Browse Topic: Reformulated diesel fuels

Items (50)
Diesel Fuel Lubricity Comparisons with HFRR and Scuffing Load Ball-on-Cylinder Lubricity Evaluator Methods2014-01-276110/13/2014
Diesel fuel requires sufficient lubricity to prevent excessive wear in fuel injection equipment. The processes for removing sulfur from diesel fuel also eliminate compounds that are responsible for its lubricating properties. This phenomenon is counterbalanced by employing lubricity additives to restore fuel lubricity to an acceptable level. The aim of this study was to compare the two different laboratory methods for testing lubricity. The two methods were the EN 590 standard method high frequency reciprocating rig (HFRR) and a less utilized method scuffing load ball-on-cylinder lubricity evaluator (SLBOCLE). Two different commercial lubricity additives were used. In addition, rapeseed methyl ester (RME) was used for lubricity purposes in the same way as the additives. To study the possible effect of the base fuel, the tests were performed with fossil diesel fuel, paraffinic diesel (Hydrotreated vegetable oil, HVO), and a blend of these. The best HFRR - SLBOCLE correlation was found with RME used as a lubricity additive, but the results were still conflicting concerning the approval limits. With the commercial lubricity additives, the best correlation was achieved with paraffinic diesel base fuel and acidic type of lubricity additive. Ester based lubricity additives gave seemingly random SLBOCLE results while the acid based lubricity additive produced slightly more coherent results. The correlation was poor with all different additives when the base fuel was 100 % fossil. The results indicate that the correlation between HFRR and SLBOCLE is generally poor. While HFRR showed improved lubricity trend by increasing dosing level of the additive, SLBOCLE did not. The reason for this may be that the methods are measuring two different types of phenomena - wear and seizure. SLBOCLE also seems to rule out fuels which have shown good behavior in the market, if the suggested limit is applied. The writers feel that the repeatability and reproducibility of SLBOCLE method would need substantial improvement.
Lehto, KalleVepsäläinen, AkiKiiski, UllaKuronen, Markku
Experimental Investigations on Performance and Emission Characteristics of Diesel Fuel Blended with 2-Ethoxy Ethyl Acetate and 2-Butoxy Ethanol2008-01-16816/23/2008
The demand for compression ignition engines is continuously growing due to their good fuel efficiency. But they cause lot of concern with regard to exhaust emissions. This concern sought to examine ways by which the composition of the fuel used by CI engines could be changed to reduce emissions. The addition of oxygen containing compounds to diesel fuel has been proposed as a method to complete the oxidation of carbonaceous particulate matter and associated hydrocarbons. In addition many oxygenate have high cetane number and their association with diesel results in high cetane number and hence lower exhaust emissions. Due to this advantages, there is growing interest in the introduction of oxygenates into diesel fuel. The performance and emission characteristics of two kinds of oxygenates 2-Ethoxy Ethyl Acetate, 2-Butoxy Ethanol with three different blends were investigated. A considerable reduction of Smoke emission, Carbon monoxide and Unburned Hydrocarbon is obtained and Nitrogen Oxides emissions are increased when the oxygen content is increased from 5% to 15%. In addition, a slight increase of brake specific fuel consumption is observed due to the small decrease of fuel heating value with the increase of the oxygen content. Brake thermal efficiency increased when the oxygen content was increased.
Srinivasan, P.Devaradjane, G.
Glycerol derivatives for diesel fuel reformulation2005-01-22035/11/2005
Biofuels are an important means of progress to reduce greenhouse gases and local pollution and to diversify energy. For diesel engines, FAME (Fatty Acid Methyl Ester), coming from trans esterification of vegetable oils, have already shown their potential as fuel substitutes. Nevertheless, this trans esterification induces glycerol production as a co - product. At the same time, oxygenated compounds have been shown to have great potential for reducing diesel particulate emissions. So using glycerol as a basis to synthesize new oxygenated compounds, for diesel fuel formulation could be promising. This paper deals with the synthesis of oxygenated compounds coming from glycerol, such as acetals, ethers, or carbonates, and their evaluation as blending components in diesel fuel. The objective of this work is to evaluate their potential, in terms of pollutant emissions, with different engine technologies. Their impact on particulate emissions depends on the engine technology and the chemical structure of the glycerol derivatives. For the Euro II vehicle, the decrease in particulate emissions is up to 20% on NEDC cycle. Although the Euro III vehicle is less sensitive than the Euro II, with only 5% in volume of glycerol derivatives, up to 12% of particulate reduction is possible. The impact on NOx emissions is rather low especially for the Euro III vehicle. Tests with an HCCI engine have shown that some glycerol compounds could improve the running of HCCI engine.
