Prediction of CO and NOx Pollutants in a Stratified Bluff Body Burner

The major exhaust gas pollutants from heavy duty gas turbine engines are CO and NOx. The difficulty of predicting the concentration of these combustion products originates from their wide range of chemical time scales. In this paper, a combustion model that includes the prediction of the carbon monoxide and nitric oxide emissions is tested. Large eddy simulations (LES) are performed using a compressible code (OpenFOAM). A modified flamelet generated manifolds (FGM) approach is applied with an artificially thickened flame approach (ATF) to resolve the flame on the numerical grid, with a flame sensor to ensure that the flame is only thickened in the flame region. For the prediction of the CO and NOx emissions, pollutant species transport equations and a second, CO based, progress variable are introduced for the flame burnout zone to account for slow chemistry effects. For the validation of the models, the Cambridge burner of Sweeney et al. (2012, “The Structure of Turbulent Stratified and Premixed Methane/Air Flames—I: Non-Swirling Flows,” Combust. Flame, 159, pp. 2896–2911; 2012, “The Structure of Turbulent Stratified and Premixed Methane/Air Flames—II: Swirling Flows,” Combust. Flame, 159, pp. 2912–2929.) is employed, as both carbon monoxide and nitric oxide [Apeloig et al. (2016, “PLIF Measurements of Nitric Oxide and Hydroxyl Radicals Distributions in Swirl Stratified Premixed Flames,” 18th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics, Lisbon, Portugal, July 4–7.)] data are available.

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The Role of Host-Generated H2S in Microbial Pathogenesis: New Perspectives on Tuberculosis

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2020.586923 ◽

2020 ◽

Vol 10 ◽

Author(s):

Md. Aejazur Rahman ◽

Joel N. Glasgow ◽

Sajid Nadeem ◽

Vineel P. Reddy ◽

Ritesh R. Sevalkar ◽

...

Keyword(s):

Nitric Oxide ◽

Carbon Monoxide ◽

Hydrogen Sulfide ◽

Host Immunity ◽

Microbial Pathogens ◽

Microbial Pathogenesis ◽

Enzymatic Production ◽

Growth And Survival ◽

Wide Range

For centuries, hydrogen sulfide (H2S) was considered primarily as a poisonous gas and environmental hazard. However, with the discovery of prokaryotic and eukaryotic enzymes for H2S production, breakdown, and utilization, H2S has emerged as an important signaling molecule in a wide range of physiological and pathological processes. Hence, H2S is considered a gasotransmitter along with nitric oxide (•NO) and carbon monoxide (CO). Surprisingly, despite having overlapping functions with •NO and CO, the role of host H2S in microbial pathogenesis is understudied and represents a gap in our knowledge. Given the numerous reports that followed the discovery of •NO and CO and their respective roles in microbial pathogenesis, we anticipate a rapid increase in studies that further define the importance of H2S in microbial pathogenesis, which may lead to new virulence paradigms. Therefore, this review provides an overview of sulfide chemistry, enzymatic production of H2S, and the importance of H2S in metabolism and immunity in response to microbial pathogens. We then describe our current understanding of the role of host-derived H2S in tuberculosis (TB) disease, including its influences on host immunity and bioenergetics, and on Mycobacterium tuberculosis (Mtb) growth and survival. Finally, this review discusses the utility of H2S-donor compounds, inhibitors of H2S-producing enzymes, and their potential clinical significance.

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Trajectory and Characteristics of Buoyancy and Momentum Dominated Horizontal Jet Flames From Circular and Elliptic Burners

Journal of Energy Resources Technology ◽

10.1115/1.2358145 ◽

2005 ◽

Vol 128 (4) ◽

pp. 300-310 ◽

Cited By ~ 22

Author(s):

Tracy Smith ◽

Chendhil Periasamy ◽

Benjamin Baird ◽

S. R. Gollahalli

Keyword(s):

