Aviation Gasoline Research Articles

Hydrocarbon Fuel Flash Vaporization for Pulsed Detonation Combustion

Practical operation of pulsed detonation propulsion requires operation on kerosene-based jet fuels. These low vapor pressure fuels remain in liquid form at typical pulsed detonation inlet conditions and residence times, and the subsequent presence of fuel droplets significantly slows the combustion and hinders engine operability. A fuel flash vaporization system was designed and built to reduce evaporation time and provide gaseous fuel to the pulsed detonation engine. Four fuels that vary in volatility were tested: n-heptane, isooctane, aviation gasoline, and JP-8. Results showed the flash vaporization system quickly provides a detonable mixture for all of the fuels tested without coking the fuel lines. A significant result of this work was the successful detonation of flash vaporized JP-8 in air over a range of fuel temperatures and fuel-to-air ratios.

Modeling representations of canola oil catalytic cracking for the production of renewable aromatic hydrocarbons

The US Environmental Protection Agency (EPA) banned lead in motor gasoline in 1996. Aviation gasoline was not included in the ban but due to the environmental pollution, the industry is looking for unleaded replacement fuels with a high octane number. Catalytic cracking of renewable biomass-derived raw materials such as vegetable oils could convert them into valuable raw materials such as aromatic hydrocarbons which can be added to the motor and aviation gasoline fuels for the octane number enhancement. This paper distills the systematics of a large number of experimental yields data of canola oil catalytic cracking using HZSM-5 catalyst, for the production of renewable aromatic hydrocarbons obtained at University of Saskatchewan (USK), Canada. The products were mainly gases, organic liquid products (OLPs) and solid coke. The large body of data is organized using an analytical semi-empirical model (ASEM) developed at the University of Florida (UF) that provides a reasonable account using only a small number of adjusted parameters. The model fits very well with the experimental data in the temperature range of 200–600 °C. The influence of catalyst types on the conversion of canola oil to aromatic hydrocarbons is also discussed. The analytical methodology should be useful for organizing catalytic cracking yields of other materials containing carbon, hydrogen and oxygen.

Sealability Properties of Fluorine-Free Fire-Fighting Foams (FfreeF)

This contribution compares the sealability performance of recently developed three synthetic foam formulations (that do not contain fluorosurfactants or fluoropolymers) with that of an aqueous film forming foam (AFFF). We apply the sealability methodology outlined in the Australian Defence Force Specification, DEF(AUST)5706. This methodology specifies a 0.28 m2 small-scale indoor fire pan. The pan is first filled with 10 L of water and then 5 L of AVGAS (aviation gasoline, flash point of −50°C) or heptane (flash point of −4°C) is placed on top of the water. Foams were generated from a pressurised extinguisher with a foam nozzle as described in the standard’s specification, set to create foams with expansion of 4:1. The foam spread across the fuel until the entire fuel surface was covered with foam. At 5 min intervals, a lit taper was introduced into the space above the pan area by passing it twice around the surface of the foam in a circular motion at a height of approximately 15 mm from the surface of the foam. The results demonstrate differences in the sealability performance between AFFF and fluorine-free foams (FfreeF). Under laboratory conditions, with a foam blanket 1–2 cm deep, best-performing FfreeF formulation (RF6) provides about 30% of the durability of an AFFF for protection against evaporation of low-flashpoint flammable liquids. We also note in the results the significant differences among FfreeF with almost no sealability of AVGAS vapours offered by the two other formulations.

Study of using JP-8 aviation fuel and biodiesel in CI engines

The first jet fuels were aviation gasoline (avgas), and the characteristics of subsequent jet fuels have evolved from this original choice, the available supply infrastructure, and the refiners’ capabilities. Earlier on, it was evident that avgas would have to be altered to operate satisfactorily in jet powered aircraft. The present contribution outlines the various requirements that led to development of various operational jet fuels, including United States Jet A (European Jet A-1), JP-4 (NATO code, F-40), JP-5 (NATO code, F-44), JP-7 (US only), JP-8 (F-34), JP-TS (US only), and JP-8+100. To reduce this fuel logistic burden, the NATO Armed Forces are advancing the use of a single fuel for both aircraft and ground equipment. To this end, F-34 is replacing distillate Diesel fuel in many applications. In order to make this type of fuel compatible with direct injection compression engines, the Fuels and Lubricants Laboratory of the National Technical University of Athens, used a stationary Diesel engine fueled with fuel blends containing two different types of biodiesel, at proportions up to 50%. In this paper, fuel consumption and exhaust emission measurements from a single cylinder, stationary, Diesel engine are described. The two types of biodiesel appeared to have equal performance, and irrespective of the raw material used for their production, their addition to the JP-8 aviation fuel improved the particulate matter emissions.

Book Review: War and Power in the 21st century

Paul Hirst Oxford: Polity, 2001, vi + 170pp., 11.99 [pounds sterling] (paperback). This is a comparatively slight book that attempts the daunting task of predicting the major developments in war, armed conflict and international relations in the 21st century. In particular it explores the potential impact of changes in military technology; information and communications technology; economic and environmental conditions; demography; international relations and trade; and political regimes and systems of governance. Despite its brevity it seeks to provide some historical depth to its analysis by reviewing major changes in warfare since the 1500s, pointing out that the present revolution in military affairs is but one in a series of similar events over the past 400 years. Central to this analysis is the role of the state and of the international system of states. The author rejects the notion that we are witnessing the terminal decline of the nation-state--quite the contrary in fact, as he foresees the status of the state as the principal political actor in international affairs being enhanced by the imperatives of a globalized system based on economic liberalism. He also argues that the present concern with human rights was presaged by earlier campaigns to abolish the slave trade and establish rights of national self-determination. Similarly, he points out that globalization has its roots in the expansion of the international economy prior to World War One and should not be considered as a unique contemporary phenomenon. Overall, Hirst's prognosis is rather bleak, with future conflict being seen as inherent in the present global system of inequality of wealth and power, while the chances of conflict will increase if the global system of economic liberalism breaks down. This book might have been regarded as a good primer on its subject matter prior to 11 September 2001. Indeed, Hirst was prescient enough to remark that terrorist groups are highly likely to carry out major attacks using weapons of mass destruction (WMD) against the advanced countries, and that `one such action may lead to a campaign of extermination against such groups sanctioned by the major powers' (p. 98). This prediction has largely come true. Unfortunately, Hirst did not foresee that it would be highjacked aircraft full of aviation gasoline and suicide squads of prospective martyrs rather than WMD, as such, that would accomplish the outrage on such a scale. What 9/11 has revealed is the potentially catastrophic vulnerability of advanced societies to attacks on infrastructure and civilian targets utilizing non-military and opportunistic means of assault. …

Test method to measure gasoline lubricity

The lubricity of gasoline is the least understood of all three types of liquid fuels (aviation kerosene,diesel fuel and gasoline fuel), due largely to the lack of a reliable test method for measuring the lubricity of such a much volatile and contamination sensitive material. A simple and easy to use HFRR gasoline test method has been successfully developed by(i) redesigning the fuel bath/reciprocating ball holder system to solve the high volatility problem of gasoline in HFRR tests, (ii) enclosing HRFF in a sealable perspex box with a hole fitted with a ground perspex plug for convenient humidity control, (iii) using water vapour pressure (WVP) instead of relative humidity (RH) as an index of humidity to correctly reflect the true water content in the air, and (iv) designing a very strict cleaning procedure so as to avoid cross contamination and guarantee good repeatability. It has been found that HFRR test method has good repeatability and differentiating ability.

