A numerical investigation on methane combustion and emissions from a natural gas-diesel dual fuel engine using CFD model

Yu, Long; Li, Hailin; Guo, Hongsheng; Li, Yongzhi; Yao, Mingfa

doi:10.1016/j.apenergy.2017.07.071

Cited by 107 publications

(35 citation statements)

References 39 publications

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“…26 Many studies have been conducted to investigate the diesel/gas injection process, the oxidation of diesel and methane, and the formation of pollutants in HPDI combustion through CFD modeling studies coupled with chemical kinetic mechanisms. 26 Many studies have been conducted to investigate the diesel/gas injection process, the oxidation of diesel and methane, and the formation of pollutants in HPDI combustion through CFD modeling studies coupled with chemical kinetic mechanisms.…”

Section: Introductionmentioning

confidence: 99%

“…Computational fluid dynamics (CFD) modeling has been recognized as a reliable method for the investigation of combustion processes and emission formation, especially in compression ignition engines involving diffusion combustion. 26 Many studies have been conducted to investigate the diesel/gas injection process, the oxidation of diesel and methane, and the formation of pollutants in HPDI combustion through CFD modeling studies coupled with chemical kinetic mechanisms. [27][28][29][30][31] Agarwal and Assanis 27 carried out detailed multidimensional modeling of a direct-injection natural gas engine with self-ignition conditions for the purpose of examining ignition, combustion, and formation processes of NO by using KIVA-3 code with the eddy breakup model coupled with a chemical kinetic mechanism for natural gas simulation.…”

Section: Introductionmentioning

confidence: 99%

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Effects of injection strategies on low‐speed marine engines using the dual fuel of high‐pressure direct‐injection natural gas and diesel

Liu

Wang

et al. 2019

Energy Science & Engineering

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Pilot‐ignited high‐pressure direct‐injection (HPDI) natural gas engines have drawn much attention since being proposed, as these engines can maintain high performance and lead to clean combustion compared with conventional diesel engines. This prospective concept is not only used in vehicle engines but also used in large‐scale marine engines. In this study, the effects of injection strategies of dual fuels on combustion characteristics and emissions were investigated using the computational fluid dynamics (CFD) code CONVERGE coupled with a reduced n‐heptane/methane mechanism. The results showed that the effects of absolute injection timing (AIT) on the combustion characteristics and emissions are similar to those of traditional diesel engines. As the AIT varies from advanced by 4°CA to retarded by 4°CA, the peak values of the in‐cylinder pressure and temperature decrease gradually. However, a conventional trade‐off between NOx and soot/CO/HC/ISFC emissions can also be observed as the AIT is retarded. In contrast, relative injection timing (RIT) has more complicated impacts on the combustion and emissions characteristics. The in‐cylinder temperature distribution and concentration stratification change as the gas jet initially interacts with the pilot flame. The effects of the gas injection timing on the combustion characteristics and indicated specific fuel consumption are also similar to those of the AIT, but the emissions are quite different. The pilot injection timing shows minimal influence on the main combustion process. Better performance can be obtained with partially premixed combustion with a slightly late injection timing compared with that of the original (ORG) base case.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of injection strategies on low‐speed marine engines using the dual fuel of high‐pressure direct‐injection natural gas and diesel

Liu

Wang

et al. 2019

Energy Science & Engineering

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“…Therefore, surrogate fuels were defined for the simulation. n-heptane is a common diesel substitute in dual fuel investigations [8][9][10] and was used as a surrogate. It is therefore well suited as diesel substitute, since with a cetane number (which describes the flammability of the fuel) of 56 [11], n-heptane is in the range of the diesel cetane number, which has to be 51 or higher according to the DIN EN590 standard of October 2009.…”

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confidence: 99%

“…In analogy to diesel fuel, it is necessary to define a substitute fuel for natural gas. A frequently used substitute fuel is methane [8,10]. To better reflect the methane number (which is a measure of the knock resistance) of natural gas, a mixture of methane and propane was defined as a surrogate.…”

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confidence: 99%

Dual Fuel Reaction Mechanism 2.0 including NOx Formation and Laminar Flame Speed Calculations Using Methane/Propane/n-Heptane Fuel Blends

