Study on effect CO2 diluent on fuel cоmbustion in methane-oxygen combustion chambers

Studying closed gas turbine cycles on supercritical carbon dioxide is currently a promising issue in the development of power energy sector in terms of increasing energy efficiency and minimizing greenhouse gas emissions into the atmosphere. Combustion of methane with oxygen in the combustion chamber occurs not in the nitrogen environment, but in the environment of carbon dioxide, that is the working fluid of the cycle, which is an inhibitor of chemical reactions. A large mass content of such a diluent of the reaction mixture in the volume of the chamber leads to the risks of significant chemical underburning, efficiency decrease of the combustion chamber and the cycle as a whole. The aim of the research is to study the kinetic parameters of the combustion of methane with oxygen in a supercritical CO2 diluent medium to ensure reliable and stable combustion of fuel by assessing the degree of the inhibitory effect of CO2 and determining its permissible amount in the active combustion zone of the combustion chamber. The research method is a numerical simulation of turbulent-kinetic processes of methane combustion in the combustion chamber using the reduced methane combustion mechanism. Ansys Fluent software package has been used. The authers have studied the impact of CO2 diluent on fuel cоmbustion in methane-oxygen combustion chambers. It is found that the combustor flame stabilization takes place if the content of СО2 diluent supplied to the mixture with oxidizer is 0,46–0,5 of mass fraction; additional СО2 diluent forms local low temperature zones which slow down the combustion process. When this happens, adding cooling СО2 into the flame stabilization zone should be eliminated. The study has found that no more than 20 % of the total carbon dioxide content should be supplied to the combustion chamber; to stabilize the flame and reduce its length, it is necessary to install blades to swirl the fuel and oxidizer mixed with CO2 at the inlet of the combustion chamber; CO2 supply for cooling should be carried out not less than 130 mm away from the burner mouth.

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Mathematical modeling of a swirling jet in applications to low-emission combustion of low-grade fuels

Zhurnal Srednevolzhskogo Matematicheskogo Obshchestva ◽

10.15507/2079-6900.23.202103.308-317 ◽

2021 ◽

Vol 23 (3) ◽

pp. 308-317

Author(s):

Usama J. Mizher ◽

Peter A. Velmisov

Keyword(s):

Carbon Dioxide ◽

Natural Gas ◽

Combustion Chamber ◽

Negative Impact ◽

Numerical Study ◽

Combustion Process ◽

Theoretical Data ◽

Modern Society ◽

Low Grade ◽

Impact of Internal Entrainment on High Intensity Distributed Combustion

ASME 2015 Power Conference ◽

10.1115/power2015-49034 ◽

2015 ◽

Author(s):

Ahmed E. E. Khalil ◽

Ashwani K. Gupta

Keyword(s):

Carbon Dioxide ◽

Gas Turbine ◽

Oxygen Concentration ◽

High Intensity ◽

Flame Structure ◽

Flame Stabilization ◽

Low Oxygen ◽

Gas Turbine Combustors ◽

Reactive Gases ◽

The Impact

Colorless Distributed Combustion (also referred to as CDC) has been shown to provide ultra-low emissions and enhanced performance of high intensity gas turbine combustors. To achieve distributed combustion, the flowfield needs to be tailored for adequate mixing between reactants and hot reactive species from within the combustor to result in high temperature low oxygen concentration environment prior to ignition. Such reaction distribution results in uniform thermal field and also eliminates any hot spots for mitigating NOx emission. Though CDC have been extensively studied using a variety of geometries, heat release intensities, and fuels, the role of internally recirculated hot reactive gases needs to be further investigated and quantified. In this paper, the impact of internal entrainment of reactive gases on flame structure and behavior is investigated with focus on fostering distributed combustion and providing guidelines for designing future gas turbine combustors operating in distributed combustion mode. To simulate the recirculated gases from within the combustor, a mixture of nitrogen and carbon dioxide is introduced to the air stream prior to mixing with fuel and subsequent combustion. Increase in the amounts of nitrogen and carbon dioxide (simulating increased entrainment), led to volume distributed reaction over a larger volume in the combustor with enhanced and uniform distribution of the OH* chemiluminescence intensity. At the same time, the bluish flame stabilized by the swirler is replaced with a more uniform almost invisible bluish flame. The increased recirculation also reflected on the pollutants emission, where NO emissions were significantly decreased for the same amount of fuel burned. Lowering oxygen concentration from 21% to 15% (due to increased recirculation) resulted in 80∼90% reduction in NO with no impact on CO emission with sub PPM NO emission achieved at an equivalence ratio of 0.7. Flame stabilization at excess recirculation can be achieved using preheated nitrogen and carbon dioxide, achieving true distributed conditions with oxygen concentration below 13%.

