AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Experimental and Computational Study of Reaerosolization of 1 to 5 micro-meter PSL Microspheres using Jet Impingement
JANA KESAVAN, Pamela Humphreys, Babak Nasr, Goodarz Ahmadi, Craig Knox, Erica Valdes, Vipin Rastogi, Suresh Dhaniyala, US ARMY ECBC
Abstract Number: 4 Working Group: Health Related Aerosols
Abstract Chemical, biological, radiological and explosive incidents produce immediate as well as delayed hazards as a result of reaerosolization of deposited particles from surfaces. Understanding reaerosolization mechanisms is important for hazard prediction and mitigation processes. Efficient reaerosolization methodology of small particles is currently not available; therefore, this study was conducted to test a simple and effective method to reaerosolize small particles in the size range of bacterial spores. In this work, we adapted a high-speed vertical impinging jet to reaerosolize small (1 – 5 micro-meter) polystyrene latex microspheres from a substrate, and compared our measured removal efficiencies with numerical predictions. Experiments were conducted to determine the effect of location, number of puffs, particle size, aerosol generation methodology (wet and dry), and relative humidity (RH) on the amount of reaerosolization. The experimental results agreed with numerical predictions of maximal reaerosolization location of about 1 mm from the center. Reaerosolization increased slightly with increasing number of puffs at the peak removal location, and reaerosolization amount decreased as the particle size decreased. Dry deposited particles also had significantly higher reaerosolization compared to the wet deposited particles. Two hours of equilibration of samples at high (80%) or low (20%) RH showed higher reaerosolization with lower RH conditions for dry deposited particles compared to the high RH conditions. In conclusion, this study demonstrated the effectiveness of using a single vertical impinging jet for local reaerosolization of bacteria-sized particles from surfaces.