size of 0.05 μm grow to a count median diameter (CMD) of 0.54 μm at an inlet air relative humidity (RH) of 10%. At an RH of 80%, the CMD of the particles increases to 1.44 μm. When the growth tube operates at 1 LPM, the CMD of the particles grows to 5.39 μm and 5.48 μm at RH levels of 10% and 80%, respectively, indicating that the influence of ambient air humidity decreases as the flow velocity through the growth tube decreases. Since the operating flow rate of the sampler is an important factor in determining the sampling time, we identified the need to optimize the operating flow rate based on the sampling air conditions.