NOx Emissions Modeling and Uncertainty for Exhaust-Gas-Diluted Flames

Oxides of nitrogen (NOx) are pollutants emitted by combustion processes during power generation and transportation that are subject to increasingly-stringent regulations due to their impact on human health and the environment. One NOx reduction technology being investigated for gas-turbine engines is exhaust gas recirculation (EGR), either through external exhaust-gas recycling or staged combustion. In this study, the effects of different percentages of EGR on NOx production will be investigated for methane-air and propane-air flames at a selected adiabatic flame temperature of 1800K. The variability and uncertainty of the results obtained by the Gri-Mech 3.0, San-Diego 2005, and the CSE thermochemical mechanisms are assessed. It was found that that key parameters associated with postflame NO emissions can vary up to 192% for peak CH values, 35% for thermal NO production rate, and 81% for flame speed, depending on the mechanism used for the simulation. A linear uncertainty analysis, including both kinetic and thermodynamic parameters, demonstrates that simulated post-flame nitric oxide levels have uncertainties on the order of ±50–60%. The high variability of model predictions, and their relatively-high associated uncertainties, motivates future experiments of NOx formation in exhaust-gas-diluted flames under engine-relevant conditions to improve and validate combustion and NOx design tools.

NOx Emissions Modeling and Uncertainty From Exhaust-Gas-Diluted Flames

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4031603 ◽

2015 ◽

Vol 138 (5) ◽

Cited By ~ 7

Author(s):

Antonio C. A. Lipardi ◽

Jeffrey M. Bergthorson ◽

Gilles Bourque

Keyword(s):

Nox Reduction ◽

Flame Temperature ◽

No Production ◽

Exhaust Gas ◽

Oxides Of Nitrogen ◽

Nox Formation ◽

Kinetic And Thermodynamic Parameters ◽

Emissions Modeling ◽

Combustion Processes ◽

Oxides of nitrogen (NOx) are pollutants emitted by combustion processes during power generation and transportation that are subject to increasingly stringent regulations due to their impact on human health and the environment. One NOx reduction technology being investigated for gas-turbine engines is exhaust-gas recirculation (EGR), either through external exhaust-gas recycling or staged combustion. In this study, the effects of different percentages of EGR on NOx production will be investigated for methane–air and propane–air flames at a selected adiabatic flame temperature of 1800 K. The variability and uncertainty of the results obtained by the gri-mech 3.0 (GRI), San-Diego 2005 (SD), and the CSE thermochemical mechanisms are assessed. It was found that key parameters associated with postflame NO emissions can vary up to 192% for peak CH values, 35% for thermal NO production rate, and 81% for flame speed, depending on the mechanism used for the simulation. A linear uncertainty analysis, including both kinetic and thermodynamic parameters, demonstrates that simulated postflame nitric oxide levels have uncertainties on the order of ±50–60%. The high variability of model predictions, and their relatively high associated uncertainties, motivates future experiments of NOx formation in exhaust-gas-diluted flames under engine-relevant conditions to improve and validate combustion and NOx design tools.

Design, Operation, and Application of Modern Internal Combustion Engines and Associated Systems ◽

Stabilizing Excessive EGR With an Oxidation Catalyst on a Modern Diesel Engine

10.1115/ices2002-455 ◽

2002 ◽

Cited By ~ 7

Author(s):

Ming Zheng ◽

David K. Irick ◽

Jeffrey Hodgson

Keyword(s):

Diesel Engine ◽

Oxidation Catalyst ◽

Stable Operation ◽

Exhaust Gas ◽

Oxides Of Nitrogen ◽

Engine Operation ◽

Turbocharged Diesel Engine ◽

New Approach ◽

Cyclic Variations ◽

For diesel engines (CIDI) the excessive use of exhaust gas recirculation (EGR) can reduce in-cylinder oxides of nitrogen (NOx) generation dramatically, but engine operation can also approach zones with high instabilities, usually accompanied with high cycle-to-cycle variations and deteriorated emissions of total hydrocarbon (THC), carbon monoxide (CO), and soot. A new approach has been proposed and tested to eliminate the influences of recycled combustibles on such instabilities, by applying an oxidation catalyst in the high-pressure EGR loop of a turbocharged diesel engine. The testing was directed to identifying the thresholds of stable operation at high rates of EGR without causing cycle-to-cycle variations associated with untreated recycled combustibles. The elimination of recycled combustibles using the oxidation catalyst showed significant influences on stabilizing the cyclic variations, so that the EGR applicable limits are effectively extended. The attainability of low NOx emissions with the catalytically oxidized EGR is also evaluated.

