Year 3 of the National Jet Fuels Combustion Program: Practical and Scientific Impacts of Alternative Jet Fuel Research

Author(s):  
Joshua S. Heyne ◽  
Erin Peiffer ◽  
Meredith B. Colket ◽  
Aniel Jardines ◽  
Cecilia Shaw ◽  
...  
2016 ◽  
Vol 10 (4) ◽  
pp. 485-492 ◽  
Author(s):  
Anna Iakovlieva ◽  
◽  
Oksana Vovk ◽  
Sergii Boichenko ◽  
Kazimierz Lejda ◽  
...  

The work is devoted to the development of alternative jet fuel blended with rapeseed oil-derived biocomponents and study of their physical-chemical properties. The modification of conventional jet fuel by rapeseed oil esters was chosen for this work among the variety of technologies for alternative jet fuels development. The main characteristics of conventional jet fuel and three kinds of biocomponents were determined and compared to the standards requirements to jet fuel of Jet A-1 grade. The most important or identifying physical-chemical properties of jet fuels were determined for the scope of this study. Among them are: density, viscosity, fractional composition, freezing point and net heat of combustion. The influence of rapeseed oil-derived biocomponents on the mentioned above characteristics of blended jet fuels was studied and explained.


Author(s):  
Kumaran Kannaiyan ◽  
Reza Sadr

Abstract In recent years, Gas-to-Liquid (GTL) jet fuel is considered as an alternative jet fuel because of its cleaner combustion characteristics. The chemical and physical properties of GTL fuels are different from those of the conventional jet fuels. The objective of the present work is to investigate the effect of ambient conditions and fuel volatilization characteristics on the macroscopic spray features. To this end, the macroscopic spray performance is visualized using the shadowgraph imaging technique at elevated ambient conditions. The near nozzle spray parameters like spray cone angle, sheet breakup length, and the sheet velocity, are determined from the shadowgraph images using an in-house program. The effect of ambient conditions on the near nozzle spray characteristics for conventional fuels has been reported in the literature. However, these effects have not been reported in detail for the alternative, GTL jet fuels. The results show that the ambient gas pressure has a significant effect on the spray performance when compared to that of the ambient gas temperature. At atmospheric conditions, the spray performance of GTL fuel is comparable to those of Jet A-1 fuel. However, with the increase in ambient conditions, the difference in spray performance of GTL and Jet A-1 is significant.


Author(s):  
P. Gokulakrishnan ◽  
M. S. Klassen ◽  
R. J. Roby

Ignition delay times of a “real” synthetic jet fuel (S8) were measured using an atmospheric pressure flow reactor facility. Experiments were performed between 900 K and 1200 K at equivalence ratios from 0.5 to 1.5. Ignition delay time measurements were also performed with JP8 fuel for comparison. Liquid fuel was prevaporized to gaseous form in a preheated nitrogen environment before mixing with air in the premixing section, located at the entrance to the test section of the flow reactor. The experimental data show shorter ignition delay times for S8 fuel than for JP8 due to the absence of aromatic components in S8 fuel. However, the ignition delay time measurements indicate higher overall activation energy for S8 fuel than for JP8. A detailed surrogate kinetic model for S8 was developed by validating against the ignition delay times obtained in the present work. The chemical composition of S8 used in the experiments consisted of 99.7 vol% paraffins of which approximately 80 vol% was iso-paraffins and 20% n-paraffins. The detailed kinetic mechanism developed in the current work included n-decane and iso-octane as the surrogate components to model ignition characteristics of synthetic jet fuels. The detailed surrogate kinetic model has approximately 700 species and 2000 reactions. This kinetic mechanism represents a five-component surrogate mixture to model generic kerosene-type jets fuels, namely, n-decane (for n-paraffins), iso-octane (for iso-paraffins), n-propylcyclohexane (for naphthenes), n-propylbenzene (for aromatics) and decene (for olefins). The sensitivity of iso-paraffins on jet fuel ignition delay times was investigated using the detailed kinetic model. The amount of iso-paraffins present in the jet fuel has little effect on the ignition delay times in the high temperature oxidation regime. However, the presence of iso-paraffins in synthetic jet fuels can increase the ignition delay times by two orders of magnitude in the negative temperature (NTC) region between 700 K and 900 K, typical gas turbine conditions. This feature can have a favorable impact on preventing flashback caused by the premature autoignition of liquid fuels in lean premixed prevaporized (LPP) combustion systems.


