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Title: Shock-tube study of the autoignition of n-heptane/toluene/air mixtures at intermediate temperatures and high pressures

Abstract

The ignition delay times of mixtures containing 35% n-heptane and 65% toluene by liquid volume at room temperature (i.e., 28% n-heptane/72% toluene by mole fraction) were determined in a high-pressure shock tube in the temperature range 620{<=} T{<=}1180 K at pressures of about 10, 30, and 50 bar and equivalence ratios, {phi}, of 0.3 and 1.0. The equation {tau}/{mu}s=9.8 x 10{sup -3} exp (15,680 K/T)(p/bar){sup -0.883} represents the data for {phi}=0.3 in the temperature range between 980 and 1200 K. At lower temperatures no ignition was found at 10 bar within the maximum test time of 15 ms, whereas for 50 bar, a reduced activation energy was observed. A pressure coefficient of -1.06 was found for the data with {phi}=1.0. No common equation for the data at {phi}=1.0 could be found analogous to that for {phi}=0.3 because the ignition delay times show no Arrhenius-like behavior. A comparison with ignition delay times of n-heptane/air and toluene/air for {phi}=1.0 and 30 bar shows that the values of the mixture of the two components are between the values of the single substances. Furthermore, the results confirm the negative temperature coefficient behavior found for the mixtures at 30 and 50 bar, similar to n-heptane/air.more » A comparison for the other pressure and equivalence ratio values of this study was not possible because of the lack of data for pure toluene. These experimental data have been used in the development of a chemical kinetics model for toluene/n-heptane mixtures as described in a companion paper. (author)« less

Authors:
; ; ; ; ;  [1];  [2]
  1. IVG, Universitaet Duisburg-Essen, D-47048 Duisburg (Germany)
  2. Shell Global Solutions, P.O. Box 1, Chester CH1 3SH (United Kingdom)
Publication Date:
OSTI Identifier:
20880638
Resource Type:
Journal Article
Resource Relation:
Journal Name: Combustion and Flame; Journal Volume: 149; Journal Issue: 1-2; Other Information: Elsevier Ltd. All rights reserved
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; HEPTANE; TOLUENE; PRESSURE RANGE MEGA PA 10-100; AIR; MIXTURES; EXPERIMENTAL DATA; AUTOIGNITION; TEMPERATURE RANGE 0400-1000 K; TEMPERATURE RANGE 1000-4000 K; SHOCK TUBES; TEMPERATURE DEPENDENCE; PRESSURE DEPENDENCE; ACTIVATION ENERGY; COMBUSTION KINETICS; PRESSURE RANGE MEGA PA 01-10

Citation Formats

Herzler, J., Fikri, M., Hitzbleck, K., Starke, R., Schulz, C., Roth, P., and Kalghatgi, G.T. Shock-tube study of the autoignition of n-heptane/toluene/air mixtures at intermediate temperatures and high pressures. United States: N. p., 2007. Web. doi:10.1016/J.COMBUSTFLAME.2006.12.015.
Herzler, J., Fikri, M., Hitzbleck, K., Starke, R., Schulz, C., Roth, P., & Kalghatgi, G.T. Shock-tube study of the autoignition of n-heptane/toluene/air mixtures at intermediate temperatures and high pressures. United States. doi:10.1016/J.COMBUSTFLAME.2006.12.015.
Herzler, J., Fikri, M., Hitzbleck, K., Starke, R., Schulz, C., Roth, P., and Kalghatgi, G.T. Sun . "Shock-tube study of the autoignition of n-heptane/toluene/air mixtures at intermediate temperatures and high pressures". United States. doi:10.1016/J.COMBUSTFLAME.2006.12.015.
@article{osti_20880638,
title = {Shock-tube study of the autoignition of n-heptane/toluene/air mixtures at intermediate temperatures and high pressures},
author = {Herzler, J. and Fikri, M. and Hitzbleck, K. and Starke, R. and Schulz, C. and Roth, P. and Kalghatgi, G.T.},
abstractNote = {The ignition delay times of mixtures containing 35% n-heptane and 65% toluene by liquid volume at room temperature (i.e., 28% n-heptane/72% toluene by mole fraction) were determined in a high-pressure shock tube in the temperature range 620{<=} T{<=}1180 K at pressures of about 10, 30, and 50 bar and equivalence ratios, {phi}, of 0.3 and 1.0. The equation {tau}/{mu}s=9.8 x 10{sup -3} exp (15,680 K/T)(p/bar){sup -0.883} represents the data for {phi}=0.3 in the temperature range between 980 and 1200 K. At lower temperatures no ignition was found at 10 bar within the maximum test time of 15 ms, whereas for 50 bar, a reduced activation energy was observed. A pressure coefficient of -1.06 was found for the data with {phi}=1.0. No common equation for the data at {phi}=1.0 could be found analogous to that for {phi}=0.3 because the ignition delay times show no Arrhenius-like behavior. A comparison with ignition delay times of n-heptane/air and toluene/air for {phi}=1.0 and 30 bar shows that the values of the mixture of the two components are between the values of the single substances. Furthermore, the results confirm the negative temperature coefficient behavior found for the mixtures at 30 and 50 bar, similar to n-heptane/air. A comparison for the other pressure and equivalence ratio values of this study was not possible because of the lack of data for pure toluene. These experimental data have been used in the development of a chemical kinetics model for toluene/n-heptane mixtures as described in a companion paper. (author)},
doi = {10.1016/J.COMBUSTFLAME.2006.12.015},
journal = {Combustion and Flame},
number = 1-2,
volume = 149,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}