Jaecker-Voirol, A.Delfort, B.Montagne, X.Durand, I.Hillion, G.
Experimental Investigation to Specify the Effect of Oxygenated Additive Content and Type on DI Diesel Engine Performance and Emissions2004-01-00973/8/2004
The reduction of brake specific consumption and pollutant emissions are issued as future challenges to diesel engine designers due to the depletion of fossil fuel reserves and to the continuous suppression of emission regulations. These mandates have prompted the automotive industry to couple the development of combustion systems in modern diesel engines with an adequate reformulation of diesel fuels and have stirred interest in the development of “clean” diesel fuels. The use of oxygenated fuels seems to be a promising solution towards reducing particulate emissions in existing and future diesel motor vehicles. The prospective of minimizing particulate emissions with small fuel consumption penalties seems to be quite attractive in the case of biodiesel fuels, which are considered as an alternative power source. Studies conducted in diffusion flames and compression ignition engines have shown a reduction of soot with increasing oxygen percentage. However, the effects of the type of oxygenated additive and oxygen content on gaseous and particulate emissions obtained from modern DI diesel engines have not been fully investigated. An experimental investigation is conducted to determine the effect of oxygen content and oxygenate type on DI diesel engine performance and emissions. One conventional and three oxygenated fuels are examined having an oxygen content ranging from 0% to 9%. The fuels are prepared by blending a biodiesel compound (RME), Diglyme and Butyl-Diglyme with a low sulfur diesel fuel in various proportions. An experimental installation is prepared and engine tests are conducted on a naturally aspirated single-cylinder Ricardo Hydra research engine. The measurements are carried out at various operating conditions. The experimental findings reveal an increase of in-cylinder pressure due to the increase of cetane number. In addition, a slight increase of bsfc is observed due to the small decrease of fuel heating value with the increase of the oxygen content. A decrease of ignition delay is observed with increasing oxygen content following thus, the increase of cetane number. A considerable reduction of soot, carbon monoxide and unburned hydrocarbon emissions is witnessed while; nitric monoxide emissions are increased when the oxygen content is increased from 3% to 9%. Similar effects are observed when replacing the rapeseed methyl ester with a mixture of diglyme and butyl-diglyme and the oxygen percentage remains unaltered. As revealed, a reduction of tailpipe soot without overall considerable penalties in bsfc and NOx emissions can be achieved in modern DI diesel engines using oxygenated additives at elevated percentages (30% by mass).
Zannis, T.C.Hountalas, D.T.Kouremenos, D.A.
Evaluating a Fischer-Tropsch Fuel, Eco-Par™, in a Valmet Diesel Engine2002-01-272610/21/2002
Reports have stated that Fischer Tropsch (FT) fuels are high quality, low emission diesel fuel substitutes. The purpose of this study is compare the emissions from a heavy-duty, Valmet, diesel engine running on a commercial available FT fuel, Eco-Partm, with the emissions obtained when the same engine is running on a low sulfur diesel fuel with low aromatic content, Swedish environmental class 1 (EC-1) diesel fuel. The two fuels have been analyzed by Fourier transform infrared spectroscopy and Raman Fourier transform infrared spectroscopy. The analyses showed that main constituents in the two fuels are alkanes with no substituents. No aromates or olefines could be detected. A small difference, later verified by gas chromatographic analyses, was noted; the Swedish EC-1 fuel consisted of a larger portion of straight chain, heavier hydrocarbons while the FT fuel consisted of more branched hydrocarbons. The overall impression of the emission analyses is that Eco-Partm gives lower emission than the EC-1 fuel during the modes employed in the ISO 8178 test. Emissions of acetaldehyde, benzaldehyde and acrolein were generally decreased 3-6 times when using FT fuel instead of EC-1 fuel while the emission of formaldehyde was unaffected. Fifteen volatile organic hydrocarbons were also included in the investigation-ethane, ethene, acetylene, propane, propene, propyne, propadiene, isobutene, isobutene, 1-butene, 1,3-butadiene, benzene, toluene, O-xylene and M-xylene. The emissions of the fifteen mentioned hydrocarbons were reduced between 20% - 93% when using Eco-Partm instead of EC-1. Measurements of the regulated emissions during an ISO 8178 test confirmed the obtained results; the emissions of total hydrocarbon (HC) decreased approx. 14% while the emissions of carbon monoxide, CO, and nitrogen oxides, NOx were almost unaffected. The test results in this investigation may indicate that diesel engines running on Eco-Partm can have a lower impact on environment and health than the, in Sweden, commonly used EC-1 fuel.
