Development of a simplified n-heptane/methane model for high-pressure direct-injection natural gas marine engines

Li, Jingrui; Liu, Haifeng; Liu, Xinlei; Ye, Ying; Wang, Hu; Wang, Xinyan; Zhao, Hua; Yao, Mingfa

doi:10.1007/s11708-021-0718-3

Cited by 14 publications

(5 citation statements)

References 67 publications

(73 reference statements)

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“…The physical and chemical properties of diesel are approximated as those of n-dodecane and n-heptane, respectively, and the natural gas is approximated as methane. For WSR model, a reduced chemical kinetic mechanism of methane/n-heptane with 79 species and 262 reactions [24] was employed to simulate the natural-gas/diesel dual-fuel combustion. This chemical mechanism was validated for both methane and n-heptane combustion experiments and showed quite good agreement with the experiments in terms of laminar flame speed and ignition delay.…”

Section: Mapping Methods and Numerical Modelsmentioning

confidence: 99%

A Mapping Approach for Efficient CFD Simulation of Low-Speed Large-Bore Marine Engine with Pre-Chamber and Dual-Fuel Operation

Yue

Wang

et al. 2021

Energies

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A natural-gas-diesel dual-fuel marine engine with a pre-chamber is a promising solution for ocean transportation to meet the International Maritime Organization (IMO) emission regulations. This engine system employs a pre-chamber with direct injection of diesel to ignite premixed natural gas due to its higher ignition energy, which can enable lower lean limit and higher thermal efficiency. The dual-fuel pre-chamber marine engine presents complex multi-regime combustion characteristics in- and outside the pre-chamber, thus posing challenges in its numerical simulation in a cost-effective manner. Therefore, this paper presents a three-dimensional modeling study for the multi-regime combustion in a large-bore two-stroke marine dual-fuel engine, proposing a novel mapping approach, which couples the well-stirred reactor (WSR) model with the G-equation model to achieve high computational accuracy and efficiency simultaneously. In-depth analysis is performed using representative exothermic reaction (RXR) analysis and premixed turbulent combustion fundamentals to better understand the combustion process and to provide guidance in the selection of mapping timing. The results show that the use of mapping to switch from the WSR to the G-equation model can effectively reduce the runtime significantly by 71.5%, meanwhile maintaining similar accuracies in predictions of in-cylinder pressure traces, HRR and NOx emissions, compared to using WSR all along. Additionally, the choice of mapping timing based on several parameters is preliminarily discussed.

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Section: Mapping Methods and Numerical Modelsmentioning

confidence: 99%

A Mapping Approach for Efficient CFD Simulation of Low-Speed Large-Bore Marine Engine with Pre-Chamber and Dual-Fuel Operation

Yue

Wang

et al. 2021

Energies

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“…Although many works of literature on diesel and NG dual-fuel combustion have been published including the zero-dimensional model [25,26] and the three-dimensional spray study [27,28], however, previous studies mainly focused on the ignition characteristics of diesel and NG mixture when diesel is injected into NG. ere is still an obvious gap in understanding the ignition and flame characteristics of H 2 and CO additives in different combinations of dual-fuel blends.…”

Section: Introductionmentioning

confidence: 99%

A Numerical Study of the Effects of Using Reformer Gas on Ignition Characteristics under Dual-Fuel Engine-Relevant Conditions

