Comparison of Experimental and Theoretical Heterogeneous Nucleation on Ultrafine Carbon Particles

Abstract

Using a modified turbulent mixing CNC, the heterogeneous nucleation of different compounds (working fluids) on nanometer sized carbon particles was examined. The working fluids were dibutyl phthalate, octadecane, octadecanol, and octadecanoic acid. Based on the particle size distributions measured with a scanning mobility particle sizer system, nucleation and consequent growth were examined with respect to different temperature and vapor pressure for each working fluid. Nucleation rates for all conditions were calculated from the fitted size distribution data by subtracting the residual nonactivated particle concentration for each condition. Experimental nucleation rates were compared to the calculated ones based on Fletcher's heterogeneous nucleation theory. This theory matches well with the experiments with octadecanol and octadecanoic acid, and at high supersaturation ratios for dibutyl phthalate. However, the theory shows discrepancies with the observed phenomena at low supersaturation for dibutyl phthalate, and especially for octadecane. Several possible hypotheses for the discrepancies and observed particle growth are discussed.

The effect of particle chemical composition on the activation probability in n-butanol condensation particle counters

“…4a) reproduce experimental data at 23 and 41 nm for CAST particles with y$10À121, and for diesel exhaust particles (diesel soot) with y$5À101. These values are in reasonable agreement with the contact angle measured by Lee, Hopke, Rasmussen, Wang, and Rashid (2003) who found y=151 for octadecanol onto carbon particles produced by burning natural gas. The soot (CAST) data reported by Wang et al (2010) (Fig.…”

Source Apportionment: Findings from the U.S. Supersites Program

“…Thermally derived C fractions, [53][54][55][56] which are a free byproduct of thermal/optical C analyses, have been found useful for distinguishing between diesel exhaust and other C source types. [57][58][59][60][61] For example, high-temperature EC (e.g., EC2, EC evolved at 740°C in a 98% helium [He]/2% oxygen [O 2 ] atmosphere) dominates particulate emissions from diesel engines. 54 Specific organic markers (Table 2) have also proven useful in PMF modeling studies, [63][64][65][66] but advances are needed to make them more available in source and receptor samples.…”

Vapor–gas/liquid nucleation experiments: A review of the challenges

“…Thus, turbulent flow systems are rarely used for homogeneous nucleation measurements. However, they have proved useful for heterogeneous (Lee, Hopke, Rasmussen, Wang, & Mavliev, 2003;Mavliev, Hopke, Wang, & Lee, 2004) and ion-induced (Gamero-Castano & Fernández de la Mora, 2002; Seto, Okuyama, de Juan, & Fernández de la Mora, 1997) nucleation measurements.…”