Effect of Cetane Improver on Autoignition Characteristics of Low Cetane Sasol IPK Using Ignition Quality Tester (IQT)

Zheng, Zhimin; Badawy, Tamer; Henein, Naeim A.; Sattler, Eric; Johnson, Nicholas C.

doi:10.1115/icef2013-19061

Cited by 9 publications

(5 citation statements)

References 30 publications

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“…There is no universally accepted definition for the PID. The present study adopts the point of inflection [25,26], defined as the departure point between the pressure traces predicted by the reactive and the corresponding nonreactive simulations. The TID is then defined as the intersection of maximum pressure gradient during thermal runaway (slope II) and the pressure gradient at pressure recovery point (slope I), namely the gradient method [9].…”

Section: Reacting Casesmentioning

confidence: 99%

Auto-Ignition and Spray Characteristics of n-Heptane and iso-Octane Fuels in Ignition Quality Tester

Ali¹,

Elhagrasy²,

Sarathy³

et al. 2018

SAE Technical Paper Series

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Numerical simulations were conducted to systematically assess the effects of different spray models on the ignition delay predictions and compared with experimental measurements obtained at the KAUST ignition quality tester (IQT) facility. The influence of physical properties and chemical kinetics over the ignition delay time is also investigated. The IQT experiments provided the pressure traces as the main observables, which are not sufficient to obtain a detailed understanding of physical (breakup, evaporation) and chemical (reactivity) processes associated with auto-ignition. A threedimensional computational fluid dynamics (CFD) code, CONVERGE TM , was used to capture the detailed fluid/spray dynamics and chemical characteristics within the IQT configuration. The Reynolds-averaged Navier-Stokes (RANS) turbulence with multi-zone chemistry sub-models was adopted with a reduced chemical kinetic mechanism for n-heptane and iso-octane. The emphasis was on the assessment of two common spray breakup models, namely the Kelvin-Helmholtz/Rayleigh-Taylor (KH-RT) and linearized instability sheet atomization (LISA) models, in terms of their influence on auto-ignition predictions. Two spray models resulted in different local mixing, and their influence in the prediction of auto-ignition was investigated. The relative importance of physical ignition delay, characterized by spray evaporation and mixing processes, in the overall ignition behavior for the two different fuels were examined. The results provided an improved understanding of the essential contribution of physical and chemical processes that are critical in describing the IQT auto-ignition event at different pressure and temperature conditions, and allowed a systematic way to distinguish between the physical and chemical ignition delay times.

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Section: Reacting Casesmentioning

confidence: 99%

Auto-Ignition and Spray Characteristics of n-Heptane and iso-Octane Fuels in Ignition Quality Tester

Ali¹,

Elhagrasy²,

Sarathy³

et al. 2018

SAE Technical Paper Series

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“…Commercially available constant-volume chambers (e.g., IQT, Fuel Ignition Tester (FIT)) have been used successfully to investigate multi-component fuel blends (e.g., gasoline and diesel surrogates) [10,11] as well as the impact of blending alcohol (e.g., butanol, ethanol) on n-heptane autoignition [12,13]. However, there remains a need for additional data to provide insight into the effects of ethanol blending on iso-octane across a wide temperature range, capturing the effects in the high-temperature, low-temperature, and negative temperature coefficient (NTC) region with the IQT.…”

Section: Introductionmentioning

confidence: 99%

Effects of iso-octane/ethanol blend ratios on the observance of negative temperature coefficient behavior within the Ignition Quality Tester

Bogin

Luecke

Ratcliff

et al. 2016

Fuel

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An ignition delay study investigating the reduction in low temperature heat release (LTHR) and negative temperature coefficient (NTC) region with increasing ethanol concentration in binary blends of ethanol/isooctane was conducted in the Ignition Quality Tester (IQT). The IQT is advantageous for studying multi-component fuels such as iso-octane/ethanol which are difficult to study at lower temperatures covering the NTC region in traditional systems (e.g., shock tubes, rapid compression machines, etc.). The high octane numbers and concomitant long ignition delay times of ethanol and isooctane are ideal for study in the IQT allowing the system to reach a quasi-homogeneous mixture;allowing the effect of fuel chemistry on ignition delay to be investigated with minimal impact from the fuel spray due to the relatively long ignition times. NTC behavior from iso-octane/ethanol blends was observed for the first time using an IQT. Temperature sweeps of iso-octane/ethanol volumetric blends (100/0, 90/10, 80/20, 50/50, and 0/100) were conducted from 623 -993 K at 0.5, 1.0 and 1.5 MPa and global equivalence ratios ranging from 0.7 to 1.0. Ignition of the iso-octane/ethanol blends in the IQT was also modeled using a 0-D homogeneous batch reactor model. Significant observations include: 1) NTC behavior was observed for ethanol/iso-octane fuel blends up to 20% ethanol. 2) Ethanol produced shorter ignition delay times than iso-octane in the high temperature region. 3) The initial increase in ethanol from 0% to 10% had a lesser impact on ignition delay than increasing ethanol from 10% to 20%. 4)The 0-D model predicts that at 0.5 and 1.0 MPa ethanol produces the shortest ignition time in the high-temperature regime, as seen experimentally.

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“…First, in the study by Zheng et al, 51 it was pointed out that higher volatility promotes fuel–air mixing and result in shorter ignition delays, which is consistent with the fact found here, that the n -decane/toluene binary fuel exhibits shorter ignition delay times. Furthermore, according to Zheng et al’s 57 study, the physical dominant ignition delay defined in this study is also associated with the onset of exothermic reactions during fuel initial auto-ignition. Somers et al 58 also highlighted that the endothermic reactions in the spray combustion process contributes to the pressure decrease before fuel auto-ignition, and influences the determination of the end of physical delay period and the start of chemical delay period.…”

Section: Resultsmentioning

confidence: 65%

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

Duan

Liu

Liang

et al. 2020

International Journal of Engine Research

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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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Effect of Cetane Improver on Autoignition Characteristics of Low Cetane Sasol IPK Using Ignition Quality Tester (IQT)

Cited by 9 publications

References 30 publications

Auto-Ignition and Spray Characteristics of n-Heptane and iso-Octane Fuels in Ignition Quality Tester

Auto-Ignition and Spray Characteristics of n-Heptane and iso-Octane Fuels in Ignition Quality Tester

Effects of iso-octane/ethanol blend ratios on the observance of negative temperature coefficient behavior within the Ignition Quality Tester

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

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