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American Institute of Aeronautics and Astronautics
1
Reference Jet Fuels for Combustion Testing
Tim Edwards1
Air Force Research Laboratory, Dayton, OH, 45433
This paper provides a summary of the composition and properties of reference jet fuels
used in the National Jet Fuel Combustion Program. Additional data is provided for common
alternative jet fuels. Two classes of fuels are discussed: (1) “Category A” fuels which represent
the range of properties seen in current petroleum-derived jet fuels, and (2) “Category C” test
fuels which have certain properties well outside of experience. Combustion test and modeling
results for a number of these fuels are becoming available in the literature, with this paper
serving as a detailed reference on the properties of these reference fuels.
Nomenclature
AFPET - Air Force Petroleum Agency
AFRL - Air Force Research Laboratory
ASTM - American Society for Testing and Materials (ASTM International)
ATJ - Alcohol-to-jet (alternative jet fuel)
Cp = Heat capacity (of fuel)
Cx = Hydrocarbon fuel component with x atoms of carbon per molecule
CRATCAF Combustion Rules and Tools for the Characterization of Alternative Fuels (program)
CRC - Coordinating Research Council
CTL = Coal-To-Liquid (Fischer-Tropsch)
DLA - Defense Logistics Agency
F-T = Fischer-Tropsch fuel processing
FAA - Federal Aviation Administration (United States)
FAME - Fatty Acid Methyl Ester (biodiesel)
GTL = (natural) Gas-To-Liquid (Fischer-Tropsch)
Hcontent = Hydrogen content in the fuel by mass
HEFA - Hydroprocessed Esters and Fatty Acids (alternative jet fuel)
HOC = Heat of Combustion (MJ/kg) (net)
HRJ = Hydrotreated Renewable Jet (fuel) – predecessor name for HEFA
IPK = Iso-Paraffinic Kerosene (Sasol)
MURI = Multidisciplinary University Research Initiative
MW = Average Molecular Weight of a complex fuel
NJFCP - National Jet Fuel Combustion Program
OEM - Original Equipment Manufacturer
POSF - fuel designation, not an acronym
PQIS - Petroleum Quality Information System (DLA database)
P = Pressure (bar or atm)
SPK - Synthetic Paraffinic Kerosene (alternative jet fuel)
SwRI - Southwest Research Institute, San Antonio, Texas
T = Temperature (K)
UDRI - University of Dayton Research Institute
WPAFB - Wright-Patterson Air Force Base
1 Principal Chemical Engineer, Aerospace Systems Directorate, AFRL/RQ, WPAFB, OH 45433; AIAA Associate
Fellow
American Institute of Aeronautics and Astronautics
2
I. Introduction
The ongoing effort to evaluate the performance of alternative aviation fuels has renewed the interest in the effect
of jet fuel composition changes on gas turbine operability and performance. Aviation’s current focus is on “drop-in
fuels”, which are composed solely of hydrocarbons, but produced from alternative sources/feedstocks such as biomass.
Aviation is not considering oxygenated jet fuel components such as alcohols or fatty acid methyl esters (FAMEs) due
to their negative impacts on performance and handling. A previous paper [1] described an ongoing program to
streamline the combustion evaluation of alternative aviation fuels under the umbrella of the National Jet Fuel
Combustion Program (NJFCP) – this paper is a significant expansion of the fuels section of that paper. Based on
requirements developed in an earlier program (Combustion “Rules and Tools” or CRATCAF [2]), the NJFCP program
has developed/acquired a suite of conventional jet fuels and “test fuels” to characterize the fuel sensitivity/response
of combustion devices. These fuels were developed to span the range of jet fuel composition and properties that could
be encountered with conventional and alternative jet fuels. The fuels are being acquired and distributed by the Air
Force Research Laboratory’s Fuels Branch in Dayton Ohio. AFRL has also distributed “typical” and “average” fuels
to the research community in the past, and some of these fuels will be included in this paper. This paper will also
include the properties of common alternative jet fuels distributed by AFRL. The test fuels and alternative fuels do not
meet the all the jet fuel specifications (such as density); the test fuels were designed to explore a particular aspect of
the fuel property/composition space such as boiling range or viscosity, while many of the alternative fuels have been
approved in fuel specifications such as ASTM D7566 for use as 50% blends (or less) with conventional fuels. The
“Rules and Tools” program had defined several categories of fuels to be used to characterize fuel effects on
combustion, some of which are being carried forward by NJFCP:
Category A - conventional fuels derived from petroleum, encompassing the range of properties typically
encountered (viscosity, flash point, aromatic content, etc.)
Category B – alternative jet fuels found to have unacceptable combustion properties (not used in NJFCP)
Category C – test fuels designed to explore the “edges” of the jet fuel composition-property space, such as
fuels being at the viscosity limit of the specification or fuels whose composition is outside of typical
experience (such as cycloparaffin content)
This paper includes data for Category A and Category C fuels as utilized by the NJFCP, as well as data for common
alternative fuels. The data presented includes:
Specification properties important to combustion: flash point, viscosity, aromatic content, hydrogen content,
ASTM D86 distillation, smoke point, measured heat of combustion, measured cetane number
Composition: GCxGC distribution of major hydrocarbon classes across carbon number, average molecular weight
“Fit-for-purpose properties” - density vs T, viscosity vs T, Cp vs T, surface tension vs T, vapor pressure vs T
ASTM Calculation methods for properties such as heat of combustion (ASTM D3338), hydrogen content (ASTM
D3343), and cetane index (ASTM D4737) are typically not validated for alternative fuels or “test fuels” and thus are
not included, with this paper focusing on the actual measurements. Cetane index (calculation) has been found to be
very inaccurate for some alternative fuels. Note that oxygenate-free jet fuels allow hydrogen content to be converted
to H/C ratio directly by making the valid assumption that the non-hydrogen portion of the fuel is entirely carbon.
Also included as part of the data is the AFRL identification number, which identifies specific batches of fuel. This
ID number takes the form of POSF XXXXX, where POSF is the Fuels Branch’s organizational designation back in
1981 when the numbering began (with 001), thus it is NOT an acronym. The number are assigned roughly in order
received, with POSF 10000 assigned in late 2012.
When available, comparison data is presented from common sources, such as the Coordinating Research Council’s
(CRC) Handbook of Aviation Fuel Properties [3], the CRC World Fuel Sampling Program [4] (often termed the World
Survey), and the Defense Logistics Agency’s (DLA) Petroleum Quality Information Service (PQIS) database [5].
There is a current FAA program collating airport property data that should generate a very useful set of data available
in 2017. There are a number of petroleum industry references for calculating most physical properties of petroleum
fractions such as jet fuel, typically using commonly measured properties such as specific gravity/density and mean
boiling point from ASTM D86 [6,7,8]. Thus, while the ASTM D86 distillation does not represent a true boiling curve
for jet fuels, its use since the 1930s allows it to be correlated to a large amount of historical data. NIST has developed
an “advanced distillation” method, and has recently published data on Category A fuels [30]. NIST has also very
American Institute of Aeronautics and Astronautics
3
recently published densities of the Category A fuels as a function of pressure up to 45 MPa [31]. The densities
presented in this paper are the conventional jet fuel densities by ASTM D4052 at 1 atm. Other properties are also
measured at atmospheric pressure – a potential shortcoming for applications at high pressure such as aviation diesel
engines with high-pressure common rail fuel injectors.
The NJFCP program is also a successor to earlier DoD and NASA programs in the late 1970s (e.g., [9]), which
looked at the effect of fuel composition and property changes on 1970s-vintage combustors. These earlier programs
also focused on “broadened” jet fuel specifications that could be used to increase supply, such as increasing the jet
fuel aromatic limit above 25 vol%. In contrast, NJFCP is looking at the effects on current and future combustor
operability of various jet fuel composition changes that might be driven by modern alternative (bio) fuels.
II. Conventional/Reference Fuels – “Category A” A. Overview
The Category A jet fuels were defined by selecting important combustion-related properties and attempting to find
production fuels that would represent the range of properties of jet fuels in use today. The CRATCAF program
included a detailed literature review of prior work, from which the OEMs selected three combustion-related properties
that represented the variations seen in practice - flash point, viscosity, and aromatics content - that would be expected
to have the greatest impact on combustor behavior. Three fuels were sought: a fuel with low flash/viscosity/aromatics
(“A-1”), “average/nominal” properties (“A-2”), and high flash/viscosity/aromatics (“A-3”). Table 1 shows the OEM-
selected desired properties. Cliff Moses, retired from Southwest Research Institute, referenced the Petroleum Quality
Information System (PQIS) database from DLA to identify originating sources for these three fuels. It was desired
that 6,000 gallons (23,000 L) be obtained for the A-1 and A-3 fuels, and 22,000 gallons (83,000 L) for the “nominal”
A-2 fuel. After some time (and effort), suitable fuels were identified and obtained directly from refineries (many
refineries have no ability to load trucks). The A-2 fuel (POSF 10325) was a Jet A procured from the Shell Mobile*
refinery in June 2013. The A-1 fuel was a JP-8 fuel procured from NuStar Refining* in April 2013. The A-3 fuel
was a JP-5 fuel from Valero* procured in May 2013. As shown in Table 1, the average/nominal fuel goals were met
with A-2. The A-1 fuel goals were nearly met. The A-3 (JP-5) had a flash point lower than desired. (It was
demonstrated at AFRL that, if necessary, the flash point of this fuel could be raised to 70 °C by distilling off the lower
boiling components.) Also, the aromatic goal was not met – but the hydrogen content of this fuel is 13.4 mass% (due
to high cycloparaffin content), which is the lower limit of JP-8 specifications and is at the low end of the jet fuel
“experience base”. Previous programs (such as described in [9]) have shown that fuel soot production is controlled
by overall fuel hydrogen content or H/C ratio for hydrocarbon fuels, rather than by aromatic level. This has been
verified in engine testing where aromatic-free but decalin-rich fuels burn very similarly to fuels with 25% aromatics
and the same hydrogen content.
*Any identifications of commercial products within this paper is for information only and does not indicate
recommendation or endorsement by FAA, AFRL, or DLA.
Table 1. Pertinent Properties of Procured Category A Conventional Fuels
Fuel Flash Point, °C Viscosity, mm2s-1 (cSt)
( at -20 °C)
Aromatics, % (vol)
Desired Actual Desired Actual Desired Actual
A-1, POSF
10264
≤40 42 ≤3.4 3.5 ≤14 11.2
A-2, POSF
10325
50±3 48 4.5±0.5 4.5 17±1 17.0
A-3, POSF
10289
≥66 60 ≥6.5 6.5 ≥21 18.0
American Institute of Aeronautics and Astronautics
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B. Specification Properties
Specification properties were obtained from the Air Force Petroleum Agency laboratory at WPAFB, the University
of Dayton’s laboratories at WPAFB, and Southwest Research Institute in San Antonio TX. Not surprisingly, the fuel
properties cannot be varied independently; rather they are interdependent. For example, distilling off portions of a
fuel to change the flash point or the freeze point also affects the distillation curve (obviously) and also affects the
viscosity significantly. The heat of combustion is directly related to the fuel hydrogen content – and properties of
most (petroleum-derived) fuels in general can be correlated to the fuel density and average molecular weight/boiling
range [6]. A complete set of specification properties was obtained for the Category A fuels. A summary of key
properties of the fuels is given in Figure 1, which shows that the three fuels do indeed encompass a wide range of
properties within the jet fuel “experience base”. Tabular data is shown in Appendix A. All three fuels are relatively
wide-boiling middle distillate fuels. This characteristic is important to note since narrow-boiling fuels will be a target
of research through “Category C” “test fuels” described below. The boiling ranges of the three fuels are illustrated in
Figure 2. The D86 limits for jet fuel (ASTM D1655) and kerosene (ASTM D6399) are T10 < 205 C and final boiling
point <300 C. Note that jet fuel, kerosene, and diesel fuel are all “middle distillates” per ASTM D4175, but kerosene
and jet fuel fall into the class of “light” middle distillates. Diesel fuel (per ASTM D975) also uses D86, but has 282 C
<T90 <338 C, thus has a significantly higher boiling point at the end of the distillation curve.
