Modeling Aerosol Formation from α-Pinene + NOxin the Presence of Natural Sunlight Using Gas-Phase Kinetics and Gas-Particle Partitioning Theory

2001 ◽  
Vol 35 (7) ◽  
pp. 1394-1405 ◽  
Author(s):  
R. M. Kamens ◽  
M. Jaoui
Keyword(s):  
Gas Phase ◽  
Aerosol Formation ◽  
Natural Sunlight ◽  
Gas Phase Kinetics

Aerosol Formation from the Reaction of α-Pinene and Ozone Using a Gas-Phase Kinetics-Aerosol Partitioning Model

1999 ◽  
Vol 33 (9) ◽  
pp. 1430-1438 ◽  
Author(s):  
Richard Kamens ◽  
Myoseon Jang ◽  
Chao-Jung Chien ◽  
Keri Leach
Keyword(s):  
Gas Phase ◽  
Aerosol Formation ◽  
Gas Phase Kinetics

Kinetic Analysis of C4 Alkane and Alkene Pyrolysis: Implications for SOFC Operation

2010 ◽  
Vol 7 (4) ◽  
Author(s):  
Ahmed Al Shoaibi ◽  
Anthony M. Dean
Keyword(s):  
Gas Phase ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Pyrolysis Kinetics ◽  
Fuel Conversion ◽  
Substantial Impact ◽  
Gas Phase Chemistry ◽  
Gas Phase Kinetics ◽  
Hydrocarbon Gas ◽  
Phase Chemistry

Pyrolysis experiments of isobutane, isobutylene, and 1-butene were performed over a temperature range of 550–750°C and a pressure of ∼0.8 atm. The residence time was ∼5 s. The fuel conversion and product selectivity were analyzed at these temperatures. The pyrolysis experiments were performed to simulate the gas-phase chemistry that occurs in the anode channel of a solid-oxide fuel cell (SOFC). The experimental results confirm that molecular structure has a substantial impact on pyrolysis kinetics. The experimental data show considerable amounts of C5 and higher species (∼2.8 mole % with isobutane at 750°C, ∼7.5 mole % with isobutylene at 737.5°C, and ∼7.4 mole % with 1-butene at 700°C). The C5+ species are likely deposit precursors. The results confirm that hydrocarbon gas-phase kinetics have substantial impact on a SOFC operation.

scholarly journals Modeling organic aerosols in a megacity: comparison of simple and complex representations of the volatility basis set approach

2010 ◽  
Vol 10 (12) ◽  
pp. 30205-30277 ◽  
Author(s):  
M. Shrivastava ◽  
J. Fast ◽  
R. Easter ◽  
W. I. Gustafson ◽  
R. A. Zaveri ◽  
...  
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Computational Cost ◽  
Organic Aerosols ◽  
Field Measurements ◽  
Organic Aerosol ◽  
Basis Set ◽  
Aerosol Formation ◽  
Secondary Organic Aerosol Formation ◽  
The City

Abstract. The Weather Research and Forecasting model coupled with chemistry (WRF-Chem) is modified to include a volatility basis set (VBS) treatment of secondary organic aerosol formation. The VBS approach, coupled with SAPRC-99 gas-phase chemistry mechanism, is used to model gas-particle partitioning and multiple generations of gas-phase oxidation of organic vapors. In addition to the detailed 9-species VBS, a simplified mechanism using 2 volatility species (2-species VBS) is developed and tested for similarity to the 9-species VBS in terms of both mass and oxygen-to-carbon ratios of organic aerosols in the atmosphere. WRF-Chem results are evaluated against field measurements of organic aerosols collected during the MILAGRO 2006 campaign in the vicinity of Mexico City. The simplified 2-species mechanism reduces the computational cost by a factor of 2 as compared to 9-species VBS. Both ground site and aircraft measurements suggest that the 9-species and 2-species VBS predictions of total organic aerosol mass as well as individual organic aerosol components including primary, secondary, and biomass burning are comparable in magnitude. In addition, oxygen-to-carbon ratio predictions from both approaches agree within 25%, providing evidence that the 2-species VBS is well suited to represent the complex evolution of organic aerosols. Model sensitivity to amount of anthropogenic semi-volatile and intermediate volatility (S/IVOC) precursor emissions is also examined by doubling the default emissions. Both the emission cases significantly under-predict primary organic aerosols in the city center and along aircraft flight transects. Secondary organic aerosols are predicted reasonably well along flight tracks surrounding the city, but are consistently over-predicted downwind of the city. Also, oxygen-to-carbon ratio predictions are significantly improved compared to prior studies by adding 15% oxygen mass per generation of oxidation; however, all modeling cases still under-predict these ratios downwind as compared to measurements, suggesting a need to further improve chemistry parameterizations of secondary organic aerosol formation.

scholarly journals The quantitative infrared and NIR spectrum of CH<sub>2</sub>I<sub>2</sub> vapor: vibrational assignments and potential for atmospheric monitoring

2006 ◽  
Vol 6 (1) ◽  
pp. 1275-1299
Author(s):  
T. J. Johnson ◽  
T. Masiello ◽  
S. W. Sharpe
Keyword(s):  
Gas Phase ◽  
Near Infrared ◽  
Point Group ◽  
Aerosol Formation ◽  
Atmospheric Monitoring ◽  
Vibrational Assignments ◽  
Quantitative Absorption ◽  
First Time ◽  
Phase Spectra ◽  
Ft Raman

Abstract. Diiodomethane (CH2I2) photolysis in the presence of ozone is a suggested precursor to new particle aerosol formation, particularly in coastal areas. As part of the PNNL database of gas-phase infrared spectra, the quantitative absorption spectrum of CH2I2 has been acquired at 0.1 cm−1 resolution. Two strong b2 symmetry A-type bands at 584 and 1114 cm−1 are observed, but are not resolved at 760 Torr and appear as B-type. In contrast, the b1 symmetry C-type bands near 5953, 4426 and 3073 cm−1 are resolved with rotational structure, including Q-branches with widths ≤1 cm−1. The quantitative infrared and near-infrared vapor-phase spectra (600–10 000 cm−1) are reported for the first time and discussed in terms of atmospheric monitoring. FT-Raman spectra and ab initio calculations are used to complete vibrational assignments in the C2v point group.

scholarly journals A semi-analytical method for calculating rates of new sulfate aerosol formation from the gas phase

2007 ◽  
Vol 7 (1) ◽  
pp. 2169-2196 ◽  
Author(s):  
J. Kazil ◽  
E. R. Lovejoy
Keyword(s):  
Steady State ◽  
Gas Phase ◽  
Nucleation Rate ◽  
Atmospheric Modeling ◽  
Sulfate Aerosol ◽  
Nucleation Theory ◽  
Rate Coefficients ◽  
Classical Nucleation Theory ◽  
Aerosol Formation ◽  
Aerosol Model

Abstract. The formation of new sulfate aerosol from the gas phase is commonly represented in atmospheric modeling with parameterizations of the steady state nucleation rate. Such parameterizations are based on classical nucleation theory or on aerosol nucleation rate tables, calculated with a numerical aerosol model. These parameterizations reproduce aerosol nucleation rates calculated with a numerical aerosol model only imprecisely. Additional errors can arise when the nucleation rate is used as a surrogate for the production rate of particles of a given size. We discuss these errors and present a method which allows a more precise calculation of steady state sulfate aerosol formation rates. The method is based on the semi-analytical solution of an aerosol system in steady state and on parameterized rate coefficients for H2SO4 uptake and loss by sulfate aerosol particles, calculated from laboratory and theoretical thermodynamic data.

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