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Understanding Diesel Lubricity
Abstract
Diesel fuel injection pumps are lubricated primarily by the fuel itself. Traditionally, fuel viscosity was used as a rough indicator of a fuel's ability to provide wear protection, but since the advent of low sulphur diesel, even some fuels of higher viscosity have been found capable of producing wear. This paper provides further insights into the main contributors to diesel fuel lubricity, their source and the impact of refinery processing. The most effective way to monitor lubricity is also considered. We have found that diesel lubricity is largely provided by trace levels of naturally occurring polar compounds which form a protective layer on the metal surface. Typical sulphur compounds do not confer this wear protection themselves rather it is the nitrogen and oxygen containing hetero-compounds that are most important. A complex mixture of polar compounds is found in diesel and some are more active than others. The process of hydrotreating to reduce sulphur levels also destroys some of these natural lubricants. Other refinery processes also influence the concentration of the lubricity agents in the final fuel blend. Lubricity additives have been developed to compensate for the deterioration in natural lubricity observed in low S diesels. The interaction between natural polars and lubricity additive has been investigated and the findings may explain why some poor lubricity fuels are more responsive to lubricity additive than other. Difficulties are encountered when using knowledge of refinery streams to predict the lubricity of a diesel blend. The most effective way to monitor lubricity performance is by making measurements on the finished fuels. Vehicle tests have shown that the High Frequency Reciprocating Rig is a good indicator of diesel lubricity performance.
... Past studies of diesel fuel lubricity have used column chromatography to fractionate fuel components by polarity for testing in high-frequency reciprocating rigs (HFRRs). 7,9 The HFRR test (described in ASTM D6079) is a model tribosystem that physically replicates the plasticity-dominated wear mechanisms at steel-on-steel sliding contacts in the boundary lubrication regime. 11 It is important to note that the HFRR test does not replicate wear mechanisms typically observed in actual machine components; instead, it is used principally as a way to differentiate diesel fuels on the basis of their lubricity. ...
... 16 PAH compounds containing three or more aromatic rings are structurally similar to graphene, which has been reported to be an effective boundary lubricant for steel surfaces in sliding contact. 17 Previous investigations of diesel fuel lubricity either fractionated fuel samples to concentrate surface-active compounds 7,9 or added surface-active model compounds to neat diesel fuels for HFRR testing. 18−20 We report for the first time direct measurement of trace PAH compounds in diesel fuel samples through nuclear magnetic resonance (NMR) spectroscopy, and compare the PAH content of each sample to their respective average wear scar diameters (WSDs) derived from HFRR testing. ...
... 39 A similar linear relationship between kinematic viscosity and HFRR WSD was noted by Barbour et al. in their study on the lubricity of diesel fuels without PAH compounds. 7 Figure 6 provides a summary of published HFRR wear scar values as a function of kinematic viscosity. 7,39,40 Linear regression analysis of the literature data yields the following wear equation: ...
Surface-active trace compounds present in diesel fuels protect pumps and injectors against premature wear through boundary lubrication. Due to the vast number of hydrocarbon compounds found in petroleum distillate fuels, it is difficult to measure the concentration of trace lubricity-enhancing compounds in neat diesel fuel samples. We report herein the direct measurement of trace polycyclic aromatic hydrocarbons (PAH) in diesel fuels through 1H and 13C nuclear magnetic resonance spectroscopy and relate the PAH content with fuel lubricity measured with a high-frequency reciprocating rig (HFRR). Carboxylic acids and nitrogen heterocyclic polyaromatic hydrocarbons (NPAH) were not detected in the diesel fuels tested. The data provides further evidence that surface-active PAH compounds improve the lubricity of diesel fuels.
... A number of studies have shown that triglycerides hold promise as alternative diesel engine fuel [6]. The high viscosity, carbon deposits, acid composition, free fatty acid content of such oils, gum formation due to oxidation and polymerization during storage and combustion, oil ring sticking, lubricating problems, cooking and trumpet formation on the injectors to such an extent that fuel atomization does not occur properly or is even prevented as a result of plugged orifices, thickening and gelling of the lubricating oil as a result of contamination by vegetable oils, lower volatilities content which causes formation of deposits in engines due to incomplete combustion and incorrect vaporization characteristics are some of the more obvious problems [7]. ...
... Consequently, considerable effort has gone into developing vegetable oil derivatives that approximate the properties and performance of hydrocarbon-based diesel fuels. Problems encountered in substituting triglycerides for diesel fuels are mostly associated with high viscosity, low volatility and polyunsaturated character [7]. The following processes have been used in attempts to overcome these drawbacks and allow vegetable oils and oil waste to be utilized as a ...
The research presents experimental study and investigation on the production of biodiesel from African sweet orange seeds oil. The seeds were obtained, sundried, crushed and weighed. Chemical extraction method was used to extract oil from the crushed seeds using soxhlet extractor with n-hexane as a solvent. The physicochemical properties of the oil determined were; flash 1510C, fire point 1730C, acid value 82%, product percentage yield 40% and specific gravity 0.920 at 150C. The production of Biodiesel was carried out through transesterification process from the extracted oil using methanol as catalyst. The results of the physicochemical properties of the produced biodiesel are; Cloud point 60C, Pour point 20C, Flash point 1400C, Density 0.86g/cm and Kinematic viscosity 1.938 mm2/s. The effect of methanol on the yielding of biodiesel at constant ratios of oil and catalyst was determined to be 68% at 10ml, 77% at 9ml and 72% at 7ml. The results obtained are in conformity when compared with ASTM standard D6571 and imply that the African sweet orange seeds oil can be used to produce biodiesel
... During desulfurization, some non-sulphur compounds are also removed. It is possible that loss of these compounds and not the sulphur causes the loss of lubricity [55]. It is reported that phenols and poly-cyclic aromatic compounds are essential components/species imparting lubricity to mineral diesel [56]. ...
... The film reduces the wear in the FIE components, which are lubricated by fuel alone. Hydro-desulfurization process during petroleum refining removes polar and sulphur compounds from mineral diesel, which are responsible for its lubricity and in a way, protect the FIE components from wear [55,58]. Due to enforcement of stringent emission legislation, sulfur is required to be removed from mineral diesel therefore mineral diesel fuelled FIE exhibits higher component wear, dimensional loss and weight loss compared to biodiesel and SVO FIE, both of which contain naturally occurring lubricating compounds [59]. ...
In this study, a fuel injection equipment (FIE) test rig was designed and fabricated to investigate the wear characteristics of FIE components used by a single cylinder diesel engine using Karanja oil (KO100), and Karanja biodiesel (KOME100) vis-a-vis baseline mineral diesel. A 250 h endurance test was performed in the FIE test rig to evaluate the wear, weight loss, dimensional loss and alterations to the surface texture at different locations in various components used in the FIE such as nozzle needle, plunger, valve and valve holder. Cam and follower mechanism was used for developing fuel injection pressure in the fuel pump of the test rig, which was operated at 1500 rpm. Karanja oil showed the lowest wear and mineral diesel showed the highest wear of the FIE components, except for plunger. The same was confirmed by surface texture images obtained by optical microscopy at magnifications of 100, 200 and 500×. Wear of FIE components took place primarily due to mechanical and thermal stresses, and chemical reactivity of test fuels with the FIE components. Overall, the wear of FIE components was relatively lower with biodiesel and SVO usage compared to baseline mineral diesel usage in the test rig.
... The low sulfur diesel fuel has poor lubricity, caused by the removal of polar oxygen and nitrogen compounds, which happens during the process of sulfur species extraction. These polar compounds are adsorbed on the rubbed metal surfaces providing a protective layer that reduces adhesion and limit friction or wear [1]. ...
... It is important to indicate that this effect is opposite to the behavior of these compounds concerning their viscosity. The viscosity decreases with the number of double bonds, so between the three compounds depicted in the graphic, ethyl linoleate is the one with better lubricity but worse viscosity, confirming that viscosity and lubricity not always are correlated, especially in low-sulfur fuels [1]. Fig. 6 shows the relationship between MWSD and vapor pressure for different biodiesel fuels from different oils. ...
Lubricity of individual fatty acid methyl or ethyl esters and biodiesel fuels has been measured using a high frequency reciprocating rig (HFRR). Tests have been carried out varying the ambient humidity to assess the effect of this parameter on the lubricity of the fuels. The European standard proposes a single humidity correction factor for all the fuels, regardless their composition. It has been proved in this study that this factor is not constant and it depends on the fuel composition. For this reason two different correlations have been proposed for the estimation of the humidity correction factor and normalized wear scar as a function of different fuel compositional characteristics. The influence of the water content on the lubricity and the relationship between humidity and water content of the fuel has been studied revealing that the effect of the air humidity is an indirect effect of the hygroscopy of the fuel.
