AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Investigating the Coagulation Coefficient and Sticking Probability of Nanoparticles at High Temperatures
GIRISH SHARMA, Yang Wang, Rajan Chakrabarty, Pratim Biswas, Washington University in St Louis
Abstract Number: 253 Working Group: Aerosol Physics
Abstract Nanoparticles are widely synthesized using high temperature flame and furnace aerosol reactors (800-2000 K). At such high temperatures, the particles collide with each other and coagulate to form larger particles. The Fuchs-Sutugin interpolation expression is widely used to calculate the coagulation coefficient in the free molecular, continuum and transition regime. This theory is verified both experimentally and through modeling, but only at ambient temperatures. Ideally, a factor of sticking probability should be incorporated, especially at high temperatures while calculating the coagulation coefficient, which is usually assumed to be unity. A few previously reported modeling studies have shown that the sticking probability, even at ambient temperatures, is less than 1 for free molecular regime because of high thermal velocity of the nanoparticles. In fact, at high temperatures, this value should be much less than 1 because of even higher thermal velocity of these particles.
In this work, the aim is to investigate the coagulation coefficient and sticking probability of nanoparticles at high temperatures. To achieve this, particles with different initial lognormal size distributions are passed through furnace at different temperatures and final size distribution is measured using scanning mobility particle sizer (SMPS). The experimental measurement is then coupled with the theoretical aerosol dynamic equation to determine the exact coagulation coefficient as a function of different particle sizes and furnace temperatures. The coagulation coefficient, thus obtained is compared with the Fuchs-Sutugin expression to get the size and temperature dependent sticking probability.