High-Accuracy, Temperature Dependent Density and Viscosity

Feb 23, 2018 - a Rackett equation, and the compressed-liquid density data have been fit to a ... of the TDF, while creating a fuel with a lower viscos...
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High-Accuracy, Temperature Dependent Density and Viscosity Measurements of a 50/50 JP-10 + Terpene Mixture Stephanie L. Outcalt* and Tara J. Fortin Material Measurement Laboratory, Applied Chemicals and Materials Division, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305-3337, United States ABSTRACT: Densities of a 50/50 by volume mixture of JP-10 + a turpentine dimer fuel (TDF) have been measured in the compressed-liquid state from 270 to 470 K and at 0.5−45 MPa and at ambient pressure from 263.15 to 373.15 K. Ambientpressure dynamic viscosity has also been measured over the same temperature range. The density data have been correlated with a Rackett equation, and the compressed-liquid density data have been fit to a Tait equation. Correlation parameters are given. Results of the mixture measurements presented here are compared with previously measured densities of the individual components, TDF and JP-10. Measurements of density over large ranges of temperature and pressure, as well as viscosity measurements, provide information as to the suitability of a fuel for use as a drop-in replacement for traditional petroleum-based fuels. The large range in temperature and pressure of the measurements is important to more closely capture engine operating conditions and better access the potential of alternative fuel candidates.

1. INTRODUCTION The effort to find renewable fuels, particularly in the aviation sector, has produced some viable candidates. Often, however, while the prototype fuel may have several desirable characteristics, it may also exhibit one or two that cause it to be outside specifications set forth for aviation fuels. Thus, the practice of blending renewable fuels with generic petroleum-based fuels to extend the supply of the petroleum-based fuel while still staying within specifications has become common. An example of this is the 50/50 mixture of S-8 (a synthetic fuel produced via the Fischer−Tropsch process) + JP-8, which has been used successfully in both commercial and military applications.1 Researchers at the United States Naval Air Warfare Center, Weapons Division, have developed several prototype fuels from renewable sources in an effort to replace or supplement the supply of traditional petroleum-based fuels with fuels that are sustainable, are more efficient, and have less adverse environmental impacts.2−10 One of those fuels, turpentine dimer fuel (TDF), is being investigated for possible use with the missile fuel JP-10. Unlike aviation turbine fuels, which can contain hundreds of hydrocarbons and are generally defined by their properties rather than their composition, missile fuels are synthesized from a very limited number of pure hydrocarbon compounds and are tailored to their operational use, with high energy density and high thermal stability as the primary requirements.11 JP-10 is essentially pure exo-tetrahydrodicyclopentadiene and exhibits high density, high volumetric net heat of combustion (NHOC), and favorable low-temperature properties.12 Although JP-10 represents an improvement over its predecessor, JP-9, it is still relatively costly to produce, whereas TDF has the potential to serve as a more affordable alternative given that it is derived from crude turpentine, a readily available, relatively low cost, feedstock. Furthermore, TDF has both an NHOC and a density very similar to those of JP-10.7 One drawback to the turpentine derived fuel is its high viscosity. In keeping with other U.S. Department of Defense biofuel blend testing programs, a 50/50 blend by volume of the TDF and JP-10 was formulated in an This article not subject to U.S. Copyright. Published XXXX by the American Chemical Society

effort to investigate taking advantage of the desirable properties of the TDF, while creating a fuel with a lower viscosity than the pure TDF.7 Ambient-pressure and compressed-liquid density (ρ) measurements, as well as ambient-pressure dynamic viscosity (η) measurements, are reported in this work. These measurements are critical to the evaluation of 50/50 JP-10 + TDF as a potential drop-in replacement for JP-10. The data can be used in the formulation of equations of state that can help to optimize new candidate fuels as drop-in substitutes and/or additives to traditional aviation kerosene. Compressed-liquid density data reported here have been extrapolated to 0.083 MPa to correlate a Rackett equation for density. Additionally, compressed-liquid densities have been correlated with a Tait equation. Parameters for both correlations are reported.

2. MATERIALS AND METHODS 2.1. Sample Liquid. The sample measured in this work was obtained from the China Lake Naval Air Warfare Center, Weapons Division (NAWCWD). The TDF was synthesized by the NAWCWD using a process that is described in detail in Meylemans et al.9 The mixture sample studied in this work was prepared by the NAWCWD in a 50/50 by volume ratio of TDF to JP-10. Prior to measurements of both the compressed-liquid density and the ambient-pressure density and dynamic viscosity, the sample was degassed following our standard procedure.13,14 First, sample was transferred to a secondary container (stainless steel cylinder and glass bulb for compressed-liquid and ambient-pressure measurements, respectively). The sample was then frozen by submerging the container in liquid nitrogen. The sample bottle was then opened to evacuate the vapor space. Once evacuated, the container was sealed and the sample was heated to drive any air that might still be entrained in the liquid phase into the vapor space. This “freeze−pump−thaw” cycle was repeated several times to ensure the complete removal of air from the Received: November 8, 2017 Revised: February 23, 2018

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DOI: 10.1021/acs.energyfuels.7b03467 Energy Fuels XXXX, XXX, XXX−XXX

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Table 1. Compressed-Liquid Densities of 50/50 JP-10 + TDFa 270 K p/MPa 45.01 39.99 35.01 30.00 24.99 20.00 14.99 9.99 4.99 4.00 3.00 2.00 1.00 0.50

a

290 K

ρ/kg·m−3 970.8 968.6 966.3 964.0 961.7 959.3 956.8 954.3 951.7 951.2 950.7 950.1 949.6 949.3 390 K

p/MPa

310 K

ρ/kg·m−3

44.96 40.00 34.99 30.00 25.00 20.00 15.00 9.99 4.99 3.99 2.99 1.99 0.99 0.50

958.0 955.7 953.3 950.8 948.2 945.6 943.0 940.2 937.4 936.8 936.2 935.6 935.1 934.8 410 K

330 K

350 K

370 K

p/MPa

ρ/kg·m−3

p/MPa

ρ/kg·m−3

p/MPa

ρ/kg·m−3

45.03 40.00 34.99 30.00 25.00 20.00 15.00 10.00 5.00 4.00 3.00 2.00 0.99 0.50

945.5 942.9 940.3 937.6 934.9 932.1 929.2 926.2 923.1 922.5 921.8 921.2 920.5 920.2

44.99 40.00 35.00 30.00 25.00 20.00 15.01 10.00 5.00 3.99 3.00 1.99 1.00 0.50

932.9 930.2 927.4 924.6 921.6 918.6 915.5 912.2 908.8 908.1 907.4 906.7 906.0 905.6

45.00 40.00 34.99 30.00 24.99 19.99 15.00 9.99 5.00 3.99 3.00 2.00 1.00 0.50 450 K

920.5 917.6 914.6 911.5 908.3 905.1 901.6 898.1 894.3 893.6 892.8 892.0 891.2 890.8

430 K

p/MPa 44.99 40.00 35.00 30.00 25.00 20.00 14.99 9.99 4.99 3.99 2.99 2.00 1.00 0.49 470 K

ρ/kg·m−3 908.3 905.2 902.0 898.7 895.2 891.7 887.9 884.0 879.9 879.1 878.2 877.3 876.4 876.0

p/MPa

ρ/kg·m−3

p/MPa

ρ/kg·m−3

p/MPa

ρ/kg·m−3

p/MPa

ρ/kg·m−3

p/MPa

ρ/kg·m−3

44.98 39.99 35.00 30.00 25.00 19.99 14.99 10.00 5.00 3.99 3.00 1.99 0.99 0.50

896.2 892.9 889.5 885.9 882.2 878.3 874.2 870.0 865.5 864.5 863.6 862.6 861.6 861.1

44.98 39.99 35.00 30.00 25.00 20.00 14.99 9.99 5.00 4.00 3.00 2.00 1.00 0.49

884.2 880.7 877.0 873.2 869.1 864.9 860.5 855.8 850.8 849.7 848.7 847.6 846.5 846.0

44.97 39.99 34.99 29.99 25.00 19.99 14.99 10.00 4.99 3.99 3.00 1.99 1.00 0.49

872.3 868.5 864.6 860.4 856.1 851.5 846.7 841.5 835.9 834.8 833.6 832.4 831.2 830.6

45.02 40.00 35.00 29.99 24.99 20.00 14.99 9.99 5.00 4.00 2.99 2.00 0.99 0.50

860.8 856.7 852.5 848.0 843.3 838.3 833.0 827.3 821.1 819.8 818.5 817.2 815.8 815.1

44.99 39.99 35.00 30.00 24.99 20.00 14.99 10.00 4.99 3.99 3.00 2.00 1.00 0.49

849.2 844.9 840.3 835.5 830.4 825.0 819.1 812.8 805.9 804.5 803.0 801.5 799.9 799.1

The combined expanded uncertainties, Uc, are Uc(T) = 30 mK, Uc(p) = 0.01 MPa, and Uc(ρ) = 0.81 kg·m−3 (level of confidence = 0.95).

Figure 1. Compressed-liquid densities of 50/50 JP-10 + TDF, JP-10,18 and TDF19 as a function of pressure.

B

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Table 2. Measured Densities (ρ̅) and Dynamic Viscosities (η)̅ and Calculated Kinematic Viscosities (ν)̅ of 50/50 JP-10 + TDF at Ambient Pressure T/K 263.15 268.15 273.15 278.15 283.15 288.15 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15 358.15 363.15 368.15 373.15

ρ̅/kg·m−3 956.27 952.60 948.92 945.22 941.52 937.87 934.17 930.48 926.77 923.08 919.43 915.73 912.05 908.33 904.67 900.98 897.28 893.58 889.85 886.13 882.40 878.68 874.95

t95a 2.035 2.035 2.035 2.035 2.035 2.035 2.035 2.036 2.036 2.037 2.037 2.037 2.037 2.037 2.037 2.038 2.038 2.038 2.037 2.037 2.038 2.038 2.038

U(ρ̅)b/kg·m−3 1.20 1.20 1.20 1.20 1.20 1.20 1.20 1.20 1.20 1.20 1.20 1.20 1.19 1.19 1.19 1.19 1.19 1.19 1.19 1.19 1.19 1.19 1.19

η̅/mPa·s 35.06 26.85 21.02 16.78 13.62 11.22 9.374 7.926 6.775 5.848 5.093 4.472 3.955 3.523 3.157 2.845 2.578 2.348 2.147 1.972 1.819 1.683 1.563

t95a 2.003 2.002 2.000 2.000 1.999 2.000 2.000 2.001 2.002 2.003 2.005 2.006 2.008 2.009 2.011 2.012 2.013 2.014 2.015 2.016 2.017 2.018 2.018

U(η̅)b/mPa·s 0.48 0.35 0.26 0.20 0.16 0.12 0.101 0.083 0.069 0.058 0.050 0.043 0.038 0.033 0.029 0.026 0.024 0.021 0.019 0.018 0.016 0.015 0.014

ν̅/mm2·s−1 36.66 28.18 22.15 17.75 14.46 11.97 10.04 8.518 7.310 6.335 5.539 4.883 4.337 3.878 3.489 3.158 2.873 2.627 2.413 2.226 2.061 1.916 1.787

U(ν̅)b/mm2·s−1 0.51 0.37 0.28 0.21 0.17 0.13 0.11 0.090 0.075 0.064 0.055 0.048 0.042 0.037 0.033 0.029 0.027 0.024 0.022 0.020 0.019 0.017 0.016

a

Coverage factor from the t-distribution for each corresponding degrees of freedom and a 95% level of confidence. bExpanded uncertainty at the 95% confidence level. sample: a total of three cycles for the compressed-liquid sample and five cycles for the ambient-pressure sample. 2.2. Experimental Procedures. Densities in the compressed-liquid state were measured with the instrument described in Outcalt and McLinden.15 The main component of the apparatus is a commercial vibrating-tube densimeter. The uncertainty of the measurements obtained from the instrument have been minimized and better quantified through several improvements to the standalone densimeter. Some of those include housing the commercial instrument in a specially designed thermostat, making the temperature and pressure measurements with more accurate instrumentation than that provided in the commercial density meter, and improved calibration (incorporating high-purity propane and toluene as calibration fluids) and operating procedures. Temperature control and pressure control of the instrument are completely automated as well as data acquisition. The overall combined uncertainty in density is 0.81 kg·m−3, corresponding to a relative uncertainty in density of 0.08−0.10%. This uncertainty represents a 95% confidence level. In this work, we measured 11 isotherms over the range 0.5−45 MPa. Ambient-pressure (∼0.083 MPa in Boulder, CO) density and dynamic viscosity were simultaneously measured over the temperature range 263.15−373.15 K using a commercial viscodensimeter that combines a vibrating-tube densimeter in series with a Stabinger rotating concentric cylinder viscometer. Whereas the vibrating tube in the compressed-liquid instrument is made of Hastelloy to allow for measurements at elevated pressure, the vibrating tube in the viscodensimeter is made of borosilicate glass. Both the density and viscosity measurement cells are housed in a single thermostated copper block whose temperature is controlled using thermoelectric Peltier elements, an integrated Pt-100 resistance thermometer, and an external circulating bath (for measurements below 273.15 K). The viscometer was adjusted using a combination of four certified viscosity reference standards (CVRS) from Cannon Instrument Co. (S3, N14, N44, and N415). (Commercial equipment, instruments, or materials are identified only in order to adequately specify certain procedures. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology,

nor does it imply that the products identified are necessarily the best available for the purpose.) The viscosities of these standards ranged from a minimum of 0.9331 mPa·s (S3 at 373.15 K) to a maximum of 1148 mPa·s (N415 at 293.15 K). The densimeter was adjusted using air and two CVRS (N14 and N44) covering the range from 0.78 kg·m−3 (air at 373.15 K and 83 kPa) to 828.0 kg·m−3 (N44 at 293.15 K). It should be noted that a proprietary, built-in viscosity correction was applied to all ambient-pressure density data reported herein ranging in magnitude from 0 to 0.8 kg·m−3. For measurements, previously degassed sample was transferred to a gastight glass syringe for injection into the instrument in approximately 3 mL aliquots. After each injection, a programmed scan was performed from 263.15 to 373.15 K in 5 K increments; a total of six injections/scans were made for the JP-10 + TDF sample. Additional details about the viscodensimeter and its adjustment and calibration can be found in Laesecke et al.16 and Fortin et al.17

3. RESULTS AND DISCUSSION Compressed-liquid densities from 270 to 470 K at pressures to 45 MPa are listed in Table 1. Figure 1 shows the data in Table 1, as well as previously measured data for the components JP-1018 and TDF19 as a function of pressure. The JP-10 and TDF were measured at the same temperatures reported here for the mixture: JP-10 to pressures of 30 MPa and the TDF to 50 MPa. Figure 1 illustrates that the densities of JP-10, TDF, and the 50/ 50 mixture are all within 10 kg·m−3 of one another at similar state points. It can also be seen that there is a crossover in the densities of the three samples; at the lower temperatures (toward the top of the plot) the order of densities is JP-10 > 50/50 mixture > TDF. At approximately 390 K the order becomes 50/50 mixture > JP-10 > TDF. Finally, at 470 K the densities follow the order 50/50 mixture > TDF > JP-10. This is indicative of the JP-10 density having a much stronger temperature dependence than that of the terpene. C

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Measurement results for density (ρ̅) and dynamic viscosity (η)̅ at ambient pressure are presented in Table 2. Tabulated property values are averages of the six temperature scans. Associated expanded uncertainties (U(ρ̅) and U(η̅)) are also included. These are calculated by multiplying the combined standard measurement uncertainty by the coverage factor corresponding to a 95% confidence level. Corresponding coverage factors (t95) are included in Table 2 for clarity. The resulting expanded uncertainties range from 1.19 to 1.20 kg·m−3 (0.13−0.14%) and from 0.014 to 0.48 mPa·s (0.89−1.4%) for density and dynamic viscosity, respectively. Additional details regarding the density and dynamic viscosity uncertainty analysis can be found in the Supporting Information of Fortin et al.17 Also shown in Table 2 are calculated kinematic viscosities (ν)̅ and their associated expanded uncertainties (U(ν)). ̅ Kinematic viscosity is calculated using the following expression: η ν= ρ (1)

328 K. Finally, the measured ambient-pressure density of the JP10 + TDF at 288.15 K presented here is 937.87 kg·m−3; this is within the allowable limits of the military specification for the density of JP-10 (MIL-DTL-87107D)20 at 288.15 K, which ranges from 935 to 943 kg·m−3. The dynamic viscosity results reported in Table 2 are plotted as a function of temperature in Figure 3. Previously measured

Kinematic viscosity expanded uncertainties are calculated using standard propagation of error methods. Ambient-pressure density results reported in Table 2 are plotted as a function of temperature in Figure 2. For comparison,

Figure 3. Dynamic viscosities of 50/50 JP-10 + TDF as a function of temperature at atmospheric pressure. Previously determined dynamic viscosities for pure JP-10,12 as well as literature values for 50/50 JP-10 + TDF7 and pure TDF,7 are shown for comparison.

