Influences of C5 esters addition on anti-knock and auto-ignition tendency of a gasoline surrogate fuel

The research octane numbers and auto-ignition characteristics of a toluene primary reference fuel (TPRF), when blended with three C5 esters, γ-valerolactone (GVL), methyl butanoate (MB), and methyl crotonate (MC), were investigated on a cooperative fuel research (CFR) engine and a constant volume combustion chamber (CVCC). In fuel preparation, ethanol was used to improve the miscibility, and the total additive comprised 1/3 ethanol and 2/3 GVL/MB/MC on a molar basis. The experimental results first reveal that the addition of the three series of additives boost fuel octane rating, and their boosting effects rank as MB > GVL ∼ MC when fuels are blended on a molar basis. In contrast, the auto-ignition tendency of the three series of fuel blends, when blended on the molar basis, ranks as the MC blends > the GVL blends> the MB blends. Different from the similar reactivities observed for the MC blends and the GVL blends in the RON tests, the MC blends exhibit higher auto-ignition propensity than the GVL blends, probably because the higher enthalpy of vaporization of GVL causes a more significant cooling effect. Finally, different from the literature studies that reported similar reactivities for pure MB and MC, in this study MB shows lower reactivity than MC when blending with the TPRF gasoline surrogate.

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Auto-ignition characteristics of a near-term light surrogate fuel for marine diesel: An experimental and modeling study

Combustion and Flame ◽

10.1016/j.combustflame.2021.02.003 ◽

2021 ◽

Vol 228 ◽

pp. 302-314

Author(s):

Zhiyong Wu ◽

Yebing Mao ◽

Liang Yu ◽

Yong Qian ◽

Xingcai Lu

Keyword(s):

Auto Ignition ◽

Marine Diesel ◽

Near Term ◽

Ignition Characteristics ◽

Surrogate Fuel ◽

Modeling Study

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Influences of isomeric butanol addition on anti-knock tendency of primary reference fuel and toluene primary reference fuel gasoline surrogates

International Journal of Engine Research ◽

10.1177/1468087419850704 ◽

2019 ◽

Vol 22 (1) ◽

pp. 39-49 ◽

Cited By ~ 10

Author(s):

Yunchu Fan ◽

Yaozong Duan ◽

Dong Han ◽

Xinqi Qiao ◽

Zhen Huang

Keyword(s):

Combustion Kinetics ◽

Molar Percentage ◽

Research Octane Number ◽

Fuel Blends ◽

Ignition Delay Times ◽

Auto Ignition ◽

Delay Times ◽

Primary Reference ◽

Primary Reference Fuels

The anti-knock tendency of blends of butanol isomers and two gasoline surrogates (primary reference fuels and toluene primary reference fuels) was studied on a single-cylinder cooperative fuel research engine. The effects of butanol molecular structure (n-butanol, i-butanol, s-butanol and t-butanol) and butanol addition percentage on fuel research octane numbers were investigated. The experimental results revealed that butanol addition to either PRF80 or TPRF80 increased research octane numbers, and the research octane numbers of fuel blends showed higher linearity with the molar percentage than with the volumetric percentage of butanol addition. Furthermore, the research octane number boosting effects of butanol isomers were observed to change with the fuel compositions, that is, i-butanol >s-butanol >n-butanol >t-butanol for primary reference fuels and i-butanol >s-butanol >t-butanol >n-butanol for toluene primary reference fuels. In addition, butanol/primary reference fuel blends exhibited higher research octane numbers than butanol/toluene primary reference fuel blends. We thereafter tried to elucidate the underlying fuel combustion kinetics for the observed anti-knock quality of different butanol/gasoline surrogate blends. It was found that the measured research octane numbers of fuel blends showed the best correlation with the calculated ignition delay times at the thermodynamic condition of 770 K and 2 MPa, and the reaction sensitivity analysis in auto-ignition at this condition revealed that the H-abstraction reactions of butanol isomers by OH radical suppressed fuel reactivity, thus elevating the fuel research octane numbers when butanol was added to the gasoline surrogates. Compared with the butanol/primary reference fuel blends, the positive sensitive reactions related to n-heptane were of higher importance, while the inhibitive effects of sensitive reactions related to butanol and iso-octane decreased for the toluene primary reference fuel/butanol blends, thus leading to lower research octane numbers of the toluene primary reference fuel/butanol blends than those of the butanol/primary reference fuel blends.