Nitric Oxide ◽

Reynolds Number ◽

Flame Temperature ◽

Major Axis ◽

Equivalent Diameter ◽

Flame Stability ◽

Temperature Profiles ◽

Burner Exit ◽

Wide Range ◽

Nitric Oxide Emissions

Relative effects of buoyancy and momentum on the characteristics of horizontally oriented circular (Circ) and elliptic (E) burner flames in a quiescent environment over a wide range of jet exit velocities are presented. The major axis of the elliptic burner was oriented horizontally and vertically (referred to as Emaj and Emin flames, respectively). Propane was used as fuel and a small amount of hydrogen was piloted to attach flames to the burner. Global flame characteristics such as flame dimensions, centerline trajectory, emission indices (EI) and radiative fraction, and in-flame transverse concentration and temperature profiles were measured. At a jet exit Reynolds number (Rej) of 2000, based on the area-equivalent diameter of the burner, the flame characteristics were affected by the burner geometry and its orientation. Also, the vertical dimension of the burner exit dictated buoyancy effects. At Rej=12,500, the influence of burner geometry or its orientation was negligible. Elliptic burner flames exhibited lower liftoff and blowout velocities than circular burner flames. Furthermore, the flame stability and nitric oxide emissions were not much affected by the orientation of elliptic burner. Although the elliptic burners produced higher EINO at lower jet exit velocities, the variation in EINO among three burners (Circ, Emaj, and Emin) was insignificant at higher velocities. Some effects of buoyancy on EICO were observed at lower jet exit velocities and the EICO was the lowest for the burners with largest buoyancy flux. Elliptic burner flames produced greater peak flame temperature than the corresponding circular burner flames under most conditions.

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CFD modeling and experimental study of combustion and nitric oxide emissions in hydrogen-fueled spark-ignition engine operating in a very wide range of EGR rates

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2012.04.067 ◽

2012 ◽

Vol 37 (14) ◽

pp. 10917-10934 ◽

Cited By ~ 37

Author(s):

G.M. Kosmadakis ◽

C.D. Rakopoulos ◽

J. Demuynck ◽

M. De Paepe ◽

S. Verhelst

Keyword(s):

Nitric Oxide ◽

Experimental Study ◽

Spark Ignition ◽

Spark Ignition Engine ◽

Cfd Modeling ◽

Wide Range ◽

Nitric Oxide Emissions

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The Rotary Fuel-Injection Pump as a Source of Cyclic Variation in Diesel Engines, and its Effect on Nitric Oxide Emissions

Proceedings of the Institution of Mechanical Engineers ◽

10.1243/pime_proc_1975_189_061_02 ◽

1975 ◽

Vol 189 (1) ◽

pp. 497-505 ◽

Cited By ~ 22

Author(s):

R. D. Wing

Keyword(s):

Nitric Oxide ◽

Fuel Injection ◽

Direct Injection ◽

Strong Relationship ◽

Test Facility ◽

Combustion Model ◽

Injection Pump ◽

Fuel Injection Pump ◽

On Line ◽

Nitric Oxide Emissions

Cyclic combustion variations have been demonstrated to exist in a direct injection Diesel engine to a surprisingly large extent. With the aid of an on-line computer engine-test facility statistical and correlation analyses were carried out to verify a strong relationship between the cyclic combustion variations and variations in the timing of fuel injection. The importance of these cyclic variations in the reduction of nitric oxide emissions from the engine is shown by experimental results and computer combustion model predictions. The overall effect on nitric oxide emissions is, however, small over most of the operating range of the engine.

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The Use of a Three-Zone Combustion Model to Determine Nitric Oxide Emissions From a Homogeneous-Charge, Spark-Ignited Engine

Design, Application, Performance and Emissions of Modern Internal Combustion Engine Systems and Components ◽

10.1115/ices2003-0598 ◽

2003 ◽

Cited By ~ 2

Author(s):

Jerald A. Caton

Keyword(s):

Nitric Oxide ◽

Engine Speed ◽

Combustion Process ◽

Core Region ◽

Operating Conditions ◽

Combustion Model ◽

Nitric Oxides ◽

Cycle Simulation ◽

Nitric Oxide Emissions ◽

Homogeneous Charge

Nitric oxide emissions were estimated for a homogeneous-charge, spark-ignited automotive engine using a cycle simulation which employed three zones for the combustion process: (1) unburned gas, (2) adiabatic core region, and (3) boundary-layer gas. The use of the adiabatic core region has been shown to be especially necessary to capture the production of nitric oxides which are highly temperature dependent. The effects of major engine parameters such as equivalence ratio, spark timing, inlet manifold pressure, and engine speed on nitric oxide emissions are examined. In particular, the detail reasons for the effects of these engine parameters on the nitric oxide emissions are presented. Comparisons are completed between the computed values and a set of published measurements for the nitric oxide concentrations. Although not all engine parameters were known, reasonable agreement is demonstrated for most cases. In particular, the variations of nitric oxide concentrations as engine speed increased were duplicated. As an example, four operating conditions are examined in detail to help explain the measured results. Nitric oxide emissions are shown to be mainly the net result of gas temperatures, oxygen concentrations, and residence times.

