AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Size, Structure, and Phase of Carbon Dioxide Aerosols Formed by Homogeneous Nucleation in a Supersonic Laval Nozzle
KAYANE DINGILIAN, Ruth Signorell, Barbara Wyslouzil, The Ohio State University
Abstract Number: 270 Working Group: Aerosol Physics
Abstract Supersonic separation is a promising technology that has been proposed for carbon capture. Twister BV and TransLang Technologies Ltd. have already integrated this method into field plants for the large-scale separation of hydrocarbons from natural gas. Understanding and characterizing carbon dioxide particle formation and growth is crucial for the successful adaptation of supersonic separation to the removal of carbon dioxide (CO2) from exhaust gas. Previously, we used position-resolved pressure trace measurements (PTM) and small angle x-ray scattering (SAXS) to characterize the onset conditions for homogeneous carbon dioxide nucleation and to calculate experimental nucleation and growth rates. Particle sizes and number densities were obtained by fitting the SAXS spectra assuming the aerosol is a polydisperse collection of spheres. Here, we combine the results from SAXS with new data from Fourier transform infrared (FTIR) spectroscopy measurements to characterize the structure and shape of the condensed CO2 particles. Position-resolved FTIR spectroscopy measurements are performed over the range of 1000 to 4000 cm-1 with particular focus on the ν3 fundamental vibration peak near 2350 cm-1. Spectra from measurements on a system of CO2 expanding from a stagnation pressure of 7327 Pa suggest the transition from the vapor to condensed phase is dominated by direct deposition of solid CO2. As the condensed phase grows, the ν3 peak shifts to 2359 cm-1 with a shoulder at 2360 cm-1. Ongoing collaborations with molecular dynamics and spectroscopy simulation groups provide insight on the shape and structure of the CO2 particles as they evolve from the smallest particles we can detect to the final size at the nozzle exit.