Aspects of Jet Fuel Oxidation

1998 ◽  
Vol 120 (3) ◽  
pp. 519-525 ◽  
Author(s):  
S. Zabarnick ◽  
S. D. Whitacre
Keyword(s):  
Oxidation Rate ◽  
Oxygen Sensor ◽  
Jet Fuel ◽  
Jet Fuels ◽  
Surface Deposition ◽  
Fuel Oxidation ◽  
Headspace Oxygen ◽  
Sensor Technique ◽  
Metal Deactivator ◽  
Alkylperoxy Radicals

A quartz crystal microbalance (QCM)/Parr bomb system with a headspace oxygen sensor is used to measure oxidation and deposition during thermal oxidative stressing of jet fuel. The advantages of the oxygen sensor technique in monitoring fuel oxidation is demonstrated. Simultaneous measurement of deposition using the QCM shows a strong correlation between oxidation and deposition in jet fuels. Studies performed over the temperature range 140 to 180°C show that surface deposition peaks at an intermediate temperature, while bulk deposition increases with temperature. In studies of jet fuel antioxidants, we find that rapid increases in oxidation rate occur upon consumption of the antioxidant. The antioxidant appears to be consumed by reaction with alkylperoxy radicals. In studies of metal deactivator (MDA) additives, we find that MDA is consumed during thermal stressing, and this consumption results in large increases in the oxidation rate of metal containing fuels. Mechanisms of MDA consumption are hypothesized.

scholarly journals Aspects of Jet Fuel Oxidation

1997 ◽  
Author(s):  
Steven Zabarnick ◽  
Shawn D. Whitacre
Keyword(s):  
Oxidation Rate ◽  
Oxygen Sensor ◽  
Jet Fuel ◽  
Jet Fuels ◽  
Surface Deposition ◽  
Fuel Oxidation ◽  
Headspace Oxygen ◽  
Sensor Technique ◽  
Metal Deactivator ◽  
Alkylperoxy Radicals

A quartz crystal microbalance (QCM)/Parr bomb system with a headspace oxygen sensor is used to measure oxidation and deposition during thermal oxidative stressing of jet fuel. The advantages of the oxygen sensor technique in monitoring fuel oxidation is demonstrated. Simultaneous measurement of deposition using the QCM shows a strong correlation between oxidation and deposition in jet fuels. Studies performed over the temperature range 140 to 180°C show that surface deposition peaks at an intermediate temperature, while bulk deposition increases with temperature, in studies of jet fuel antioxidants, we find that rapid increases in oxidation rate occur upon consumption of the antioxidant. The antioxidant appears to be consumed by reaction with alkylperoxy radicals. In studies of metal deactivator (MDA) additives, we find that MDA is consumed during thermal stressing, and this consumption results in large increases in the oxidation rate of metal containing fuels. Mechanisms of MDA consumption are hypothesized.

scholarly journals The Effects of Different Sulfur Compounds on Jet Fuel Oxidation and Deposition

1995 ◽  
Author(s):  
Robert E. Kauffman
Keyword(s):  
Jet Fuel ◽  
Sulfur Compounds ◽  
Oxidation Products ◽  
Jet Fuels ◽  
Acid Base ◽  
Deposition Mechanism ◽  
Fuel Oxidation ◽  
Basic Nitrogen ◽  
Elemental Analyses ◽  
Steel Surfaces

This paper presents research which supports a proposed fuel oxidation/deposition mechanism involving acid: base reactions between “oxidizable” sulfur compounds, “basic” nitrogen compounds, and oxygen containing polymers. The reported research presents experiments which study the effects of different sulfur compounds on the high temperature (160–220°C) oxidation products and deposition tendencies of jet fuel. Surface analyses incorporating elemental analyses and depth profiles of deposits formed on steel surfaces were performed to identify the species involved in the initial stages of deposition by jet fuels. Experiments to study the effects of acid neutralizing compounds on the deposition tendencies of jet fuels are also presented.