viscosity values for pure JP-10,12 as well as literature values for 50/50 JP-10 + TDF7 and pure TDF,7 are also shown for comparison. The JP-10 viscosity values represented in Figure 3 were calculated using the authors’ reported viscosity correlation derived using data from the identical viscodensimeter employed in this work. The 50/50 JP-10 + TDF values were calculated using the authors’ reported correlation.7 In contrast to what was observed with density, the dynamic viscosity of JP-10 is lower than that of the 50/50 JP-10 + TDF mixture over the entire temperature range: deviations span from −82.0% at 263.15 K to −41.2% at 373.15 K. Also in contrast to the density observations, the dynamic viscosity of pure TDF is significantly higher than that of the 50/50 JP-10 + TDF mixture, with deviations spanning a couple orders of magnitude between 263.15 and 303.15 K. The deviations in viscosity values between the work of Meylemans et al.7 and this work range from −36.8% at 263.15 K to −11.9% at 303.15 K, significantly larger than the reported uncertainties. Similarly large deviations were observed for JP-10. Previous measurements made using the same instrument employed in this work indicate a viscosity of 6.313 mPa·s−1 at 263.15 K,12 while Meylemans et al.7 report a value of 3.78 mPa·s−1 at the same temperature, corresponding to a difference of −40.1%. When compared to values found in the Handbook of Aviation Fuel Properties,11 the above JP-10 viscosities at 263.15 K deviate by approximately +5% for the work of Bruno et al.12 and by approximately −37% for the work of Meylemans et al.7 Additional work is required to determine whether these large deviations can be definitively attributed to differences in

Figure 2. Densities of 50/50 JP-10 + TDF as a function of temperature at atmospheric pressure. Previously determined ambient-pressure densities for pure JP-1012,18 are also shown for comparison.

previously measured density values for pure JP-1012 are also shown in Figure 2. The JP-10 values represented in Figure 2 were calculated using the authors’ reported density correlation. The experimental data used to develop the reported correlation were obtained from two separate instruments: one was the identical viscodensimeter employed in this work and the other was a commercial density and sound speed analyzer. Like the viscodensimeter, the density and sound speed analyzer utilizes a vibrating-tube densimeter made of borosilicate glass and measures at atmospheric pressure, but its temperature range is more limited (278.15−343.15 K). At 263.15 K, JP-10 has a density that is 0.28% higher than that of the 50/50 JP-10 + TDF mixture, while at 373.15 K JP-10 has a density that is 0.27% lower than that of the mixture. The crossover from higher to lower densities for JP-10 relative to the mixture occurs at approximately D

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instrumentation and/or measurement practices or to changes in sample composition that may have resulted from issues with sample handling or shelf life. The military specification for JP-1020 allows for a maximum dynamic viscosity of 10 mPa·s−1 at 255.15 K. The lowest temperature measured in this work is 263.15 K, at which the viscosity is 35.06 mPa·s−1. As such, it is not feasible that the 50/ 50 JP-10 + TDF mixture would meet the viscosity specifications at 255 K.

The resulting correlation parameters and their associated standard deviations are listed in Table 3. The original Rackett equation21 relates the reduced volume of a given saturated liquid to the reduced temperature of the liquid as well as the compressibility factor. In eq 2, parameters β1 and β3 are loosely representative of the critical density and critical temperature of the fluid being fitted. Figure 4 illustrates the deviations of the density data extrapolated from the compressed-liquid measurements as well as the measured ambient-pressure densities from the Rackett correlation. Vertical error bars indicate that the agreement between the two sets of data are within the combined uncertainties with better agreement at higher temperatures. Compressed-liquid density data were correlated with a Tait equation similar to that of Dymond and Malhotra22 of the form

4. CORRELATION OF DATA To validate the internal consistency of the ambient-pressure densities and the compressed-liquid densities reported here, the Table 3. Parameters of the Rackett Correlation for 50/50 JP10 + TDF parameter

value

std dev

β1 (kg·m−3) β2 β3 (K) β4

166.1 0.382 746.2 0.4650

0.9 1.0 × 10−3 0.7 9.6 × 10−4

1 − C ln

β4 )

p + D(T ) pref + D(T )

