Validation of a ternary gasoline surrogate in a CAI engine

Knop, Vincent; Pera, Cécile; Duffour, Florence

doi:10.1016/j.combustflame.2013.04.029

Cited by 23 publications

(20 citation statements)

References 39 publications

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“…Knop et al 10 identified six mechanisms for toluene reference fuel (TRF) mixtures 15,18,[24][25][26][27] and tested them against engine data under CAI combustion mode. They concluded that Andrae and Head's 18 mechanism was the best performer because of a distinct toluene reactivity.…”

Section: Detailed Kinetics Mechanismsmentioning

confidence: 99%

“…The variety of available sub-models, which are representative of the most relevant engine components, allowed for an uncomplicated, accurate description of the CAI engine. 10,41,47 We checked the tool's validity by comparing experimental and numerical quantities, such as instantaneous pressure traces in the intake port, in the exhaust port, and in the combustion chamber, as well as cycleaveraged flow rates, intake and exhaust gas temperatures and fuel/air equivalence ratios (FAERs). We were able to build confidence for the extracted additional non-measurable data (mainly in-cylinder temperature and mixture composition) by carefully checking that the physical phenomena we observed on the dynometer were accurately reproduced.…”

Section: System Simulationmentioning

confidence: 99%

“…Both sets of properties can be emulated using a ternary mixtures of n -heptane, iso -octane and toluene, as demonstrated in Pera and co-workers. 9,10 The second pitfall is the availability of an accurate kinetics mechanism for the selected surrogate. There are many existing mechanisms for ternary mixtures of n -heptane, iso -octane and toluene but the most accurate ones have all already been shown to have limitations when considering CAI combustion mode.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of mixture structure and of its influence on combustion in a CAI engine

Knop

2017

International Journal of Engine Research

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Homogeneous Charge Compression Ignition (HCCI) combustion mode theoretically relies on a perfectly homogeneous air/fuel mixture simultaneously releasing heat across the whole combustion chamber. However, practical implementation always leads to a staged combustion process that is still significantly quicker than conventional sparkignition or compression-ignition combustion modes. The degree of combustion staging is central to the limitation of combustion-induced noise, to cycle efficiency, as well as to combustion stability and completion. The present study numerically explored on the whole operating map the mixture structure at ignition for a specific type of HCCI combustion, namely the Controlled Auto-Ignition (CAI) combustion mode attained through burnt gas trapping with negative valve overlap. The analysis of the complete CAI operating map outlined the similarity of mixture structure for any operating condition and the mixture/chemistry interactions depending on the end-of-compression temperature domain. Temperature stratification appeared as the key input defining combustion-induced noise and combustion stability but mean in-cylinder temperature and dilution combine with temperature stratification to define operating map limitations.

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Section: Detailed Kinetics Mechanismsmentioning

confidence: 99%

Section: System Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of mixture structure and of its influence on combustion in a CAI engine

Knop

2017

International Journal of Engine Research

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“…The conditions for these laboratory measurements are similar to those which prevail before ignition in homogeneous charge compression ignition (HCCI) or controlled autoignition (CAI) engine, and the recent kinetic mechanisms, e.g., [4][5][6], perform remarkably well in these regimes. Application of such gasoline surrogate mechanisms have been seen in various studies demonstrating autoignition predictions in HCCI and CAI engines, [4,7]. The question arises of whether the reduced chemical mechanisms will perform equally well in predicting autoignition in SI engines.…”

Section: Introductionmentioning

confidence: 99%

Modelling of Self-Ignition in Spark-Ignition Engine Using Reduced Chemical Kinetics for Gasoline Surrogates

Khan

Roberts

Burluka

2019

Fluids

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A numerical and experimental investigation in to the role of gasoline surrogates and their reduced chemical kinetic mechanisms in spark ignition (SI) engine knocking has been carried out. In order to predict autoignition of gasoline in a spark ignition engine three reduced chemical kinetic mechanisms have been coupled with quasi-dimensional thermodynamic modelling approach. The modelling was supported by measurements of the knocking tendencies of three fuels of very different compositions yet an equivalent Research Octane Number (RON) of 90 (ULG90, PRF90 and 71.5% by volume toluene blended with n-heptane) as well as iso-octane. The experimental knock onsets provided a benchmark for the chemical kinetic predictions of autoignition and also highlighted the limitations of characterisation of the knock resistance of a gasoline in terms of the Research and Motoring octane numbers and the role of these parameters in surrogate formulation. Two approaches used to optimise the surrogate composition have been discussed and possible surrogates for ULG90 have been formulated and numerically studied. A discussion has also been made on the various surrogates from the literature which have been tested in shock tube and rapid compression machines for their autoignition times and are a source of chemical kinetic mechanism validation. The differences in the knock onsets of the tested fuels have been explained by modelling their reactivity using semi-detailed chemical kinetics. Through this work, the weaknesses and challenges of autoignition modelling in SI engines through gasoline surrogate chemical kinetics have been highlighted. Adequacy of a surrogate in simulating the autoignition behaviour of gasoline has also been investigated as it is more important for the surrogate to have the same reactivity as the gasoline at all engine relevant p − T conditions than having the same RON and Motored Octane Number (MON).

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“…Several recent studies have instead proposed a ternary mixture of PRF/toluene (also known as toluene primary reference fuels, TPRFs) as gasoline surrogates [13][14][15]. By adding toluene to PRFs, TPRFs possess gasoline's inherent fuel sensitivity and have gone some way in assisting the development of simple gasoline surrogate models which capture important combustion metrics [16,17] such as ignition delay time and flame speed. With the availability of complex reaction mechanisms for many different alkenes [18] and cycloalkanes [19], four-and five-component surrogates containing 1-hexene and 1-pentene representing alkenes and methylcyclohexane representing cycloalkanes, respectively, have also been proposed [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Autoignition characteristics of oxygenated gasolines

Lee

Ahmed

Nasir

et al. 2017

Combustion and Flame

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Gasoline anti-knock quality, defined by the research and motor octane numbers (RON and MON), is important for increasing spark ignition (SI) engine efficiency. Gasoline knock resistance can be increased using a number of blending components. For over two decades, ethanol has become a popular anti-knock blending agent with gasoline fuels due to its production from bio-derived resources. This work explores the oxidation behavior of two oxygenated certification gasoline fuels and the variation of fuel reactivity with molecular composition. Ignition delay times of Haltermann (RON = 91) and Coryton (RON = 97.5) gasolines have been measured in a high-pressure shock tube and in a rapid compression machine at three pressures of 10, 20 and 40 bar, at equivalence ratios of φ = 0.45, 0.9 and 1.8, and in the temperature range of 650-1250 K. The results indicate that the effects of fuel octane number and fuel composition on ignition characteristics are strongest in the intermediate temperature (negative temperature coefficient) region. To simulate the reactivity of these gasolines, three kinds of surrogates, consisting of three, four and eight components, are proposed and compared with the gasoline ignition delay times. It is shown that more complex surrogate mixtures are needed to emulate the reactivity of gasoline with higher octane sensitivity (S = RON-MON). Detailed kinetic analyses are performed to illustrate the dependence of gasoline ignition delay times on fuel composition and, in particular, on ethanol content.

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Validation of a ternary gasoline surrogate in a CAI engine

Cited by 23 publications

References 39 publications

Analysis of mixture structure and of its influence on combustion in a CAI engine

Analysis of mixture structure and of its influence on combustion in a CAI engine

Modelling of Self-Ignition in Spark-Ignition Engine Using Reduced Chemical Kinetics for Gasoline Surrogates

Autoignition characteristics of oxygenated gasolines

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