Hydroprocessed Esters And Fatty Acids Research Articles

Combustion kinetics of alternative jet fuels, Part-I: Experimental flow reactor study

A comprehensive collection of technical aviation fuels enabled an experimental and numerical study on detailed combustion chemistry and pollutant formation presented in a series of 3 interlinking parts. Part-I: Experimental Flow Reactor Study focuses on the characterization of 42 technical jet fuels and provides experimental speciation data for model development presented in Part-II: Model and Surrogate Strategy. Model validation based on the presented technical fuels here is presented in Part-III: Model Application on Technical Jet Fuels.The fuels investigated in this study cover a broad range of approved SAFs (Sustainable Aviation Fuels), candidates for approval, and technical products outside the present ASTM-D7566 specification and is completed by reference fuels (ASTM-D1655). This includes SAF components such as HEFA (Hydroprocessed Esters and Fatty Acids), ATJ (Alcohol-To-Jet), SIP (Synthesized Iso-Paraffins), and Fischer-Tropsch-products as well as their blends.A systematic investigation of the soot precursor chemistry by analyzing the influence of the complex chemical fuel composition on the intermediate species pool is presented. The experimental set-up consists of an atmospheric flow reactor with coupled molecular-beam mass spectrometer (MBMS). Quantitative evolution of combustion reaction intermediates is recorded for fuel-rich (Φ = 1.2) and fuel-lean (Φ = 0.8) conditions at intermediate temperatures up to 1200 K including small intermediate species (e.g. ethylene, butene) and soot precursor species (e.g. benzene, naphthalene, phenanthrene).A general systematic dependency of the soot precursor concentration on the degree of unsaturation (Index of Hydrogen Deficiency) or the hydrogen content, respectively, is demonstrated. Furthermore, larger soot precursor concentrations depend on the naphthalene content of the fuel.

Process simulation and techno-economic assessment of Salicornia sp. based jet fuel refinery through Hermetia illucens sugars-to-lipids conversion and HEFA route

Succulent halophyte Salicornia sp. was characterized to evaluate its suitability for biorefinery, as soil salinization is seen as a major agricultural issue and the demand for biofuel is increasing. Green fractionation of biomass approach was chosen, with liquid and solid fractions of the biomass considered separately. Soxhlet extractions were used to separate different biochemical groups from the pulp, and the lignocellulosic residue was hydrothermally pretreated, enzymatically hydrolyzed, mixed with an existing agricultural feedstock, and fed to black soldier fly larvae (BSFL) for sugars-to-lipids conversion. The ASTM approved route of hydroprocessed esters and fatty acids (HEFA) was applied using in silico study of processing BSFL lipids to sustainable jet fuel, using SuperPro Designer and Aspen HYSYS. Simulations and techno-economic assessment showed, with the applied process routes, inputs and production rates, the biorefinery process will be profitable in 7 years, with a biomass input flow rate of over 60 ton h−1Salicornia sp. with decreasing payback time as the biomass input flow rate increases. Therefore, Salicornia sp. feedstock and sugars-to-lipids conversion method for biorefinery and liquid fuel production can function as a feasible biorefinery process with a normalized CO2-e reduction of HEFA-SPK of 95.5% compared to similar fossil fuels.

Performance and Emissions of a Microturbine and Turbofan Powered by Alternative Fuels

Alternative fuels containing biocomponents produced in various technologies are introduced in aviation to reduce its carbon footprint but there is little data describing their impact on the performance and emissions of engines. The purpose of the work is to compare the performance and gas emissions produced from two different jet engines—the GTM-140 microturbine and the full-size DGEN380 turbofan, powered by blends of Jet A-1 and one of two biocomponents: (1) Alcohol-to-Jet (ATJ) and (2) Hydroprocessed Esters and Fatty Acids (HEFA) produced from used cooking oil (UCO) in various concentrations. The acquired data will be used to develop an engine emissivity model to predict gas emissions. Blends of the mineral fuel with synthetic components were prepared in various concentrations, and their physicochemical parameters were examined in the laboratory. Measurements of emissions from both engines were carried out in selected operating points using the Semtech DS gaseous analyzer and the EEPS spectrometer. The impact of tested blends on engine operating parameters is limited, and their use does not carry the risk of a significant decrease in aircraft performance or increase in fuel consumption. Increasing the content of biocomponents causes a noticeable rise in the emission of CO and slight increase for some other gasses (HC and NOx), which should not, however, worsen the working conditions of the ground personnel. This implies that there are no contraindications against using tested blends for fuelling gas-turbine engines.