Nord, KentHaupt, Dan
Emission Characteristics of a Navistar 7.3L Turbodiesel Fueled with Blends of Dimethyl Ether and Diesel Fuel2001-01-36269/24/2001
Several oxygenates have been proposed and tested for use with diesel fuel as a means of reducing exhaust emissions. This paper examines dimethyl ether (DME), which can be produced in many ways including via Air Products and Chemicals, Inc's Liquid Phase Technology (LPDME ™). Modest additions of DME into diesel fuel (2 wt.% oxygen) showed reductions in particulate matter emissions, but the previous data reported by the author from a multicylinder Navistar 7.3L Turbodiesel engine were scattered. In this study, experiments were performed on a multi-cylinder Navistar 7.3L Turbodiesel engine to repeatably confirm and extend the observations from the earlier studies. This is an important step in not only showing that the fuel does perform well in an engine with minor modifications to the fuel system, but also showing that DME can give consistent, significant results in lowering emissions. The DME and diesel blends tested were to achieve a net addition of 5 and 10 wt. % oxygen in the blended fuel. The data confirms that the addition of DME can reduce the particulate emissions from a compression ignition engine. However, the NOx emissions were not favorable for all conditions. It is believed that through further modification of injection timing, NOx emissions can be effectively reduced.
Chapman, Elana M.Boehman, André L.Tijm, PeterWaller, Francis
Experimental Studies of the Impact of CETANER™ on Diesel Combustion and Emissions2000-01-288610/16/2000
Oxygenated fuels have been used successfully as blending agents to improve combustion and reduce emissions from spark-ignition fuels. For compression-ignition engines, similar benefits may accrue from the use of oxygenated fuels and blending agents, however, the combustion and physical properties of the oxygenates appropriate for diesel applications are significantly different. In this study, a blend of 20% monoglyme and 80% diglyme, referred to as CETANER™, has been examined as a reformulating agent in a single-cylinder IDI diesel engine and a 4-cylinder DI turbodiesel engine. Gaseous and particulate emissions measurements, as well as pressure trace analyses, have been used to examine how this additive affects diesel combustion and emissions. This blend of glycol ethers has both a high cetane number and a high oxygen content; its performance stems from both characteristics. Blend ratios were considered that provided approximately 2, 4 and 6 wt.% oxygen to a premium diesel fuel. The results demonstrate that the oxygenated fuel provides significant reduction in particulate matter emissions and mixed effects on NOx, CO and HC emissions. Ignition delay was not significantly altered in the IDI engine, although only the main chamber pressure was monitored. The impact of this blend of glycol ethers is to provide greater than 5 wt.% particulate matter emissions reduction for each 1 wt.% oxygen addition, although the effectiveness of particulate mass reduction decreases with increasing oxygen addition and is affected by engine configuration.
Hess, Howard S.Boehman, André L.Tijm, Peter J. A.Waller, Francis J.
