skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

This content will become publicly available on November 29, 2020

Title: High-pressure shock tube study of ethanol oxidation: Ignition delay time and CO time-history measurements

Abstract

Ethanol oxidation was studied by measuring CO time-histories and ignition delay times behind reflected shockwaves at elevated pressures. In this study, experimental conditions included a temperature range of 960–1580 K, pressure range of 17.8–23.9 atm, and initial fuel concentrations of 6.54% and 0.25% with nitrogen and argon used as bath gasses, respectively. The equivalence ratio for high fuel loading was kept constant at 1.0, and for low fuel loading equivalence ratios were 1.0 and 0.5. For high fuel loading, early heat/energy release was observed in nearly all ignition delay time measurements, indicative of preignition; however, data collected are in good agreement with model predictions. These events are interpreted as a transition from mild to strong ignition. For the low fuel loading cases (Φ = 1.0 and 0.5), no early heat/energy release was observed. Comparisons of measured CO concentration profiles with the predictions from kinetic mechanisms of Metcalfe et al. (2013), Mittal et al. (2014), and Zhang et al. (2018) were made assuming constant internal energy and volume for the test gas. Such comparisons in addition with performed sensitivity and pathway analyses for CO formation revealed lower temperature sensitivity to the bimolecular reaction of methyl and hydroperoxyl radicals given by CHmore » 3 + HO 2CH 3O + OH, and H-atom abstraction by the hydroperoxyl radical at the alpha site on ethanol given by elementary reaction C 2H 5OH + HO 2=sC 2H 4OH + H 2O 2. Furthermore, the current study provides important validation targets for ethanol chemical kinetic mechanisms and highlights the benefits of time-history measurements at various temperatures and pressures in a shock tube, which are scare in the literature.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [2];  [3];  [1]
  1. Univ. of Central Florida, Orlando, FL (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC)
OSTI Identifier:
1580016
Alternate Identifier(s):
OSTI ID: 1576655
Report Number(s):
LLNL-JRNL-795653
Journal ID: ISSN 0010-2180; 989388
Grant/Contract Number:  
AC52-07NA27344; EE0007982; AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
Combustion and Flame
Additional Journal Information:
Journal Volume: 212; Journal Issue: C; Journal ID: ISSN 0010-2180
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Ethanol; Shock tube; Oxidation; Ignition; Laser absorption

Citation Formats

Laich, Andrew R., Ninnemann, Erik, Neupane, Sneha, Rahman, Ramees, Barak, Samuel, Pitz, William J., Goldsborough, S. Scott, and Vasu, Subith S. High-pressure shock tube study of ethanol oxidation: Ignition delay time and CO time-history measurements. United States: N. p., 2019. Web. doi:10.1016/j.combustflame.2019.11.016.
Laich, Andrew R., Ninnemann, Erik, Neupane, Sneha, Rahman, Ramees, Barak, Samuel, Pitz, William J., Goldsborough, S. Scott, & Vasu, Subith S. High-pressure shock tube study of ethanol oxidation: Ignition delay time and CO time-history measurements. United States. doi:10.1016/j.combustflame.2019.11.016.
Laich, Andrew R., Ninnemann, Erik, Neupane, Sneha, Rahman, Ramees, Barak, Samuel, Pitz, William J., Goldsborough, S. Scott, and Vasu, Subith S. Fri . "High-pressure shock tube study of ethanol oxidation: Ignition delay time and CO time-history measurements". United States. doi:10.1016/j.combustflame.2019.11.016.
@article{osti_1580016,
title = {High-pressure shock tube study of ethanol oxidation: Ignition delay time and CO time-history measurements},
author = {Laich, Andrew R. and Ninnemann, Erik and Neupane, Sneha and Rahman, Ramees and Barak, Samuel and Pitz, William J. and Goldsborough, S. Scott and Vasu, Subith S.},
abstractNote = {Ethanol oxidation was studied by measuring CO time-histories and ignition delay times behind reflected shockwaves at elevated pressures. In this study, experimental conditions included a temperature range of 960–1580 K, pressure range of 17.8–23.9 atm, and initial fuel concentrations of 6.54% and 0.25% with nitrogen and argon used as bath gasses, respectively. The equivalence ratio for high fuel loading was kept constant at 1.0, and for low fuel loading equivalence ratios were 1.0 and 0.5. For high fuel loading, early heat/energy release was observed in nearly all ignition delay time measurements, indicative of preignition; however, data collected are in good agreement with model predictions. These events are interpreted as a transition from mild to strong ignition. For the low fuel loading cases (Φ = 1.0 and 0.5), no early heat/energy release was observed. Comparisons of measured CO concentration profiles with the predictions from kinetic mechanisms of Metcalfe et al. (2013), Mittal et al. (2014), and Zhang et al. (2018) were made assuming constant internal energy and volume for the test gas. Such comparisons in addition with performed sensitivity and pathway analyses for CO formation revealed lower temperature sensitivity to the bimolecular reaction of methyl and hydroperoxyl radicals given by CH3 + HO2CH3O + OH, and H-atom abstraction by the hydroperoxyl radical at the alpha site on ethanol given by elementary reaction C2H5OH + HO2=sC2H4OH + H2O2. Furthermore, the current study provides important validation targets for ethanol chemical kinetic mechanisms and highlights the benefits of time-history measurements at various temperatures and pressures in a shock tube, which are scare in the literature.},
doi = {10.1016/j.combustflame.2019.11.016},
journal = {Combustion and Flame},
number = C,
volume = 212,
place = {United States},
year = {2019},
month = {11}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on November 29, 2020
Publisher's Version of Record

Save / Share: