Modeling NOx Emissions from Lean-Burn Natural Gas Engines

Dodge, Lee G.; Kubesh, John T.; Naegeli, D. W.; Campbell, Patrick F.

doi:10.4271/981389

Cited by 12 publications

(17 citation statements)

References 20 publications

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“…Increasingly stringent restrictions on vehicle emissions have led to much research into reducing these emissions. Spark ignition (SI) engine NO x emissions have been studied both experimentally [1] and with models of varying complexity [2][3][4][5]. The high temperatures reached in SI engines cause the conversion of atmospheric nitrogen to nitric oxide (NO).…”

Section: Introductionmentioning

confidence: 99%

Modelling cycle to cycle variations in an SI engine with detailed chemical kinetics

Etheridge

Mosbach

Kraft

et al. 2011

Combustion and Flame

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Section: Introductionmentioning

confidence: 99%

Modelling cycle to cycle variations in an SI engine with detailed chemical kinetics

Etheridge

Mosbach

Kraft

et al. 2011

Combustion and Flame

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“…According to mate engine flamefront NO emissions, based on these and later models, nitric oxide in engines is therempirical data. Recently, Dodge et al [12] estimated mal NO x formed in the post-flame gases according engine flamefront NO emissions in a lean-burn methto the Zeldovich reactions with O atom concentration ane-fuelled engine using the same method as Lavoie obtained from chemical equilibrium calculations.…”

Section: Introductionmentioning

confidence: 99%

Computation of flamefront NO emissions from spark ignition engines

Narayan

Rajan

2001

International Journal of Engine Research

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Flamefront NO emissions from spark ignition The Fenimore mechanism [5] is yet another reacengines are estimated in this work using a two-zone thermo-tion pathway that leads to 'prompt' NO formation dynamic combustion model, an unsteady engine flame in a flamefront and also in post-flame gases of very model, the wrinkled laminar flame model of Bray and Moss, rich premixed flames [6]. In all premixed flames, O the k-å theory and simplified flamefront NO chemistry atom concentrations are much above chemical equiwhich has been verified in steady laminar premixed flames. librium levels, augmenting the rates within the The results show that as much as 230 ppm of flamefront NO flamefront of the Zeldovich and N 2 O reaction rates may be formed under stoichiometric engine operating con-[6]. Flamefront NO emissions, including Fenimore's ditions. The present approach is an alternative to the empiriprompt NO, from steady laminar methane/air cal correlations used to compute engine flamefront NO flames have been successfully predicted by a number which are based on highly extrapolated data. of workers [6-9], because of exponential increases in computing capabilities and more accurate chemical Key words: flamefront NO emissions, prompt NO, kinetic data. The flamefront NO mechanism in prespark ignition engine, methane fuel, two-zone engine mixed flames is very complex [6], but has recently combustion model been simplified by a number of workers [9, 10]. It is difficult to predict flamefront NO emissions from turbulent flames because turbulent flame codes cannot incorporate more than a few chemical reac-

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“…A range of temperatures was used with the assumption that the highest temperature of any packet would not exceed the adiabatic flame temperature of 1900 K as calculated below. In 1998 Dodge et al [33] found that a similar zero-dimensional model well predicted the NOx emission from lean burn natural gas engines.…”

Section: Chemical Kinetic Modelingmentioning

confidence: 99%

SELECTIVE NOx RECIRCULATION FOR STATIONARY LEAN-BURN NATURAL GAS ENGINES

Clark¹,

Thompson²,

Atkinson³

et al. 2005

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The research program conducted at the West Virginia University Engine and Emissions Research Laboratory (EERL) is working towards the verification and optimization of an approach to remove nitric oxides from the exhaust gas of lean burn natural gas engines. This project was sponsored by the US Department of Energy, National Energy Technology Laboratory (NETL) under contract number: DE-FC26-02NT41608.Selective NOx Recirculation (SNR) involves three main steps. First, NOx is adsorbed from the exhaust stream, followed by periodic desorption from the aftertreatment medium. Finally the desorbed NOx is passed back into the intake air stream and fed into the engine, where a percentage of the NOx is decomposed. This reporting period focuses on the NOx decomposition capability in the combustion process.Although researchers have demonstrated NOx reduction with SNR in other contexts, the proposed program is needed to further understand the process as it applies to lean burn natural gas engines. SNR is in support of the Department of Energy goal of enabling future use of environmentally acceptable reciprocating natural gas engines through NOx reduction under 0.1 g/bhp-hr.The study of decomposition of oxides of nitrogen (NOx) during combustion in the cylinder was conducted on a 1993 Cummins L10G 240 hp lean burn natural gas engine. The engine was operated at different air/fuel ratios, and at a speed of 800 rpm to mimic a larger bore engine. A full scale dilution tunnel and analyzers capable of measuring NOx, CO 2 , CO, HC concentrations were used to characterize the exhaust gas. Commercially available nitric oxide (NO) was used to mimic the NOx stream from the desorption process through a mass flow controller and an injection nozzle. The same quantity of NOx was injected into the intake and exhaust line of the engine for 20 seconds at various steady state engine operating points.NOx decomposition rates were obtained by averaging the peak values at each set point minus the baseline and finding the ratio between the injected NO amounts.It was observed that the air/fuel ratio, injected NO quantity and engine operating points affected the NOx decomposition rates of the natural gas engine. A highest NOx decomposition 3 rate of 27% was measured from this engine. A separate exploratory tests conducted with a gasoline engine with a low air/fuel ratio yielded results that suggested, that high NOx decomposition rates may be possible if a normally lean burn engine were operated at conditions closer to stoichiometric, with high exhaust gas recirculation (EGR) for a brief period of time during the NOx decomposition phase and with a wider range of air/fuel ratios.Chemical kinetic model predictions using CHEMKIN were performed to relate the experimental data with the established rate and equilibrium models. NOx decomposition rates from 35% to 42% were estimated using the CHEMKIN software. This provided insight on how to maximize NOx decomposition rates for a large bore engine. In the future, the modeling will be used to examine the...

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Modeling NOx Emissions from Lean-Burn Natural Gas Engines

Cited by 12 publications

References 20 publications

Modelling cycle to cycle variations in an SI engine with detailed chemical kinetics

Modelling cycle to cycle variations in an SI engine with detailed chemical kinetics

Computation of flamefront NO emissions from spark ignition engines

SELECTIVE NOx RECIRCULATION FOR STATIONARY LEAN-BURN NATURAL GAS ENGINES

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