A New Method for Diesel HC Collection and Speciation2000-01-295110/16/2000
As interest in diesel emissions has grown, so has the importance of analyzing the components of the exhaust. These compounds include alkanes, aromatics and alkenes, ranging in carbon number from C1 - C24, and polycyclic aromatic hydrocarbons (PAHs). These hydrocarbons can be in gaseous, semi-volatile and particulate form and cannot be collected accurately by conventional Tedlar™ bag sampling due to deposition of condensing vapor on bag walls. There are some sorbent methods used currently for the speciation of this exhaust, which require either thermal desorption and/or solvent extraction equipment. Automotive Testing Laboratories, Inc. (ATL) reports here on the use of a gas chromatography (GC) method designed to specifically look at hydrocarbons in the diesel (C9 - C24) range. Also described is the use of an impinger trapping method for collecting the hydrocarbons in diesel exhaust, a type of sampling which is most commonly used in the automotive emission community for the collection of alcohols and carbonyls. In the work described here, impingers filled with organic solvent were used to trap exhaust components, and this sample was subsequently concentrated by solvent evaporation and analyzed by GC. An approximately one-hour GC method for diesel-range hydrocarbons has been developed, which allows a time-efficient, yet thorough analysis of hydrocarbons in the exhaust. Diesel fuel has been analyzed with this method, and the chromatogram exhibited comparable patterns to those described in the literature. The emissions sampling method described here collected a range of hydrocarbon species that were comparable to those collected with other sorbent methods, described in the literature as well. Tests performed include sampling cold-start exhaust from a light-duty diesel truck during bag 1 of an FTP chassis-emissions test. Impinging using hexane was performed and species from C9 through C24 quantified. Heated flame ionization detector (FID) and non-heated FID results were recorded for total hydrocarbons. Gas-phase bag samples were taken for typical C1-C12 GC analysis for hydrocarbons. Comparison of C9 through C12 analyzed via the gas phase analysis versus that observed with the impinger method was made. Total hydrocarbon as determined from gas phase measured C1-C12 plus impinger phase C12 through C24, versus the total hydrocarbon observed with heated FID, is also discussed.
Lanning, Lisa A.Smith, Kurt W.Tennant, Christopher J.
Fuel Lubricity: Statistical Analysis of Literature Data2000-01-19176/19/2000
A number of laboratory-scale test methods are available to predict the effects of fuel lubricity on injection system wear. Anecdotal evidence exists to indicate that these methods produce poor correlation with pump wear, particularly for fuels that contain lubricity additives. The issue is further complicated by variations in the lubricity requirements of full-scale equipment and the test methodologies used to evaluate the pumps. However, the cost of performing full-scale equipment testing severely limits the quantity of data available for validation of the laboratory procedures at any single location. In the present study, the technical literature was reviewed and all previously published data was combined to form a single database of 175 pump stand results. This volume of data allows far more accurate statistical analysis than is possible with tests performed at a single location. The results indicate differences in the effectiveness of the standardized laboratory-scale methods. The High Frequency Reciprocating Rig (HFRR) produced much lower correlation with pump wear than did the Scuffing Load Ball on Cylinder Lubricity Evaluator (SLBOCLE), with HFRR tests performed at 60°C being even less accurate than those performed at 25°C. Correlation was also lower for fuels that contain lubricity additives as opposed to neat fuels. Multi-variable regression analysis of the data indicates that correlation with injection equipment is improved by combining the results from different laboratory-scale test procedures using simple mathematical formulae. The squared correlation (R2) of laboratory-scale wear tests with pump wear rating is unlikely to greatly exceed 77%, due to the inherent variability of the pump data. Combination of three or more laboratory tests using the equations derived from the multi-variable regression analysis allowed this maximum value to be achieved. As a result, it is hoped that the equations derived in the present paper may become more widely used to better predict full-scale pump wear.
Lacey, P. I.Mason, R. L.
