Formation and Growth Analysis of Combustion-Generated Particles Using Size Distribution Measurements from 0.8 to 100 nm
CHANAKYA BAGYA RAMESH, Daoru Han, Yang Wang, University of Miami
Abstract Number: 233
Working Group: Instrumentation and Methods
Abstract
The development of the high-resolution differential mobility analyzer (HRDMA) has enabled researchers to obtain high-resolution size distributions of particles smaller than 3 nm. This advancement has allowed several studies to examine particles in the sub-3 nm range (Bagya Ramesh & Wang, 2023). Other studies have focused on ultrafine particles (4 nm ≤ Dp ≤ 100 nm) using the nano-DMA. However, no study to date has examined a continuous particle size distribution spanning from the molecular scale (1 nm) to the larger particulate scale (100 nm) that captures the entire formation and growth process of combustion-generated particles. A key challenge arises from the fact that the HRDMA and nano-DMA use different transfer functions and loss corrections. This could lead to a mismatch in the size distribution data when attempting to combine measurements from both instruments. In this study, our goal is to (1) develop a framework for data inversion that allows us to obtain a continuous size distribution and minimize discrepancies between HRDMA and nano-DMA measurements, and (2) use the combined size distributions to quantitatively understand the formation and growth of combustion-generated particles. Our preliminary data shows that, in the premixed-flat flame synthesizing titanium dioxide, under the precursor (titanium isopropoxide) feed rate of 490 μmol/hr, the particle size distribution shows a peak diameter of 14.6 nm. In the overlapping transition size range (2 to 7 nm), where both HRDMA and nano-DMA measure particle sizes, we observed a mismatch between the size distributions (-53% to +61%), but the derived size distributions are in the same order of magnitude and have a similar shape. By using an aerosol population balance mode, we further examined the formation and coagulation growth rates of the titanium dioxide nanoparticles. The combination of the HRDMA and nano-DMA can enable detailed diagnosis and prediction of aerosol formation and growth in high-temperature reactors.
Bagya Ramesh, C., & Wang, Y. (2023). Ions Generated from a Premixed Methane-Air Flame: Mobility Size Distributions and Charging Characteristics. Combustion Science and Technology, 196(16), 4041–4056.