The combustion-related specification properties are shown in Table 2. For reference, the effect on the boiling
range of distilling off the “light ends” of the A-3 fuel to raise its flash point to 70 C is shown in Figure 3. Raising the
flash point from 60 to 70 C also increases the viscosity at -20 C from 6.5 to 6.8 cSt and raises the freeze point from -
50 C to -49 C. This increased viscosity/freeze point is probably the explanation why the A-3 fuel in Figure 2 has had
some of the higher-boiling material removed and has a lower final boiling point than the “average” fuel – the higher-
boiling materials has been removed to meet the JP-5 freeze point and viscosity requirements. Comparison of various
specification distillation methods (ASTM D86, D7345, and D2887) for the three Category A fuels is presented in
Appendix C. D86 data can be converted to true boiling point data using equation 3.14 in Reference 6. As shown in
Appendix C, ASTM D86 does not represent the true boiling point, but has been in use since the 1930s to conveniently
characterize petroleum fractions like jet fuel. Reference 6 defines “narrow boiling [petroleum] fraction” as one whose
ASTM 10-90% distillation slope is < 0.8 C/%. As discussed later, jet fuels are typically right at this limit, so can be
defined as “narrow boiling” with caution.
As mentioned previously, the Category A fuels do encompass the wide variety of jet fuels produced (as desired).
For example, the range of densities seen in the PQIS data base is shown in Figure 4, with the A-1 and A-3 fuels well
out on the ends of the distribution as desired. Density was not a criteria for the Category A fuels, but the viscosity
and aromatic requirements also effectively drove the density of the fuels to the edges of the distribution.
Figure 1. Property Range of the Category A Conventional Fuels with Respect to Allowed Limits (Red
Established, Yellow Proposed)
American Institute of Aeronautics and Astronautics
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Table 2 – Specification Test Results for Category A Fuels (from AF Petroleum Agency unless otherwise noted)
Category A Fuels
Property Test
Method
Spec limits A-1, 10264 A-2, 10325 A-3, 10289 PQIS 2012
wt mean
Density D4052 0.775-0.84 0.780 0.803 0.827 0.8022
Flash point, C D93 >38 42 48 60 47.6
Viscosity, -20 C
(cSt)
D445 <8 3.5 4.5 6.5 4.399
Aromatics, vol% D1319 <25 11.2 17.0 18.0 17.1
Heat of
Combustion, MJ/kg
D4809 >42.8 43.2 43.1 43.0 43.2
Heat of
Combustion, MJ/kg
D4809
(SwRI[32])
43.24 43.06 42.88
H content, mass%
(meas) SwRI
D3701 >13.4 14.26 13.84 13.68 n/a
H content, mass %
(meas)
D7171 >13.4 14.4 13.7, 13.9 13.4 n/a
H content, mass % GCxGC
(UDRI)
>13.4 14.4, 14.5 14.0 13.7 n/a
H/C ratio (based on
D3701)
calculation n/a 1.99 1.91 1.89 n/a
Molecular formula GCxGC n/a C10.8H21.8 C11.4H22.1 C11.9H22.6 n/a
Derived cetane #,
SwRI
D6890 n/a 48.8 48.3 39.2 n/a
Distillation, C D86
IBP 145 159 174 160*
10% <205 164 176 192 176*
20% 171 184 199 183*
50% 189 205 218 201*
90% 234 244 244 238*
FBP <300 256 269 258 254*
Engine cetane,
SwRI
D613 n/a 48.0 47.9 40.4 n/a
Smoke pt, mm D1322 >18 28.5 23 20 22.8
Freeze pt, C D5972 >-47 (JP-8) -51 -51 -50 -51.3
*D86 data from World Survey, since PQIS is a combination of D86 and D2887
American Institute of Aeronautics and Astronautics
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140
160
180
200
220
240
260
280
0 20 40 60 80 100
A-1 10264 AFA-2 10325 AFA-3 10289 AFA-1 10264 SwRIA-2 10325 SwRIA-3 10289 SwRIWorld Survey avg
Te
mpe
ratu
re ,
°C
D86 % Distilled
Figure 2. ASTM D86 distillation for Category A fuels [SwRI]
160
180
200
220
240
260
0 20 40 60 80 100
POSF 10289 - JP-5, 60 C flashPOSF 10376 - JP-5, 70 C flash
Te
mp
era
ture
, C
D86 % Distilled
Figure 3. Change in D86 results obtained by distilling off low boiling point material to raise flash point of
A-3 fuel from 60 to 70 C.
American Institute of Aeronautics and Astronautics
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0
200
400
600
800
1000
0.775
0.78
0.785
0.79
0.795
0.8
0.805
0.81
0.815
0.82
0.825
0.83
0.835
0.84
Nu
mb
er
of
sa
mp
les
Density
POSF 10289 - 0.827
POSF 10325 - 0.803
POSF 10264 - 0.780
Figure 4. Density histogram from 2013 PQIS, with Category A fuels labeled.
C. Composition
The fuel specification properties don’t control the fuel composition directly, aside from the 25 vol% limit on total
aromatics by ASTM D1319. The indirect effect of the specification limits lead to the distribution of hydrocarbons
shown in Figure 5 (A-2/POSF 10325 “average” Jet A) and Figure 6 (hydrocarbon distribution of 55 World Survey
fuels averaged together). This data comes from GCxGC measurements by UDRI [10]. The lack of hydrocarbons
below about C8 is due to the flash point limit (>38 C). The lack of hydrocarbons above about C17 is due to the freeze
point limit (<-40 C for Jet A) and the D86 end point limit (<300 C) (and influenced by the -20 C viscosity limit).
There are some inter-relations – one can distill off the “light ends” of a fuel to raise the flash point, but that also tends
to increase the viscosity at low temperatures, as mentioned earlier. In any case, typical jet fuels (Figures 5 and 6) have
the four types/classes of hydrocarbons (olefins are low in jet fuels) distributed across many carbon numbers. The
numerical GCxGC data is included in Appendix A. One area where GCxGC is weak is differentiating the level of
branching in iso-paraffins and in side-chains on aromatics and cycloparaffins – which can affect combustion properties
such as cetane number/ignition delay. NMR is good option for this (e.g., Reference 35 for diesel), but NMR data is
not yet available for the Category A fuels. NMR is being used in the development of surrogate fuels, as discussed in
Section VI below.
Reference 30 includes composition estimates for a number of boiling fractions. The aromatics are the only
hydrocarbon class that are not distributed relatively even across the distillation range – the aromatics tend to be
concentrated in the lower-boiling fractions [30].
This data is used to define the compositional “experience base” for current/conventional fuels – important for
evaluating some of the alternative and Category C fuels, whose compositions can be noticeably different from Figure
5 and 6. These figures do confirm that the A-2 fuel is very typical in terms of composition. The composition of the
A-3 and A-1 fuels are shown in Figure 7 and 8, respectively.
American Institute of Aeronautics and Astronautics
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0
1
2
3
4
5
6
7 8 9 10 11 12 13 14 15 16 17 18
n-paraffinsiso-paraffinsaromaticscycloparaffins
Co
mp
ositio
n,
ma
ss%
Carbon number
Figure 5. Nominal Category A fuel (A-2) composition
0
1
2
3
4
5
6
7
8
7 8 9 10 11 12 13 14 15 16 17 18
n-paraffinsiso-paraffins
aromaticscycloparaffins
Co
mp
ositio
n,
ma
ss %
Carbon Number
Figure 6. Averaged composition of 55 World Survey fuels (Stoddard solvent removed)
American Institute of Aeronautics and Astronautics
9
0
2
4
6
8
10
7 8 9 10 11 12 13 14 15 16
n-paraffinsiso-paraffinsaromaticscycloparaffins
Com
positio
n,
mass%
Carbon number
Figure 7. “A-3” composition
0
2
4
6
8
10
7 8 9 10 11 12 13 14 15 16 17 18
n-paraffinsiso-paraffinsaromaticscycloparaffins
Co
mp
ositio
n,
ma
ss%
Carbon number
Figure 8. “A-1” composition
American Institute of Aeronautics and Astronautics
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D. Fit-for-Purpose Properties
The alternative fuel approval process (ASTM D4054) defines a class of properties that are not limited by the
specification, but are limited to an expected range for fuels that are acceptable (“fit-for-purpose”). A set of
combustion-relevant physical properties was obtained for the A-1, A-2, and A-3 fuels: density vs T, viscosity vs T, Cp
vs T, surface tension vs T, vapor pressure vs T. Each fit-for-purpose property is discussed separately below. Published
estimation methods are also presented for non-specification properties.
1. Density vs T
The density-vs-temperature line (Figure 9) for the A-1 and A-3 fuels are very consistent with the World Survey
minimums and maximums. The A-2 fuel density and viscosity is close to the average as reflected in the CRC Aviation
Fuel Properties Handbook [3]. Extensive density data on the Category A fuels as a function of pressure has recently
been published by NIST [31]; the lowest pressure data (0.5 MPa) is consistent with the data in Figure 9. Other high
pressure density data [32] is not entirely consistent with Reference 31. Density is a linear function of temperature in
the range shown, which is significantly below the jet fuel critical temperature (~400 C [33]). This is perhaps not
surprising since the density of various pure hydrocarbons and petroleum distillates as a function of temperature has
been shown to have a similar slope versus temperature [34]. For the temperature range shown, it would seem
reasonably accurate to extrapolate density of an unknown jet fuel based on this slope and the 15 C specification
density.
0.74
0.76
0.78
0.8
0.82
0.84
-50 0 50 100 150
DLA 24 10289DLA 23 10264DLA 22 10325
10289 spec10264 spec10325 spec
De
nsity,
g/c
m3
Temperature, C
CRC Handbook Jet A
CRC World Fuel
Survey (max)
CRC World Fuel
Survey (min)
Spec limits at 15 C
Figure 9. Density vs T data for Category A fuels
American Institute of Aeronautics and Astronautics
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2. Viscosity vs T
The kinematic viscosity-vs-temperature line (Figure 10, note strong temperature dependence) shows that the viscosity
of A-1 and A-3 is similar to the minimum and maximum from the World Survey. A-2 is very similar in viscosity
behavior to the average shown in the CRC Handbook. Given the strong temperature dependence of viscosity,
measurements at -20 C (at least) appear to be warranted for any new fuel, rather than an estimate based on ambient
temperature viscosity or based on correlations with other properties. ASTM D7566 has started using a 12 cSt limit at
-40 C for alternative fuels. The data in Figure 10 has been linearized per ASTM D341 using the correlation: log log
(viscosity + 0.7) = A – B Log T, where A and B are constants.
POSF 10264 (A-1)
POSF 10325 (A-2)
POSF 10289 (A-3)
Vis
co
sity,
cS
t
Temperature, C
20
10
1
5
3
2
-20 40 100
World Survey
minimum
World Survey
maximum
CRC Jet A
Figure 10. Viscosity vs T data for Category A fuels. (1 cSt = 0.000001 m2/s)
American Institute of Aeronautics and Astronautics
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3. Other Combustion-Related Properties (not in specification)
A number of other liquid fuel “fit-for-purpose” properties are relevant to combustion – for example, heat capacity,
surface tension, vapor pressure, and thermal conductivity. Measured values of these properties were obtained from
SwRI for the Category A fuels. Calculated values are also available using petroleum industry correlations dating back
many years [6-8]. These properties are usually calculated as a function of density/specific gravity, average boiling
point, and/or equivalent molecular weight. The mean average boiling point is typical used for property correlations,
although Riazi [6] recommends volume average boiling point for Cp. Using the data for the A-2 fuel from Table 2,
some typical calculations will be shown. Some of these correlations are very old – apologies in advance for the
engineering units! API gravity is often used in some of these correlations, where API gravity = (141.5/specific
gravity)-131.5. Specific gravity (SG) = 0.803 in Table 2 for the A-2 fuel gives API gravity = 44.7.
1) Calculate volume average boiling point: (T10+T50+T90)/3 = 208 C (406 F). Note: Riazi [6] states mean average
boiling point ~ T50 for narrow fractions like jet (T50=205 C = 400 F). Charts in Maxwell [8] pg 14-15 give
conversions from volume average boiling temperature to molal, mean average, and weight-average boiling point.
These results are molal average = 396 F, mean average = 400 F, weight average = 404 F.
2) ASTM slope = (T90-T10)/(90%-10%) = 0.85 C/% = 1.5 F/% (small slope indicates small correction in going from
volume average boiling point to molal average boiling point) (unlike crude)
3) Chart in Maxwell [8] gives a characterization factor of 11.85 (or equation Kw=Tb(in R)0.33/specific gravity).
Characterization factor is related to “paraffinicity” of fuel.
4) Fig 5-5 in Nelson [7] yields MW~ 160 (Maxwell [8] ~160); GCxGC ~ 159 (Table 2). Princeton
measurements~148.
5) Check – Riazi [6] has MW=1.6604X10-4 Tb2.1962 SG-1.0164 (Tb in K) ~ 159
6) Dryer et al have patented a direct physical measurement of equivalent molecular weight (patent 9,410,876, August
9, 2016). Comparison ongoing – should use direct measurement if available.
7) Nelson [7] chart for heat of vaporization (HOV) ~115 BTU/lb (267 kJ/kg); Check – CRC gives HOV ~ 275 kJ/kg
at 208 C (118 BTU/lb) – using 208 C as the equivalent “normal boiling point” (nbp) of the A-2 fuel. Riazi equation
for HOV (pg 327, below) ~ 258 J/g at 208 C. Roughly consistent.
∆Hvap (nbp)=37.32315 (Tb1.12086)(SG0.00977089)
Lefebvre [9] has ∆Hvap (nbp)=(360-0.39T[in K])/SG, yielding a HOV value of 307 kJ/kg – a bit higher than the other
results.
8) Riazi has equations for Tc, Pc – 737 F (392 C), 21.2 bar result. Maxwell pg 72 eq has 725F pseudocritical T, true
Tc ~ 735 F. Tc data for jet fuels is typically 700-750 F [33].
References 6-8 can now be used to generate calculated values of heat capacity and surface tension to compare to
measured data.
American Institute of Aeronautics and Astronautics
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4. Heat Capacity (Cp) vs T
Heat capacity (Cp) is not a specification property (in contrast to density and viscosity), but is a fit-for-purpose property
and was measured at SwRI for the three Category A fuels using ASTM E1269. The results are shown in Figure 11.
There is some spread in the data, similar to the spread shown in the CRC Handbook [3], which shows differences
among fuels, probably due to density differences. Cp calculations based on density and average boiling point [6-8]
for the A-2 fuel match the data well. But the density difference between A-1 and A-3 in the calculations is not as
large as in the data.
Riazi [6] recommends the use of the Kesler/Lee equation:
CpL=a(b+cT), with T in K and Cp in kJ/kg
a=1.4651+0.2302Kw where Kw is Watson K factor
b=0.306469-0.16734 SG
c=0.001467-0.000551 SG
This equation leads to Cp at 15 C/60 F of 2.06 kJ/kg (A-1), 1.96 (A-2), and 1.94 (A-3). Maxwell [8] has a chart which
yields Cp=1.99 kJ/kg-K for A-2 (and 2.15 for A-1, 1.92 for A-3) at 15 C. Lefebvre [9] includes an equation
Cp=(0.76+0,00335T)/SG0.5, which yields a Cp for A-2 of 1.92 kJ/kg-K at 15 C, pretty consistent with Kesler/Lee
equation. Thus, Maxwell’s charts show a (calculated) spread in Cp across the Category A fuels similar to the SwRI
data, while the Kesler/Lee equation predicts significantly less difference. The CRC Handbook yields a Cp for typical
jet fuels of 1.92 kJ/kg-K at 15 C. The World Survey has Cp data, but as is discussed in an Appendix in that report [3],
there are some issues with the data. Thus, the magnitude of the heat capacity is fairly consistent among the various
sources, so the use of the Cp data for A-2 for a typical jet fuel seems valid. Note that the data for jet fuels presented
in Reference 39 is non-linear with temperature and is inconsistent with the current data.
1.8
2
2.2
2.4
2.6
2.8
-50 0 50 100 150 200 250
POSF 10264, A-1 (light JP-8)POSF 10325, A-2 (avg Jet A)POSF 10289, A-3 (JP-5)CRC JP-5
CRC Jet A/A-1/JP-8CRC JPTS
Calculated [6]
He
at C
apa
city (
Cp
), k
J/k
g-K
Temperature, C
Figure 11. Heat Capacity vs T data for Category A fuels (1 kJ/kg-K = 0.239 BTU/lb-F)
American Institute of Aeronautics and Astronautics
14
The heat capacity can also be calculated from enthalpy data since Cp is the slope of enthalpy-vs-temperature at a
given temperature. There is some enthalpy data in the literature that can be used to estimate Cp [37]. “The kerosine”
in Reference 37 is very similar to the A-2 fuel, as shown in Figure 12 where the D86 data is compared. The enthalpy
from Reference 37 is shown in Figure 13 for two pressures. The heat capacity at 100 C can be estimated by the
enthalpy change from 24 C to 200 C, divided by the temperature rise. The result is 2.38 kJ/kg-K – very consistent
with Figure 11. Obviously, as the temperature rises above 200 C, fuel vaporization complicates the picture.
Incidentally, Lenoir and Hipkin in Reference 37 use the measured enthalpy data for the kerosene to estimate the critical
condition for this fuel – their tabulated Tc~739 F (393 C) and Pc~361 psia (24.6 atm) are very consistent with the Tc
values calculated above from equations in Riazi [6]. Reference 37 has enthalpy data at a number of pressures – this
data could represent an average jet fuel, given its resemblance to the A-2 fuel. From Figure 13, the heat of vaporization
can be estimated as the enthalpy difference between the fuel initially vaporizing (at ~ 225 C) and completing
vaporization (at above 250 C), which yields a value of approximately 300 kJ/kg – roughly consistent with the results
presented in section 3 above. Lefebvre [9] shows an enthalpy curve for Jet A that is more detailed than Figure 13, but
yields a heat of vaporization of similar magnitude.
140
160
180
200
220
240
260
280
0 20 40 60 80 100
A-2 (POSF 10325)Kerosine [37]
Te
mp
era
ture
, C
D86 % distilled
Figure 12. “Kerosine” D86 data from Reference 37
American Institute of Aeronautics and Astronautics
15
0
200
400
600
800
1000
0 50 100 150 200 250 300 350
95 atm (1400 psia)
2 atm (30 psia)
En
tha
lpy k
J/k
g
Temperature, C
Ref 37
Figure 13. Enthalpy data for “kerosine” from Reference 37.
American Institute of Aeronautics and Astronautics
16
5. Surface tension vs T
Similarly to Cp, surface tension (Figure 14) is also not a specification property. In this case, however, the current data
from SwRI using ASTM D1331A (du Noüy ring) does not match well with the CRC Handbook (lower than data) or
with the calculation (higher than data) – although the trends are the same, again the trends are probably due to density
differences. There is surface tension data in the World Survey (higher than SwRI data) – to get a feel for the magnitude
of the density effect, the World Survey data and the current data for A-2 at 22 C is plotted as a function of density in
Figure 15. In this case, the measured data is below the World Survey and the calculations are above, but the trend
with density is correct. Given the disparity of the literature data and the small span of surface tensions covered by the
three Category A fuels, it would seem prudent not to try and draw any conclusion about surface tension effect from
the use of the various Category A fuels.
For the calculations, Riazi [6] (pg 359) has a surface tension equation as a function of reduced temperature (Tr = T/Tc)
and Kw (Watson K factor).
Again, this equation yields trends that agree with the data, but are as far above the data as the CRC results are below
the data. Lefebvre [9] shows a graph of surface tension versus T that is consistent with the CRC Handbook data.
18
20
22
24
26
28
30
32
-40 -20 0 20 40 60
A-1 10264
10264 calcA-2 10325
10325 calc
A-3 1028910289 calc
CRC JPTSCRC Jet A/Jet A-1/JP-8CRC JP-5
Su
rfa
ce
te
nsio
n,
dyne
/cm
Temperature, C
Figure 14. Surface tension vs T data for Category A fuels.
American Institute of Aeronautics and Astronautics
17
23
24
25
26
27
28
29
0.77 0.78 0.79 0.8 0.81 0.82 0.83
22 CSwRI measurements A-2Calculations [6]World Survey all fuels
Su
rfa
ce
te
nsio
n,
dyn
e/c
m
Density, g/cm3
Figure 15. Surface tension vs density data (22 C) for various fuels.
American Institute of Aeronautics and Astronautics
18
6. Vapor Pressure vs T
Vapor pressure is not a specification property. Vapor pressure is not independent of the other properties discussed –
it is likely that one could calculate the vapor pressure from the D86 and/or flash point. For example, the CRC
Handbook shows separate vapor pressure curves for JP-8/JetA/Jet A-1 (flash >38 C) and JP-5 (flash > 60 C). The
vapor pressures of the three Category A fuels was measured at SwRI yielding the results shown in Figure 16. And,
yes, the data comes as vapor pressure in psia versus temperature in C, so those mixed units are plotted directly. The
vapor pressures track with D86 and flash point, as expected.
0
1
2
3
4
5
0 50 100 150
10264 JP-8
10325 Jet A
10289 JP-5, psia
CRC JP-8
CRC JP-5
Va
po
r p
ressure
, p
sia
Temperature, C
Range in HEFA
Research Report
Figure 16. Vapor pressure vs T data for Category A fuels
American Institute of Aeronautics and Astronautics
19
7. Thermal conductivity vs T
Thermal conductivity data was not obtained for the Category A fuels. Thermal conductivity of liquid jet fuel is not a
specification property, and is presented in the CRC Handbook as a single line for all jet fuels (but a line that has moved
over the years – the line from the 2004 Handbook best matches the data collected in the 1980s and 1990s). It has not
been typically measured for alternative fuels due to its expected small variation with fuel composition. Riazi [6]
presents an equation for thermal conductivity that basically “splits the difference” between the two CRC lines (Figure
17) when the values for the A-2 fuel are plugged into the equation.
Where Tb and T are in K and k (thermal conductivity) is in W/m-K. Lefebvre [9] includes a simpler equation:
k=(0.134-0.000063)/SG, which yields a thermal conductivity of 0.143 for A-2 at 15 C, well above any of the data in
Figure 17.
In the absence of other data, approximating the thermal conductivity of a jet fuel with the data from the CRC 2004 (or
later) handbook is probably the best option.
0.1
0.105
0.11
0.115
0.12
0.125
0.13
-20 0 20 40 60 80 100 120
CRC jet 2004CRC jet 1983Riazi equation for A-2
Th
erm
al co
nductivity,
W/m
-K
Temperature, C
Figure 17. Thermal conductivity as a function of temperature
American Institute of Aeronautics and Astronautics
20
8. Heat of formation
For some computer calculations, the heat of formation of various fuels is needed to calculate flame properties. As
described in Reference 38, the heat of formation can be (back)calculated from the measured hydrogen content and
measured heat of combustion.
CaHb + (a+ (b/4)) O2 a CO2 + (b/2) H2O
a(ΔHf CO2) + (b/2)(ΔHf H2O (gas)) - (ΔHf fuel) – (a+(b/4))(ΔHf O2) = Heat of combustion, in (typically) kcal/mole fuel, ΔHf
where the only unknown in the second equation is the heat of formation of the fuel (since b/a=H/C and the heat of
formation of water and CO2 are known). In this calculation below, the fuel H/C ratio is used to artificially define the
fuel as (e.g.) CH1.9818. This abstraction is used to initially (mis)define a mole of fuel to end up with the heat of
formation in cal/g (as is typical in some calculations). Since a “mole” of fuel, or the fuel equivalent molecular
weight, is an abstraction – typically heat of formation is reported in cal/g. However, an equivalent molecular weight
by GCxGC or other means can be used to get heat of formation in terms of kcal/mol that is more realistic than
defining the fuel as CH1.9818. Such a calculation is performed in Table 3 below. Within the accuracies of the
measured H content and heat of combustion, it appears the heat of formation of the three Category A fuels is
essentially the same.
Table 3. Heat of formation calculations
1 calorie/gram = 4.184 Joules/gram = 1.8 BTU/lb
Fuel wt% H
(meas)
SwRI
D3701
H/C molar
(calc from H
content)
Mass heat of
comb, MJ/kg
(SwRI, meas
D4809)
Mass heat
of comb,
kcal/g
Heat of
formation
(calc), cal/g
MW,
GCxGC
Heat of
formation,
kcal/mol
A-1 10264 14.260 1.9818 43.24 -10335 -467.7 152 -71.1
A-2 10325 13.840 1.9141 43.06 -10292 -423.2 159 -67.3
A-3 10289 13.680 1.8885 42.88 -10249 -432.9 166 -71.9
American Institute of Aeronautics and Astronautics
21
III. Test Fuels – “Category C” A. Overview of Category C Fuels [1]
The main objective of the Category C “test fuels” was to identify hydrocarbon blends that had “unusual” (outside
of experience) properties, such as narrowly distributed aromatics at the “front end” of the boiling range or high
viscosities. The CRATCAF Phase IIa report [2] had a list of potential blending components and several blended
“fuels” listed for testing in later phases. For the NJFCP, in consultation with the OEMs, six “test fuels” of interest
were selected based on properties and availability; components were acquired in “neat” form as necessary and
blending was performed at AFRL. It was decided that these test fuels were to be tested in their neat form without
blending with petroleum jet fuels to increase the likelihood of observing differences. Thus some of the Category C
fuels do not meet all the jet fuel specifications (like density), so they are best called “test fuels” rather than jet fuels.
Six Category C test fuels were chosen initially for study in Year 1. One of them (C-6, a high-cycloparaffin test
fuel) has not been obtained in sufficient quantities for testing and could not be included in this paper. The
characteristics of the remaining five fuels are compared in Table 4. A seventh Category C test fuel considered was
the high flash point A-3 fuel, with the “front end” of the fuel distilled off to raise the flash point to 70 °C, as described
in the prior section. This test fuel is available for testing in subsequent years if there is interest in a higher-flash-point
fuel. In the 2015 mid-year meeting of the NJFCP team, results for tests of the Category C test fuels were reviewed
and it was decided to focus on the C-1 and C-5 test fuels in the near-term, since the various tests seemed to be the
most sensitive to those fuels, and each represented extremes in chemical and physical properties. Combustion test
results for the various Category C fuels will be reported separately (e.g., [28,29]).
Table 4. Category C Fuel Types
NJFCP Test Fuels
NJFCP Fuel ID C-1 C-2 C-3 C-4 C-5
POSF numbers 11498,
12368,
12384
11813,
12223
12341,
12363
12344, 12489 12345,
12713,
12789, 12816
Composition Gevo ATJ;
C12/C16
highly-
branched
iso-paraffins
84% C14
iso-
paraffins;
16% 1,3,5
trimethyl
benzene
from Swift*
64% A-3;
36% Amyris
farnesane
(C15 iso-
paraffin)
60% Sasol*
IPK (C10-C13
highly
branched iso-
paraffins)/40%
C-1
74% C10 iso-
paraffins,
26% 1,3,5
trimethyl
benzene
Notable
characteristics
Very low
cetane,
unusual
boiling
range
On-spec
fuel,
extremely
chemically-
asymmetric
boiling
range
High
viscosity
fuel, at -20 C
viscosity
limit for jet
fuel
Low cetane,
conventional,
wide-boiling
range
Very flat
boiling range
(fuel boils at
one
temperature)
*Any identifications of commercial products within this paper is for information only and does not indicate
recommendation or endorsement by FAA, AFRL, or DLA.
American Institute of Aeronautics and Astronautics
22
B. Specification Properties
The specification properties of the various Category C fuels are shown in Table 5.
Table 5 – Category C Fuel Properties
C-1 C-2 C-3 C-4 C-5
Property Test method
Density D4052 0.760 0.781 0.808 0.760 0.769
Flash point, C D93 50 58 66 46 44
Viscosity, -20
C (cSt)
D445 4.9 5.2 8.0, 8.3 3.9 1.9
Aromatics,
vol%
D1319 1 17.6 11.2 2.3 26.2
Heat of
Combustion,
MJ/kg
D4809 AF, SwRI 43.88±0.09
(15 meas.)
43.6, 43.4 43.3, 43.3 43.8, 43.8 42.8, 43.0
H content,
mass%
(meas)
D3701 SwRI 15.28, 15.43 14.42 14.18 15.33 13.96
H content,
mass %
(meas)
D7171 AF 15.2 14.1 14.1 15.5 14.1
H content,
mass %
(meas)
D5291 SwRI 15.34 14.31 14.05 15.33 13.93
H content,
mass%
GCxGC 15.3 14.4 14.2 15.4 13.9
H/C ratio
(based on
D3701)
calculation 2.17 2.00 1.97 2.15 1.94
Molecular
formula
GCxGC C12.6H27.2 C12.4H24.8 C12.8H25.3 C11.4H24.8 C9.7H18.7
Derived
cetane #
D6890 17.1 (range
15.1-18.1)
50.4 47 28 39.6
Smoke pt,
mm
D1322 29.0 30.0 26.0 26.0 25.0
Freeze pt, C D5972 <-61 -45 -54 <-61 -56
Distillation,
C
D86
IBP 173 172 183 161 156
10% 178 190 204 169 161
20% 179 198 212 170 162
50% 182 224 230 179 162
90% 228 233 245 206 164
FBP 263 236 256 239 174
Some of the differences among the Category C test fuels are evident in Figure 18, where the various distillation
curves are plotted (compare to Figure 2 for the petroleum-derived/conventional fuels). C-5 was set up to be a fully-
formulated fuel (including aromatics), but has an extremely flat boiling range (i.e., boiling at essentially one
temperature, like a pure hydrocarbon fluid). This test fuel was created by blending 1,3,5 trimethyl benzene with a C10
iso-paraffinic solvent, both of which boil at roughly 165 °C. This test fuel was designed to evaluate the impact of a
very limited vaporization range of the fuel on combustor operability. However, this fuel also has a low (outside of
experience) viscosity which may impact its performance and make interpretation more difficult. In contrast, the C-2
American Institute of Aeronautics and Astronautics
23
test fuel is a fully formulated fuel, but has the same low-boiling aromatic compound combined with higher-boiling
C14 iso-paraffins. This fuel is thus the “opposite” of the C-5 fuel in one sense – with one class of materials vaporizing
at an entirely different temperature than the other.
140
160
180
200
220
240
260
280
0 20 40 60 80 100
C-1 11498 AFC-2 12223 AF
C-3 12341 AFC-4 12344 AFC-5 12345 AFC-1 11498 SwRI
C-2 12223 SwRI
C-3 12341 SwrIC-4 12344 SwRIC-5 12345 SwRI
Te
mpe
ratu
re,
°C
D86 % Distilled
"flat"
bimodal
"low cetane bimodal"
"low cetane wide boiling"
"high viscosity"
Figure 18. D86 distillation curves for Category C fuels
The C-1 test fuel is representative of a fuel composed of heavily branched iso-alkanes. This specific fuel is notable
for having two carbons numbers only (12 and 16) and an extremely low derived cetane number (16) relative to other
fuels (typical jet fuels have DCNs of 40-50). Testing of the neat C-1 fuel in this program is to determine the effect of
low cetane on combustor operability. In an attempt to isolate the effect of low cetane number from the unusual carbon
number distribution, the C-4 fuel was created by blending C-1 with a C9 to C12 blend of isoparaffins (Sasol IPK with
a derived cetane number of 31) to create a test fuel with more typical boiling characteristics, but with an intermediate
(but still low) cetane number of 28. The C-3 test fuel was formulated to have a viscosity at the jet fuel specification
limit (8 cSt or mm2s-1 at -20 °C). This test fuel was created by adding farnesane (trimethyl dodecane) to the A-3
conventional high-viscosity JP-5 fuel, with the effect of farnesane addition shown in Figure 19. Note that the C-3 fuel
exceeds the 12 cSt at -40 C limit used in ASTM D7566 – this 12 cSt limit has been proposed to replace the 8 cSt limit
at -20 C to ensure proper APU altitude start after cold soak.
American Institute of Aeronautics and Astronautics
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7
7.2
7.4
7.6
7.8
8
8.2
15 20 25 30 35 40
Vis
co
sity a
t -2
0 C
, cS
t
Vol % farnesane 10370 in JP-5 10289 (A-3)
POSF 12341 = 8 cSt at -20 C
Figure 19. Increase in viscosity by adding farnesane (2,6,10 trimethyl dodecane) to JP-5 (A-3).
C. Composition
The composition of the Category C fuels is simpler in general than that of the Category A fuels. The two simplest
Category C fuels are C-2 (Figure 20) and C-5 (Figure 21). The C-5 fuel was designed to be a fully-formulated fuel
that meets all of the jet fuel specification requirements, but has a very “flat” boiling range (boils at one temperature).
In contrast, the C-2 fuel was designed to be a fully-formulated fuel that had a “bimodal” boiling distribution, with an
aromatic component boiling first, followed by an iso-paraffin. It was determined that isomerization of a C14 alpha-
olefin to the point that it meets the jet fuel freeze point required essentially complete removal of n-C14. As shown in
Figure 20, the C-2 fuel is predominantly C14 iso-paraffins blended with 1,3,5 trimethyl benzene (C9). The thought
behind this fuel was that preferential vaporization (if important) of the trimethyl benzene would create a very difficult
fuel to ignite/burn. In contrast, the C-5 fuel would not have preferential vaporization issues, but might evaporate quite
differently from a conventional fuel. The C-5 fuel’s composition is shown in Figure 21. Figure 18 shows that this
fuel is indeed quite “flat boiling”. Properties of these fuels are shown in Appendix B.
The C-3 fuel is a modification of the A-3 (JP-5) fuel, with its viscosity increased by adding farnesane (2,6,10 trimethyl
dodecane) to hit the specification limit (8 cSt at -20 C), as discussed in reference to Figure 19. The resulting
composition is shown in Figure 22.
The C-1 fuel is was designed to be the lowest cetane jet fuel available, which turned out to the Gevo ATJ fuel,
consisting primarily of C12 and C16 iso-paraffins. There was some concern about the bimodal nature of the D86
curve for this fuel (C-1), so the “C-4” fuel was created by blending in Sasol IPK (another relatively low-cetane fuel,
but one with a very different boiling range. The resulting composition is shown in Figure 23. This fuel has a cetane
number in the mid 20s, but a much broader boiling range.
American Institute of Aeronautics and Astronautics
25
0
10
20
30
40
50
60
70
80
7 8 9 10 11 12 13 14 15 16
n-paraffinsiso-paraffins1,3,5 trimethyl benzene
Com
positio
n,
mass%
Carbon number
Figure 20. C-2 fuel composition
0
10
20
30
40
50
7 8 9 10 11 12 13 14 15 16
n-parafffinsiso-paraffins1,3,5 trimethyl benzene
Com
positio
n,
mass%
Carbon number
Figure 21. C-5 fuel composition
American Institute of Aeronautics and Astronautics
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0
2
4
6
8
10
7 8 9 10 11 12 13 14 15 16
n-paraffinsiso-paraffinsaromaticscyclo-paraffins
Co
mp
ositio
n,
ma
ss%
Carbon number
36
Figure 22. C-3 fuel composition (A-3 + farnesane to increase viscosity)
0
10
20
30
40
50
60
70
80
7 8 9 10 11 12 13 14 15 16 17 18 19 20
Gevo ATJ, POSF 11498, "C-1"Sasol IPK, POSF 7629, "CRATCAF C1"POSF 12344, "C-4", 60/40 7629/11498 blend
Iso
pa
raff
ins,
ma
ss%
Carbon number
Figure 23. C-1 and C-4 fuel compositions.
American Institute of Aeronautics and Astronautics
27
D. Fit for Purpose Properties
Fit-for-properties were measured for the Category C fuels, as for the Category A fuels. The correlations discussed
in the previous section were validated for petroleum fractions, so their relevance to these “constructed” Category C
fuels is questionable – so calculations were not performed for the Category C fuels.
In Figure 24, density as a function of temperature is shown (again) to be linear with temperature over the range of
-40 to +85 C. Two sets of measurements are represented – SwRI (5 to 85 C) and UDRI (-20 and -40 C). For Category
C fuels that are blends, the density was linear with blending, as shown in Figure 25. Thus, even for very asymmetric
mixtures like “C-2”, blending of these hydrocarbons was linear in density. C-1, C-4, and C-5 do not meet the jet fuel
density spec at 15 C (0.77-0.84).
Viscosity versus temperature for the Category C fuels is shown in Figure 26. Most blends fall within experience,
except C-5 (low) and C-3 (high). C-3 was designed to be outside of experience in viscosity –this is illustrated in
Figure 26. Alas, C-5 was designed to be flat-boiling (which it is), but the available ingredients led to a fuel with an
unusually low viscosity, as shown in Figure 26, clouding the combustion results to some extent.
0.7
0.75
0.8
0.85
0.9
-50 0 50 100
10264 A-110325 A-2
10289 A-311498, C-112223, C-212341 C-312344, C-412345, C-5
De
nsity,
g/c
m3
Temperature, C
specification range
Figure 24. Density data for Category C fuels (note - points for C-1 lie underneath C-4 fuel symbols)
American Institute of Aeronautics and Astronautics
28
0.72
0.74
0.76
0.78
0.8
0.82
0.84
0.86
0.88
0 20 40 60 80 100
Density in 12223; TMB in C14Density in 12345; TMB in C10Density in 12341; farnesane in JP-5 10289
De
nsity,
g/c
m3
Vol% TMB or farnesane
Figure 25. Demonstration of linear blending in “C-2” (POSF 12223), “C-5” (POSF 12345), and “C-3” (POSF
12341).
0
5
10
15
-40 -20 0 20 40 60 80 100
A-1 10264A-2 10325A-3 10289C-1 11498C-2 12223C-3 12341C-4 12344C-5 12345WS min 720WS max 007
D44
5 V
iscosity,
cS
t
Temperature, C
JP-5/high visc
Jet A/Jet A-1
Figure 26. Temperature dependence of viscosity for Category C fuels
American Institute of Aeronautics and Astronautics
29
Figure 27. Viscosity (-20 C) for several Category C fuels that are “outside of experience”.
Heat capacity (specific heat) data for the Category C test fuels is shown in Figure 28. Many properties seem to
trend with density – heat capacity in this case is not one of them (15 C densities are shown in the legend). It isn’t
clear if the differences among the fuels is real or an artifact of the measurement. The CRC Handbook shows
separate Cp lines for JP-5, Jet A/Jet A-1/JP-8, JP-TS, and JP-4/Jet B, varying by about 0.1 kJ/kg-K at a given
temperature. The CRC Handbook shows a Cp for Jet A/Jet A-1/JP-8 of 2.3 kJ/kg-K at 100 C, consistent with the A-
2 value shown in Figure 28. A recent analysis of specific heat data for jet fuels, alternative fuels, and pure jet fuel-
range hydrocarbons [40] has shown that heat capacity trends more with chemical composition than density. Pure n-
paraffins and iso-paraffins lie above the CRC Handbook jet fuel line, while aromatics lie below. That is broadly
consistent with the data of Figure 28, although the low Cp value for the C-1 fuel (a pure iso-paraffin) is puzzling, as
are the relatively high Cp values for the C-3 fuel (11% aromatics).
Figure 29 shows the surface tension data for the Category C fuels. The data is broadly consistent with the
Category A fuels, although trends with fuel properties are not clear. As shown in Figure 30, surface tension at a
given temperature correlates roughly with density, although there is significant scatter. In Figure 31, vapor pressure
for the Category C test fuels is generally as expected, with the high-viscosity C-3 fuel (based on JP-5) at the low end
and the C-5 fuel on the high end (as expected from its composition).
American Institute of Aeronautics and Astronautics
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1.8
2
2.2
2.4
2.6
2.8
0 50 100 150 200
POSF 11498, C-1, 0.759POSF 12223, C-2, 0.782
POSF 12341, C-3, 0.808POSF 12344, C-4, 0.760POSF 12345, C-5, 0.770POSF 10325, A-2, 0.803
He
at C
ap
acity (
Cp
), k
J/k
g-K
Temperature, C
Figure 28. Heat capacity as a function of temperature for Category C fuels (SwRI). 15 C density is shown in
legend.
20
22
24
26
28
30
-20 -10 0 10 20 30 40 50
A-1 10264
A-2 10325
A-3 10289C-1 11498
C-2 12223C-3 12341C-4 12344
C-5 12345
Su
rfa
ce
te
nsio
n,
dyne
/cm
Temperature, C
Figure 29. Surface tension as a function of temperature for Category C fuels (SwRI). Compare Figure 14 for
CRC Handbook data.
American Institute of Aeronautics and Astronautics
31
20
22
24
26
28
30
0.75 0.76 0.77 0.78 0.79 0.8 0.81 0.82 0.83
-10 C
22 C
Su
rfa
ce
te
nsio
n,
dyne
/cm
Density (15 C) g/cm3
A-3
C-3
C-1
C-4A-1
C-2
A-2C-5
Figure 30 – Surface tension correlation with density
0
1
2
3
4
5
0 50 100 150
C-1 11498
C-2 12223
C-3 12341
C-4 12344
C-5 12345
CRC JP-8
CRC JP-5
Va
po
r p
ressure
, p
sia
Temperature, C
Range in HEFA
Research Report
Figure 31 – Vapor pressure data for Category C fuels
American Institute of Aeronautics and Astronautics
32
As part of this program, blends of the A-2 Jet A and the C-1 test fuel were made – see Figures 32 to 35. Bulk
properties such as heat of combustion and hydrogen content should be linear with blending – the non-linearity in the
H content is due to scatter in the data/measurement. Density is expected to be linear with blending (as mentioned
earlier) – and is (Figure 34). Viscosity was not expected to be linear with blending – and was not (especially at
lower temperatures – Figure 35).
Over the course of four years, multiple batches of the C-1 fuel were received and multiple measurements were
made of the properties. From the AF Petroleum Agency lab, the heat of combustion measurements were 43.93,
43.90, 43.94, 43.95, 43.77, 44.00, 43.85, 43.74, 43.86, and 44.04 MJ/kg. Measurements at SwRI were 43.82 and
43.95 MJ/kg. So, the mean is 43.90 and the standard deviation is 0.09 MJ/kg. The H content by D7171 (AF) and
D3701 (SwRI) was 15.4, 15.7, 15.2, 15.4, 15.5, 15.2, 15.5, 15.2, 15.2, 15.5, and 15.45 (D3701). The mean was thus
15.4 mass% H, and the standard deviation was 0.17 mass%. Since the C-1 fuel is mostly pentamethyl heptane
(C12H26) isomers, the calculated H content can be estimated as 26(1.008)/(26(1.008)+12(12.011))~15.38 mass%.
So the mean value on H content is apparently relatively accurate, but the standard deviation is higher than desirable.
ASTM D5291 gives 15.34 mass% hydrogen.
43
43.2
43.4
43.6
43.8
44
0 20 40 60 80 100
y = 43.087 + 0.0085882x R= 0.99725
Hea
t o
f co
mb
ustio
n,
MJ/k
g
Vol% C-1 in A-2/C-1 blend
Figure 32 – Heat of combustion as a function of blend ratio for C-1/A-2 blends
American Institute of Aeronautics and Astronautics
33
13.5
14
14.5
15
15.5
16
0 20 40 60 80 100
y = 13.929 + 0.014864x R= 0.96296
H c
on
ten
t, m
ass %
(D
71
71
)
Vol% C-1 in A-2/C-1 blend
Figure 33 – H content as a function of blend ratio for C-1/A-2 blends
0.76
0.77
0.78
0.79
0.8
0.81
0 20 40 60 80 100
y = 0.803 - 0.00042794x R= 0.99924
De
nsity,
g/m
L
Vol %C-1 in A-2/C-1 blend
Figure 34 – Density as a function of blend ratio for C-1/A-2 blends
American Institute of Aeronautics and Astronautics
34
4.4
4.5
4.6
4.7
4.8
4.9
5
1.25
1.3
1.35
1.4
1.45
1.5
1.55
0 20 40 60 80 100
Vis
co
sity a
t -2
0 C
, cS
t Vis
co
sity
at 4
0 C
, cS
t
%C-1 in A-2/C-1 blendC-1A-2
Figure 35. Viscosity as a function of blend ratio for C-1/A-2 blends
It was not part of this program, but several sets of blending data for the C-1 (Gevo ATJ fuel) have been obtained
for derived cetane number. As shown in Figure 36, the blending curve of the low cetane “C-1” fuel is not linear
with a number of fuels. A number of different samples of the C-1 fuel have been tested, with DCN ranging from
15.1 to 18.1.
15
20
25
30
35
40
45
50
0 20 40 60 80 100
JP-8"low cetane" JP-5
JP-5 6637JP-5 7382
AS
TM
D6
89
0 D
erive
d C
eta
ne
Nu
mb
er
Volume % ATJ
Figure 36. Derived cetane number for various blends of C-1 fuel with jet fuel
American Institute of Aeronautics and Astronautics
35
Heat of formation
As mentioned above, the heat of formation might be needed for the Category C fuels, and can be calculated from
the measured hydrogen content and heat of combustion (Table 6). There is more variation in heat of formation
amongst the Category C fuels than the Category A fuels.
Table 6 – Heat of formation calculations
Fuel wt% H
(meas)
SwRI
D3701
H/C molar
(calc from H
content)
Mass heat of
comb, MJ/kg
(AF/SwRI,
meas D4809)
Mass heat
of comb,
kcal/g
Heat of
formation
(calc), cal/g
MW,
GCxGC
Heat of
formation,
kcal/mol
C-1 11498 15.36 2.162 43.88 -10488 -544.04 178 -96.8
C-2 12223 14.42 2.008 43.5 -10397 -438.95 173 -75.9
C-3 12341 14.18 1.969 43.3 -10349 -436.73 180 -78.6
C-4 12344 15.33 2.157 43.8 -10468 -556.91 162 -90.2
C-5 12345 13.96 1.933 42.9 -10253 -486.48 135 -65.7
American Institute of Aeronautics and Astronautics
36
s
IV. Other “Average” Jet Fuels Distributed
A number of previous “average” fuels have been distributed to researchers over the past 15 years. POSF 6169,
5699, 4177, and 3773 are JP-8 fuels obtained from the active airfield at WPAFB. It is perhaps coincidental that they
are fairly “average”. In contrast, POSF 4658 was created by taking 2000 gallons of each of five different Jet As
(each from a different part of the U.S.) and blending them all together. As can be seen in Table 7, all of these fuels
are similar to the A-2 fuel and are, indeed, pretty average in terms of their properties. GCxGC data is presented in
Appendix D.
Table 7 – Specification data for previous reference fuels
Property Test
Method
Spec
limits
POSF 4658 POSF
6169
POSF 5699 POSF
4177
POSF
3773
PQIS
2012 wt
mean
Density D4052 0.775-0.84 0.806 0.798 0.795 0.814 0.799 0.8022
Flash point, C D93 >38 51 46 50 52 48 47.6
Viscosity, -20
C (cSt)
D445 <8 5.2 4.2 3.8 4.8 4.1 4.399
Aromatics,
vol%
D1319 <25 19 15.7 16.9 16.9 17.2 17.1
Heat of
Combustion,
MJ/kg
D4809 >42.8 43.2
(D3338)
43.5 43.4 43.0 43.1 43.2
H content,
mass% (calc)
D3343 >13.4 14.0 13.7 13.9 13.85
Derived
cetane number
D6890 46.8 47.7 n/a 41.5 49.3 n/a
Smoke pt, mm >19 21.0, 25.0 26.0 26.0 20.0,
22.0
25.0 22.8
Freeze pt, C >-47 (JP-
8)
-48 -50 -51 -58 -49 -51.3
GCxGC est
formula
C11.7H22.6 C11.3H22.1
American Institute of Aeronautics and Astronautics
37
V. Alternative Jet Fuels A. Introduction
Large alternative fuel programs established in 2006 have led to the certification of 5 alternative “drop-in”
hydrocarbon jet fuels in ASTM D7566 by mid-2016. The properties of these fuels can be found in Research Reports
[11,12,15,18] and other reports [13,14,16,17]. The purpose of this section is to list POSF numbers for common
alternative fuels shipped by the Air Force since 2006. Supplies of many of these fuels still exist.
Often, when fuels are combined, moved, received back from a shipment, or additives are added – a new number
is assigned for a fuel that is chemically identical to a previous number. For example, Sasol IPK was purchased in a
300,000 gallon batch by the AF. When 6000 gallons of that was received by AFRL, it was given the number POSF
5642. A large part of the original 300,000 gallons went to various AF locations for testing – when the excess fuel was
collected at WPAFB by the AF several years later and combined with remaining POSF 5642 at WPAFB, the IPK was
given a new number POSF 7629, although the hydrocarbon composition of the fuel is identical to the original
shipment/batch. Typically a set of jet fuel spec tests is associated with a given POSF ID number. Thus, for example,
the numerous ATJ batches listed below all have a set of (very similar) spec tests so the consistency of the various
batches can be assessed.
(a) ASTM D7566 Annex 1 – Synthetic Paraffinic Kerosene (aka Fischer-Tropsch fuels)
--Sasol IPK (made in South Africa), AF purchase, 2008, same large batch – POSF 5642, 7629, 5959, 5654, 7279,
7280.
--Shell GTL (made in Bintulu Malaysia), AF purchase, 2007, same large batch – POSF 5172, 5729
--Syntroleum GTL (made in Tulsa OK), AF/Army purchases – 2004: POSF 4734 (drums), 2005: POSF 4820 (drums),
2006: POSF 5018 (tanker trucks). Composition very similar between 2004, 2005, 2006 batches
--Rentech GTL – POSF 5698, 7457
(note – these first three fuels make up most of the data in the SPK Research Report [11-12], although the IPK data in
the Research report was largely from Sasol production prior to the batch produced for the Air Force)
(b) ASTM D7566 Annex 2 - Hydroprocessed Esters and Fatty Acids (HEFA) (aka Hydroprocessed Renewable Jet
(HRJ))
--Tallow-based HRJ fuel produced by UOP for AF in 2010 (large batch) – POSF 6308, 6346, 9584, 9585
--Camelina-based HRJ fuel produced by UOP for AF in 2009 – POSF 6152, large batches=POSF 11714, 7720 (not
identical to 6152)
--Mixed-fat-based HRJ produced by Dynamic Fuels/Syntroleum in 2010 (aka “R-8”): large batch – POSF 7272, 7635;
2008 drums: POSF 5469.
(c) ASTM D7566 Annex 5 - Alcohol-to-Jet Synthetic Paraffinic Kerosene
Gevo initial batch - POSF 7504 (1 drum, 2011, lower C16/C12 ratio than all other batches, which are basically
identical)
Subsequent Gevo batches (many were 6000 gallons) - POSF 7695, 7699, 7712, 7788, 7817, 8092, 8158, 8289, 8438,
9641, 10151, 10262, 10373, 11498, 12368, 12384 (2012-2015)
American Institute of Aeronautics and Astronautics
38
VI. Surrogate Fuels
The focus of this section is much narrower than surrogate fuels in general [19-21]. Here we discuss only two jet
fuel surrogates produced in the hundreds of gallons to compare experimentally to results for the “real” fuel which the
surrogate is supposed to mimic. This builds on the approach developed in a recent MURI [22, 23]. Technically, the
surrogate fuel could be designed to simulate only the combustion chemistry of the parent fuel, but a surrogate which
also mimics the physical properties has the potential to be used to model the fuel throughout the entire
injection/combustion process. One can easily envision a blend of a few hydrocarbons that would match the bulk
physical properties of the fuel being modeled – density, H/C ratio (and sooting), average molecular weight, cetane
number. The difficulty comes with trying to match properties that are dependent upon the multicomponent nature of
the fuel, such as viscosity and (especially) boiling range (as approximated by ASTM D86 distillation). A key
simplification applied is that the boiling range of the entire fuel is being simulated – the boiling range of each class of
hydrocarbons is NOT being simulated – that would require many more surrogate components. Some more complex
surrogates for jet fuels in diesel engines (4 components) [24] and diesel fuel in diesel engines (8-11 components) [25]
have been described. From ongoing testing in NJFCP, it appears that matching the boiling range of individual fractions
is not necessary in the turbulent environment of a gas turbine combustor (as noted above and in other papers at this
meeting, fuels with abnormal boiling distributions in Category C were generally found to burn similarly to
conventional fuels).
These initial surrogates were combination of three hydrocarbons – an n-paraffin, an iso-paraffin, and an aromatic.
The need for including a cyclo-paraffin to match all the major classes of jet fuels is still being debated. In an overall
sense, a surrogate could not consist of just n-paraffins, because the cetane number would be too high and the density
too low. Inclusion of aromatics increases the density and decreases the cetane number, while the effect of adding iso-
paraffins would depend upon the degree of branching. Typically, lightly-branched iso-paraffins make up the largest
hydrocarbon class in conventional jet fuels and have a relatively high cetane number. Highly branched iso-paraffins
have low cetane numbers, as do aromatics.
Alas, the flexibility of surrogate creation is limited by the cost of the ingredients (500 gallons was deemed to be a
good batch size, enabling in use of the surrogate in several larger rigs). This cost issue was recognized early on [19,
20]. In 2016, with jet fuel cost of $2-3/gallon, the cheapest surrogate ingredients were on the order $50/gallon. Some
desirable ingredients were hundreds of dollars/gallon and more. Lightly-branched iso-paraffins in the jet fuel range
are especially expensive. Cyclo-paraffins in the jet fuel range are also currently very high-priced, although some
solvent options may be available.
With that background in mind, two surrogates for the “average” Jet A fuel described earlier (A-2, POSF 10325)
were blended in 2016, as shown in Table 8. The surrogates were 1,3,5 trimethyl benzene and iso-octane blended with
either n-dodecane or n-hexadecane to match H/C ratio, smoke point, and DCN [22,23]. Typically technical grades of
the hydrocarbons were purchased. These surrogates roughly match the DCN, H/C ratio, and smoke point of the
average jet fuel (A-2). The density and average molecular weight of surrogate #1 is somewhat lower than the target
jet fuel. Surrogate #2 increases the MW and density by replacing n-dodecane with n-hexadecane (Table 9). The
ASTM D86 boiling range is shown in Figure 37, and compared to the three Category A fuels. The lower initial boiling
point is due to the compromise of being forced to use iso-octane as the iso-paraffin. Technical grade iso-octane can
be found for under $100/gallon, no doubt because of its use as a component of gasoline primary reference fuels. The
preference was to have iso-dodecane (penta-methyl heptane) as a component [26]– but it was not available in drum
quantities at the time of this paper, even at $100/gallon. Lightly-branched iso-paraffins (e.g., 2-methyl decane) cost
about $1/gram. As discussed in Section 3, 1,3,5 trimethyl benzene has a boiling point of ~160 C, so the replacement
of iso-octane with iso-dodecane would bring the initial boiling point of such a surrogate up into the jet fuel range (IBP
~ 160 C) and increase the MW and density. Note also in Figure 37 that the substitution of dodecane with hexadecane
raises the last 50% of the boiling range significantly – even above typical jet fuels – so an optimized surrogate might
not use n-hexadecane. Some of the specification properties of the surrogates are shown in Table 10.
The combustion behavior of these two surrogates is being assessed and some results may be available in other
papers presented at this meeting [28, 29]. The relationship between the ASTM D86 distillation curve and the actual
fuel evaporation under combustor conditions is uncertain. It was surprising that the three-component nature of the
surrogates was not more evident in the D86 curve, so two other distillation techniques were utilized to characterize
the surrogates. ASTM D7345 “mini-distillation” closely resembled D86, while the ASTM D2887 “simulated
distillation” (GC) technique did more closely resemble the actual boiling points of the three components, as shown in
Figure 37 and 38. The D7345 and D2887 data for the Category A fuels is shown in Appendix C.
American Institute of Aeronautics and Astronautics
39
Table 8 – Surrogate composition data
Surrogate 1 as
specified, vol %
Surrogate 1 (POSF
12765) as blended
- UDRI GCxGC,
vol %
Surrogate 2 as
specified, vol
%
Surrogate 2
(POSF 12785) as
blended - UDRI
GCxGC, vol %
n-dodecane 59.3 56.7 0
n-hexadecane 0
52.6 50.4
iso-octane 18.4 18.2 25.1 24.9
1,3,5 trimethyl benzene 22.2 22.4 22.2 22.4
iso-C12 (impurity in dodecane)
1.3
iso-C16 (impurity in hexadecane)
1.5
n-C10 (impurity)
0.3
n-C14 (impurity)
0.6
0.3
Table 9 – Surrogate property data (Princeton surrogate calculator)
Surrogate 1 Surrogate 2 Target (A-2 (POSF
10325))
Density ASTM D4052, g/cm3 0.769 0.778 0.803
DCN 50.0 50.6 50.0
Smoke point/TSI 23.8 25.5 25.5
MW 143.2 156.9 160.8
H/C 1.961 1.947 1.961
Table 10 – AFRL surrogate property data on bulk batches
Surrogate 1
(POSF 12765)
Surrogate 2
(POSF 12785)
A-2 (POSF 10325)
D86 distillation, C
IBP 106.7 102.3 159
10% 139 121 176
20% 157 131 184
50% 194 234 205
90% 212 278 244
FBP 226 281 269
ASTM D1319 aromatics, vol% 23 25, 26.8, 25.6 17.0
ASTM D93 flash point, C 24 16 48
ASTM D445 viscosity at -20 C, cSt 2.7 n/a 4.5
ASTM D7171 H content, mass% 14.1 14.305, 14.261 13.8
ASTM D4809 heat of comb., MJ/kg 43.03 42.92 43.1
ASTM D5972 freeze point, C -15.4 -8.1 -51
Molecular formula (GCxGC) C10.3H20.1 C11.2H21.9 C11.4H22.1
ASTM D4052 density, g/ cm3 0.769 0.778 0.803
American Institute of Aeronautics and Astronautics
40
100
150
200
250
300
0 20 40 60 80 100
POSF 12765 surrogate 1
POSF 12785 surrogate 2POSF 10325 Jet A
POSF 10264 JP-8
POSF 10289 JP-5
AS
TM
D8
6 T
em
pe
ratu
re,
C
% Distilled
Figure 37. ASTM D86 distillation results for surrogates as compared to conventional fuels
50
100
150
200
250
300
0 20 40 60 80 100
12765 D8612765 D7345
12765 D2887
Te
mpe
ratu
re,
C
% distilled
b.p. 216C
59.3 vol% n-C12, 18.4% iso-C8, 22.2% TMB
99 C 165C
Figure 38. ASTM D86/D7345/D2887 distillation results for surrogate fuel #1
American Institute of Aeronautics and Astronautics
41
50
100
150
200
250
300
0 20 40 60 80 100
12785 D8612785 D7345
12785 D2887
Te
mp
era
ture
, C
% distilled
52.6 vol% n-C16, 25.1% iso-C8, 22.2% TMB
b.p. 287 C 99 C 165C
Figure 39. ASTM D86/D7345/D2887 distillation results for surrogate fuel #2
Note from Table 9 that the freeze point of surrogate 2 is higher than desired for jet fuel, and the viscosity could not be
measured at -20 C because of solidification of the n-hexadecane. However, the density and average MW are close to
the desired values. A third surrogate is being planned with iso-dodecane in place of iso-octane, which should enable
matching DCN, MW, density, smoke point, and viscosity (and perhaps D86 distillation) more effectively than
surrogates #1 and #2.
American Institute of Aeronautics and Astronautics
42
VII. Conclusion This paper summarizes the various fuels being used as reference fuels for the National Jet Fuel Combustion Program,
as well as other fuels used recently as reference fuels. The paper includes the physical properties of the fuels. The
fuels cover a wide range of combustion-related properties. The fuels are available
to researchers outside of the National Jet Fuel Combustion Program.
Acknowledgments DLA funding support for CRATCAF and NJFCP programs is gratefully acknowledged, as is their assistance with fuel
procurement and shipping.
