A kinetic modeling study on octane rating and fuel sensitivity in advanced compression ignition engines

Tao, Mingyuan; Wu, Tong; Ge, Haiwen; DelVescovo, Dan; Zhao, Peng

doi:10.1016/j.combustflame.2017.07.020

Cited by 23 publications

(4 citation statements)

References 54 publications

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“…We have shown previously that PRF, matching the RON of the real fuel, is a good surrogate for near-zero sensitivity fuels at high and intermediate temperatures [28,34,35]. However, the low-temperature reactivity is not strongly correlated to octane numbers but rather depends on the non-paraffinic components present in the real fuel [27,28,35,36]. Therefore, in this work, we have prioritized matching the RON, MON and aromatic/naphthenic composition of the GCI blend while formulating the multi-component surrogate (MCS).…”

Section: Fuel Characterization and Surrogate Formulationmentioning

confidence: 99%

Ignition delay measurements of a low-octane gasoline blend, designed for gasoline compression ignition (GCI) engines

Alabbad

Badra

Djebbi

et al. 2019

Proceedings of the Combustion Institute

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A blend of low-octane (light and heavy naphtha) and high-octane (reformate) distillate fuels has been proposed for powering gasoline compression ignition (GCI) engines. The formulated 'GCI blend' has a research octane number (RON) of 77 and a motor octane number (MON) of 73.9. In addition to ~ 64 mole% paraffinic components, the blend contains ~ 20 mole% aromatics and ~ 15 mole% naphthenes.Experimental and modelling studies have been conducted in this work to assess autoignition characteristics of the GCI blend. Ignition delay times were measured in a shock tube and a rapid comparison machine over wide ranges of experimental conditions (20 and 40 bar, 640 -1175 K,  = 0.5, 1 and 2). Reactivity of the GCI blend was compared with experimental measurements of two surrogates: a multi-component surrogate (MCS) and a two-component primary reference fuel (PRF 77). Both surrogates capture the reactivity of the fuel quite well at high and intermediate temperatures.The MCS does a better job of emulating the fuel reactivity at low temperatures, where PRF 77 is more reactive than the GCI blend. Ignition delay times of the two surrogates are also simulated using detailed chemical kinetic models, and the simulations agree well with the experimental findings. The results of rate-of-production analyses show important role of cycloalkane chemistry in the overall autoignition behavior of the fuel at low temperatures.

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Section: Fuel Characterization and Surrogate Formulationmentioning

confidence: 99%

Ignition delay measurements of a low-octane gasoline blend, designed for gasoline compression ignition (GCI) engines

Alabbad

Badra

Djebbi

et al. 2019

Proceedings of the Combustion Institute

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“…Previous work 40 conducted kinetic investigation on the manifestation of octane rating and sensitivity of various gasoline surrogates under representative compression ignition conditions and demonstrate such effects using a pressure-temperature framework, as an extension of the Livengood-Wu integral analysis. 41 The role of conventional fuel metrics such as octane rating and octane sensitivity has been found to be substantially different in different engine operating regimes, that is, beyond RON and beyond MON conditions. Their results are intriguing but are solely based on thermodynamics and chemical kinetics.…”

Section: Introductionmentioning

confidence: 99%

“…The engine thermodynamic conditions are selected from the previous 0D kinetic study of fuel metric under ACI conditions along the combustion phasing iso-contour. 40,41,45 Detailed in-cylinder flow, spray dynamics and mixing are systematically considered in the current computational study. The results are further compared with the 0D kinetic study without considering stratification and charge cooling.…”

Section: Introductionmentioning

confidence: 99%

Effects of stratification and charge cooling on combustion in a gasoline direct-injection compression ignition (GDCI) engine

