scholarly journals Modeling Pollutant Emissions of Flameless Combustion With a Joint CFD and Chemical Reactor Network Approach

2019 ◽  
Vol 5 ◽  
Author(s):  
André A. V. Perpignan ◽  
Rishikesh Sampat ◽  
Arvind Gangoli Rao
Keyword(s):  
Chemical Reactor ◽  
Pollutant Emissions ◽  
Network Approach ◽  
Flameless Combustion ◽  
Chemical Reactor Network ◽  
Reactor Network

A review on the applications of the chemical reactor network approach on the prediction of pollutant emissions

2020 ◽  
Vol 92 (4) ◽  
pp. 551-570
Author(s):  
Hamidreza Khodayari ◽  
Fathollah Ommi ◽  
Zoheir Saboohi
Keyword(s):  
Flow Field ◽  
Chemical Reactor ◽  
Pollutant Emissions ◽  
Network Approach ◽  
Content Type ◽  
Modeling Methods ◽  
Chemical Reactor Network ◽  
Field Modeling ◽  
Reactor Network ◽  
Homogeneous Regions

Purpose The purpose of this paper is to review the applications of the chemical reactor network (CRN) approach for modeling the combustion in gas turbine combustors and classify the CRN construction methods that have been frequently used by researchers. Design/methodology/approach This paper initiates with introducing the CRN approach as a practical tool for precisely predicting the species concentrations in the combustion process with lower computational costs. The structure of the CRN and its elements as the ideal reactors are reviewed in recent studies. Flow field modeling has been identified as the most important input for constructing the CRNs; thus, the flow field modeling methods have been extensively reviewed in previous studies. Network approach, component modeling approach and computational fluid dynamics (CFD), as the main flow field modeling methods, are investigated with a focus on the CRN applications. Then, the CRN construction approaches are reviewed and categorized based on extracting the flow field required data. Finally, the most used kinetics and CRN solvers are reviewed and reported in this paper. Findings It is concluded that the CRN approach can be a useful tool in the entire process of combustion chamber design. One-dimensional and quasi-dimensional methods of flow field modeling are used in the construction of the simple CRNs without detailed geometry data. This approach requires fewer requirements and is used in the initial combustor designing process. In recent years, using the CFD approach in the construction of CRNs has been increased. The flow field results of the CFD codes processed to create the homogeneous regions based on construction criteria. Over the past years, several practical algorithms have been proposed to automatically extract reactor networks from CFD results. These algorithms have been developed to identify homogeneous regions with a high resolution based on the splitting criteria. Originality/value This paper reviews the various flow modeling methods used in the construction of the CRNs, along with an overview of the studies carried out in this field. Also, the usual approaches for creating a CRN and the most significant achievements in this field are addressed in detail.

Uncertainty Analysis of the Chemical Reactor Network Approach for Predicting the Pollutant Emissions in a Double-Swirl Combustor

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Hamidreza Khodayari ◽  
Fathollah Ommi ◽  
Zoheir Saboohi
Keyword(s):  
Uncertainty Analysis ◽  
Thermal Power ◽  
Chemical Reactor ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Inlet Temperature ◽  
Computational Domain ◽  
Experimental Database ◽  
Chemical Reactor Network ◽  
Reactor Network

Abstract The purpose of this study is to predict the pollutant emissions generated within an aero-engine combustor model using the computational fluid dynamics-chemical reactor network (CFD-CRN) approach by modeling combustion in highly swirled flows. The selected test case is a laboratory double swirled combustor that came with an extensive experimental database from previous works for CH4/air diffusion flames at atmospheric pressure. The CFD-CRN modeling approach is initiated by solving Reynolds-averaged Navier–Stokes (RANS) equations for a 3D computational domain. The numerically achieved time-averaged values of the velocity components are in good agreement with the experimental data for two different thermal power. The CRN is obtained by dividing the flow field into ideal chemical reactors using various filters on the CFD results. The temperature, axial velocity, CH4, and O2 mass fractions distributions are selected as the splitting criteria for constructing the CRN. An uncertainty analysis is carried out to investigate the effects of different splitting approaches for the temperature criteria since it significantly affected the pollutant emissions in the gas turbine combustor. The simulations of the pollutant emissions are performed via the detailed gas-phase chemical kinetic mechanism of GRI-Mech 3.0. The nonlinear distribution of the temperature intervals result in lower uncertainty and provide reliable results even with a small number of ideal reactors. Also, it is observed that the CRN can be used in different operating conditions and provide suitable results if it is constructed with exceptional consideration. Moreover, a parametric study is performed by varying the equivalence ratio and air inlet temperature to investigate the trends of the NO and CO emissions.