Junwu

Guo

2022

International Journal of Chemical Engineering

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Natural gas/diesel dual-fuel engine has become an urgent need to alleviate the energy crisis and reduce emissions. As an additive, reforming gas can improve the combustion process of dual-fuel engines because it improves the combustion rate and compensates for the low reactivity of natural gas. Therefore, it is of great significance to study the ignition characteristics of natural gas diesel blends by adding H2 and syngas. Based on ANSYS Chemkin 17.0 software, the ignition delay time was solved by a closed uniform model. The effects of H2 and syngas on the ignition performance of a natural gas/diesel engine were studied. The results showed that the ignition delay time of the methane/n-heptane mixture was prolonged after adding H2 in the range of medium and low temperatures. This was due to the fact that reaction R3 (OH + H2 = H + H2O) was an endothermic reaction, which consumed OH radicals and inhibited the ignition process. In the high-temperature range, adding H2 reduced the ignition delay time of the mixture system, which was because of the significant increase in the sensitivity coefficients of R1(H + O2 = O + OH) and R3 and the generation of OH radicals. Therefore, the reduction in ignition delay caused by H2 addition in the high-temperature regions was mainly attributed to R3 and R1. In syngas, CO reduced the ignition delay time of methane/syngas/n-heptane. However, the addition of CO could reduce the importance of R3 in the reaction process—resulting in the weakening of the influence of H2 on ignition delay. This study can expand the theoretical basis of ignition characteristics of methane/n-heptane mixture with H2 and syngas under dual-fuel engine-relevant conditions.

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“…A promising NG operating mode is fueled with diesel/NG dual fuel, in which the low-reactivity NG is supplied as the primary energy source, whereas of the high-reactivity diesel is supplied as the ignition source, which is directly injected into the combustion chamber. 2,3 The NG dual fuel engines can be roughly categorized into the low-pressure dual fuel (LPDF) engine and high-pressure direct injection (HPDI) engine. 4 For LPDF engines, NG is mixed with air outside the cylinder or injected into the cylinder relatively early, which is then primarily consumed during the premixed-combustion process.…”

Section: Introductionmentioning

confidence: 99%

“…Natural gas (NG) is a promising alternative fuel for engine combustion owing to its abundant resources and low pollutant emissions. , Due to the long ignition delay and high autoignition temperature, NG engine requires additional energy or ignition source to ignite. A promising NG operating mode is fueled with diesel/NG dual fuel, in which the low-reactivity NG is supplied as the primary energy source, whereas of the high-reactivity diesel is supplied as the ignition source, which is directly injected into the combustion chamber. , …”

Section: Introductionmentioning

confidence: 99%

Investigation of the Combustion Kinetics Process in a High-Pressure Direct Injection Natural Gas Marine Engine

Liu

et al. 2021

Energy Fuels

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The detailed combustion kinetic processes of a high-pressure direct injection (HPDI) natural gas (NG) marine engine was investigated in the present work. A postprocessing code was employed to visualize the characteristic reactions that determine the combustion process. To evaluate the effect of mixture stratification on the combustion process, various NG injection timings were employed and four representative combustion periods were selected, including the timings when 1% (CA1), 5% (CA5), 10% (CA10), and 50% (CA50) of the total fuel energy are released. A higher heat release rate (HRR) was generated with a more advanced NG start of injection (SOI) timing, which, however, had limited effects on the main representative exothermic reactions (REXRs) within the high heat release (HHR) region and the dominant formation reactions of CH 2 O and OH, which are known as the indicators of low heat release (LHR) and HHR, respectively. Besides, for different NG SOI timing simulation, the consumption of CH 4 was all dominated by reactions H + CH 4 = CH 3 + H 2 and OH + CH 4 = CH 3 + H 2 O and the dominated REXR of the LHR region was reaction CH 3 + O 2 = CH 3 O 2 . Furthermore, with an advanced NG injection timing, significant changes were observed for the reaction paths of CH 2 , CH 2 O, and HCO from the premixed-combustion phase (CA10) to the mixing-controlled combustion phase (CA50). The results of the present study are able to provide a theoretical fundamental for the practical control of the HPDI NG marine engine.

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Development of a simplified n-heptane/methane model for high-pressure direct-injection natural gas marine engines

Cited by 14 publications

References 67 publications

A Mapping Approach for Efficient CFD Simulation of Low-Speed Large-Bore Marine Engine with Pre-Chamber and Dual-Fuel Operation

A Mapping Approach for Efficient CFD Simulation of Low-Speed Large-Bore Marine Engine with Pre-Chamber and Dual-Fuel Operation

A Numerical Study of the Effects of Using Reformer Gas on Ignition Characteristics under Dual-Fuel Engine-Relevant Conditions

Investigation of the Combustion Kinetics Process in a High-Pressure Direct Injection Natural Gas Marine Engine

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