Experimental Investigation on High-Quality Diesel Fuels Effects in a Light Duty CR Diesel Engine2000-01-19116/19/2000
In this paper some preliminary results on the emission performance of a modern CR DI diesel engine running on reformulated diesel fuels are discussed. The engine employed in the tests was a Fiat M724 1910cc, installed on Alfa Romeo 156 1.9 JTD. Modern injection systems can modify the spray structure with respect to a spray of a classical rotary injection pump so the well-consolidated knowledge on the correlation between fuel parameters and pollutant emissions may not be valid for the new generation of DI diesel engines. Two high quality fossil fuels and a synthetic fuel were selected for the tests. Tests were directed to analyze the relative influence on exhaust emissions between injection parameters and fuel quality. One engine test point (2000 rpm × 2 bar of b.m.e.p.) was chosen, with different setting of injection pressure, EGR ratio and pilot injection activation. Moreover a comparison between the performance of the CR engine and a light duty DI engine equipped with a classical distributor pump (Bosch VE pump) is also presented. With common rail systems, the soot increase, due to the EGR, is evident only at relatively low rail pressure while at high injection pressure the soot emissions are not influenced by the EGR rate. Contrary to the engine with the distributor pump injection system, the main characteristic of CR engine appears a moderate sensibility of NOx emissions and a poor particulate dependence from fuel quality.
Beatrice, C.Bertoli, C.Del Giacomo, N.Migliaccio, M.na.
The Effects of Oxygenate and Gasoline-Diesel Fuel Blends on Diesel Engine Emissions2000-01-11733/6/2000
A study was performed in which the effects on the regulated emissions from a commercial small DI diesel engine were measured for different refinery-derived fuel blends. Seven different fuel blends were tested, of which two were deemed to merit more detailed evaluation. To investigate the effects of fuel properties on the combustion processes with these fuel blends, two-color pyrometry was used via optically accessible cylinderheads. Additional data were obtained with one of the fuel blends with a heavy-duty DI diesel engine. California diesel fuel was used as a baseline. The fuel blends were made by mixing the components typically found in gasoline, such as methyl tertiary-butyl ether (MTBE) and whole fluid catalytic cracking gasoline (WH-FCC). The mixing was performed on a volume basis. Cetane improver (CI) was added to maintain the same cetane number (CN) of the fuel blends as that of the baseline fuel. However, other fuel properties, such as density, distillation temperatures, and viscosity were not controlled. The effects of the fuel blends on engine performance were similar for both the small and large engines. Ignition delay was increased with the fuel blends for both engines. The transition from premixed-burning to diffusion-burning phases was difficult to discern with the small engine. However, premixed-burning phase was dominant at low load; diffusion-burning phase dominated at high load. The fuel blends showed slightly higher premixed-burning peaks and lower diffusion-burning peaks than the baseline fuel. Decreases in smoke, CO, and THC emissions were observed with MTBE-mixed diesel fuel (MD). The effects of oxygenate- and gasoline-blending components on NOx were negligible at high load. Two-color pyrometry showed different combustion characteristics between fuels. Flame temperature and soot KL factor of MD were uniform. Major differences in flame temperatures between fuels were observed from 5∼35° aTDC. A decrease in soot KL factor was observed with MD for both engines after approximately 30° aTDC.
Kweon, Chol-BumFoster, David E.Shibata, Gen
A Comparison of Emissions from Clean Diesel Fuels1999-01-11213/1/1999
Exhaust emissions from various kinds of clean diesel fuels were evaluated using a commercial DI diesel engine in comparison with the emissions from a commercial diesel fuel containing 0.05% sulfur. The blending of a light paraffinic fuel to a commercial diesel fuel reduces HC, CO, PM and NOx emissions and a light fuel with aromatics or kerosene reduces PM and NOx but not HC and CO. The PM and NOx emissions from the paraffinic fuel are lower than these from the kerosene, and these emissions are decreased with an increase in the blending ratio of both light fuels to a commercial diesel fuel. Reformulated diesel fuels such as a clean city diesel fuel and fuels with few aromatics reduce PM and NOx emissions more than commercial diesel fuel, and the reduction rate is highly dependent on aromatic content. The effects on emissions of blending soybean methyl ester or tripropylene glycol methyl ether to a commercial diesel fuel were evaluated. The results showed that the PM reduction rate increases with an increase in the oxygenate content in the sample, and the PM emission from a mixture of 25% glycol and 75% commercial diesel fuel is almost equal to that from a light paraffinic fuel. The analysis of PM composition showed that a reduction in aromatics reduces the SOF caused by the reduction of the unburned fuel portion in the SOF, but not soot. On the other hand, the glycol reduces both the SOF and soot. The PM reduction rate highly depended on aromatic and oxygen content in the sample, and the NOx on aromatic content, according to statistical analysis using all test samples.