Strategic assessment of sustainable aviation fuel production technologies: Yield improvement and cost reduction opportunities

The aviation industry has been studying strategies to produce sustainable aviation fuels (SAF) for over ten years. Our objective is to conduct detailed techno-economic analyses (TEA) of six SAF production technologies and to develop a simplified cost estimation method. Triglyceride based Hydroprocessed esters and fatty acids (HEFA) was compared against five lignocellulose-based technologies using standardized criteria. TEA was conducted to determine minimum fuel selling price (MFSP). The base case annual product capacity was fixed at 60 million liters of total fuel, for which SAF MFSPs ranged from 0.88 to 3.86 $ L−1 of fuel. Triglyceride-based HEFA had the best economic performance. Although triglycerides are more expensive than lignocellulose, HEFA is still a very competitive technology due to its high fuel yield (86–91% of feedstock) and low MFSP. Lignocellulosic-based technologies have lower fuel yields (9–23% of feedstock) due to high oxygen content of initial feedstock, resulting in higher fuel cost per unit of fuel. In order to reach a market fuel price, SAF yields from lignocellulosic materials needs to achieve an estimated value of 60%. Such yields are only possible if carbon efficiencies are close to 100%. Therefore, efforts are needed to avoid the removal of oxygen as CO2. Based on these considerations, a new scheme is proposed for SAF production that could result in yields near those needed to achieve cost targets. This proposed integrated biomass/natural gas hybridized concepts to produce inexpensive SAFs should be thoroughly investigated in future work.

Comparison of three different analytical protocols for 2019 updated D2425 method for renewable jet fuel product certification analysis

ASTM standard specification D7566 covers the manufacture of synthetic aviation turbine fuel components and their blends with conventional Jet fuel (Jet A or Jet A-1). One of the components is renewable jet fuel (RJF) which is synthetic paraffinic kerosene (SPK) made from hydroprocessed esters and fatty acids (HEFA). The specification D7566 dictates property requirements for the SPK-HEFA, including concentration limits for selected hydrocarbon types (paraffins, cycloparaffins, and aromatics), which are analyzed by using the mass spectrometry (MS) based standard method D2425. The most recent update for D2425 released in 2019 includes the synthetic hydrocarbon sample type (e.g., SPK-HEFA) and defines various analytical procedures for the analysis. Notably, the procedures differ considerably from each other, and the experimental conditions are not defined in details. This leads to laboratories setting up analytical schemes for D2425 that are likely to differ from each other, which may result in variation in the quality of the results obtained in different laboratories.In the present study, the performances of D2425 analytical protocols set up by three laboratories were tested in certification analysis (D7566) of SPK-HEFA type RJF. The tested analytical protocols were proven to comply with the requirements of the 2019 version of the D2425 standard. Furthermore, the precisions of the protocols did not differ significantly from each other. However, a significant bias was found for the results obtained for cycloparaffins and aromatics. Further, considerable differences were found in the bias values between the laboratories. Based on the results of this study, the guidelines of the 2019 updated D2425 standard may result in setting up an analytical protocol for D2425 which may not be optimal for RJF certification.