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A Control-Oriented Jet Ignition Combustion Model for an SI Engine

Volume 1: Adaptive and Intelligent Systems Control; Advances in Control Design Methods; Advances in Non-Linear and Optimal Control; Advances in Robotics; Advances in Wind Energy Systems; Aerospace Applications; Aerospace Power Optimization; Assistive Robotics; Automotive 2: Hybrid Electric Vehicles; Automotive 3: Internal Combustion Engines; Automotive Engine Control; Battery Management; Bio Engineering Applications; Biomed and Neural Systems; Connected Vehicles; Control of Robotic Systems ◽

10.1115/dscc2015-9687 ◽

2015 ◽

Cited By ~ 1

Author(s):

Ruitao Song ◽

Gerald Gentz ◽

Guoming Zhu ◽

Elisa Toulson ◽

Harold Schock

Keyword(s):

Combustion Chamber ◽

Combustion Process ◽

Turbulent Jets ◽

Combustion Stability ◽

Combustion Model ◽

Combustion Chambers ◽

Si Engine ◽

Lean Operations ◽

Combustion Processes ◽

Hil Simulation

A turbulent jet ignition system of a spark ignited (SI) engine consists of pre-combustion and main-combustion chambers, where the combustion in the main-combustion chamber is initiated by turbulent jets of reacting products from the pre-combustion chamber. If the gas exchange and combustion processes are accurately controlled, the highly distributed ignition will enable very fast combustion and improve combustion stability under lean operations, which leads to high thermal efficiency, knock limit extension, and near zero NOx emissions. For model-based control, a precise combustion model is a necessity. This paper presents a control-oriented jet ignition combustion model, which is developed based on simplified fluid dynamics and thermodynamics, and implemented into a dSPACE based real-time hardware-in-the-loop (HIL) simulation environment. The two-zone combustion model is developed to simulate the combustion process in two combustion chambers. Correspondingly, the gas flowing through the orifices between two combustion chambers is divided into burned and unburned gases during the combustion process. The pressure traces measured from a rapid compression machine (RCM), equipped with a jet igniter, are used for initial model validation. The HIL simulation results show a good agreement with the experimental data.

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Zero-Emission MATIANT Cycle

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2816297 ◽

1999 ◽

Vol 121 (1) ◽

pp. 116-120 ◽

Cited By ~ 50

Author(s):

P. Mathieu ◽

R. Nihart

Keyword(s):

Gas Turbines ◽

Co2 Emission ◽

Combustion Process ◽

Advanced Materials ◽

Working Fluid ◽

Brayton Cycle ◽

Combustion Chambers ◽

Novel Technology ◽

Technical Issues ◽

Cycle Efficiency

In this paper, a novel technology based on the zero CO2 emission MATIANT (contraction of the names of the two designers MAThieu and IANTovski) cycle is presented. This latter is basically a gas cycle and consists of a supercritical CO2 Rankine-like cycle on top of regenerative CO2 Brayton cycle. CO2 is the working fluid and O2 is the fuel oxidizer in the combustion chambers. The cycle uses the highest temperatures and pressures compatible with the most advanced materials in the steam and gas turbines. In addition, a reheat and a staged compression with intercooling are used. Therefore, the optimized cycle efficiency rises up to around 45 percent when operating on natural gas. A big asset of the system is its ability to remove the CO2 produced in the combustion process in liquid state and at high pressure, making it ready for transportation, for reuse or for final storage. The assets of the cycle are mentioned. The technical issues for the predesign of a prototype plant are reviewed.

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Experimental study on combustion of CH4/NH3 fuel blends in an industrial furnace operated in flameless conditions

Thermal Science ◽

10.2298/tsci200401282s ◽

2020 ◽

Vol 24 (6 Part A) ◽

pp. 3625-3635

Author(s):

Rafal Slefarski ◽

Pawel Czyzewski ◽

Michal Golebiewski

Keyword(s):