Advanced aviation fuels: a look ahead via a historical perspective

The first ‘jet fuels’ were aviation gasoline (avgas), and the characteristics of subsequent jet fuels have evolved from this original choice, the available supply infrastructure, and the refiners’ capabilities. Earlier on, it was evident that avgas would have to be altered to operate satisfactorily in jet-powered aircraft. The present contribution outlines the various requirements that led to the development of various operational jet fuels, including United States (US) Jet A (European Jet A-1), Jet Propellant JP-4 (European F-40), JP-5 (European F-44), JP-7 (US only), JP-8 (F-34), JP-TS (US only), and JP-8+100 (US only). The composition of aviation fuels has generally been determined by specifications that are primarily based upon operational requirements. These include heat content, fluidity, corrosion protection and stability. Moreover, cost is often a primary driver. The chemical composition variations of prototype aviation fuels are compared. Chemical and physical characteristics of the fuels are reviewed within the context of operational requirements. The development of each product is put into the context of two very distinct models, which highlight the importance of cost considerations. A final aim is to foreshadow what may be to come, in the context of JP-8+225, JP-900, ‘controlled chemically reacting fuels’, and alternative fuel sources.

Measurement of Petroleum Fuel Contamination in Water by Solid-Phase Microextraction with Direct Raman Spectroscopic Detection

A method is described for determining petroleum fuel contamination in water based on solid-phase microextraction and Raman spectroscopy (SPME/Raman). In this method, contaminants are extracted from aqueous solutions into a solid phase and then detected directly by using spontaneous Raman spectroscopy. The solid phase consists of a small volume (∼ 20 μL) of poly(dimethylsiloxane) that has an optical window in the 830–1600 cm−1 Raman shift region. This region is suitable for determining both aromatic and aliphatic fuel components. Four “real world” fuels—aviation gasoline, unleaded gasoline, jet fuel A, and #1 fuel oil—were used to test this new method. As shown, the SPME/Raman determinations performed in the visible spectral region were not adversely affected from the fluorescence of the marker dyes in these fuels. The linear dynamic ranges for the determinations exceeded the water solubility limits and spanned 1–3 orders of magnitude. The limits of detection with the use of the most sensitive Raman bands in each fuel were in the 8–12 ppm range with the exception of #1 fuel oil (25 ppm), and relative standard deviations typically were 2–10%. Finally, the SPME/Raman method was applied to the determination of total petroleum hydrocarbons in natural water matrices. With the use of hexane and undecane as standards, the results of the determinations compared favorably to the standard methods of purge-and-trap gas chromatography and liquid-liquid extraction followed by infrared detection.

An electromagnetic modelling tool for the detection of hydrocarbons in the subsoil

Electromagnetic geophysical methods, such as ground‐penetrating radar (GPR), have proved to be optimal tools for detecting and mapping near‐surface contaminants. GPR has the capability of mapping the location of hydrocarbon pools on the basis of contrasts in the effective permittivity and conductivity of the subsoil. At radar frequencies (50 MHz to 1 GHz), hydrocarbons have a relative permittivity ranging from 2 to 30, compared with a permittivity for water of 80. Moreover, their conductivity ranges from zero to 10 mS/m, against values of 200 mS/m and more for salt water. These differences indicate that water/hydrocarbon interfaces in a porous medium are electromagnetically ‘visible’. In order to quantify the hydrocarbon saturation we developed a model for the electromagnetic properties of a subsoil composed of sand and clay/silt, and partially saturated with air, water and hydrocarbon. A self‐similar theory is used for the sandy component and a transversely isotropic constitutive equation for the shaly component, which is assumed to possess a laminated structure. The model is first verified with experimental data and then used to obtain the properties of soils partially saturated with methanol and aviation gasoline. Finally, a GPR forward‐modelling method computes the radargrams of a typical hydrocarbon spill, illustrating the sensitivity of the technique to the type of pore‐fluid. The model and the simulation algorithm provide an interpretation methodology to distinguish different pore‐fluids and to quantify their degree of saturation.

Occupational risk factors for renal cell carcinoma in Montreal.

Little is known about the role of workplace exposures on the risk of renal cell cancer. A population-based case-control study was undertaken in Montreal to assess the association between hundreds of occupational circumstances and several cancer sites, including the kidney. A total of 142 male patients with pathologically confirmed renal cell carcinoma, 1900 controls with cancer at other sites and 533 population-based controls were interviewed. Detailed job histories and relevant data on potential confounders were obtained. A group of chemists-hygienists evaluated each job reported and translated them into a history of occupational exposures using a checklist of 294 substances. Multivariate logistic regression models using either population, cancer controls, or a pool of both groups were used to estimate odds ratios. There were some indications of excess risks among printers, nursery workers (gardening), aircraft mechanics, farmers, and horticulturists, as well as in the following industries: printing-related services, defense services, wholesale trade, and retail trade. Notwithstanding the low precision of many of the odds ratio estimates, the following workplace exposures showed some evidence of excess risk: chromium compounds, chromium (VI) compounds, inorganic acid solutions, styrene-butadiene rubber, ozone, hydrogen sulphide, ultraviolet radiation, hair dust, felt dust, jet fuel engine emissions, jet fuel, aviation gasoline, phosphoric acid and inks. For most of these associations there exist no, or very little, previous data. Some associations provide suggestive evidence for further studies.

Fuel identification by neural network analysis of the response of vapor-sensitive sensor arrays.

Neural network analysis of the response of an array of vapor-sensitive detectors has been used to identify six different types of aviation fuel. The data set included 96 samples of JP-4, JP-5, JP-7, JP-8, JetA, and aviation gasoline (AvGas). A sample of each neat fuel was injected into a continuous stream of breathing air through an injection port from a gas chromatograph. The aspirated sample was then swept from the injection port to the chamber without separation. In the chamber, the sample was exposed to an array of eight vapor-sensitive detectors. The analog output of each detector was digitized and stored while the sample was swept into and through the chamber. The response of each detector was then averaged and stored as the final response or pattern of each sample. It was clear from a visual inspection of each of the radar plots that there was a characteristic pattern in the response of the array to five of the six different fuel types. This was confirmed using neural network analysis to study the entire data set. A two-step procedure was developed to separate the patterns of all six fuel tyes into their respective classes. In the first step, fuels were separated into one of five groups: JP-4, JP-5, JP-7, AvGas, or a combined JP-8/JetA group. In the second step, the fuels in the combined group were separated into either JP-8 or JetA groups.

Petroleum Hydrocarbon Bioventing Kinetics Determined in Soil Core, Microcosm, and Tubing Cluster Studies

AbstractAerobic biodegradation of vapor‐phase petroleum hydrocarbons was evaluated in an intact soil core from the site of an aviation gasoline release. An unsaturated zone soil core was subjected to a flow of nitrogen gas, oxygen, water vapor, and vapor‐phase hydrocarbons in a configuration analogous to a biofilter or an in situ bioventing or sparging situation. The vertical profiles of vapor‐phase hydrocarbon concentration in the soil core were determined by gas chromatography of vapor samples. Biodegradation reduced low influent hydrocarbon concentrations by 45 to 92 percent over a 0.6‐m interval of an intact soil core. The estimated total hydrocarbon concentration was reduced by 75 percent from 26 to 7 parts per million. Steady‐state concentrations were input to a simple analytical model balancing advection and first‐order biodegradation of hydrocarbons. First‐order rate constants for the major hydrocarbon compounds were used to calibrate the model to the concentration profiles. Rate constants for the seven individual hydrocarbon compounds varied by a factor of 4. Compounds with lower molecular weights, fewer methyl groups, and no quaternary carbons tended to have higher rate constants. The first‐order rate constants were consistent with kinetic parameters determined from both microcosm and tubing cluster studies at the field site.