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Effects of branch structure of alkylbenzenes on spray auto-ignition of n-decane and alkylbenzenes blends

International Journal of Engine Research ◽

10.1177/1468087420914716 ◽

2020 ◽

pp. 146808742091471 ◽

Cited By ~ 1

Author(s):

Yaozong Duan ◽

Wang Liu ◽

Xin Liang ◽

Dong Han

Keyword(s):

Ignition Delay ◽

Cetane Number ◽

Methyl Groups ◽

Fuel Blend ◽

Fuel Blends ◽

Ignition Delay Times ◽

Auto Ignition ◽

Combustion Duration ◽

Ignition Characteristics ◽

Ignition Propensity

Spray auto-ignition characteristics of the blends of n-decane and several alkylbenzenes were carried out on a heated constant-volume spray combustion chamber. The derived cetane numbers of the fuel blends were determined, and the temperature-dependent ignition delay times and combustion durations were measured across a range of temperatures from 808 to 911 K. The results reveal that blending alkylbenzene to n-decane inhibits fuel spray auto-ignition propensity. For mono-alkylbenzenes, the fuel blend containing toluene has a higher derived cetane number than those with ethylbenzene and n-propylbenzene, but has a lower derived cetane number than the fuel blend containing n-butylbenzene. For those binary fuels containing ethylbenzene, n-propylbenzene and n-butylbenzene, their derived cetane numbers increase with the side alkyl chain length. The derived cetane numbers of the fuel blends with C8H10 isomers follow the trend of n-decane/ o-xylene > n-decane/ethylbenzene > n-decane/ m-xylene ∼ n-decane/ p-xylene, given the alkylbenzene blending fraction. For the blends with C9H12 isomers, those containing 1,2,3-trimethylbenzene and 1,3,5-trimethylbenzene have the highest and lowest derived cetane numbers, respectively, while the fuel blends containing 1,2,4-trimethylbenzene, n-propylbenzene and i-propylbenzene have comparatively intermediate derived cetane numbers. The blending effects of alkylbenzenes on ignition delay time are consistent with the observation on fuel derived cetane numbers. Both the number and proximity of substituted methyl groups significantly affect fuel auto-ignition propensity, and the adjacent methyl groups could increase the auto-ignition propensity. The combustion duration for the test fuels, except for n-decane and the n-decane/ n-butylbenzene blend, monotonically decreases with increased temperature. The non-monotonic dependence of combustion duration on temperature, for neat n-decane and the n-decane/ n-butylbenzene blend, may result from the increased diffusive burnt fraction. Finally, the comparison between gas-phase and spray auto-ignition reactivity of the test fuels highlights the contribution of both fuel physics and chemistry in spray auto-ignition.

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An Experimental Investigation of the Auto-Ignition Properties of Two C5 Esters: Methyl Butanoate and Butyl Methanoate

Volume 6: Energy Systems: Analysis, Thermodynamics and Sustainability ◽

10.1115/imece2007-41944 ◽

2007 ◽

Cited By ~ 1

Author(s):

Stephen M. Walton ◽

Carlos Perez ◽

Margaret S. Wooldridge

Keyword(s):

Low Temperature ◽

High Speed ◽

Combustion Engine ◽

Low Temperature Combustion ◽

Moderate Pressure ◽

Molecular Weights ◽

Auto Ignition ◽

Methyl Butanoate ◽

Temperature Combustion ◽

Time Histories

Ignition studies of two small esters were performed using a rapid compression facility (RCF). The esters (methyl butanoate and butyl methanoate) were chosen to have matching molecular weights, and C:H:O ratios, while varying the lengths of the constituent alkyl chains. The effect of functional group size on ignition delay time was investigated using pressure time-histories and high speed digital imaging. The mixtures studied covered a range of conditions relevant to oxygenated fuels and fuel additives, including bio-derived fuels. Low temperature and moderate pressure conditions were selected for study due to their relevance to advanced low temperature combustion strategies, and internal combustion engine conditions. The results are discussed in terms of the reaction pathways affecting the ignition properties.

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