(3)

where ρref(T) is the temperature-dependent density at the reference pressure pref = 0.083 MPa calculated from a Rackett correlation of just the extrapolated data. The temperature dependence of the parameter C was not included because it was possible to fit the data within their experimental uncertainties without it. The temperature dependence of the Tait parameter D(T) was expressed by a quadratic polynomial:

compressed-liquid densities were extrapolated to ambient pressure (0.083 MPa, atmospheric pressure at NIST in Boulder, CO). The extrapolated data were obtained by fitting secondorder polynomials to the isothermal densities at pressures less than or equal to 10 MPa and then calculating the densities at 0.083 MPa from the polynomials. Data above 10 MPa were excluded from the formulation of the polynomial to avoid the curvature introduced at the higher pressures and thus more accurately predict the density at atmospheric pressure. The density values extrapolated to 0.083 MPa from measured compressed-liquid data presented in this work, in addition to the measured ambient-pressure densities, were correlated with a Rackett-type equation. The equation is written as ρ = β1β2−(1 + (1 − T / β3)

ρref (T , pref )

ρ (T , p) =

D(T ) = D1 + D2Tr + D3Tr 2

(4)

where Tr is the absolute temperature T divided by 273.15 K. The compressed-liquid density data are fit with an average absolute deviation (AAD) of 0.01% with the parameters for the Rackett correlation of the extrapolated density data and the corresponding Tait parameters given in Table 4.

5. CONCLUSIONS Compressed-liquid densities, ambient-pressure densities, and ambient-pressure dynamic viscosities of a 50/50 by volume sample of JP-10 + TDF have been measured. Compressed-liquid densities extrapolated to ambient pressure agree with the

(2)

Figure 4. Percent deviations of measured and extrapolated density data from Rackett correlation. E

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Table 4. Parameters of the Rackett Correlation and Tait Correlation of the Compressed-Liquid Density Data for 50/50 JP-10 + TDF Rackett

Tait

parameter

value

std dev

parameter

value

std dev

β1 (kg·m−3) β2 β3 (K) β4

161.9 0.3775 757.0 0.4635

0.2 3 × 10−4 0.2 3 × 10−4

C D1 D2 D3

7.777 × 10−2 385.3 −325.2 71.96

5 × 10−5 0.3 0.3 09 × 10−2

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measured ambient-pressure densities within experimental uncertainties. The ambient-pressure density data measured in this work are within the military specification (MIL-DTL87107D)20 and, as such, support the potential of the JP-10 + TDF being used as a drop-in replacement for JP-10. To facilitate calculations for design and engineering purposes, the measured compressed-liquid densities of the JP-10 + TDF mixture presented here have been correlated with a Tait equation. The correlation represents the data with an AAD of 0.01%. This is well within the experimental uncertainty. The 50/50 JP-10 + TDF blended fuel exhibits viscosities significantly lower than the too-viscous pure TDF, however, not low enough to meet the military specification for JP-10.20 A blend higher in JP-10 would potentially have a viscosity that meets specifications, but would rely more heavily on the existing petroleum-based component. The inability of the 50/50 JP-10 + TDF mixture to meet the viscosity specification does not necessarily speak to the viability of the mixture as a replacement fuel for pure JP-10. Unlike most aviation fuels, JP-10 is essentially a single molecule fluid (exo-tetrahydrodicyclopentadiene). Because of this, the range of density and viscosity in the specification for JP-10 is much more narrow than for most other aviation fuels and it might not be the best metric against which to compare potential replacements.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Stephanie L. Outcalt: 0000-0001-8143-7316 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We acknowledge the assistance of Dr. Benjamin Harvey at China Lake NAWCWD for providing the JP-10 + TDF sample and for many helpful comments and insights regarding this mixture and the work of his group.

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REFERENCES

(1) Sniderman, D. New Options Emerge for Aviation Fuel. https:// www.asme.org/engineering-topics/articles/aerospace-defense/newoptions-emerge-for-aviation-fuel. (2) Harrison, K. W.; Harvey, B. G. Renewable high density fuels containing tricyclic sesquiterpanes and alkyl diamondoids. Sustainable Energy & Fuels 2017, 1 (3), 467−473. (3) Harvey, B. G.; Merriman, W. W.; Koontz, T. A. High-Density Renewable Diesel and Jet Fuels Prepared from Multicyclic Sesquiterpanes and a 1-Hexene-Derived Synthetic Paraffinic Kerosene. Energy Fuels 2015, 29 (4), 2431−2436. (4) Harvey, B. G.; Meylemans, H. A.; Gough, R. V.; Quintana, R. L.; Garrison, M. D.; Bruno, T. J. High-density biosynthetic fuels: the F

DOI: 10.1021/acs.energyfuels.7b03467 Energy Fuels XXXX, XXX, XXX−XXX