Effects of three concentrations of mixed fatty acids on dechlorination of tetrachloroethene in aquifer microcosms

AbstractChloroethenes are among the most common organic contaminants of ground water. The biotransformation of these compounds by reductive dechlorination is a promising technology for in situ treatment. The effects of three concentrations of a fatty acids mixture on the reductive dehalogenation of tetrachloroethene (PCE) were studied in methanogenic microcosms. These microcosms were constructed with slurries of aquifer solids collected from an area impacted both by aviation gasoline and chlorinated ethenes at Traverse City, Michigan. The microcosms were amended with approximately 30 μM PCE and one of three concentrations (0.1, 1, or 10 mM total acids) of a mixture of low‐molecular‐weight organic acids, or were part of a control set that received no amendment. The observed lag or adaptation times before the onset of PCE dehalogenation were 51 d (10 mM acids), 65 d (1 mM acids), 86 d (0.1 mM acids), and >233 d (no acids). After 233 d of incubation, no PCE was detectable in any of the fatty‐acid‐supplemented microcosms, but 23 to 27 μM of combined tri‐ and dichloroethenes (TCEs, DCEs) was detected. PCE was not dechlonnated in microcosms without a fatty acid supplement. Although there were observed differences in the length of the lag time, the amount of ultimately dechlorinated PCE was similar. A zero‐order rate constant of 0.3 μM d−1 was calculated for PCE dechlorination and for TCE dechlorination for the two series of microcosms receiving 0.1 and 1.0 mM fatty acid supplements. Of the fatty acids tested in the mixture, butyrate oxidation appeared to be the most probable link to PCE dechlorination.

Field Trapping of Subsurface Vapor Phase Petroleum Hydrocarbons

Soil gas samples from intact soil cores were collected on adsorbents at a field site, then thermally desorbed and analyzed by laboratory gas chromatography (GC). Vertical concentration profiles of predominant vapor phase petroleum hydrocarbons under ambient conditions were obtained for the zone directly above the capillary fringe. Water and residual phase weathered aviation gasoline were present in this region of the profile. The sampling, trapping, and GC methodology was effective in most respects. Reproducibility, trapping, and desorption efficiency were generally satisfactory, and different sorbent tubes gave similar results. A minor shortcoming of the method occurred with the most volatile compound, 2,3-dimcthylbutane, which was poorly retained during several weeks of storage lime and was also poorly desorbed. Vapor phase concentrations of predominant hydrocarbon compounds all increased with depth at one sampling location. At a more highly contaminated location, concentrations of highly volatile compounds increased with depth while concentrations of less volatile compounds remained constant or decreased, possibly indicating distillation effects. Scatier in the data was attributed to heterogeneities in water and residual phase distribution.

LNAPL Retention in Sandy Soil

AbstractThe vertical distribution of free and residual aviation gasoline, a light nonaqueous phase liquid (LNAPL), through the capillary fringe of a uniform, medium sand is measured and used to calibrate an existing model. The total saturation profile is governed by a classical moisture retention characteristic, with the matric pressure head scaled by LNAPL/air surface tension in the presence of free LNAPL and water/air surface tension in the absence of free LNAPL. The residual LNAPL is described by an empirical equation reflecting hysteretical trapping due to a fluctuating water table. The existing theory is calibrated with new and published field data at an aviation gasoline spill site in Traverse City, Michigan.

Protozoa in Subsurface Sediments from Sites Contaminated with Aviation Gasoline or Jet Fuel

Numbers of protozoa in the subsurface of aviation gasoline and jet fuel spill areas at a Coast Guard base at Traverse City, Mich., were determined. Boreholes were drilled in an uncontaminated location, in contaminated but untreated parts of the fuel plumes, and in the aviation gasoline source area undergoing H(2)O(2) biotreatment. Samples were taken from the unsaturated zone to depths slightly below the floating free product in the saturated zone. Protozoa were found to occur in elevated numbers in the unsaturated zone, where fuel vapors mixed with atmospheric oxygen, and below the layer of floating fuel, where uncontaminated groundwater came into contact with fuel. The same trends were noted in the biotreatment area, except that numbers of protozoa were higher. Numbers of protozoa in some contaminated areas equalled or exceeded those found in surface soil. The abundance of protozoa in the biotreatment area was high enough that it would be expected to significantly reduce the bacterial community that was degrading the fuel. Little reduction in hydraulic conductivity was observed, and no bacterial fouling of the aquifer was observed during biotreatment.