Uchida, MitsuruAkasaka, Yukio
Fuel Lubricity Reviewed98256710/19/1998
Many components on both aircraft and ground vehicles rely on fuel for lubrication and cooling of sliding contacts. Reliable performance of these power sources depends on the fuel providing sufficient lubrication to protect each of the many contact types within the pump and injection system. This characteristic of fuel has come to be known as lubricity. The subject of fuel lubricity has gone through a number of phases, most of which resulted from changing the composition of the fuel, which historically has been driven by fuel stability and by environmental regulations. This paper reviews these phases in chronological order. Beginning with the fuel system failures reported in aviation equipment in the 1960s and 70s, through the Military experience with low lubricity kerosene fuels in compression ignition engines in the 80s and 90s, to the ongoing introduction of more severely refined diesel fuel in progress in many developed countries around the world. The paper tracks the principal wear mechanisms observed in each instance, along with the laboratory-scale wear test procedures that were developed to simulate the condition. A complete description of this rapidly developing subject is beyond the scope of the present publication. However, it is hoped that the more salient issues are addressed, with numerous references also given to allow the reader to easily obtain additional information if needed.
Lacey, P.I.Howell, S.A.
Estimation of Diesel Fuel Effects Benefits on a Representative Engine of the Urban Transport Fleet in Venezuela94240911/1/1994
Fuel reformulation represents a major approach to reduce emissions in the current fleet. In this work, a medium-duty engine was used to determine the potential benefits of using reformulated Diesel fuel with controlled composition. This particular engine technology is used approximately in more than 60% of the corresponding transport fleet. The fuel properties that received special attention were sulfur content (390 - 8670 ppm), aromatic content (9.8 - 32.6 wt %), cetane number (40 - 51.6) and distillation temperature for 90 % volume recovered T90 (307 - 350 °C). Testing was conducted on the engine installed on a test bench and operated on a 4-mode cycle with two speeds and medium to high load. Data was taken on each mode and statistical procedures for averaging, weighting and analyzing, were applied to study engine operation. Combustion performance was observed based on a heat release analysis, comparing burning rates and ignition delay. Exhaust emissions of HC, CO, NOx and specific fuel consumption were determined. Particulates were measured using a mini-dilution tunnel technique using two separate filters for each measuring condition. Chemical analysis and detailed fuel characterization is used to explain the emissions results and the effects of fuel composition on emissions. The steady state testing allowed discrimination between fuel formulations. The absolute emissions and calculated reductions, were weighted using assumed service factors, indicating the importance of properly determining representative engine operating conditions for fuel comparisons. Hydrocarbons and CO were dependent on aromatic content with reductions as high as 11 % and 12 % respectively. NOx is linearly dependent on aromatic content in the conditions studied with reductions as high as 8 %. Specific fuel consumption can be reduced as much as 2.2 % due to increased combustion efficiency. The combined effects of aromatics, sulfur content and T90 on particulate emission rates was very dependent on the operating condition, these were similar for all fuels for higher fueling rates, where in-cylinder conditions favor soot oxidation.
González, Manuel A.Leon, Aymara
A Low Emission Diesel Fuel: Hydrocracking Production, Characterization and Engine Evaluations93273110/1/1993
The new regulations for emissions in USA (California and other States), introduce a new quality requirement for diesel formulations. As an answer to these problems Intevep, S. A., has developed a hydrocracking processing technology, a very flexible process able to operate up to 100 % of cracked material and with a mixture of light to heavy gas oil in any proportion, and which operates at moderate pressure. The proper balance between hydrogenation and mildhydrocracking is obtained through controlling the temperature and by tayloring the catalyst composition. Production of diesel fuel with less than 10 % wt aromatics was targeted, in a scenario of minimum hydrogen availability. Very low sulfur levels are achieved and the aromatic fraction is composed mostly of mono-aromatic compounds. Tests were conducted using a commercial Isuzu diesel engine, installed on an engine test bench and operated on a 7-mode cycle. Data was taken on each mode and statistical procedures for averaging, weighting and analysis were applied to study engine operation. Satisfactory combustion performance relative to high aromatic content fuels, was observed, based on a heat release analysis, comparing burning rates and fuel fractions burned on premix and diffusion modes. A reduced specific fuel consumption was determined to be due to high energy content. A screening version of the California Air Resources Board certification procedure for alternative diesel fuel formulations was carried out on a Detroit Diesel Series 60 engine, following successive hot start transient evaluations. Exhaust emissions of HC, CO, NOx, Particulates, SOF and Sulfates were determined. Results indicate the potential of this fuel formulation to reach the qualification of low emission diesel fuel. Chemical analysis and detailed fuel characterization are used to explain the low emission results and the effects of fuel composition on emissions. Comparisons with exhaust emission predictions for this particular engine indicate areas for further improvements.