The Effects of Different Sulfur Compounds on Jet Fuel Oxidation and Deposition

1997 ◽  
Vol 119 (2) ◽  
pp. 322-327 ◽  
Author(s):  
R. E. Kauffman
Keyword(s):  
Jet Fuel ◽  
Sulfur Compounds ◽  
Oxidation Products ◽  
Jet Fuels ◽  
Deposition Mechanism ◽  
Fuel Oxidation ◽  
Depth Profiles ◽  
Basic Nitrogen ◽  
Elemental Analyses ◽  
Steel Surfaces

This paper presents research that supports a proposed fuel oxidation/deposition mechanism involving acid:base reactions between “oxidizable” sulfur compounds, “basic” nitrogen compounds, and oxygen-containing polymers. The reported research presents experiments that study the effects of different sulfur compounds on the high-temperature (160–220°C) oxidation products and deposition tendencies of jet fuel. Surface analyses incorporating elemental analyses and depth profiles of deposits formed on steel surfaces were performed to identify the species involved in the initial stages of deposition by jet fuels. Experiments to study the effects of acid neutralizing compounds on the deposition tendencies of jet fuels are also presented.

One-Dimensional Simulations of Jet Fuel Thermal-Oxidative Degradation and Deposit Formation Within Cylindrical Passages

2000 ◽  
Vol 122 (4) ◽  
pp. 229-238 ◽  
Author(s):  
J. S. Ervin ◽  
S. Zabarnick ◽  
T. F. Williams
Keyword(s):  
Fluid Dynamics ◽  
Jet Fuel ◽  
Thermal Oxidative Degradation ◽  
Fuel System ◽  
Flow Conditions ◽  
Surface Deposition ◽  
Deposition Rates ◽  
Fuel Oxidation ◽  
One Dimensional ◽  
Dissolved O2

Flowing aviation fuel is used as a coolant in military aircraft. Dissolved O2 reacts with the heated fuel to form undesirable surface deposits which disrupt the normal flow. For purposes of aircraft design, it is important to understand and predict jet fuel oxidation and the resulting surface deposition. Detailed multi-dimensional numerical simulations are useful in understanding interactions between the fluid dynamics and fuel chemistry. Unfortunately, the detailed simulation of an entire fuel system is impractical. One-dimensional and lumped parameter models of fluid dynamics and chemistry can provide the simultaneous simulation of all components which comprise a complex fuel system. In this work, a simplified one-dimensional model of jet fuel oxidation and surface deposition within cylindrical passages is developed. Both global and pseudo-detailed chemical kinetic mechanisms are used to model fuel oxidation, while a global chemistry model alone is used to model surface deposition. Dissolved O2 concentration profiles and surface deposition rates are calculated for nearly isothermal and nonisothermal flow conditions. Flowing experiments are performed using straight-run jet fuels, and the predicted dissolved O2 concentrations and surface deposition rates agree reasonably well with measurements over a wide range of temperature and flow conditions. The new model is computationally inexpensive and represents a practical alternative to detailed multi-dimensional calculations of the flow in cylindrical passages. [S0195-0738(00)01204-8]

Effects of Flow Passage Expansion or Contraction on Jet-Fuel Surface Deposition

2012 ◽  
Vol 28 (4) ◽  
pp. 694-706 ◽  
Author(s):  
Hua Jiang ◽  
Jamie Ervin ◽  
Steven Zabarnick ◽  
Zachary West
Keyword(s):  
Jet Fuel ◽  
Surface Deposition ◽  
Flow Passage ◽  
Fuel Surface

Ignition Characteristics of a Fischer-Tropsch Synthetic Jet Fuel

2008 ◽  
Author(s):  
P. Gokulakrishnan ◽  
M. S. Klassen ◽  
R. J. Roby
Keyword(s):  
Kinetic Model ◽  
Ignition Delay ◽  
Flow Reactor ◽  
Kinetic Mechanism ◽  
Jet Fuel ◽  
Synthetic Jet ◽  
Jet Fuels ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Ignition Characteristics

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.