Hydrocarbon Vapor Diffusion in Intact Core Sleeves

AbstractThe diffusion of 2,2,4‐trimethylpentane (TMP) and 2,2,5‐trimethylhexane (TMH) vapors put of residually contaminated sandy soil from the U.S. Environmental Protection Agency (EPA) field research site at Traverse City, Michigan, was measured and modeled. The headspace of an intact core sleeve sample was swept with nitrogen gas to simulate the diffusive release of hydrocarbon vapors from residual aviation gasoline in and immediately above the capillary fringe to a soil‐venting air flow in the unsaturated zone. The resulting steady‐state profile was modeled using existing diffusivity and air porosity estimates in a balance of diffusive flux and a first order source term. The source strength, which was calibrated with the observed flux of 2,2,4‐TMP leaving the sleeve, varied with the residual gasoline remaining in the core, but was independent of the headspace sweep flow rate. This finding suggested that lower soil‐venting air flow rates were in principle as effective as higher air flow rates in venting LNAPL vapors from contaminated soils. The saturated vapor concentration ratio of 2,2,4‐TMP to 2,2,5‐TMH decreased from 6.6 to 3.5 over the duration of the experiments in an expression of distillation effects. The vertical profile model was tested against sample port data in four separate experiments for both species, yielding mean errors ranging from 0 to—24 percent in magnitude.

Hydrocarbon dissolution and transport: a comparison of equilibrium and kinetic models

The dissolution and transport of trapped nonaqueous phase liquid hydrocarbon (oil) was examined in a laboratory column study using aquifer material from a site contaminated with aviation gasoline. Two mathematical models were compared for simulating the dissolution of trapped oil. The first model assumes that mass transfer will be rapid relative to groundwater flow and that the concentrations in the aqueous and oil phases will be at equilibrium. The second model assumes that mass transfer between the aqueous and oil phases is best described by a linear resistance relationship. Both models assume that equilibrium concentrations in the oil and the aqueous phases can be estimated by equating activities in each phase. Numerical simulations using both models are generated and compared with column study results. Overall, the kinetic model appears to provide a somewhat better description of the dissolution process, although this model requires significantly greater computation times. A simple procedure is described to develop an order of magnitude estimate of the number of pore volumes of water required to flush individual hydrocarbons from the aquifer material.

Pneumatic pumping test for soil vacuum extraction

AbstractIn‐situ pneumatic pumping tests were performed to estimate the pneumatic permeability at a site containing soils contaminated with aviation gasoline. Determination of pneumatic permeability was necessary to evaluate soil‐air discharge or pore volume exchange rates. Pressure propagation was measured in clustered vapor probes during the application of vacuum and positive pressure. An analytical solution for soil‐air pressure distribution with a non‐linear data fitting algorithm was adopted to obtain the pneumatic permeability from soil‐air pressure distribution. Pneumatic pumping tests indicated substantially higher air discharge rates in the immediate vicinity of wells. The air discharge rate dissipated rapidly as distance from the wells increased. Application of increased vacuum or injection pressure resulted in substantially increased air flow in the immediate vicinity with small changes at a distance. This fact indicates that effective design should be based on air flow fields near wells, and the site specific design criteria should be determined with carefully conducted tests.

Bioventing to treat fuel spills from underground storage tanks

Bioventilation is a procedure to cleanse soil gas of volatile fuel hydrocarbons originating from storage tank leaks. The rate of vapor degradation is a controlling parameter in the design of a bioventing system. A laboratory microcosm procedure using sandy soil from an aviation gasoline spill site was used to measure relative kinetics of some fuel vapors.