Volume 1: Large Bore Engines; Advanced Combustion; Emissions Control Systems; Instrumentation, Controls, and Hybrids ◽

Effect of Volatiles on Soot Based Deposit Layers

10.1115/icef2013-19162 ◽

2013 ◽

Cited By ~ 1

Author(s):

Ashwin Salvi ◽

John Hoard ◽

Mitchell Bieniek ◽

Mehdi Abarham ◽

Dan Styles ◽

...

Keyword(s):

Heat Exchangers ◽

Nox Reduction ◽

Infrared Camera ◽

Optical Microscope ◽

Exhaust Gas ◽

Thermogravimetric Analyzer ◽

Gas Recirculation ◽

Thermo Physical Properties ◽

Deposit Layer

The implementation of exhaust gas recirculation (EGR) coolers has recently been a widespread methodology for engine in-cylinder NOX reduction. A common problem with the use of EGR coolers is the tendency for a deposit, or fouling layer to form through thermophoresis. These deposit layers consist of soot and volatiles and reduce the effectiveness of heat exchangers at decreasing exhaust gas outlet temperatures, subsequently increasing engine out NOX emission. This paper presents results from a novel visualization rig that allows for the development of a deposit layer while providing optical and infrared access. A 24-hour, 379 micron thick deposit layer was developed and characterized with an optical microscope, an infrared camera, and a thermogravimetric analyzer. The in-situ thermal conductivity of the deposit layer was calculated to be 0.047 W/mK. Volatiles from the layer were then evaporated off and the layer reanalyzed. Results suggest that volatile bake-out can significantly alter the thermo-physical properties of the deposit layer and hypotheses are presented as to how.

Effect of Exhaust Gas Recirculation on Thermal NOx Formation Rate in Gas Turbine Engines

41st Aerospace Sciences Meeting and Exhibit ◽

10.2514/6.2003-503 ◽

2003 ◽

Cited By ~ 8

Author(s):

Nishant Muley ◽

William Lear

Keyword(s):

Gas Turbine ◽

Formation Rate ◽

Turbine Engines ◽

Exhaust Gas ◽

Gas Turbine Engines ◽

Nox Formation ◽

Thermal Nox ◽

Control-Oriented Physics-Based NOX Emission Model for a Diesel Engine With Exhaust Gas Recirculation

ASME Letters in Dynamic Systems and Control ◽

10.1115/1.4046450 ◽

2020 ◽

Vol 1 (1) ◽

Author(s):

Saravanan Duraiarasan ◽

Rasoul Salehi ◽

Anna Stefanopoulou ◽

Siddharth Mahesh ◽

Marc Allain

Keyword(s):

Diesel Engine ◽

Test Procedure ◽

Flame Temperature ◽

Nox Emission ◽

Injection Timing ◽

Exhaust Gas ◽

Engine Control ◽

Gas Recirculation ◽

The Impact

Abstract Stringent NOX emission norm for heavy duty vehicles motivates the use of predictive models to reduce emissions of diesel engines by coordinating engine parameters and aftertreatment. In this paper, a physics-based control-oriented NOX model is presented to estimate the feedgas NOX for a diesel engine. This cycle-averaged NOX model is able to capture the impact of all major diesel engine control variables including the fuel injection timing, injection pressure, and injection rate, as well as the effect of cylinder charge dilution and intake pressure on the emissions. The impact of the cylinder charge dilution controlled by the engine exhaust gas recirculation (EGR) in the highly diluted diesel engine of this work is modeled using an adiabatic flame temperature predictor. The model structure is developed such that it can be embedded in an engine control unit without any need for an in-cylinder pressure sensor. In addition, details of this physics-based NOX model are presented along with a step-by-step model parameter identification procedure and experimental validation at both steady-state and transient conditions. Over a complete federal test procedure (FTP) cycle, on a cumulative basis the model prediction was more than 93% accurate.