Regional variations in life cycle greenhouse gas emissions of canola‐derived jet fuel produced in western Canada

AbstractThis study investigates the life cycle GHG emissions of jet fuel produced via the hydroprocessed esters and fatty acids (HEFA) pathway from canola grown in western Canada, with a focus on characterizing regional influences on emissions. We examine the effects of geographic variations in soil type, agricultural inputs, farming practices, and direct land use changes on life cycle GHG emissions. We utilize GREET 2016 but replace default feedstock production inputs with geographically representative data for canola production across eight western Canadian regions (representing 99% of Canada's canola production) and replace the default conversion process with data from a novel process model previously developed in ASPEN in our research group wherein oil extraction is integrated with the HEFA‐based fuel production process. Although canola production inputs and yields vary across the regions, resulting life cycle GHG emissions are similar if effects of land use and land management changes (LMC) are not included; 44–48 g CO2e/MJ for the eight regions (45%–50% reduction compared to petroleum jet fuel). Results are considerably more variable, 16–58 g CO2e/MJ, when including effects of land use and LMC directly related to conversion of lands from other uses to canola production (34%–82% reduction compared to petroleum jet fuel). We establish the main sources of emissions in the life cycle of canola jet fuel (N‐fertilizer and related emissions, fuel production), identify that substantially higher emissions may occur when using feedstock sourced from regions where conversion of forested land to cropland had occurred, and identify benefits of less intense tillage practices and increased use of summerfallow land. The methods and findings are relevant in jurisdictions internationally that are incorporating GHG emissions reductions from aviation fuels in a low carbon fuel market or legislating carbon intensity reduction requirements.

Review of life‐cycle greenhouse‐gas emissions assessments of hydroprocessed renewable fuel (HEFA) from oilseeds

AbstractRenewable fuel from the hydroprocessed esters and fatty acids (HEFA) pathway represents a promising short‐term option for reducing fossil fuel use in transportation. However, some life‐cycle assessments (LCAs) have shown that HEFA diesel and jet fuel may have higher life‐cycle greenhouse gas (GHG) emissions than the fossil fuels they replace. Many of these studies examined HEFA fuel derived from oilseed feedstocks. Here, results and methodology from 20 LCAs of HEFA fuel from oilseeds are reviewed in an effort to determine the sources of variability in the reported life‐cycle GHG emissions of HEFA fuels. Although there was a 61–63% reduction in median life cycle GHG emissions of HEFA biojet and renewable diesel compared to conventional petroleum fuels, this review highlights the importance of standardized methodologies for life‐cycle assessment (e.g., CORSIA, RSB) and indicates the need to prevent the conversion of forest land for biofuel production, as well as the potential opportunity for alternative oilseeds such as camelina and carinata as feedstocks to produce HEFA fuels with lower life‐cycle GHG emissions. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd

THE PRODUCTION AND SPECIFICATION ANALYSIS OF AVIATION BIOFUEL AS THE ALTERNATIVE FUEL OF AIRPLANE

CO2 emissions and scarcity of petroleum supplies can be reduced by the use of renewable energy sources. This has led to the development of low emission aviation turbine fuel derived from vegetable materials. The process used Hydroprocessed Esters and Fatty Acids (HEFA) that consisted of hydrotreating and isomerization. This experiment consisted of production and analysis. The production of aviation biofuel developed based on coconut oil through the process of hydrotreating deoxygenation (HDO) and hydrotreating isomerization (HDI) on the hydrotreater reactor. Further analysis of aviation biofuel products and aviation biofuel blending includes Total Acid Number (TAN), existent gum, density at 15 °C, flash point, smoke point, freezing point, distillation, total sulfur content, distribution of C10-C14 carbon, and levels of Iso-Paraffin Olefin Naphthene (PION). Based on the experimental results, it can be concluded that the Aviation Biofuel complied for TAN, density at 15 °C, and freezing point parameters. Aviation Biofuel blending of 2%, 5%, and 10% were in accordance with the Aviation Biofuel Defence Standard 91-91 for all parameters.

Combustion and Emissions Characteristics of the Turbine Engine Fueled with HEFA Blends from Different Feedstocks

