Assessment of JP-8 and DF-2 Evaporation Rate and Cetane Number Differences on a Military Diesel Engine

Schihl, Peter; Hoogterp, Laura; Pangilinan, Harold

doi:10.4271/2006-01-1549

Cited by 23 publications

(20 citation statements)

References 29 publications

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“…Such a trend may imply that the ignition pressure dependency of these two fuels is very similar and that the primary driver for ignition delay differences between the two fuels is the variance in the activation energy especially at mean temperatures near 1000 K (and higher). This comment is made based on both SCE ignition data shown in figure 7 and the decreasing impact of bulk temperature on liquid length [11] which show a pressure dependency of modest variance between the two fuels for either nozzle size and a modest liquid length-temperature rate of change above 1000 K. The mixing portion of the physical delay also contributes to the ignition delay period and the CVB data was taken at mean injection pressures 50 to 100% percent higher than the Cummins VTA903 data which results in approximately a 14 to 40% increase in the injection velocity. Such a change in shear layer mixing time is not quantified at this time though will lead toward shorter physical delay times especially since the CVB nozzle hole size was a little smaller [23].…”

Section: Constant Volume Bomb (Cvb) Resultsmentioning

confidence: 99%

“…Likewise, the 90% distillation temperature has a worldwide mean value of 253 °C though 5% of the samples fell in the 200 and 225 °C range. ASTM D975 allows DF-2 to have a 90% distillation temperature range of 282 to 338 °C, and thus JP-8 evaporates considerably faster than DF-2 [11][12]. The impact of this difference has never been quantified to date, but it is anticipated to have a minor impact on the heat release event if the mean cetane number of DF-2 and JP-8 are close to their mean values assuming that the mean density of DF-2 is approximately 5% higher than JP-8.…”

Section: Introductionmentioning

confidence: 99%

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On the Ignition Behavior of JP-8 in Military Relevant Diesel Engines

Schihl¹,

Hoogterp-Decker²

2011

SAE Int. J. Engines

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U.S. Army ground vehicles predominately use JP-8 as the energy source for ground vehicles based on the 'one fuel forward policy'. Though this policy was enacted almost twenty years ago, there exists little fundamental JP-8 combustion knowledge at diesel engine type boundary conditions. Nevertheless, current U.S. Army ground vehicles predominately use commercial off-the-shelf or modified commercial diesel engines as the prime mover. Unique military engines are typically utilized when commercial products do not meet the mobility and propulsion system packaging requirements of the particular ground vehicle in question. In either case, such engines have been traditionally calibrated using North American diesel fuel (DF-2) and overall engine performance degradation while operating on Jet Propellant 8 (JP-8) wasn't given much consideration since any such associated power loss due to the lower volumetric energy density was not an issue for most applications at then targeted climatic conditions. It is becoming more apparent that current and future commercial diesel engine combustion system strategies will be adversely affected by use of JP-8 in comparison to DF-2 due to combustion affecting chemical and physical property differences of 'out laying' global JP-8 samples that are problematic under largely premixed combustion strategies. One important example is ignition quality where the mean cetane index for JP-8 utilized by the U.S. Army during the last five years has been typically in the 43 to 44 range, but the variance has been relatively large depending on the particular supply source with worst case scenarios exhibiting values near 30. Similar variances have been observed with other key properties such as distillation and viscosity.To date, there has been little research performed on assessing ignition behavior differences between a mean physical and chemical property JP-8 and DF-2. The objective of this submission is to study and document JP-8 autoignition characteristics under diesel engine-like thermodynamic conditions in order to provide information that might be useful in generating JP-8 ignition models. This effort includes recent ignition data from a single cylinder diesel engine, a production multi-cylinder diesel engine, a shock tube, and a constant volume bomb.

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Section: Constant Volume Bomb (Cvb) Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the Ignition Behavior of JP-8 in Military Relevant Diesel Engines

Schihl¹,

Hoogterp-Decker²

2011

SAE Int. J. Engines

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“…A mixture of 49% n-tetradecane, 30% n-decane and 21% 1-methylnaphthalene in mass basis is used for DF2. 40 A mixture of 18% n-tetradecane and 82% n-dodecane in mass basis is used 41 for JP8.…”

Section: Resultsmentioning

confidence: 99%

Enhanced spray and evaporation model with multi-fuel mixtures for direct injection internal combustion engines

Kwak

Jung

Borgnakke

2013

International Journal of Engine Research

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A spray and evaporation model has been developed and embedded in a quasi-dimensional multi-zone direct injection internal combustion engine simulation framework. The model accounts for the behavior of the spray zone and fuel evaporation including sub-models for spray breakup, improved zone velocity estimations with transient fuel injection, spray penetration and tracking of evaporated fuel components. Each sub-model deals with multi-component fuel surrogates to simulate the real fuel effects. To enhance sensitivity of the model to the fuel components, additional thermophysical properties to the traditional spray model are incorporated. The ideal gas and the ideal solution are assumed in the model to retain computational efficiency. Finally, the model was validated against experiments and compared with other numerical methods. The ability of the new model to treat a multi-component fuel provides an improvement in the simulations of modern direct injection internal combustion engine when used with alternative fuels.

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“…A better understanding of the autoignition and combustion characteristics of alternative fuels [1][2][3] in internal combustion (IC) engines is needed, to improve engine performance, emissions, and fuel economy. Gaining this understanding via experimentation is very challenging because real fuels, such as JP-8, are composed of thousands of components for which the combustion mechanisms are not known.…”

Section: Introductionmentioning

confidence: 99%

Role of Volatility in the Development of JP-8 Surrogates for Diesel Engine Application

Zheng¹,

Lee²,

Shrestha³

et al. 2014

SAE Int. J. Fuels Lubr.

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Surrogates for JP-8 have been developed in the high temperature gas phase environment of gas turbines. In diesel engines, the fuel is introduced in the liquid phase where volatility plays a major role in the formation of the combustible mixture and autoignition reactions that occur at relatively lower temperatures. In this paper, the role of volatility on the combustion of JP-8 and five different surrogate fuels was investigated in the constant volume combustion chamber of the Ignition Quality Tester (IQT). IQT is used to determine the derived cetane number (DCN) according to ASTM D6890. The surrogate fuels were formulated such that their DCNs matched that of JP-8, but with different volatilities. Tests were conducted to investigate the effect of volatility on the autoignition and combustion characteristics of the surrogates using a detailed analysis of the rate of heat release immediately after the start of injection. In addition, the effect of volatility on the spray dynamics was investigated by Schlieren imaging in an optical accessible rapid compression machine (RCM), and the imaging data supported the conclusion made in the IQT tests. Furthermore, apparent activation energies of JP-8 and surrogate fuels were determined based on the chemical delay periods, which could be considered as a new parameter for developing surrogate fuel.

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Assessment of JP-8 and DF-2 Evaporation Rate and Cetane Number Differences on a Military Diesel Engine

Cited by 23 publications

References 29 publications

On the Ignition Behavior of JP-8 in Military Relevant Diesel Engines

On the Ignition Behavior of JP-8 in Military Relevant Diesel Engines

Enhanced spray and evaporation model with multi-fuel mixtures for direct injection internal combustion engines

Role of Volatility in the Development of JP-8 Surrogates for Diesel Engine Application

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