Experimental Study ◽

Combustion Chamber ◽

Equivalence Ratio ◽

Molar Fraction ◽

Combustion Process ◽

Steel Production ◽

Methane Combustion ◽

Efficient Technology ◽

Flameless Combustion ◽

Fuel Blends

This paper presents the results of an experimental study on the combustion process of methane mixed with NH3 in flameless mode. At a time of striving for CO2-free power, NH3 became a potential energy storage carrier fuel from renewable sources. Flameless combustion features low emissions and is a very efficient technology used in the power sector, as well as steel production, ceramics, etc. Industrial furnaces were tested in the context of pure methane combustion with an addition of NH3, up to 5%. Flameless combustion conditions were achieved with a regenerative gas burner system (high regenerative system). The burner consists of four ceramic regenerators allowing for continuous preheating of air, even up to 50 K lower than the temperature of the combustion chamber wall. Constant power of the introduced fuel was kept at 150 kW and the fuel-air equivalence ratio ranged from 0.75 to 0.95. The results have shown a growth of molar fraction of NO in flue gases when NH3 content in the fuel rose. The increase is more significant for the tests with a higher amount of oxygen in the combustion chamber (a lower fuel-air equivalence ratio). An addition of 5% of NH3 into the fuel caused an emission of NO at the levels of 113 ppmv and 462 ppmv (calculated to O2 = 0%), respectively for low and high fuel-air equivalence ratios.

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The Impact of Improved Aerosol Priors on Near-Infrared Measurements of Carbon Dioxide

10.5194/amt-2018-366 ◽

2018 ◽

Author(s):

Robert R. Nelson ◽

Christopher W. O'Dell

Keyword(s):

Carbon Dioxide ◽

Near Infrared ◽

Carbon Sources ◽

Total Carbon ◽

Primary Sources ◽

Retrieval Algorithm ◽

Sources And Sinks ◽

Earth Observing System ◽

Infrared Measurements ◽

The Impact

Abstract. The Orbiting Carbon Observatory-2 (OCO-2) was launched in 2014 with the goal of measuring the column-averaged dry-air mole fraction of carbon dioxide (XCO2) with sufficient precision and accuracy to infer regional carbon sources and sinks. One of the primary sources of error in near-infrared measurements of XCO2 is the scattering effects of cloud and aerosol layers. In this work, we study the impact of ingesting intelligent aerosol priors from the Goddard Earth Observing System Model, Version 5 (GEOS-5) into the OCO-2 ACOS V8 retrieval algorithm with the objective of reducing the error in XCO2 from real measurements. Multiple levels of both aerosol setup complexity and uncertainty on the aerosol priors were tested, ranging from a mostly unconstrained aerosol optical depth (AOD) setup to ingesting full aerosol profiles with high confidence. We find that using co-located GEOS-5 aerosol types and AODs with low uncertainty results in a small improvement in the retrieved XCO2 against the Total Carbon Column Observing Network relative to V8. In contrast, attempting to use modeled vertical information in the aerosol prior to improve the XCO2 retrieval generally gives poor results, as aerosol models struggle with the vertical placement of aerosol layers. To assess regional differences in XCO2, we compare our results to a global CO2 model validation suite. We find that the GEOS-5 setup performs better than V8 over Northern Africa and Central Asia, with the standard deviation of the XCO2 error reduced from 2.12 ppm to 1.83 ppm, due to a combination of smaller prior AODs and lower prior uncertainty. In general, the use of more intelligent aerosol priors shows promise but is currently restricted by the accuracy of aerosol models.

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The impact of oxidiser humidity on methane combustion in a gas burner

French-Ukrainian Journal of Chemistry ◽

10.17721/fujcv8i2p48-59 ◽

2020 ◽

Vol 8 (2) ◽

pp. 48-59

Author(s):

Andrii Avramenko

Keyword(s):

Combustion Process ◽

Methane Combustion ◽

Environmental Indicators ◽

Hazardous Substances ◽

Simulation Methods ◽

Air Humidity ◽

Topical Problem ◽

Study Results ◽

Numerical Simulation Methods ◽

The Impact

The improvement of thermodynamic and environmental indicators of energy facilities is a vital and topical problem. Numerical simulation methods are used to investigate the processes of combustion and formation of hazardous substances by computation, and to work out recommendations on increasing the effectiveness of fuel combustion. The paper examines the impact of atmospheric air humidity on the process of combustion of a stoichiometric methane-air mixture in a burner. The combustion process is simulated in the 3D unsteady statement in Cartesian coordinates. In the investigation, the combustion of the methane-air mixture is considered in one stage. Air humidity is considered in the 0 to 100% range. The monoxide nitrogen formation process is described using the extended Zeldovich-Fenimore mechanism. A comparative study has found that increasing air humidity up to 100% reduces the mass emission of monoxide nitrogen by a factor of 1.27, as compared to dry air. The study results can be used for designing equipment that uses methane as fuel.