In the next decade, due to the desire for significant reduction in the carbon footprint left by the aviation sector and the development of a sustainable alternatives to petroleum, fuel from renewable sources will play an increasing role as a propellant for turbine aircraft engines. Currently, apart from five types of jet fuel containing synthesized hydrocarbons that are certified by the ASTM D7566 standard, there is yet another synthetic blending component that is at the stage of testing and certification. Hydroprocessed esters and fatty acids enable the production of a synthetic component for jet fuel from any form of native fat or oil. Used feedstock affects the final synthetic blending component composition and consequently the properties of the blend for jet fuel and, as a result, the operation of turbine engines. A specialized laboratory test rig with a miniature turbojet engine was used for research, which is an interesting alternative to complex and expensive tests with full scale turbine engines. The results of this study revealed the differences in the parameters of engine performance and emission characteristics between tested fuels with synthetic blending components and neat jet fuel. The synthetic blending component was obtained from two different feedstock. Noticeable changes were obtained for fuel consumption, CO and NOx emissions. With the addition of the hydroprocessed esters and fatty acids (HEFA) component, the fuel consumption and CO emissions decrease. The opposite trend was observed for NOx emission. The tests presented in this article are a continuation of the authors’ research area related to alternative fuels for aviation.

Toxicity and occupational exposure assessment for hydroprocessed esters and fatty acids (HEFA) alternative jet fuels

ABSTRACTThe U.S. Air Force (USAF) has pursued development of alternative fuels to augment or replace petroleum-based jet fuels. Hydroprocessed esters and fatty acids (HEFA) renewable jet fuel is certified for use in commercial and USAF aircraft. HEFA feedstocks include camelina seed oil (Camelina sativa, HEFA-C); rendered animal fat (tallow, HEFA-T); and mixed fats and oils (HEFA-F). The aim of this study was to examine potential toxic effects associated with HEFA fuels exposures. All 3 HEFA fuels were less dermally irritating to rabbits than petroleum-derived JP-8 currently in use. Inhalation studies using male and female Fischer-344 rats included acute (1 day, with and without an 11-day recovery), 5-, 10- or 90-day durations. Rats were exposed to 0, 200, 700 or 2000 mg/m3 HEFA-F (6 hr/day, 5 days/week). Acute, 5 – and 10-day responses included minor urinalysis effects. Kidney weight increases might be attributed to male rat specific hyaline droplet formation. Nasal cavity changes included olfactory epithelial degeneration at 2000 mg/m3. Alveolar inflammation was observed at ≥700 mg/m3. For the 90-day study using HEFA-C, no significant neurobehavioral effects were detected. Minimal histopathological effects at 2000 mg/m3 included nasal epithelium goblet cell hyperplasia and olfactory epithelium degeneration. A concurrent micronucleus test was negative for evidence of genotoxicity. All HEFA fuels were negative for mutagenicity (Ames test). Sensory irritation (RD50) values were determined to be 9578 mg/m3 for HEFA-C and greater than 10,000 mg/m3 for HEFA-T and HEFA-F in male Swiss-Webster mice. Overall, HEFA jet fuel was less toxic than JP-8. Occupational exposure levels of 200 mg/m3 for vapor and 5 mg/m3 for aerosol are recommended for HEFA-based jet fuels.

Environmental trade-offs of renewable jet fuels in Brazil: Beyond the carbon footprint

The use of renewable jet fuels (RJFs) is an option for meeting the greenhouse gases (GHG) reduction targets of the aviation sector. Therefore, most of the studies have focused on climate change indicators, but other environmental impacts have been disregarded. In this paper, an attributional life cycle assessment is performed for ten RJF pathways in Brazil, considering the environmental trade-offs between climate change and seven other categories, i.e., fossil depletion, terrestrial acidification, eutrophication, human and environmental toxicity, and air quality-related categories, such as particulate matter and photochemical oxidant formation. The scope includes sugarcane and soybean for first-generation (1G) pathways and residual materials (wood and sugarcane residues, beef tallow, and used cooking oil-UCO) for second-generation (2G) pathways. Three certified technologies to produce RJF are considered: hydroprocessed esters and fatty acids (HEFA), alcohol-to-jet (ATJ), and Fischer-Tropsch (FT). Assuming the residual feedstocks as wastes or by-products, the 2G pathways are evaluated by two different approaches, in which the biomass sourcing processes are either accounted for or not. Results show that 1G pathways lead to significant GHG reductions compared to fossil kerosene from 55% (soybean/HEFA) to 65% (sugarcane/ATJ). However, the sugarcane-based pathway generated three-fold higher values than fossil kerosene for terrestrial acidification and air quality impacts, and seven-fold for eutrophication. In turn, soybean/HEFA caused five-fold higher levels of human toxicity. For 2G pathways, when the residual feedstock is assumed to be waste, the potential GHG emission reduction is over 74% with no relevant trade-offs. On the other hand, if the residual feedstocks are assumed as valuable by-products, tallow/HEFA becomes the worst option and pathways from sugarcane residues, even providing a GHG reduction of 67% to 94%, are related to higher impacts than soybean/HEFA for terrestrial acidification and air quality. FT pathways represent the lowest impacts for all categories within both approaches, followed by UCO/HEFA.

