Influences of excess air coefficient on combustion and emission performance of diesel pilot ignition natural gas engine by coupling computational fluid dynamics with reduced chemical kinetic model

2019 ◽  
Vol 187 ◽  
pp. 283-296 ◽  
Author(s):  
Jun Shu ◽  
Jianqin Fu ◽  
Jingping Liu ◽  
Shuqian Wang ◽  
Yanshan Yin ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Model ◽  
Natural Gas ◽  
Chemical Kinetic ◽  
Chemical Kinetic Model ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Excess Air ◽  
Excess Air Coefficient

Modeling of Formaldehyde Formation From Crevices in a Large Bore Natural Gas Engine

2007 ◽  
Author(s):  
Daniel B. Olsen ◽  
Ryan K. Palmer ◽  
Charles E. Mitchell
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Natural Gas ◽  
Kinetic Modeling ◽  
The United States ◽  
Chemical Kinetic ◽  
Formation Mechanisms ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Natural Gas Engine

Formaldehyde emissions from stationary natural gas engines are regulated in the United States, as mandated by the 1990 Clean Air Act Amendments. This work aims to advance the understanding of formaldehyde formation in large bore (>36 cm) natural gas engines. Formaldehyde formation in a large bore natural gas engine is modeled utilizing computational fluid dynamics and chemical kinetics. The top land crevice volume is believed to play an important role in the formation mechanisms of engine-out formaldehyde. This work focuses specifically on the top land crevice volume in the Cooper-Bessemer LSVB large bore 4-stroke cycle natural gas engine. Chemical kinetic modeling predicts that the top land crevice volume is responsible for the formation of 22 ppm of engine-out formaldehyde. Based on a raw exhaust concentration of 80 ppm, this constitutes about 27% of engine-out formaldehyde. Simplifying assumptions made for the chemical kinetic modeling are validated using computational fluid dynamics. Computational fluid dynamic analysis provided confirmation of crevice volume mass discharge timing. It also provided detailed pressure, temperature and velocity profiles within the top land crevice volume at various crank angle degrees.

The influence of the enrichment injection angle on the performance of a pre-chamber spark ignition natural-gas engine

2017 ◽  
Vol 232 (5) ◽  
pp. 679-694 ◽  
Author(s):  
Liyan Feng ◽  
Jun Zhai ◽  
Chuang Qu ◽  
Bo Li ◽  
Jiangping Tian ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Natural Gas ◽  
Nitrogen Oxide ◽  
Spark Ignition ◽  
Nitrogen Oxide Emissions ◽  
Mixture Formation ◽  
Injection Angle ◽  
Gas Engine ◽  
Natural Gas Engine

Using an enriched pre-chamber is an effective way to extend the lean limit, to reduce the nitrogen oxide emissions and to avoid abnormal combustion in spark ignition natural-gas engines. Enrichment injection in the pre-chamber of a spark ignition natural-gas engine determines the flow field and the fuel–air mixture formation quality in the pre-chamber and has a profound influence on the combustion performance of the engine. In order to study the characteristics of enrichment injection in the pre-chamber of a natural-gas engine, two-dimensional particle image velocimetry measurements and three-dimensional computational fluid dynamics calculations were carried out. The influence of the enrichment injection angle on the engine performance was investigated with the aid of a computational fluid dynamics simulation tool. The results indicate that a change in the enrichment injection angle directly affects the gas motion, the fuel–air mixture formation, the flame propagation and the formation of nitrogen oxides in the pre-chamber and further influences the penetration of the flame jets, the combustion temperature distribution and the formation of nitrogen oxides in the main chamber. There is an optimal injection angle for this research engine. Of the four injection angles that were investigated, an injection angle of 14° results in the lowest nitrogen oxide emissions.

scholarly journals Reduced Chemical Kinetic Model for Titan Entries

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Romain Savajano ◽  
Raffaello Sobbia ◽  
Michele Gaffuri ◽  
Pénélope Leyland
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Sensitivity Analysis ◽  
Chemical Composition ◽  
Kinetic Model ◽  
Shock Tube ◽  
Chemical Kinetic ◽  
Chemical Kinetic Model ◽  
Radiative Fluxes ◽  
Equilibrium Chemical

A reduced chemical kinetic model for Titan's atmosphere has been developed. This new model with 18 species and 28 reactions includes the mainfeatures of a more complete scheme, respecting the radiative fluxes. It has been verified against three key elements: a sensitivity analysis, the equilibrium chemical composition using shock tube simulations in CHEMKIN, and the results of computational fluid dynamics (CFDs) simulations.