Effects of chemical reaction mechanism and NOx formation pathways on an inter-turbine burner

2019 ◽  
Vol 123 (1270) ◽  
pp. 1898-1918 ◽  
Author(s):  
A. A. V. Perpignan ◽  
A. Gangoli Rao
Keyword(s):  
Chemical Reaction ◽  
Equivalence Ratio ◽  
Chemical Reactor ◽  
Pollutant Emissions ◽  
Formation Mechanisms ◽  
Nox Formation ◽  
Chemical Reactor Network ◽  
Reaction Zones ◽  
Chemical Reaction Mechanisms ◽  
Reactor Network

ABSTRACTOne of the main challenges of future aircraft engines is to achieve low pollutant emissions while maintaining high combustion efficiencies and operability. The Flameless Combustion (FC) regime is pointed as one of the promising solutions due to its well-distributed reaction zones that yield low NOx emissions and oscillations. A dual-combustor configuration potentially facilitates the attainment of FC in the Inter-Turbine Burner (ITB). The development of such burner is dependent on knowledge regarding NOx formation and the parameters affecting it. It is known from the literature that the NOx formation mechanisms are different in FC. Therefore, in an attempt to clarify some of the mechanisms involved in NOx formation at relevant conditions, a chemical reactor network model developed to represent the ITB is explored. The role of prompt NOx was previously shown to be dominant at relatively low inlet temperatures and atmospheric pressure. In order to check these findings, five chemical reaction mechanisms were employed. All of them overpredicted NOx emissions and the overprediction is likely to be caused by the prompt NOx subset implemented in these mechanisms. Higher reactants temperatures and operational pressures were also investigated. Overall NOx emissions increased with temperature and the NOx peak moved to lower equivalence ratios. Operational pressure changed the emissions trend with global equivalence ratio. Leaner conditions had behaviour similar to that of conventional combustors (increase in NOx), while NOx dropped with further increase in equivalence ratio due to suppression of the prompt NOx production, as well as an increase in NO reburning. These trends highlight the differences between the emission behaviour of the ITB with those of a conventional combustion system.

Chemical Reactor Network Application to Emissions Prediction for Industial DLE Gas Turbine

2006 ◽  
Author(s):  
I. V. Novosselov ◽  
P. C. Malte ◽  
S. Yuan ◽  
R. Srinivasan ◽  
J. C. Y. Lee
Keyword(s):  
Gas Turbine ◽  
Chemical Reactor ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Ongoing Research ◽  
Chemical Reactor Network ◽  
Reaction Zones ◽  
Reactor Network

A chemical reactor network (CRN) is developed and applied to a dry low emissions (DLE) industrial gas turbine combustor with the purpose of predicting exhaust emissions. The development of the CRN model is guided by reacting flow computational fluid dynamics (CFD) using the University of Washington (UW) eight-step global mechanism. The network consists of 31 chemical reactor elements representing the different flow and reaction zones of the combustor. The CRN is exercised for full load operating conditions with variable pilot flows ranging from 35% to 200% of the neutral pilot. The NOpilot. The NOx and the CO emissions are predicted using the full GRI 3.0 chemical kinetic mechanism in the CRN. The CRN results closely match the actual engine test rig emissions output. Additional work is ongoing and the results from this ongoing research will be presented in future publications.

Development and Application of an Eight-Step Global Mechanism for CFD and CRN Simulations of Lean-Premixed Combustors

2007 ◽  
Author(s):  
Igor V. Novosselov ◽  
Philip C. Malte
Keyword(s):  
Chemical Reactor ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Lean Premixed Combustion ◽  
Chemical Reactor Network ◽  
Elevated Pressures ◽  
Nitric Oxide Formation ◽  
No Formation ◽  
Lean Premixed ◽  
Reactor Network

In this paper, the development of an eight-step global chemical kinetic mechanism for methane oxidation with nitric oxide formation in lean-premixed combustion at elevated pressures is described and applied. In particular, the mechanism has been developed for use in computational fluid dynamics (CFD) and chemical reactor network (CRN) simulations of combustion in lean-premixed gas turbine engines. Special attention is focused on the ability of the mechanism to predict NOx and CO exhaust emissions. Applications of the eight-step mechanism are reported in the paper, all for high-pressure, lean-premixed, methane-air (or natural gas-air) combustion. The eight steps of the mechanism are as follows: 1. Oxidation of the methane fuel to CO and H2O. 2. Oxidation of the CO to CO2. 3. Dissociation of the CO2 to CO. 4. Flame NO formation by the Zeldovich and nitrous oxide mechanisms. 5. Flame NO formation by the prompt and NNH mechanisms. 6. Post-flame NO formation by equilibrium H-atom attack on equilibrium N2O. 7. Post-flame NO formation by equilibrium O-atom attack on equilibrium N2O. 8. Post-flame Zeldovich NO formation by equilibrium O-atom attack on N2.

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