Analyzing the Relative Impact of Spray and Volatile Fuel Properties on Gas Turbine Combustor Ignition in Multiple Rig Geometries

Opacich, Katherine C.; Heyne, Joshua S.; Peiffer, Erin; Stouffer, Scott D.

doi:10.2514/6.2019-1434

Cited by 15 publications

(8 citation statements)

References 9 publications

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“…Cetane number of the blend increased well above the range of conventional jet fuel (CN of 64), while surface tension decreased below the typical range. The latter may have positive implications on ignition quality due to improved (decreased droplet size) fuel spray properties ( 59 ).…”

Section: Resultsmentioning

confidence: 99%

Toward net-zero sustainable aviation fuel with wet waste–derived volatile fatty acids

Huq

Hafenstine

Huo

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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With the increasing demand for net-zero sustainable aviation fuels (SAF), new conversion technologies are needed to process waste feedstocks and meet carbon reduction and cost targets. Wet waste is a low-cost, prevalent feedstock with the energy potential to displace over 20% of US jet fuel consumption; however, its complexity and high moisture typically relegates its use to methane production from anaerobic digestion. To overcome this, methanogenesis can be arrested during fermentation to instead produce C2 to C8 volatile fatty acids (VFA) for catalytic upgrading to SAF. Here, we evaluate the catalytic conversion of food waste–derived VFAs to produce n-paraffin SAF for near-term use as a 10 vol% blend for ASTM “Fast Track” qualification and produce a highly branched, isoparaffin VFA-SAF to increase the renewable blend limit. VFA ketonization models assessed the carbon chain length distributions suitable for each VFA-SAF conversion pathway, and food waste–derived VFA ketonization was demonstrated for >100 h of time on stream at approximately theoretical yield. Fuel property blending models and experimental testing determined normal paraffin VFA-SAF meets 10 vol% fuel specifications for “Fast Track.” Synergistic blending with isoparaffin VFA-SAF increased the blend limit to 70 vol% by addressing flashpoint and viscosity constraints, with sooting 34% lower than fossil jet. Techno-economic analysis evaluated the major catalytic process cost-drivers, determining the minimum fuel selling price as a function of VFA production costs. Life cycle analysis determined that if food waste is diverted from landfills to avoid methane emissions, VFA-SAF could enable up to 165% reduction in greenhouse gas emissions relative to fossil jet.

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Section: Resultsmentioning

confidence: 99%

Toward net-zero sustainable aviation fuel with wet waste–derived volatile fatty acids

Huq

Hafenstine

Huo

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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“…Mayhew (2018) observed correlation between ignition probabilities at cold altitude relight conditions in a derivative of the RR and each of four fuel properties: viscosity, surface tension, T 20 , and flash point. Opacich et al (2019) observed similar correlations within datasets derived from both the RR and the APU-CR, although vapor pressure and heat capacity were chosen instead of T 20 and flash point to represent volatile properties. Part of this work is a direct follow-up of work introduced by Opacich et al…”

Section: Background Previous Workmentioning

confidence: 68%

Comparing Alternative Jet Fuel Dependencies Between Combustors of Different Size and Mixing Approaches

2021

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Analyses used to reveal fuel dependencies on lean blow out and ignition at specific operating conditions in specific combustors show inconsistent trends with each other. Such variety is however consistent with the occurrence of transitions between the governing physical phenomena as the ratios between evaporation, mixing, or chemical time scales with their respective residence times also vary with specific operating conditions and combustor geometry. It is demonstrated here that the fuel dependencies on LBO in a large, single-cup, swirl-stabilized, rich-quench-lean combustor varies with operating conditions such that a feature importance match is attained to fuel dependencies observed in a much smaller combustor at one end of the tested range, while a qualitative match to fuel dependencies observed in a lean, premixed, swirler-stabilized combustor of comparable size at the other end of the tested range. The same reference combustor, when tested at cold conditions, is shown to exhibit similar fuel dependencies on ignition performance as the much smaller combustor, when tested at both cold and warm conditions. The practical significance of these findings is that a reference rig, such as the Referee Rig, can capture fuel performance trends of proprietary industry combustors by tailoring the inlet air and fuel temperatures of the tests. It is, therefore, a trustworthy surrogate for screening and evaluating sustainable aviation fuel candidates, reducing the dependency on proprietary industrial combustors for this purpose, thereby increasing transparency within the evaluation process while also expediting the process and reducing cost and fuel volume.

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“…Surrogates that mimic jet fuel properties have been used historically to understand combustion phenomena, while here we report potentially worst case fuel compositions. Previous efforts from the NJFCP program have shown that certain fuel properties (σ, µ, and ρ) have more of an impact on predicting ignition probabilities [14,15,30]. SAF approval could benefit from the manipulation instead of mimicking surrogate properties to illustrate the complex physical competition of properties.…”

Section: Resultsmentioning

confidence: 99%

“…Ignition probability, a metric to determine successful ignitions, is used in gas turbine combustion where turbulence and stochasticity exist. Furthermore, viscosity, density, and surface tension have a larger impact than vapor pressure and specific heat capacity on ignition behavior for both the Referee Rig and Honeywell APU [15]. At higher fuel temperatures, surface tension is the most important property to predict relative ignitability in the Honeywell APU.…”

Section: Introductionmentioning

confidence: 99%

“…Recent RFR efforts into gas turbine combustor ignition and the relative impact of spray and volatile fuel properties indicate that the down-selected properties of viscosity, density, surface tension, vapor pressure, and specific heat capacity nearly capture the variance in ignition probability [15]. Ignition probability, a metric to determine successful ignitions, is used in gas turbine combustion where turbulence and stochasticity exist.…”

Section: Introductionmentioning

confidence: 99%

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Orthogonal Reference Surrogate Fuels for Operability Testing

2020

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The approval and evaluation process for sustainable aviation fuels (SAF) via ASTM D4054 is both cost- and volume-intensive, namely due to engine operability testing under severe conditions. Engine operability tests of combustor under figures of merit (FOM) limit phenomena are the fuel effects on lean blowout, high-altitude relight, and cold-start ignition. One method to increase confidence and reduce volume in tiered testing is to use surrogate fuels for manipulation of properties. Key fuel performance properties (surface tension, viscosity, density) for cold-start ignition was determined prior to this study. Prior work regarding this FOM has not considered the combination of these properties. A surface tension blending rule was validated and incorporated into the jet fuel blend optimizer (JudO). A generalized surrogate calculator for N-dimensional surrogate components and features was developed. Jet fuel surrogates developed in this study were a mixture of conventional and sustainable aviation fuels instead of pure components. These surrogates suggested to be tested in this study could illuminate near worst-case effects for sustainable aviation fuel in a given configuration/rig. With those scenarios tested, we can further understand the influence on the key properties relative to cold-start ignition. This work and supporting experimental evidence could potentially lower the barrier for SAF approval processes.

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Analyzing the Relative Impact of Spray and Volatile Fuel Properties on Gas Turbine Combustor Ignition in Multiple Rig Geometries

Cited by 15 publications

References 9 publications

Toward net-zero sustainable aviation fuel with wet waste–derived volatile fatty acids

Toward net-zero sustainable aviation fuel with wet waste–derived volatile fatty acids

Comparing Alternative Jet Fuel Dependencies Between Combustors of Different Size and Mixing Approaches

Orthogonal Reference Surrogate Fuels for Operability Testing

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