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Distillation-Curve Method as a Basis of Comparison for Novel Fuel Development,” Energy & Fuels, in press (2016) DOI: 10.1021/acs.energyfuels.6b01837 • Publication Date (Web): 26 Oct 2016. [31] Outcalt, S. L., “Compressed Liquid Densities of Three “Reference” Turbine Fuels,” Energy & Fuels, in press
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[32] Edwards, J. T., Hutzler, S., Morris, R. E., Muzzell, P. A., “Tri-Service Jet Fuel Characterization for DOD
Applications; Task 1 Compositional Analysis/Task 2-3 Fit-For-Purpose and Trace Impurity Evaluations,” May 2015.
SwRI Project No. 08.17149.36.100.
[33] Yu, J., Eser, S., “Determination of Critical Properties of Some Jet Fuels. Ind. Eng. Chem. Res. Vol. 34, p.
404, 1995.
[34] Moses, C., “A Review of ASTM D4054 Fit-For-Purpose Results,” Presentation to D02.J0.06 Emerging Fuels
ASTM Aviation Fuels Subcommittee, Ft. Lauderdale, FL, June 24, 2015
[35] Mueller, C. J., et al, “Methodology for Formulating Diesel Surrogate Fuels with Accurate Compositional,
Ignition-Quality, and Volatility Characteristics,” Energy & Fuels, Vol. 26, pp. 3284−3303, 2012.
[36] Riazi, M. R. and Daubert, T. E., “Analytical Correlations Interconvert Distillation Curve Types,” Oil & Gas
Journal, Vol. 84, 1986, August 25, pp. 50–57.
[37] Lenoir, J. M. and Hipkin, H. G., “Measured Enthalpies of Eight Hydrocarbon Fractions,” Journal of Chemical
and Engineering Data, Vol. 18, No. 2, 1973, pp. 195–202.
[38] Edwards, T., ““Kerosene” Fuels for Aerospace Propulsion – Composition and Properties,” AIAA Paper 2002-
3874, July 2002.
[39] Moses, C., Stavinoha, L., Roets, P., “Qualification of Sasol Semi-Synthetic Jet A-1 as Commercial Jet Fuel,
SwRI-8531, Nov. 1997.
[40] Moses, C, “A Review of ASTM D4054 Fit-For-Purpose Results,” Presentation to D02.J0.06 Emerging Fuels,
ASTM Aviation Fuels Subcommittee, Ft. Lauderdale, FL, June 24, 2015
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Appendix A – Tabular Property Data for Category A Fuels
Table A-1 – GCxGC composition (UDRI)
Table A-2 – Miscellaneous compositional measurements (AFPET/SwRI/UDRI)
Table A-3 – Physical/specification properties (SwRI/UDRI)
Table A-4 – Heat Capacity as a function of temperature (SwRI)
Table A-5 – Density, speed of sound, bulk modulus as a function of P for POSF 10325 (SwRI)
Table A-6 – Density, speed of sound, bulk modulus as a function of P for POSF 10264 (SwRI)
Table A-7 – Density, speed of sound, bulk modulus as a function of P for POSF 10289 (SwRI)
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Table A-1 – GCxGC composition (UDRI)
GCxGC SummaryHydrogen content (weight %)
Average Molecular Wt (g/mole)
POSF-10264 JP-8 POSF-10289 JP-5 POSF-10325 Jet AWeight % Volume % Weight % Volume % Weight % Volume %
Aromatics
Alkylbenzenes
benzene (C06) 0.01 0.01 <0.01 <0.01 0.01 0.01
toluene (C07) 0.23 0.21 0.03 0.02 0.16 0.14
C2-benzene (C08) 1.98 1.77 0.41 0.38 1.10 1.00
C3-benzene (C09) 4.17 3.73 1.32 1.24 2.97 2.73
C4-benzene (C10) 2.33 2.09 2.09 1.97 3.32 3.05
C5-benzene (C11) 1.19 1.07 1.98 1.86 2.22 2.03
C6-benzene (C12) 0.66 0.59 1.80 1.70 1.45 1.33
C7-benzene (C13) 0.25 0.22 1.24 1.16 0.73 0.67
C8-benzene (C14) 0.12 0.11 1.05 0.99 0.52 0.48
C9-benzene (C15) 0.06 0.05 0.39 0.37 0.28 0.25
C10+-benzene (C16+) <0.01 <0.01 0.03 0.03 0.15 0.14
Total Alkylbenzenes 11.00 9.85 10.33 9.72 12.90 11.84
Diaromatics (Naphthalenes, Biphenyls, etc.)
diaromatic-C10 0.10 0.08 0.09 0.07 0.22 0.17
diaromatic-C11 0.33 0.25 0.33 0.26 0.66 0.51
diaromatic-C12 0.41 0.32 0.60 0.48 0.86 0.68
diaromatic-C13 0.18 0.14 0.29 0.24 0.43 0.34
diaromatic-C14+ 0.04 0.03 0.04 0.03 0.17 0.14
Total Alkylnaphthalenes 1.06 0.82 1.34 1.09 2.34 1.84
Cycloaromatics (Indans, Tetralins,etc.)
cycloaromatic-C09 0.02 0.02 0.03 0.03 0.02 0.02
cycloaromatic-C10 0.19 0.15 0.57 0.48 0.26 0.21
cycloaromatic-C11 0.37 0.30 1.91 1.66 0.66 0.56
cycloaromatic-C12 0.38 0.32 2.67 2.34 0.89 0.76
cycloaromatic-C13 0.34 0.29 2.27 2.01 0.85 0.73
cycloaromatic-C14 0.16 0.14 1.08 0.96 0.44 0.38
cycloaromatics-C15+ 0.03 0.02 0.14 0.12 0.17 0.15
Total Cycloaromatics 1.49 1.24 8.69 7.60 3.29 2.81
Total Aromatics 13.56 11.91 20.36 18.41 18.53 16.49
Paraffins
iso-Paraffins
C07 & lower -isoparaffins 0.21 0.24 0.02 0.02 0.15 0.18
C08-isoparaffins 0.88 0.97 0.13 0.15 0.44 0.50
C09-isoparaffins 2.59 2.80 0.48 0.54 1.05 1.17
C10-isoparaffins 8.15 8.67 1.66 1.85 4.20 4.57
C11-isoparaffins 8.38 8.73 2.73 2.98 5.70 6.08
C12-isoparaffins 5.41 5.64 3.36 3.67 5.63 6.02
C13-isoparaffins 4.63 4.73 3.57 3.82 4.22 4.41
C14-isoparaffins 3.96 4.00 3.54 3.76 4.20 4.35
C15-isoparaffins 2.28 2.30 2.70 2.85 2.51 2.59
C16-isoparaffins 0.75 0.75 0.65 0.68 1.00 1.03
C17-isoparaffins 0.20 0.20 0.08 0.09 0.39 0.40
C18-isoparaffins 0.03 0.03 <0.01 <0.01 0.11 0.11
C19-isoparaffins <0.01 <0.01 <0.01 <0.01 0.03 0.03
C20-isoparaffins <0.01 <0.01 <0.01 <0.01 0.03 0.03
C21-isoparaffins <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
C22-isoparaffins <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
C23-isoparaffins <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
C24-isoparaffins <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
Total iso-Paraffins 37.48 39.07 18.91 20.42 29.69 31.46
n-Paraffins
n-C07 & lower 0.24 0.27 0.02 0.02 0.17 0.20
n-C08 1.11 1.22 0.19 0.22 0.54 0.61
n-C09 2.97 3.20 0.64 0.72 1.42 1.57
n-C10 6.46 6.84 1.41 1.57 3.26 3.53
n-C11 5.22 5.44 2.60 2.85 4.29 4.58
n-C12 3.99 4.11 3.09 3.33 3.74 3.94
n-C13 2.97 3.03 2.50 2.68 2.80 2.93
n-C14 1.97 1.99 1.92 2.04 2.02 2.09
n-C15 0.83 0.83 0.86 0.90 1.03 1.06
n-C16 0.23 0.23 0.11 0.12 0.43 0.44
n-C17 0.06 0.06 0.01 0.01 0.21 0.22
n-C18 <0.01 <0.01 <0.01 <0.01 0.05 0.05
n-C19 <0.01 <0.01 <0.01 <0.01 0.01 0.01
n-C20 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
n-C21 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
n-C22 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
n-C23 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
Total n-Paraffins 26.05 27.23 13.35 14.47 19.98 21.23
Cycloparaffins
Monocycloparaffins
C07 & lower monocycloparaffins 0.51 0.51 0.08 0.08 0.36 0.37
C08-monocyclocycloparaffins 1.01 0.99 0.35 0.36 0.78 0.78
C09-monocyclocycloparaffins 3.06 2.98 1.53 1.57 2.30 2.29
C10-monocyclocycloparaffins 4.47 4.22 3.25 3.22 4.11 3.97
C11-monocyclocycloparaffins 3.55 3.44 5.77 5.86 5.43 5.38
C12-monocyclocycloparaffins 2.45 2.36 6.25 6.32 3.73 3.68
C13-monocyclocycloparaffins 2.25 2.15 6.11 6.11 4.19 4.09
C14-monocyclocycloparaffins 1.19 1.14 4.22 4.24 2.19 2.14
C15-monocyclocycloparaffins 0.77 0.74 2.27 2.27 1.33 1.29
C16-monocyclocycloparaffins 0.11 0.10 0.41 0.41 0.42 0.41
C17-monocyclocycloparaffins 0.02 0.02 0.01 0.01 0.18 0.18
C18-monocyclocycloparaffins <0.01 <0.01 <0.01 <0.01 0.04 0.04
C19+-monocyclocycloparaffins <0.01 <0.01 <0.01 <0.01 0.02 0.02
Total Monocycloparaffins 19.41 18.66 30.25 30.44 25.08 24.64
Dicycloparaffins
C08-dicycloparaffins 0.03 0.03 0.03 0.02 0.03 0.03
C09-dicycloparaffins 0.35 0.31 0.46 0.42 0.43 0.39
C10-dicycloparaffins 0.47 0.40 1.04 0.94 0.72 0.63
C11-dicycloparaffins 0.71 0.65 2.84 2.69 1.52 1.41
C12-dicycloparaffins 0.77 0.70 4.33 4.14 1.57 1.47
C13-dicycloparaffins 0.52 0.47 4.53 4.32 1.21 1.12
C14-dicycloparaffins 0.45 0.41 3.14 3.00 0.81 0.76
C15-dicycloparaffins 0.08 0.07 0.63 0.61 0.20 0.19
C16-dicycloparaffins <0.01 <0.01 0.03 0.03 0.04 0.04
C17+-dicycloparaffins <0.01 <0.01 <0.01 <0.01 0.02 0.02
Total Dicycloparaffins 3.39 3.05 17.02 16.17 6.56 6.06
Tricycloparaffins
C10-tricycloparaffins <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
C11-tricycloparaffins 0.11 0.09 0.10 0.09 0.16 0.13
C12-tricycloparaffins <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
Total Tricycloparaffins 0.11 0.09 0.10 0.09 0.16 0.13
Total Cycloparaffins 22.91 21.79 47.37 46.70 31.79 30.83
Average Molecular Formula - C 10.8 11.9 11.4
Average Molecular Formula - H 21.7 22.6 22.1
13.7
166
14.0
159
14.4
152
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Table A-2 – Miscellaneous compositional measurements (AFPET/SwRI/UDRI)
Property A-1 (POSF 10264) A-2 (POSF 10325) A-3 (POSF 10289)
ASTM D1319-13 Aromatics, %vol (AFPET) 11.2 17.0 18.3
ASTM D1319-13 Aromatics, %vol (SwRI) 12.3 17.1 19.8
ASTM D5186 Aromatics, %mass (SwRI) 14.4 19.3 20.7
ASTM D6379 Aromatics, %mass (SwRI) 13.7 19.1 21.5
ASTM D6379 (UDRI) 12.6 17.4 19.8
ASTM D7171-05 Hydrogen Content by NMR,
% mass (AFPET)
14.4 13.7, 13.9 13.4
ASTM D3701 H content by NMR, % mass
SwRI
14.26 13.84 13.68
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Table A-3 – Physical/specification properties (SwRI/UDRI/AFPET)
Property A-1 (POSF 10264) A-2 (POSF 10325) A-3 (POSF 10289)
Density, g/L
15 C (AFPET) 0.780 0.803 0.827
5 C (SwRI) 0.7874 0.8106 0.8339
15 C 0.7799 0.8032 0.8268
25 C 0.7724 0.7958 0.8194
35 C 0.7649 0.7884 0.8122
45 C 0.7574 0.7810 0.8048
55 C 0.7498 0.7735 0.7976
65 C 0.7422 0.7660 0.7902
75 C 0.7350 0.7584 0.7828
85 C 0.7286 0.7509 0.7754
Viscosity, cSt
-40 C (AFPET) 6.6 9.2 14.1
-20 C (AFPET) 3.5 4.5 6.5
40 C (SwRI) 1.14 1.31 1.57
100 C (SwRI) 0.61 0.68 0.76
Heat of combustion, MJ/kg (SwRI) D4809 43.239 43.058 42.878
Heat of combustion, MJ/kg (AFPET) 43.1 43.0 43.0
Surface tension, dyne/cm (SwRI) D1331A
-10 C 25.8 28.0 28.4
22 C 23.8 24.8 25.7
40 C 22.8 23.6 24.7
Cetane number, ASTM D613 47.9 47.0 40.4
Ignition Delay (ms), ASTM D6890 4.2 4.3 5.4
Derived cetane number, ASTM D6890 48.8 48.3 39.2
ASTM D86 Distillation (SwRI)
IBP 150.0 159.2 177.9
5% 162.2 173.1 190.2
10% 164.3 176.8 194.2
15 167.4 180.8 197.7
20 171.1 185.4 201.3
30 176.9 191.5 207.9
40 183.0 198.2 213.8
50 189.7 205.4 219.6
60 197.0 212.6 225.3
70 206.5 220.8 231.0
80 218.5 230.9 237.5
90 233.9 244.6 245.8
95 245.0 256.0 252.5
FBP 256.7 270.5 259.5
Flash point 42 48 60
Freeze pt, C -52 -51 -50
Smoke pt, mm 28.5 22 20
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Table A-4 – Heat Capacity as a function of temperature (SwRI)
POSF 10325 POSF 10264 POSF 10289
Table A-5 – Density, speed of sound, bulk modulus as a function of P for POSF 10325 (SwRI)
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Table A-6 – Density, speed of sound, bulk modulus as a function of P for POSF 10264 (SwRI)
Table A-7 – Density, speed of sound, bulk modulus as a function of P for POSF 10289 (SwRI)
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Appendix B – tabular property data for Category C fuels
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Appendix C – Alternative distillation data (see also [30]) As discussed briefly in Section 6, there are a number of alternative distillation techniques that can be used to assess
fuel, in addition to ASTM D86. ASTM D7345 (“Micro Distillation”) generates data similar to D86, but with a
smaller sample, as shown in Figures C-1, C-2, C-3. ASTM D2887 is a gas chromatography method. From D2887:
“Boiling range distributions obtained by this test method are essentially equivalent to those obtained by true boiling
point (TBP) distillation (see Test Method D2892). They are not equivalent to results from low efficiency distillations
such as those obtained with Test Method D86 or D1160.” There is an Annex in D2887 that allows the generation of
data analogous to D86 through correlations. Data shown in Section 6 shows that the D2887 data does more closely
mimic the boiling curve for simple three-component hydrocarbon blends than does ASTM D86.