Schuh

Winter

2020

Energies

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This study presents the further development of the TU Wien dual fuel mechanism, which was optimized for simulating ignition and combustion in a rapid compression expansion machine (RCEM) in dual fuel mode using diesel and natural gas at pressures higher than 60 bar at the start of injection. The mechanism is based on the Complete San Diego mechanism with n-heptane extension and was attuned to the RCEM measurements to achieve high agreement between experiments and simulation. This resulted in a specific application area. To obtain a mechanism for a wider parameter range, the Arrhenius parameter changes performed were analyzed and updated. Furthermore, the San Diego nitrogen sub-mechanism was added to consider NO x formation. The ignition delay time-reducing effect of propane addition to methane was closely examined and improved. To investigate the propagation of the flame front, the laminar flame speed of methane-air mixtures was simulated and compared with measured values from literature. Deviations at stoichiometric and fuel-rich conditions were found and by further mechanism optimization reduced significantly. To be able to justify the parameter changes performed, the resulting reaction rate coefficients were compared with data from the National Institute of Standards and Technology chemical kinetics database.Energies 2020, 13, 778 2 of 31 in the simulation would lead to an unmanageable simulation time. Therefore, surrogate fuels were defined for the simulation. n-heptane is a common diesel substitute in dual fuel investigations [8][9][10] and was used as a surrogate. It is therefore well suited as diesel substitute, since with a cetane number (which describes the flammability of the fuel) of 56 [11], n-heptane is in the range of the diesel cetane number, which has to be 51 or higher according to the DIN EN590 standard of October 2009. In analogy to diesel fuel, it is necessary to define a substitute fuel for natural gas. A frequently used substitute fuel is methane [8,10]. To better reflect the methane number (which is a measure of the knock resistance) of natural gas, a mixture of methane and propane was defined as a surrogate. In [7], in the first step, the ignition delay times (IDTs) of homogeneous methane-propane-n-heptane mixtures were investigated with a rapid compression machine (RCM) and a shock tube (ST) at PCFC (Physico Chemical Fundamentals of Combustion), RWTH Aachen [12,13], followed by the comparison of the measured values with simulation results using various n-heptane mechanisms available in the literature. For the simulations in [7], as well as the actual study, the program LOGEresearch (Version LSv1.09, LOGE AB, Lund, Sweden) [14] was used. The simulation of the RCM measurements was performed with the module "rapid compression machine" in LOGEresearch at a specific fuel composition, fuel-air equivalence ratio, starting temperature, and starting pressure of the mixture before compression. The RCM facility effects describe the non-ideal behavior of the test facility and the machine-specific com...

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“…There are insignificant amounts of NO and NO2 observed in the region featuring low temperature and high CH4 concentration (marked as (4) in Figure 7.6). Such a region is recognized as a "dead" one which does not participate in active chemical reactions, and does not have a chance to mix with hot combustion products but provides the main source of unburned CH4 [12,76].…”

Section: No2 Formation During the Main Combustion Stagementioning

confidence: 99%

A Numerical Investigation of Natural Gas-Diesel Dual Fuel Engine Combustion and Emissions Using CFD Model

Yu¹

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Natural gas (NG)-diesel dual fuel engines have been highlighted for their fuel flexibility and high thermal efficiency comparable to diesel engines. However, the addition of NG to compression ignition diesel engines was reported to elongate ignition delay and to increase the emissions of carbon monoxide (CO), unburned methane (CH4), and nitrogen dioxide (NO2). Past research on dual fuel engines has focused on the experimental research on the engine performance, combustion process, and exhaust emissions. The research on detailed mechanism dominating the impact of CH4 on formation of CO and NO2 in cylinder, and the mechanism for CH4 to survive the combustion process and slip through the cylinder is limited. The examinations of these mechanisms require the simulation of dual fuel engine combustion using a CFD model coupled with chemical kinetic mechanism. This research numerically investigates the combustion process and exhaust emissions from two NG-diesel dual fuel engines using a CFD model coupled with a reduced primary reference fuel (PRF) chemistry. The CFD model used is Converge-SAGE model with a maximum of 300000 grid points. The fuel chemistry used is a reduced PRF mechanism with 45 species and 142 reactions including a reduced NOx mechanism with 4 species and 12 reactions. The CFD model with reduced PRF chemistry has been validated against experimental data measured in a single-cylinder compression-ignition engine over a wide range of CH4 substitution ratio. A post-processing tool has been developed to calculate, analyze, and visualize the instantaneous rate of production (ROP) of key species in each cell with the known temperature, pressure, and species concentration exported by CFD code. The simulation results are further post-processed to numerically investigate the combustion process and the formation mechanism of CO, and NO2 in a dual fuel engine. The mechanism for CH4 to survive the main combustion process and post-combustion oxidation process is numerically examined. The research on NO2 formation identified NO+HO2→NO2+OH as the key reaction dominating the increased formation of NO2 in dual fuel engines. The HO2 necessary for the formation of NO2 emitted by the engine is produced through the post-oxidation of CH4 that survived the main combustion process. The CO emitted from the NG-diesel dual fuel engine is formed through the oxidation of CH4 during the late

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A numerical investigation on methane combustion and emissions from a natural gas-diesel dual fuel engine using CFD model

Cited by 107 publications

References 39 publications

Effects of injection strategies on low‐speed marine engines using the dual fuel of high‐pressure direct‐injection natural gas and diesel

Effects of injection strategies on low‐speed marine engines using the dual fuel of high‐pressure direct‐injection natural gas and diesel

Dual Fuel Reaction Mechanism 2.0 including NOx Formation and Laminar Flame Speed Calculations Using Methane/Propane/n-Heptane Fuel Blends

A Numerical Investigation of Natural Gas-Diesel Dual Fuel Engine Combustion and Emissions Using CFD Model

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