Experimental study of combustion strategy for jet ignition on a natural gas engine

2020 ◽  
pp. 146808742097775
Author(s):  
Ziqing Zhao ◽  
Zhi Wang ◽  
Yunliang Qi ◽  
Kaiyuan Cai ◽  
Fubai Li
Keyword(s):  
Experimental Study ◽  
Natural Gas ◽  
Efficient Points ◽  
Lean Burn ◽  
Gas Engine ◽  
Absolute Value ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Excess Air ◽  
Lean Limit

To explore a suitable combustion strategy for natural gas engines using jet ignition, lean burn with air dilution, stoichiometric burn with EGR dilution and lean burn with EGR dilution were investigated in a single-cylinder natural gas engine, and the performances of two kinds of jet ignition technology, passive jet ignition (PJI) and active jet ignition (AJI), were compared. In the study of lean burn with air dilution strategy, the results showed that AJI could extend the lean limit of excess air ratio (λ) to 2.1, which was significantly higher than PJI’s 1.6. In addition, the highest indicated thermal efficiency (ITE) of AJI was shown 2% (in absolute value) more than that of PJI. Although a decrease of NOx emission was observed with increasing λ in the air dilution strategy, THC and CO emissions increased. Stoichiometric burn with EGR was proved to be less effective, which can only be applied in a limited operation range and had less flexibility. However, in contrast to the strategy of stoichiometric burn with EGR, the strategy of lean burn with EGR showed a much better applicability, and the highest ITE could achieve 45%, which was even higher than that of lean burn with air dilution. Compared with the most efficient points of lean burn with pure air dilution, the lean burn with EGR dilution could reduce 78% THC under IMEP = 1.2 MPa and 12% CO under IMEP = 0.4 MPa. From an overall view of the combustion and emission performances under both low and high loads, the optimum λ would be from 1.4 to 1.6 for the strategy of lean burn with EGR dilution.

scholarly journals Experimental and Computational Analysis of NOx Photocatalytic Abatement Using Carbon-Modified TiO2 Materials

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1366
Author(s):  
Tatiana Zhiltsova. ◽  
Nelson Martins ◽  
Mariana R. F. Silva ◽  
Carla F. Da Silva ◽  
Mirtha A. O. Lourenço ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Kinetic Model ◽  
Photocatalytic Oxidation ◽  
Cfd Simulation ◽  
Emission Spectra ◽  
Chemical Kinetic ◽  
Solar Light ◽  
Model Parameters ◽  
Chemical Kinetic Model ◽  
Simulated Solar Light

In the present study, two photocatalytic graphene oxide (GO) and carbon nanotubes (CNT) modified TiO2 materials thermally treated at 300 °C (T300_GO and T300_CNT, respectively) were tested and revealed their conversion efficiency of nitrogen oxides (NOx) under simulated solar light, showing slightly better results when compared with the commercial Degussa P25 material at the initial concentration of NOx of 200 ppb. A chemical kinetic model based on the Langmuir–Hinshelwood (L-H) mechanism was employed to simulate micropollutant abatement. Modeling of the fluid dynamics and photocatalytic oxidation (PCO) kinetics was accomplished with computational fluid dynamics (CFD) approach for modeling single-phase liquid fluid flow (air/NOx mixture) with an isothermal heterogeneous surface reaction. A tuning methodology based on an extensive CFD simulation procedure was applied to adjust the kinetic model parameters toward a better correspondence between simulated and experimentally obtained data. The kinetic simulations of heterogeneous photo-oxidation of NOx carried out with the optimized parameters demonstrated a high degree of matching with the experimentally obtained NOx conversion. T300_CNT is the most active photolytic material with a degradation rate of 62.1%, followed by P25-61.4% and T300_GO-60.4%, when irradiated, for 30 min, with emission spectra similar to solar light.

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