Zhao

2022

International Journal of Engine Research

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With the development of low temperature engine combustion strategies, performance of gasoline-type fuels under compression ignition conditions has attracted extensive research interest. Meanwhile, for the sake of co-optimization of engines and fuels for future ground transportation, identification and evaluation of general fuel properties should be a core research priority instead of endless testing of specific fuels. In this study, the roles of fuel octane sensitivity in characterizing the ignition performance of gasoline surrogates have been systematically investigated under typical gasoline direct ignition compression ignition (GDCI) engine conditions using 3D combustion CFD simulation, especially considering the subsequent in-cylinder charge stratification and charge cooling. Two different operating conditions, high boost pressure low boost temperature (beyond-RON) case and low boost pressure high boost temperature (beyond-MON) case, were considered. By comparing with our previous zero-dimensional chemical kinetic study of gasoline surrogates in advanced compression ignition (ACI) engines, the effects of stratification and charge cooling on the combustion processes are investigated. It is found that different fuel octane sensitivities lead to slight difference in equivalence ratio stratification and charge cooling due to differences in volatility. However, fuel reactivity is still the more dominant factor than the stratification and charge cooling effects in determining combustion phasing. The present results help to justify the P-T domain framework for engine autoignition analysis of overlapping pressure-temperature trajectory with ignition delay iso-contour. The results also provide useful guidance to the understanding of GCI combustion process, and to the evaluation of controlling fuel properties and the selection of alternative fuels in GCI engines

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“…For other fuels in general, S > 0, which is mainly attributed to significantly less pronounced negative temperature coefficient (NTC) behavior exhibited by gasoline as compared to PRFs, which makes them less resistant to auto-ignition under MON conditions [1,[9][10][11]. However, it must be noted that although a fuel's knock propensity is typically associated with the fuel chemistry, recent studies have shown that other properties, such as heat of vaporization (HoV) [12] and thermodynamic compressibility [13] can also contribute to it. On the other hand, engine operating conditions also play an important role with regard to knock, by interacting with fuel properties.…”

Section: Introductionmentioning

confidence: 99%

Development of a Virtual CFR Engine Model for Knocking Combustion Analysis

Pal

Kolodziej

Choi

et al. 2018

SAE Int. J. Engines

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Knock is a major bottleneck to achieving higher thermal efficiency in spark-ignited (SI) engines. The overall tendency to knock is highly dependent on fuel anti-knock quality as well as engine operating conditions. It is, therefore, critical to gain a better understanding of fuel-engine interactions in order to develop robust knock mitigation strategies. In the present work, a numerical model based on three-dimensional (3-D) computational fluid dynamics (CFD) was developed to capture knock in a Cooperative Fuel Research (CFR) engine. For combustion modeling, a hybrid approach incorporating the G-equation model to track turbulent flame propagation, and a homogeneous reactor multizone model to predict end-gas auto-ignition ahead of the flame front and post-flame oxidation in the burned zone, was employed. In addition, a novel methodology was implemented wherein a laminar flame speed lookup table generated a priori from a chemical kinetic mechanism could be used to provide flame speed as an input to the G-equation model, instead of using conventional empirical correlations. Multi-cycle Reynolds-Averaged Navier Stokes (RANS) simulations were performed for two different spark timings (STs) corresponding to non-knocking and knocking conditions, with other operating conditions kept the same as those of a standard Research Octane Number (RON) test. Iso-octane was considered as the fuel for the numerical study. Two different reduced kinetic mechanisms were employed to describe end-gas auto-ignition chemistry and to generate the flame speed lookup table. Experimental data, including intake/exhaust boundary conditions, was provided by a spark timing sweep study conducted in an in-house CFR engine. Moreover, cylinder wall/valve/port surface temperatures and residual gas fraction (RGF) were estimated using a well-calibrated onedimensional (1-D) model. On the other hand, a novel methodology was also developed to analyze experimental data for the knocking case and identify the most representative cycle. For the non-knocking case, a good agreement was found between experiment and CFD simulation, with respect to cycle-averaged values of 10% burn point (CA10), 50% burn point (CA50) and peak pressure magnitude/location. The virtual CFR engine model was also demonstrated to be capable of predicting average knock characteristics for the knocking case, such as knock point, knock intensity and energy of resonance, with good accuracy.

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A kinetic modeling study on octane rating and fuel sensitivity in advanced compression ignition engines

Cited by 23 publications

References 54 publications

Ignition delay measurements of a low-octane gasoline blend, designed for gasoline compression ignition (GCI) engines

Ignition delay measurements of a low-octane gasoline blend, designed for gasoline compression ignition (GCI) engines

Effects of stratification and charge cooling on combustion in a gasoline direct-injection compression ignition (GDCI) engine

Development of a Virtual CFR Engine Model for Knocking Combustion Analysis

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