Exhaust Gas Recirculation Performance in Dry Low Emissions Combustors

Volume 2: Combustion, Fuels and Emissions, Parts A and B ◽

10.1115/gt2011-46482 ◽

2011 ◽

Cited By ~ 3

Author(s):

A. M. Elkady ◽

A. R. Brand ◽

C. L. Vandervort ◽

A. T. Evulet

Keyword(s):

Gas Turbine ◽

Co2 Capture ◽

Carbon Capture ◽

Power Plants ◽

Nox Reduction ◽

Co2 Concentration ◽

Exhaust Gas ◽

Low Oxygen ◽

In a carbon constrained world there is a need for capturing and sequestering CO2. Post-combustion carbon capture via Exhaust Gas Recirculation (EGR) is considered a feasible means of reducing emission of CO2 from power plants. Exhaust Gas Recirculation is an enabling technology for increasing the CO2 concentration within the gas turbine cycle and allow the decrease of the size of the separation plant, which in turn will enable a significant reduction in CO2 capture cost. This paper describes the experimental work performed to better understand the risks of utilizing EGR in combustors employing dry low emissions (DLE) technologies. A rig was built for exploring the capability of premixers to operate in low O2 environment, and a series of experiments in a visually accessible test rig was performed at representative aeroderivative gas turbine pressures and temperatures. Experimental results include the effect of applying EGR on operability, efficiency and emissions performance under conditions of up to 40% EGR. Findings confirm the viability of EGR for enhanced CO2 capture; In addition, we confirm benefits of NOx reduction while complying with CO emissions in DLE combustors under low oxygen content oxidizer.

Effect of Exhaust Gas Recirculation on Emissions of a Diesel Engine Fuelled with Castor Seed Biodiesel

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.813-814.819 ◽

2015 ◽

Vol 813-814 ◽

pp. 819-823 ◽

Cited By ~ 1

Author(s):

Pavan Bharadwaja Bhaskar ◽

S. Srihari

Keyword(s):

Diesel Engine ◽

Fossil Fuels ◽

Flame Temperature ◽

Treatment Technique ◽

Exhaust Gas ◽

Complete Combustion ◽

Performance And Emission ◽

Hc Emissions ◽

In this study the effect on exhaust gases of a diesel engine fuelled by biodiesel and coupling Exhaust Gas Recirculation (EGR) has been done. EGR is a pre-treatment technique to trim down NOx from diesel engines as it is expected to reduce the flame temperature and the oxygen concentration in the combustion chamber. Fossil fuels so-called biodiesel is picked as the blending fuel. Existence of oxygen in Biodiesel aids complete combustion and anticipated to reduce CO and HC emissions. Exhaust Gas Recirculation technique can capably reduce the amount of NOx. EGR may tend to increase the CO and HC emissions, biodiesel which has higher oxygen content is blended to diesel so that it may compensate CO and HC emissions. The performance and emission characteristics of EGR along with biodiesel in a diesel engine are discussed.

Application of an Experimental EGR System to a Medium Speed EMD Marine Engine

ASME 2009 Internal Combustion Engine Division Fall Technical Conference ◽

10.1115/icef2009-14023 ◽

2009 ◽

Author(s):

John Hedrick ◽

Steven G. Fritz ◽

Ted Stewart

Keyword(s):

Nox Reduction ◽

Injection Timing ◽

Exhaust Gas ◽

Marine Engine ◽

Air Temperatures ◽

Medium Speed ◽

Particulate Matter Emissions ◽

Baseline Test ◽

Exhaust Energy ◽

This paper focuses on quantifying emission reductions associated with various on-engine technologies applied to Electro-Motive Diesel two-cycle diesel engines, which are very popular in marine and locomotive applications in North America. This paper investigates the benefits of using exhaust gas recirculation (EGR), separate circuit aftercooler, and retarded injection timing on a EMD 12-645E7 marine engine. The EGR system alone provided up to a 32.9% reduction in brake specific Nitrogen Oxides (NOx) emissions while demonstrating less than one percent increase in cycle brake specific fuel consumption (BSFC). The brake specific particulate matter emissions increased somewhat, but at a modest rate based on the amount of NOx emission reduction. When the enhanced aftercooler system was combined with the addition of EGR, there was a 31.9% reduction in NOx and essentially no change to the BSFC when compared to the baseline test. The minimum manifold air temperature (MAT) was limited due to the size of the standard EMD aftercooler heat exchanger that is fitted on the engine. No efforts to modify the turbocharger to improve the turbo match to take advantage of the lower manifold air temperatures and the corresponding lower exhaust energy. Once 4° static injection timing retard was introduced, along with the EGR and the minimum MAT, a maximum NOx reduction of 49% was realized with only a 1.1% increase over the baseline BSFC.