100
150
200
250
300
350
0 20 40 60 80 100
D86D7345D2887
Te
mpe
ratu
re,
C
% distilled
A-1
Figure C-1 – various distillation results for A-1 (POSF 10264)
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100
150
200
250
300
350
0 20 40 60 80 100
D86D7345D2887
Te
mpe
ratu
re,
C
% distilled
A-2
Figure C-2 – various distillation results for A-2 (POSF 10325)
100
150
200
250
300
350
0 20 40 60 80 100
D86D7345D2887
Te
mpe
ratu
re,
C
% distilled
A-3
Figure C-3 – various distillation results for A-3 (POSF 10289)
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As mentioned earlier, ASTM D86 is not a “true” boiling curve as might be obtained from a distillation column in a refinery – it is
a relatively crude distillation. Riazi ([6], with data from [37]) shows a comparison of a D86 and true boiling curve in Figure C-4
reproduced below.
Figure C-4 – comparison of D86 and true boiling curve.
There are correlation equations for converting D86 curves into true boiling curves ([36] referenced in [6]). The equation is:
TBP = a(ASTM D86)b, where
Vol % a b
0 0.9177 1.0019
10 0.5564 1.0900
30 0.7617 1.0425
50 0.9013 1.0176
70 0.8821 1.0226
90 0.9552 1.0110
95 0.8177 1.0355
This equation is valid for initial boiling points from 20-320 C and final boiling points from 75-400 C, so it includes jet fuels. The
resulting estimate for true boiling point resembles the ASTM D2887 data, and does behave similarly to Figure C-4, as shown in
Figure C-5. So, if one needed true boiling point data for some type of combustion modeling, one could use ASTM D2887 data in
place of the Reference 36 calculation, if desired. This appears to validate the point seen in Figure 6-2 and 6-3, where the D2887
data appears to closely mimic the actual boiling point for simple three-component mixtures.
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100
150
200
250
300
350
0 20 40 60 80 100
D86D2887D7345TBP calc [36]
Te
mpe
ratu
re,
C
% distilled
A-2
Figure C-5 – addition of estimated true boiling point calculated point to A-2 (POSF 10325) distillation data.
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Appendix D – GCxGC for previous reference fuels (Section IV)
6169 4658 5699 3773 4177
Weight % Weight
% Weight % Weight % Weight %
Aromatics
Alkylbenzenes
benzene (C06) 0.02 <0.01 <0.01 0.00 0.00
toluene (C07) 0.14 0.16 0.08 0.06 0.10
C2-benzene (C08) 0.81 0.78 0.63 0.69 0.64
C3-benzene (C09) 2.69 2.24 3.21 3.64 1.82
C4-benzene (C10) 3.22 3.02 3.91 3.48 2.88
C5-benzene (C11) 2.32 2.48 2.63 2.31 2.79
C6-benzene (C12) 1.69 1.93 1.80 4.99 6.38
C7-benzene (C13) 1.01 1.19 1.08
C8-benzene (C14) 0.61 0.89 0.63
C9+-benzene (C15+) 0.36 1.00 0.22
C10+-benzene (C16+) 0.06
Total Alkylbenzenes 12.87 13.69 14.25 15.17 14.60
Alkylnaphthalenes
C0-naphthalene (C10) 0.16 0.12 0.07 0.15 0.16
C1-naphthalene (C11) 0.47 0.42 0.27 0.61 0.52
C2-naphthalene (C12) 0.64 0.60 0.40 1.59 0.83
C3-naphthalene (C13) 0.30 0.40 0.16
C4+-naphthalene (C14+) 0.18 0.23 0.05
Total Alkylnaphthalenes 1.76 1.76 0.96 2.35 1.51
Cycloaromatics (Indans, Tetralins,etc.)
cycloaromatic-C09 0.05 0.04 0.06
cycloaromatic-C10 0.41 0.43 0.45
cycloaromatic-C11 0.83 1.13 1.08
cycloaromatic-C12 1.08 1.63 1.40
cycloaromatic-C13 1.10 1.45 1.04
cycloaromatic-C14 0.40 0.71 0.33
cycloaromatics-C15+ 0.14 0.41 0.08
Total Cycloaromatics 4.02 5.79 4.43 2.47 4.31
Total Aromatics 18.65 21.25 19.64 19.99 20.42
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6169 4658 5699 3773 4177
Paraffins
iso-Paraffins
C07 and lower-iso 0.21 0.23 0.17 0.14 0.20
C08-isoparaffins 0.45 0.56 0.44 0.35 0.32
C09-isoparaffins 1.88 1.08 1.51 1.68 0.83
C10-isoparaffins 5.40 3.59 5.92 6.33 3.43
C11-isoparaffins 7.04 5.12 7.01 6.86 4.97
C12-isoparaffins 5.68 5.31 5.55 5.95 5.76
C13-isoparaffins 4.88 5.25 5.00 4.46 5.47
C14-isoparaffins 3.93 4.44 3.83 3.38 2.97
C15-isoparaffins 2.38 3.10 2.10 1.85 1.20
C16-isoparaffins 0.82 1.66 0.59 0.68 0.43
C17-isoparaffins 0.29 0.69 0.33 0.33 0.57
C18-isoparaffins 0.09 0.19 0.04
C19-isoparaffins 0.03 0.08 0.02
C20-isoparaffins <0.01 0.02 <0.01
C21-isoparaffins <0.01 <0.01 <0.01
C22-isoparaffins <0.01 <0.01 <0.01
C23-isoparaffins <0.01 <0.01 <0.01
C24-isoparaffins <0.01 <0.01 <0.01
Total iso-Paraffins 33.11 31.34 32.53 32.00 26.14
n-Paraffins
n-C07 0.13 0.15 0.13 0.06 0.07
n-C08 0.55 0.54 0.52 0.39 0.32
n-C09 1.84 1.14 1.94 2.14 0.71
n-C10 4.26 2.55 5.30 3.66 1.76
n-C11 4.53 3.62 5.20 4.01 3.02
n-C12 4.06 3.70 4.48 3.32 2.92
n-C13 3.07 2.86 3.44 2.74 2.13
n-C14 2.09 2.17 2.16 2.00 1.08
n-C15 0.89 1.28 0.74 1.05 0.42
n-C16 0.30 0.61 <0.01 0.34 0.18
n-C17 0.11 0.27 0.06
n-C18 0.03 0.05 0.02
n-C19 <0.01 0.02 <0.01
n-C20 <0.01 <0.01 <0.01
n-C21 <0.01 <0.01 <0.01
n-C22 <0.01 <0.01 <0.01
n-C23 <0.01 <0.01 <0.01
Total n-Paraffins 21.87 19.00 24.02 19.72 12.62
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Cycloparaffins
Monocycloparaffins
C1-monocyclo (C07) 0.18 0.20 0.14
C2-monocyclo (C08) 0.55 0.69 0.39
C3-monocyclo (C09) 1.79 1.67 1.45
C4-monocyclo (C10) 3.64 3.26 4.00
C5-monocyclo (C11) 4.17 4.11 4.34
C6-monocyclo (C12 3.75 4.07 3.96
C7-monocyclo (C13) 3.70 3.65 3.01
C8-monocyclo (C14) 1.74 2.43 1.84
C9-monocyclo (C15) 0.77 1.55 0.72
C10-monocyclo (C16) 0.23 0.64 0.14
C11-monocyclo (C17) 0.07 0.28 0.04
C12-monocyclo (C18) 0.01 0.06 <0.01
C13+-monocyclo (C19+) 0.01 0.03 0.01
Total Monocyclopar. 20.63 22.64 20.05 22.23 28.48
Dicycloparaffins
C08-dicycloparaffins 0.03 0.02 0.02
C09-dicycloparaffins 0.23 0.29 0.22
C10-dicycloparaffins 0.70 0.43 0.49
C11-dicycloparaffins 1.33 1.26 0.95
C12-dicycloparaffins 1.30 1.22 0.81
C13-dicycloparaffins 1.22 1.42 0.77
C14-dicycloparaffins 0.65 0.82 0.37
C15+-dicycloparaffins 0.13 0.21 0.06
C16-dicycloparaffins 0.02 <0.01
C17+-dicycloparaffins 0.03 <0.01
Total Dicycloparaffins 5.59 5.73 3.71 6.06 12.34
Tricycloparaffins
C10-tricycloparaffins 0.02 <0.01 <0.01
C11-tricycloparaffins 0.11 0.05 0.05
C12-tricycloparaffins 0.03 <0.01 <0.01
Total Tricycloparaffins 0.16 0.05 0.05
Total Cycloparaffins 26.38 28.42 23.81 28.29 40.82
Average Molecular Formula - C 11.69 11.3
Average Molecular Formula - H 22.62 22.1