Chemical kinetics modeling and LES combustion model effects on a perfectly premixed burner

Dual-fuel engines at part loads inevitably suffer from lower thermal efficiency and higher carbon monoxide and unburned fuel emission. The present work was carried out to investigate the combustion characteristics of a dual-fuel (diesel-gas) engine at part loads, using a single-zone combustion model with detailed chemical kinetics for combustion of natural gas fuel. The authors have developed software in which the pilot fuel is considered as a subsidiary zone and a heat source derived from two superimposedWiebe combustion functions to account for its contribution to ignition of the gaseous fuel and the rest of the total released energy. The chemical kinetics mechanism consists of 112 reactions with 34 species. This quasi-two-zone combustion model is able to establish the development of the combustion process with time and the associated important operating parameters, such as pressure, temperature, heat release rate (HRR), and species concentration. Therefore, this paper describes an attempt to investigate the combustion phenomenon at part loads and using hot exhaust gas recirculation (EGR) to improve the above-mentioned drawbacks and problems. By employing this technique, it is found that lower percentages of EGR and allowance for its thermal and radical effects have a positive influence on performance and emission parameters of dual-fuel engines at part loads. Predicted values show good agreement with corresponding experimental values under special engine operating conditions (quarter-load, 1400 r/min). Implications are discussed in detail.

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A comprehensive iso-octane combustion model with improved thermochemistry and chemical kinetics

Combustion and Flame ◽

10.1016/j.combustflame.2016.12.029 ◽

2017 ◽

Vol 178 ◽

pp. 111-134 ◽

Cited By ~ 101

Author(s):

Nour Atef ◽

Goutham Kukkadapu ◽

Samah Y. Mohamed ◽

Mariam Al Rashidi ◽

Colin Banyon ◽

...

Keyword(s):

Chemical Kinetics ◽

Combustion Model

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A Study on Biodiesel NOx Emission Control With the Reduced Chemical Kinetics Model

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4027358 ◽

2014 ◽

Vol 136 (10) ◽

Cited By ~ 1

Author(s):

Juncheng Li ◽

Zhiyu Han ◽

Cai Shen ◽

Chia-fon Lee

Keyword(s):

Chemical Kinetics ◽

Combustion Process ◽

Operating Conditions ◽

Nox Emission ◽

Kinetics Model ◽

Combustion Model ◽

Nox Emissions ◽

Soot Emission ◽

Start Of Injection ◽

Combustion Processes

In this paper, the effects of the start of injection (SOI) timing and exhaust gas recirculation (EGR) rate on the nitrogen oxides (NOx) emissions of a biodiesel-powered diesel engine are studied with computational fluid dynamics (CFD) coupling with a chemical kinetics model. The KIVA code coupling with a CHEMKIN-II chemistry solver is applied to the simulation of the in-cylinder combustion process. A surrogate biodiesel mechanism consisting of two fuel components is employed as the combustion model of soybean biodiesel. The in-cylinder combustion processes of the cases with four injection timings and three EGR rates are simulated. The simulation results show that the calculated NOx emissions of the cases with default EGR rate are reduced by 20.3% and 32.9% when the injection timings are delayed by 2- and 4-deg crank angle, respectively. The calculated NOx emissions of the cases with 24.0% and 28.0% EGR are reduced by 38.4% and 62.8%, respectively, compared to that of the case with default SOI and 19.2% EGR. But higher EGR rate deteriorates the soot emission. When EGR rate is 28.0% and SOI is advanced by 2 deg, the NOx emission is reduced by 55.1% and soot emission is controlled as that of the case with 24% EGR and default SOI. The NOx emissions of biodiesel combustion can be effectively improved by SOI retardation or increasing EGR rate. Under the studied engine operating conditions, introducing more 4.8% EGR into the intake air with unchanged SOI is more effective for NOx emission controlling than that of 4-deg SOI retardation with default EGR rate.

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Implicit Methods in Combustion and Chemical Kinetics Modeling

Multiple Time Scales ◽

10.1016/b978-0-12-123420-1.50010-0 ◽

1985 ◽

pp. 113-144 ◽

Cited By ~ 19

Author(s):

ROBERT J. KEE ◽

LINDA R. PETZOLD ◽

MITCHELL D. SMOOKE ◽

JOSEPH F. GRCAR

Keyword(s):

Chemical Kinetics ◽

Implicit Methods ◽

Kinetics Modeling

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Calibration and Chemical Kinetics Modeling of an OH Chemiluminesence Diagnostic

39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit ◽

10.2514/6.2003-4493 ◽

2003 ◽

Cited By ~ 5

Author(s):

Eric Petersen ◽

Danielle Kalitan ◽

Matthew Rickard

Keyword(s):

Chemical Kinetics ◽

Kinetics Modeling

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Multidimensional Modeling of Diesel Ignition and Combustion Using a Multistep Kinetics Model

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2906775 ◽

1993 ◽

Vol 115 (4) ◽

pp. 781-789 ◽

Cited By ~ 112

Author(s):

S.-C. Kong ◽

R. D. Reitz

Keyword(s):

Chemical Kinetics ◽

Diesel Engines ◽

Characteristic Time ◽

Kinetics Model ◽

Combustion Model ◽

Model Parameters ◽

Ignition Process ◽

Time Model ◽

Combustion Heat ◽

Ignition And Combustion

Ignition and combustion mechanisms in diesel engines were studied using the KIVA code, with modifications to the combustion, heat transfer, crevice flow, and spray models. A laminar-and-turbulent characteristic-time combustion model that has been used successfully for spark-ignited engine studies was extended to allow predictions of ignition and combustion in diesel engines. A more accurate prediction of ignition delay was achieved by using a multistep chemical kinetics model. The Shell knock model was implemented for this purpose and was found to be capable of predicting successfully the autoignition of homogeneous mixtures in a rapid compression machine and diesel spray ignition under engine conditions. The physical significance of the model parameters is discussed and the sensitivity of results to the model constants is assessed. The ignition kinetics model was also applied to simulate the ignition process in a Cummins diesel engine. The post-ignition combustion was simulated using both a single-step Arrhenius kinetics model and also the characteristic-time model to account for the energy release during the mixing-controlled combustion phase. The present model differs from that used in earlier multidimensional computations of diesel ignition in that it also includes state-of-the-art turbulence and spray atomization models. In addition, in this study the model predictions are compared to engine data. It is found that good levels of agreement with the experimental data are obtained using the multistep chemical kinetics model for diesel ignition modeling. However, further study is needed of the effects of turbulent mixing on post-ignition combustion.

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