Oleaginous feedstocks for hydro-processed esters and fatty acids (HEFA) biojet production in southeastern Brazil: A multi-criteria decision analysis

This work establishes a ranking of the potential oleaginous feedstocks for HEFA biojet production in southeast Brazil, and consolidates their advantages and limitations, in order to assist in prioritizing strategic actions, such as research, R&D investment, and incentives for the most promising regional oilseeds. The oilseeds and the criteria considered were determined from a bibliographical review, using two multi-criteria tools in the evaluation: the analytic hierarchy process (AHP) and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The economic criterion and the oil cost sub-criterion were considered the determining factors for the choice of oilseeds, which obtained the following ranking: soybean, jatropha, sunflower, castor bean, macauba palm, cotton, and peanut. Soybean ranked first mainly because of the lower cost of its oil and high agricultural maturity. Hence, soybean should be used first in HEFA biojet production. However, considering that soybean oil is the main feedstock for biodiesel production in the country, it is also important to evaluate other potential crops. Thus, stimulating research aimed at reaching the technological domain of new local oleaginous plants is essential to increase the scale of production, reduce oil costs, and make HEFA production more competitive and sustainable.

Potential for biojet production from different biomass feedstocks and consolidated technological routes: a georeferencing and spatial analysis in Brazil

AbstractThis paper assesses the biojet fuel production potential in Brazil. It evaluates feedstock availability by applying a georeferencing analysis, and determines the cost‐effectiveness and greenhouse gas (GHG) emissions of selected production routes throughout their entire life cycle. This study identifies and locates Brazilian hotspots in terms of bioenergy availability and proximity to the main sites of fuel consumption and handling in the country. Findings show that the biomass availability for each crop in the hotspots would be sufficient to feed the biojet conversion plants proposed in this study. The biojet production potential in the hotspots would represent 48% of the country's jet fuel consumption in 2014, allowing the current certificated 50% blend with conventional fuel. The major biomass hotspots are close to airport and fuel logistic basis. However, even with a US$ 200.tCO–1 2 tax, hydroprocessed esters and fatty acids (HEFA) biojet is far from being competitive with petroleum‐based jet fuel, whereas the Fischer–Tropsch synthetic paraffinic kerosene (FT‐SPK) route may produce a competitive biojet. One possible pathway to incentivize biojet fuel production in Brazil would be, first, to implement carbon taxes that would allow the development of smaller plants. Then, with technological learning and larger production scales, it would be possible to reduce or even eliminate the carbon taxes. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

Lean flammability limits of alternative aviation fuels

Alternative fuels are being certified to be used in aircraft. However, the fire-safety properties of these fuels are unknown. The present work focused on measurements of the lean flammability limits (LFLs) of three alternative aviation fuels including Hydroprocessed Esters and Fatty Acids (HEFA), Synthesized Iso-Paraffins (SIP), and Fischer-Tropsch Iso-Paraffinic Kerosene (FT-IPK). The results were compared to that of conventional petroleum-based Jet A. The results showed that only FT-IPK had higher LFLs than that of Jet A. Additionally, the LFLs of four pure hydrocarbons including n-heptane, iso-octane, n-decane, and n-dodecane were measured since they are the major components of transportation fuels. The LFLs were within the range of 0.032–0.040 in terms of the fuel-air mass ratio for all four aviation fuels in the temperature range of 350–420 K. Unlike temperature, pressure had a minor influence on the lean flammability limit. For all measured samples (pure hydrocarbons and fuels), the lean limit decreases with increasing molecular weight.