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Analysis of Thermal Efficiency in a Hydrogen Premixed Spark Ignition Engine

10.1115/imece1999-0844 ◽

1999 ◽

Author(s):

Toshio Shudo ◽

Yasuo Nakajima ◽

Takayuki Futakuchi

Keyword(s):

Combustion Chamber ◽

Thermal Efficiency ◽

Internal Combustion Engines ◽

Combustion Process ◽

Methane Combustion ◽

Spark Ignition ◽

Hydrogen Combustion ◽

Spark Ignition Engine ◽

Chamber Wall ◽

Flame Velocity

Abstract Hydrogen has higher flame velocity and smaller quenching distance than hydrocarbon fuels, and is supposed to have special characteristics in combustion process of internal combustion engines. In this research, contributors to thermal efficiency in a hydrogen premixed spark ignition engine were analyzed and compared with methane combustion. Results showed hydrogen combustion had higher cooling loss to combustion chamber wall, and thermal efficiency of hydrogen combustion was mainly dominated by both cooling loss to combustion chamber wall and degree of constant volume combustion.

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The impact of improved aerosol priors on near-infrared measurements of carbon dioxide

Atmospheric Measurement Techniques ◽

10.5194/amt-12-1495-2019 ◽

2019 ◽

Vol 12 (3) ◽

pp. 1495-1512 ◽

Cited By ~ 6

Author(s):

Robert R. Nelson ◽

Christopher W. O'Dell

Keyword(s):

Carbon Dioxide ◽

Near Infrared ◽

Carbon Sources ◽

Total Carbon ◽

Primary Sources ◽

Retrieval Algorithm ◽

Sources And Sinks ◽

Earth Observing System ◽

Infrared Measurements ◽

The Impact

Abstract. The Orbiting Carbon Observatory-2 (OCO-2) was launched in 2014 with the goal of measuring the column-averaged dry-air mole fraction of carbon dioxide (XCO2) with sufficient precision and accuracy to infer regional carbon sources and sinks. One of the primary sources of error in near-infrared measurements of XCO2 is the scattering effects of cloud and aerosol layers. In this work, we study the impact of ingesting better informed aerosol priors from the Goddard Earth Observing System Model, Version 5 (GEOS-5) into the OCO-2 ACOS V8 retrieval algorithm with the objective of reducing the error in XCO2 from real measurements. Multiple levels of both aerosol setup complexity and uncertainty on the aerosol priors were tested, ranging from a mostly unconstrained aerosol optical depth (AOD) setup to ingesting full aerosol profiles with high confidence. We find that using co-located GEOS-5 aerosol types and AODs with low uncertainty results in a small improvement in the retrieved XCO2 against the Total Carbon Column Observing Network relative to V8. In contrast, attempting to use modeled vertical information in the aerosol prior to improve the XCO2 retrieval generally gives poor results, as aerosol models struggle with the vertical placement of aerosol layers. To assess regional differences in XCO2, we compare our results to a global CO2 model validation suite. We find that the GEOS-5 setup performs better than V8 over northern Africa and central Asia, with the standard deviation of the XCO2 error reduced from 2.12 to 1.83 ppm, due to a combination of smaller prior AODs and lower prior uncertainty. In general, the use of better informed aerosol priors shows promise but may be restricted by the current accuracy of aerosol models.

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Methods for the Extraction and Analysis of the Global Mode in Swirling Jets Undergoing Vortex Breakdown

Volume 4A: Combustion, Fuels and Emissions ◽

10.1115/gt2016-56588 ◽

2016 ◽

Cited By ~ 1

Author(s):

Lothar Rukes ◽

Moritz Sieber ◽

C. Oliver Paschereit ◽

Kilian Oberleithner

Keyword(s):

Vortex Breakdown ◽

Control Strategies ◽

Combustion Process ◽

Flame Stabilization ◽

Global Mode ◽

Swirling Jets ◽

Precessing Vortex Core ◽

Finite Time Lyapunov Exponent ◽

Image Velocimetry ◽

The Impact

Swirling jets undergoing vortex breakdown are widely used in combustion applications, due to their ability to provide aerodynamic flame stabilization. It is well known that vortex breakdown is accompanied by a dominant coherent structure, the so called precessing vortex core (PVC). Reports on the impact of the PVC on the combustion process range from beneficial to detrimental. In any event, efficient methods for the analysis of the PVC help to increase the benefit or reduce the penalty resulting from it. This study uses Particle Image Velocimetry (PIV) measurements of a generic non-isothermal swirling jet to demonstrate the use of advanced data analysis techniques. In particular, the Finite Time Lyapunov Exponent (FTLE) and local linear stability analysis (LSA) are shown to reveal deep insight into the physical mechanisms that drive the PVC. Particularly, it is demonstrated that the PVC amplitude is strongly reduced, if heating is applied at the wavemaker of the flow. These techniques are complemented by the traditionally used Proper Orthogonal Decomposition (POD) and spatial correlation techniques. It is demonstrated how these methods complement each other and lead to a comprehensive understanding of the PVC that lays out the path to efficient control strategies.

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