Author(s):  
Tak W. Chan ◽  
Pervez Canteenwalla ◽  
Wajid A. Chishty

The effects of altitude and fuel composition on gaseous and particle emissions from a turbojet engine were investigated as part of the National Jet Fuels Combustion Program (NJFCP) effort. Two conventional petroleum based jet fuels (a “nominal” and a “worst-case” jet fuel) and two test fuels with unique characteristics were selected for this study. The “worst-case” conventional jet fuel with high flash point and viscosity resulted in reduced combustion efficiency supported by the reduced CO2 emissions and corresponding increased CO and THC emissions. In addition, increased particle number (PN), particle mass (PM), and black carbon (BC) emissions were observed. Operating the engine on a bimodal fuel, composed of heavily branched C12 and C16 iso-paraffinic hydrocarbons with an extremely low cetane number did not significantly impact the engine performance or gaseous emissions but significantly reduced PN, PM, and BC emissions when compared to other fuels. The higher aromatic content and lower hydrogen content in the C-5 fuel were observed to increase PN, PM, and BC emissions. It is also evident that the type of aromatic hydrocarbons has a large impact on BC emissions. Reduction in combustion efficiency resulted in reduced CO2 emissions and increased CO and THC emissions from this engine with increasing altitudes. PN emissions were moderately influenced by altitude but PM and BC emissions were significantly reduced with increasing altitude. The reduced BC emissions with increasing altitude could be a result of reduced combustion temperature which lowered the rate of pyrolysis for BC formation, which is supported by the NOx reduction trend.


2021 ◽  
Author(s):  
Nawa Raj Baral ◽  
Minliang Yang ◽  
Benjamin G. Harvey ◽  
Blake A Simmons ◽  
Aindrila Mukhopadhyay ◽  
...  

<div> <div> <div> <p>Near-term decarbonization of aviation requires energy-dense, renewable liquid fuels. Biomass- derived 1,4-dimethylcyclooctane (DMCO), a cyclic alkane with a volumetric net heat of combustion up to 9.2% higher than Jet-A, has the potential to serve as a low-carbon, high- performance jet fuel blendstock that may enable paraffinic bio-jet fuels to operate without aromatic compounds. DMCO can be produced from bio-derived isoprenol (3-methyl-3-buten-1- ol) through a multi-step upgrading process. This study presents detailed process configurations for DMCO production to estimate the minimum selling price and life-cycle greenhouse gas (GHG) footprint considering three different hydrogenation catalysts and two bioconversion pathways. The platinum-based catalyst offers the lowest production cost and GHG footprint of $9.0/L-Jet-Aeq and 61.4 gCO2e/MJ, given the current state of technology. However, when the conversion process is optimized, hydrogenation with a Raney nickel catalyst is preferable, resulting in a $1.5/L-Jet-Aeq cost and 18.3 gCO2e/MJ GHG footprint if biomass sorghum is the feedstock. This price point requires dramatic improvements, including 28 metric-ton/ha sorghum yield and 95-98% of the theoretical maximum conversion of biomass-to-sugars, sugars-to-isoprenol, isoprenol-to-isoprene, and isoprene-to-DMCO. Because increased gravimetric energy density of jet fuels translates to reduced aircraft weight, DMCO also has the potential to improve aircraft efficiency, particularly on long-haul flights. </p> </div> </div> </div>


2019 ◽  
Author(s):  
Giacomo Flora ◽  
Shane T. Kosir ◽  
Lily Behnke ◽  
Robert D. Stachler ◽  
Joshua S. Heyne ◽  
...  

Author(s):  
Philippe Dagaut ◽  
Pascal Diévart

Research on the production and combustion of synthetic jet fuels has recently gained importance because of their potential for addressing security of supply and sustainable air transportation challenges. The combustion of a 100% naphtenic cut that fits with typical chemical composition of products coming from biomass or coal liquefaction (C12.64H23.64; M=175.32 g.mol−1; H/C=1.87; DCN=39; density=863.1 g.L−1) and a 50% vol. mixture with Gas to Liquid from Shell (mixture: C11.54H23.35; M=161.83 g.mol−1; H/C=2.02; DCN=46; density=800.3 g.L−1) were studied in a jetstirred reactor under the same conditions (temperature, 550–1150 K; pressure, 10 bar; equivalence ratio, 0.5, 1, and 2; initial fuel concentration, 1000 ppm). Surrogate model-fuels were designed based on fuel composition and properties for simulating the kinetics of oxidation of these fuels. We used new model-fuels consisting of mixtures of n-decane, decalin, tetralin, 2-methylheptane, 3-methylheptane, n-propyl cyclohexane, and n-propylbenzene. The detailed chemical kinetic reaction mechanism proposed was validated using the entire experimental database obtained in the present work and for the oxidation of pure GtL, we used previous results. Kinetic computations involving reaction paths analyses and sensitivity analyses were used to interpret the results.


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