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Assessment of a Finite-Rate-Chemistry Model for ANSYS® CFX® Using Experimental Data of a Downsized Gas Turbine Combustor

Volume 4A: Combustion, Fuels, and Emissions ◽

10.1115/gt2018-75638 ◽

2018 ◽

Author(s):

A. Fiolitakis ◽

R. Lückerath ◽

O. Lammel ◽

G. Schmitz ◽

H. Ax ◽

...

Keyword(s):

Nitric Oxide ◽

Carbon Monoxide ◽

Gas Turbine ◽

Transport Processes ◽

Operating Conditions ◽

Combustion Model ◽

Splitting Scheme ◽

Finite Rate ◽

Validation Data ◽

Model Approach

In this work the implementation and validation of a finite-rate-chemistry (FRC) combustion model for ANSYS® CFX® 15.0 is presented. For the solution of the stiff system of species transport equations a splitting scheme is used where transport processes and chemical reactions are solved numerically in separate steps. In this splitting scheme the software Cantera is used for the integration of the chemistry sub-step. It is coupled via user-defined-functions (“USER-Fortran”) to ANSYS® CFX® 15.0. To provide validation data for this model under gas turbine relevant conditions, a down sized version of an industrial burner is investigated experimentally at different operating conditions and with different fuels. The burner is operated in a high-pressure combustion test rig with optical access at technically relevant pressures. Data for emissions of nitric oxide and carbon monoxide are obtained along with OH* chemiluminescence images of the flame. Additionally, investigations are made on the risk of flashback in this burner. The operating points are simulated using the FRC model developed in this work. It is demonstrated that this model approach can predict carbon monoxide and nitric oxide emissions very well, despite the simplistic treatment of turbulence-chemistry interaction. Moreover, it is shown that this model approach can also predict the onset of flashback: the change in flame shape, which is an indicator for flashback, can be well reproduced with this model.

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Investigation of the Effects of Steam Injection on Equilibrium Products and Thermodynamic Properties of Diesel and Biodiesel Fuels

Journal of Combustion ◽

10.1155/2020/2805125 ◽

2020 ◽

Vol 2020 ◽

pp. 1-14

Author(s):

Jean Paul Gram Shou ◽

Marcel Obounou ◽

Timoléon Crépin Kofané ◽

Mahamat Hassane Babikir

Keyword(s):

Nitric Oxide ◽

Carbon Dioxide ◽

Carbon Monoxide ◽

Thermodynamic Properties ◽

Specific Heat ◽

Steam Injection ◽

Combustion Products ◽

Waste Cooking Oil ◽

Cooking Oil ◽

Biodiesel Fuels

The effects of steam injection on combustion products and thermodynamic properties of diesel fuel, soybean oil-based biodiesel (NBD), and waste cooking oil biodiesel (WCOB) are examined in this study by considering the chemical equilibrium. The model gives equilibrium mole fractions, specific heat of the exhaust mixtures of 10 combustion products, and adiabatic flame temperatures. The results show that the mole fractions of carbon monoxide (CO) and carbon dioxide (CO2) decrease with the steam injection ratios. Nitric oxide (NO) mole fractions decrease with the steam injections ratios for lean mixtures. The specific heat of combustion products increases with the steam injection ratios. The equilibrium combustion products obtained can be used to calculate the nonequilibrium values of NO in the exhaust gases using some existing correlations of NO kinetics.

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Application of CFD-Based Analysis Technique for Design and Optimization of Gas Turbine Combustors

Volume 1: Turbo Expo 2004 ◽

10.1115/gt2004-53398 ◽

2004 ◽

Cited By ~ 2

Author(s):

I. G. Koutsenko ◽

S. F. Onegin ◽

A. M. Sipatov

Keyword(s):

Nitric Oxide ◽

Combustion Chamber ◽

Gas Turbine ◽

Combustion Products ◽

Combustion Chambers ◽

Design And Optimization ◽

Gas Turbine Combustors ◽

Analysis Technique ◽

Nitric Oxide Emissions ◽

Operational Development

The design and operational development of gas turbine combustors is a complex process, involving a great volume of design and experimental work. The application of computational fluid dynamics (CFD) methods allows to lower the volume of experimental works on operational development of combustors and to make changes to the design of combustion chambers on early design stages. In this paper the application of commercial CFD package CFX-TASCflow for calculation of flow structure and analysis of nitric oxide formation process in the combustion chamber of the PS-90A gas turbine and its modifications is considered. The results of the analysis show, that the basic determinative criterion of a nitric oxide emission level is the residence time of a combustion products in high-temperature zones. With help of this criterion, an optimization of the PS-90A combustion chamber was performed. A design of an optimized combustion chamber allows to achieve a low level of nitric oxide emissions.

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