Characterization of Fuel Composition and Altitude Impact on Gaseous and Particle Emissions From a Turbojet Engine

2017 ◽  
Author(s):  
Tak W. Chan ◽  
Pervez Canteenwalla ◽  
Wajid A. Chishty
Keyword(s):  
Co2 Emissions ◽  
Nox Reduction ◽  
Cetane Number ◽  
Combustion Efficiency ◽  
Jet Fuel ◽  
Jet Fuels ◽  
Fuel Composition ◽  
Worst Case ◽  
Particle Emissions ◽  
Turbojet Engine

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.

scholarly journals Simple Analytical Techniques to Determine the Disperant Capacity and Metal Deactivator Additive Concentration of JP-8+100 and Other Jet Fuels

1997 ◽  
Author(s):  
Robert E. Kauffman
Keyword(s):  
Field Tests ◽  
Analytical Techniques ◽  
Maintenance Cost ◽  
Jet Fuels ◽  
Additive Concentration ◽  
Additive Package ◽  
Us Air Force ◽  
The Us ◽  
Metal Deactivator ◽  
Thermal Stability Of

The US Air Force is developing an additive package to improve the thermal stability of JP-8 fuels by 100°F. Consequently, JP-8 fuels containing the developed additive package are referred to as JP-8+100 fuels. Field tests of the JP-8+100 fuels have shown that the additive package greatly reduces maintenance cost and labor in comparison to JP-8 fuels by minimizing fuel system malfunctions caused by fuel deposition, e.g., fuel control changeouts, combustor damage, etc. The developed additive package contains three components: antioxidant, dispersant/detergent, and metal deactivator. This paper presents simple analytical techniques that can be performed on-site or in the laboratory to determine the dispersant capacity and metal deactivator additive concentrations of JP-8+100 fuels. Since several dispersant/detergent candidates are being evaluated for use in the JP-8+100 additive package, the analytical techniques were developed to measure the dispersant capacity of the additive package instead of the concentration of one particular dispersant/detergent. The dispersant capacity test measures the ability of a fuel sample to suspend a metal oxide powder/water/isopropanol mixture. The dispersant capacity test can be used to identify jet fuels which contain the JP-8+100 additive package and to rate the dispersant capacity of a JP-8+100 fuel. In contrast to the dispersant capacity test, the metal deactivator additive (MDA) tests were designed to determine the concentration of N,N′-disalicylidene-1,2-propanediamine which is the primary MDA used in jet fuels. The MDA tests use fuel soluble compounds or aqueous extraction to chemically react MDA to form colored species. The color of the MDA compound is measured visually for qualitative determinations or spectrometrically for quantitative determinations. Combination of the different MDA tests allows MDA to be detected down to 0.1 ppm regardless of fuel color, age, or type.

scholarly journals Production Cost and Carbon Footprint of Biomass-Derived Dimethylcyclooctane as a High Performance Jet Fuel Blendstock

2021 ◽  
Author(s):  
Nawa Raj Baral ◽  
Minliang Yang ◽  
Benjamin G. Harvey ◽  
Blake A Simmons ◽  
Aindrila Mukhopadhyay ◽  
...  
Keyword(s):  
Production Cost ◽  
High Performance ◽  
Jet Fuel ◽  
Liquid Fuels ◽  
Jet Fuels ◽  
Selling Price ◽  
Low Carbon ◽  
Hydrogenation Catalysts ◽  
Raney Nickel Catalyst ◽  
Biomass Sorghum

<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>

Impact of deep hydrogenation on jet fuel oxidation and deposition

Fuel ◽  
2020 ◽  
Vol 264 ◽  
pp. 116843 ◽  
Author(s):  
Tinghao Jia ◽  
Si Gong ◽  
Lun Pan ◽  
Chuan Deng ◽  
Ji-Jun Zou ◽  
...  
Keyword(s):  
Jet Fuel ◽  
Fuel Oxidation
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