Combustion Characteristics of n-heptane Through Temperature Variation Measurements Using Ignition Quality Tester

An innovative and informed methodology for the rational design and testing of anti-knock additives is reported. Interaction of the additives with OH● and HO2● is identified as the key reaction pathway by which non-metallic anti-knock additives are proposed to operate. Based on this mechanism, a set of generic design criteria for anti-knock additives is outlined. It is suggested that these additives should contain a weak X-H bond and form stable radical species after hydrogen atom abstraction. A set of molecular structural, thermodynamic, and kinetic quantities that pertain to the propensity of the additive to inhibit knock by this mechanism are identified and determined for a set of 12 phenolic model compounds. The series of structural analogues was carefully selected such that the physical thermodynamic and kinetic quantities could be systematically varied. The efficacy of these molecules as anti-knock additives was demonstrated through the determination of the research octane number (RON) and the derived cetane number(DCN), measured using an ignition quality tester (IQT), of a RON 95 gasoline treated with 1 mole % of the additive. The use of the IQT allows the anti-knock properties of potential additives to be studied on one tenth of the scale, compared to the analogous RON measurement. Using multiple linear regression, the relationship between DCN/RON and the theoretically determined quantities is studied. The overall methodology reported is proposed as an informed alternative to the non-directed experimental screening approach typically adopted in the development of fuel additives.

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A Proposed Biodiesel Combustion Kinetics Based on the Computational Fluid Dynamics Results in an Ignition Quality Tester

Journal of Energy Resources Technology ◽

10.1115/1.4042530 ◽

2019 ◽

Vol 141 (8) ◽

Author(s):

Mahmoud Elhalwagy ◽

Chao Zhang

Keyword(s):

Methyl Ester ◽

Ignition Delay ◽

Methyl Esters ◽

Direct Injection ◽

Combustion Process ◽

Major Fatty Acid ◽

Combustion Behavior ◽

Ignition Quality ◽

Reaction Constants ◽

Ignition Quality Tester

In this paper, five biodiesel global combustion decomposition steps are added to a surrogate mechanism to accurately represent the chemical kinetics of the decomposition of different levels of saturation of biodiesel, which are represented by five major fatty acid methyl esters. The reaction constants were tuned based on the results from the numerical simulations of the combustion process in an ignition quality tester (IQT) in order to obtain accurate cetane numbers. The prediction of the complete thermophysical properties of the five constituents is also carried out to accurately represent the physics of the spray and vaporization processes. The results indicated that the combustion behavior is controlled more by the spray and breakup processes for saturated biodiesel constituents than by the chemical delay, which is similar to the diesel fuel combustion behavior. The chemical delay and low temperature reactions were observed to have greater effects on the combustion and ignition delay for the cases of the unsaturated biodiesels. The comparison between the physical ignition delay and overall ignition delay between the saturated and unsaturated biodiesel constituents has also confirmed those stronger effects for the physical delay in the saturated compounds as compared to the unsaturated compounds. The validation of the proposed model is conducted for the simulations of two direct injection diesel engines using palm methyl ester and rape methyl ester.

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Development of JP-8 Surrogates and their Validation using Ignition Quality Tester

SAE International Journal of Fuels and Lubricants ◽

10.4271/2014-01-9077 ◽

2014 ◽

Vol 7 (1) ◽

pp. 337-351 ◽

Cited By ~ 13

Author(s):

Amit Shrestha ◽

Ziliang Zheng ◽

Tamer Badawy ◽

Naeim Henein ◽

Peter Schihl

Keyword(s):

Ignition Quality ◽

Ignition Quality Tester

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Improving Vegetable Oil Fueled CI Engine Characteristics Through Diethyl Ether Blending

ASME 2016 Internal Combustion Engine Fall Technical Conference ◽

10.1115/icef2016-9339 ◽

2016 ◽

Author(s):

S. Vedharaj ◽

R. Vallinayagam ◽

S. Mani Sarathy ◽

Robert W. Dibble

Keyword(s):

Vegetable Oil ◽

Diethyl Ether ◽

Cetane Number ◽

Gaseous Emissions ◽

Engine Operation ◽

Lower Viscosity ◽

Ignition Quality ◽

Ci Engine ◽

Ignition Characteristics ◽

Ignition Quality Tester

In this research, the flow and ignition properties of vegetable oil (VO) are improved by blending it with diethyl ether (DEE). DEE, synthesized from ethanol, has lower viscosity than diesel and VO. When DEE is blended with VO, the resultant DEEVO mixtures have favorable properties for compression ignition (CI) engine operation. As such, DEEVO20 (20% DEE + 80% VO) and DEEVO40 (40% DEE + 60% VO) were initially considered in the current study. The viscosity of VO is 32.4*10−6 m2/s; the viscosity is reduced with the increase of DEE in VO. In this study, our blends were limited to a maximum of 40% DEE in VO. The viscosity of DEEVO40 is 2.1*10−6 m2/s, which is comparable to that of diesel (2.3*10−6 m2/s). The lower boiling point and flash point of DEE improves the fuel spray and evaporation for DEEVO mixtures. In addition to the improvement in physical properties, the ignition quality of DEEVO mixtures is also improved, as DEE is a high cetane fuel (DCN = 139). The ignition characteristics of DEEVO mixtures were studied in an ignition quality tester (IQT). There is an evident reduction in ignition delay time (IDT) for DEEVO mixtures compared to VO. The IDT of VO (4.5 ms), DEEVO20 (3.2 ms) and DEEVO40 (2.7 ms) was measured in IQT. Accordingly, the derived cetane number (DCN) of DEEVO mixtures increased with the increase in proportion of DEE. The reported mixtures were also tested in a single cylinder CI engine. The start of combustion (SOC) was advanced for DEEVO20 and DEEVO40 compared to diesel, which is attributed to the high DCN of DEEVO mixtures. On the other hand, the peak heat release rate decreased for DEEVO mixtures compared to diesel. Gaseous emissions such as nitrogen oxide (NOX), total hydrocarbon (THC) and smoke were reduced for DEEVO mixtures compared to diesel. The physical and ignition properties of VO are improved by the addition of DEE, and thus, the need for the trans-esterification process is averted. Furthermore, this blending strategy is simpler and enables operation of straight run oils and fats in CI engine, replacing diesel completely.

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