Synthesis of Bio Jet Fuel from Crude Palm Oil by HEFA (Hydroprocessed Esters and Fatty Acids) Using Ni-Mo Catalyst Supported by Rice Husk Ash-Based SiO<sub>2</sub>

Bio jet fuel becomes one of the feasible solutions for jet fuel inadequate supply in Indonesia. However, study in this field by far has been limited. In this study, bio jet fuel was synthesized from Crude Palm Oil (CPO) by Hydroprocessed Esters and Fatty Acid (HEFA) facilitated by Ni-Mo/SiO2 catalyst, in which the support was derived from rice husk ash. The study focused on investigating the influence of catalyst-CPO mass ratio and temperature of the catalytic process. Experimental works consisted of silica-based catalyst preparation via impregnation method, followed by sample assessments. Catalytic reactions were conducted at 20-50 bars, with temperature of reaction 300°C and 400°C. Catalyst performance were evaluated from crystallinity, composition, and activity in the reaction. Catalyst characterization shows an amorphous structured with high dispersion of Ni-Mo in rice husk ash have been produced. The HEFA process successfully obtained bio jet fuel (C10-C15 hydrocarbons) with yield and selectivity of 45.17% and 45.46%, respectively. Overall, a systematic approach shows rice husk ash has potential to be developed as a catalyst support for bio jet fuel production from crude palm oil.

Characterization of Nile Red as a Tracer for Laser-Induced Fluorescence Spectroscopy of Gasoline and Kerosene and Their Mixture with Biofuels.

Suitable fluorescence tracers (“dyes”) are needed for the planar measurement of droplet sizes by using a combination of laser-induced fluorescence (LIF) and Mie scattering. Currently, no suitable tracers have been characterized for application in planar droplet sizing in gasoline and kerosene fuels, as well as biofuel blends. One promising tracer is nile red, which belongs to the fluorophore group. For its utilization for droplet size measurements, preliminary characterization of the fluorescence of the respective fuel tracer mixtures are mandatory. For this purpose, the fluorescence and absorption behavior of nile red dissolved in the surrogate fuels Toliso and Jet A-1 as well as in biofuel blends was investigated. The fluorescence signal for nile red that was dissolved in the two base fuels Toliso and Jet A-1 showed a linear behavior as a function of dye concentration. The temperature effect on spectral absorption and emission of nile red was investigated in a specially designed test cell. An ethanol admixture to Toliso led to a spectral shift towards higher wavelengths. The absorption and emission bands were shifted towards lower wavelengths with increasing temperature for all fuels. Both absorption and fluorescence decreased with increasing temperature for all fuels, except for E20, which showed an increased fluorescence signal with increasing temperature. Jet A-1 and its blends with hydroprocessed esters and fatty acids (HEFA) and farnesane did not exhibit explicit variations in spectral absorption or emission, but these blends showed a more distinct temperature dependence compared to the Toliso-ethanol-blends. The effect of photo-dissociation of the LIF signal of the fuel tracer mixtures was studied, and all fuel mixtures besides Toliso showed a more or less distinct decay in the fluorescence signal with time. In summary, all investigated fuel-tracer mixtures are suitable for LIF/Mie ratio droplet sizing in combination with nile red at moderate temperatures and low evaporation cooling rates.

Socioeconomic effects of aviation biofuel production in Brazil: A scenarios-based Input-Output analysis