González D., Manuel A.B., Guillermo RodríguezGaliasso, RobertoRodriguez, Edilberto
Lubricity of Low Sulfur Diesel Fuels93274010/1/1993
The sulfur content of all highway diesel fuel was required to be reduced to a maximum of 0.05 wt % starting October 1993. This federal requirement results in further fuel processing by refineries. The hydrotreating process used to reduce fuel sulfur has the potential to reduce the fuel's lubricating characteristics. Fuel producers and fuel injection equipment suppliers have been concerned about the likelihood of increased component wear upon the introduction of these new fuels. Low sulfur fuels have been produced and marketed in Southern California since 1985 with no apparent evidence of any field problem. Nevertheless, concern outside of this area exists. Therefore, one such fuel with a sulfur content well below 0.05% was used to conduct a vehicle test to evaluate its effect on the fuel injection pump. This fuel and a low aromatics diesel fuel were used to investigate the effect of various levels of two different sulfur compounds on the lubricity characteristics of the fuels. The standard Ball-on-Cylinder Lubricity Evaluator (BOCLE) test method as well as a modified version of this test were used. In a cooperative test between Chevron Research and Technology Company and Stanadyne Automotive Corp., pump stand testing was also conducted to characterize the low sulfur fuel. The addition of sulfur had no positive effect on fuel lubricity and, in some cases, had negative effects.
Nikanjam, ManuchHenderson, Paul T.
Effect of Low-Lubricity Fuels on Diesel Injection Pumps - Part II:Laborator Evaluation9208242/1/1992
This paper is the second of two that describe the effects of low-lubricity fuels on diesel injection pump performance. The first paper describes the primary failure mechanisms and wear processes in a number of failed pumps removed from both military and civilian vehicles that had been operated on Jet A-1 and diesel fuels. However, the multitude of unregulated parameters in practical operation renders quantitative comparison between different fuels and pump combinations impractical. This paper describes the degradation in pump performance and the wear processes associated with fuels of varying lubricity in the well-defined environment of a pump test stand. The test methodology concentrates on those areas previously demonstrated to be most susceptible to wear. The results indicate that pump durability is reduced by highly refined low-viscosity fuels, but may be successfully counteracted by either improved metallurgy or lubricity additives. The measured wear rate from the full-scale pump stand tests is compared with results from a lubricity measurement technique commonly used in aviation. Based on this comparison, initial criteria for the minimum fuel lubricity requirements of the injection system are suggested. MANY FUELS PROVIDE a limited range of contact conditions in which successful lubrication is possible. Fuel systems are designed to reflect these needs; however, seemingly minor changes in fuel composition or equipment design may significantly alter component durability. The Part I Field Performance paper (1)* described post-failure disassembly and examination of failed pumps returned from the field. However, in many instances ultimate failure was promoted by a number of causes, and the effects of fuel lubricity could not be isolated. The surface protection provided by a fuel is not a unique characteristic, but rather is highly dependent on the test environment and mechanical configuration. The selection of a laboratory test to accurately, yet rapidly, simulate field conditions is necessarily a compromise among competing variables. The fuel pump and injection components perform under a variety of contact geometries, pressures, and velocities to cover lubrication conditions from boundary to fully developed hydrodynamic film. However, preliminary tests and calculations reported in Reference 1 indicated that pump seizure was not primarily due to the decreased viscosity of the aviation fuels. As a result, the test series was designed to highlight the effects of oxidative/corrosive wear.
Lacey, Paul I.Lestz, Sidney J.
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