Emission Characteristics of a Natural Gas Engine Operating in Lean-Burn and Stoichiometric Modes
Publication: Journal of Energy Engineering
Volume 142, Issue 3
Abstract
To comply with the stringent Euro VI emission standards, two techniques have been proposed for natural gas engines, namely, lean-burn combustion with oxidation catalyst (OC) and stoichiometric combustion with three-way catalyst (TWC). In this paper, comparisons are drawn between the two techniques in terms of carbon monoxide (CO), nitrogen oxides (), and methane () emissions and fuel economy. The results indicated that the postcatalyst CO emissions of lean-burn combustion with OC are lower, whereas the postcatalyst and emissions are higher than those of stoichiometric combustion with TWC. This can be explained by the combined effects of lower engine-out CO emissions and higher engine-out and emissions as well as lower overall conversion efficiency for all emissions with the adoption of lean-burn combustion with OC. Thus, it can be concluded that although the fuel economy of stoichiometric combustion with TWC is inferior to lean-burn combustion with OC, it is still considered a more preferred technique when aiming at achieving Euro VI emission standards for its distinctive advantages in emission performance. However, it is also pointed out that further optimization of the calibration of air-to-fuel ratio is necessary for the stoichiometric operation.
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Acknowledgments
This work is funded by the Ministry of Industry and Information Technology of the People’s Republic of China (2060303). Weichai and Westport New Energy Inc. is also acknowledged for the assistance in conducting the experiments.
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Published In
Journal of Energy Engineering
Volume 142 • Issue 3 • September 2016
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Apr 28, 2015
Accepted: Jul 1, 2015
Published online: Sep 8, 2015
Discussion open until: Feb 8, 2016
Published in print: Sep 1, 2016
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