Derived from renewable feedstocks, aviation biofuel is generally perceived as inherently sustainable. However, its production involves a wide range of sectors and interacts with different actors in society. It is therefore important to understand and evaluate not only the environmental impacts of that process, but also its socioeconomic effects. At present, empirical studies assessing socioeconomic aspects of aviation biofuel are rare in scientific literature. The aim of this study, therefore, is to assess key effects of aviation biofuel production on employment, GDP, and trade balance. A scenarios-based Input-Output (IO) analysis was used to evaluate these socioeconomic effects, taking Brazilian aviation biofuel production to 2050 as an example. To address the uncertainty of IO analysis, we have proposed a stochastic simulation approach for the technical coefficients in the IO model. Four distinct scenarios were developed. In each, three potential combinations of technologies and feedstocks for producing aviation biofuel were evaluated: sugarcane via alcohol to jet (ATJ), macauba via hydro-processed esters and fatty acids (HEFA), and eucalyptus via Fischer-Tropsch (FT). Among other things, we found that the production of aviation biofuel would create around 12,000–65,000 jobs, while contributing US$200-1100 million to Brazil's GDP under different scenarios with different supply chains. The socioeconomic effects calculated deterministically were generally higher than the stochastic outcomes, which can be explained by factors such as technological learning and economic growth. Aviation biofuel production showed large positive net socioeconomic effects on employment and GDP, although some of the fossil sectors would be negatively affected. Overall, the macauba-HEFA chain (with the highest effects on employment and GDP, and the lowest effects on imports) seemed to be the most favorable of the scenarios studied, despite the relatively high level of uncertainty associated with it.

Application of a hygroscopicity tandem differential mobility analyzer for characterizing PM emissions in exhaust plumes from an aircraft engine burning conventional and alternative fuels

Abstract. In the last several decades, significant efforts have been directed toward better understanding the gaseous and particulate matter (PM) emissions from aircraft gas turbine engines. However, limited information is available on the hygroscopic properties of aircraft engine PM emissions which play an important role in the water absorption, airborne lifetime, obscuring effect, and detrimental health effects of these particles. This paper reports the description and detailed lab-based performance evaluation of a robust hygroscopicity tandem differential mobility analyzer (HTDMA) in terms of hygroscopic properties such as growth factor (GF) and the hygroscopicity parameter (κ). The HTDMA system was subsequently deployed during the Alternative Aviation Fuel EXperiment (AAFEX) II field campaign to measure the hygroscopic properties of aircraft engine PM emissions in the exhaust plumes from a CFM56-2C1 engine burning several types of fuels. The fuels used were conventional JP-8, tallow-based hydroprocessed esters and fatty acids (HEFA), Fischer–Tropsch, a blend of HEFA and JP-8, and Fischer–Tropsch doped with tetrahydrothiophene (an organosulfur compound). It was observed that GF and κ increased with fuel sulfur content and engine thrust condition, and decreased with increasing dry particle diameter. The highest GF and κ values were found in the smallest particles, typically those with diameters of 10 nm.

Prediction of HEFA content in jet fuel using FTIR and chemometric methods

Alternative aviation fuel blending components are becoming a common component in gas turbine engines fuels. One of the blending components is Hydroprocessed Esters and Fatty Acids (HEFA). Predictive models based on a chemometric processing of FTIR spectra were developed as a reliable method for the determination of HEFA in petroleum jet fuel/HEFA blends. The concentration of HEFA in blends with jet fuel ranged between 0 and 60 wt%. The sample set composed of calibration and validation subsets. Additionally, several pre-processing techniques were evaluated, such as mean centering, variance scaling, derivation, and smoothing. The effectiveness of these models was highly dependent on the model parameters (pre-processing techniques and latent variables). The most robust model was able to predict HEFA content in all samples with a good predictive ability (root mean square error of prediction of 0.7 wt%).

Impact of HEFA Feedstocks on Fuel Composition and Properties in Blends with Jet A

Alternative aviation fuels and their approval process contribute to one of the biggest challenges in deployment of an enhanced volume of aviation fuels. One of the approved fuel blending components is hydroprocessed esters and fatty acids (HEFAs) for mixing with petroleum-derived fuel (Jet A/A-1) up to 50 vol %. As the ASTM fuel specification (D7566) is merely based on the performance expected, the final blend concentration of HEFA in Jet A/A-1 can vary depending on the resultant fuel properties. Currently, there is a lack of information on how these properties are affected by the constituent chemical composition. The aim of this study was to compare three HEFAs sourced from different feedstocks (camelina, tallow, and mixed fat) and their blends with Jet A (10–60 vol %) based on the detailed chemical composition. The chemical composition was obtained using two-dimensional gas chromatography with mass spectrometry and flame ionization detector. The properties of interest were the distillation profile, dens...