... The poor lubricity of low-sulfur petrodiesel requires additives or blending with another fuel of sufficient lubricity to regain lubricity. The reason for the poor lubricity of low-sulfur petrodiesel is not the removal of the sulfur-containing compounds but rather that polar compounds with other heteroatoms such as oxygen and nitrogen are also reduced in low-sulfur petrodiesel (Wei and Spikes, 1986;Dimitrakis, 2003;Barbour et al., 2000). ...
... To meet the established limits of wear scar in diesel fuel standards, 460 μm in European (EN 590-09) and 520 μm in U.S.A. (ASTM D 975) regulations, a variety of lubricity additives can be used,which have a high affinity to metallic surfaces forming a thin protective metal-metal contact layer. This lubricant film is formed by the adsorption of the polar molecules of the additives on the metal surface, which is negatively charged (Barbour et al., 2000). ...
In Brazil has stepped up social, economic and technological incentives for biodiesel´s production through the various oilseed crop species and its utilization by the ethylic transesterification process. Biodiesel is responsible for restoring the lubricity of the ultra-low sulfur diesel fuel and, furthermore it is less polluting, and thus extends the life of diesel fuel injection system, (including injector nozzle). This property is extremely important from the point of view of the integrity of the injection system, since the diesel fuel is primarily responsible for lubrication of injector nozzle. Thus it is necessary that all diesel fuel meets a minimum limit of 460 µm maximum the Wear Scar Diameter (WSD) by HFRR – High Frequency Reciprocating Test Rig (ISO 12156-01). However, much has to be investigated in relationship to physicochemical properties of such blends and, that they can result in performance of components of the injection system. The lubricity of the fluids (Ethyl Ester of Sunflower Oil-B0, B5, B20, B50 and B100) was evaluated by the HFRR, according to ASTM D 6079-04. The thermoacoustic answers (contact temperature, sound pressure level and accumulated numbers of cycles) were obtained during these tests due to the coupling of a SPL meter and temperature sensors. All fluids offered values of the WSD lower 300 µm, but minimum values were found for B5 and B100 blends of sunflower oil, WSD <200 µm. Therefore, these renewable biofuels provide appropriate lubricity in any percentage blend, besides they have better performance than B0-Diesel (pure mineral diesel fuel).
... In the now-common ULSD fuels, sulphur-containing dibenzothiophenes with alkyl (often methyl) substituents are removed from petrodiesel. Minor oxygen-and nitrogen-containing molecules that had been responsible for petrodiesel's lubricity are also eliminated during the hydrodesulfurization process that results in ULSD fuels (Barbour, Rickeard, & Elliott, 2000). As a result, ULSD fuels have poor lubricity. ...
The search for alternate energy sources has intensified due to
growing concerns. These worries include the availability of feed�stock in relation to supply security and the utilisation of domes�tic energy sources, volatility of cost, the ongoing depletion of
non-renewable petroleum reserves, and greenhouse gas emis�sions. It is beyond the scope of this chapter to list all of the legal,
regulatory, and incentive measures implemented to address these
concerns. The importance of fuels generated from biological
sources, including lipid substances like fats and oils, has grown.
Fuels produced through various production methods employing
fats and oils as feedstocks have varying compositions and physi�cal characteristics. Biodiesel is the most well-known of these
fuels
... Keith and Conley (1995) stated that the production of a cleaner diesel fuel could lower the lubricity of diesel fuel. The lubricating quality of diesel fuel dropped significantly, when the United States mandated the use of a diesel fuel that had less than or equal to 500 parts per millions (ppm) sulphur and that the petroleum industry expects the lubricity of petroleum diesel to drop even lower (sulphur <15ppm) Viscosity of diesel fuel is related to lubricity (Lacey and Mason, 2000), in such a way that many researchers suggested that the lubricity of the fuel is not provided by fuel viscosity (Barbour, Rickeard and Elliott, 2000). It was also reported that oxygen definitely contributes to the natural lubricity of diesel fuel, but that nitrogen is more active lubricity agent than oxygen and maintained that diesel fuels that are high in sulphur but low in nitrogen exhibit poor lubricity. ...
The role being played by fuel oil (diesel oil) in compression ignition engines and machines cannot be overemphasized due to its high efficiency. However, there are some flaws in its usage which give rise to environmental concern; such as emission of toxic gases like carbon monoxide, oxides of nitrogen and so on. The aforementioned gases contribute to cancer in human and lead to increase in global warming and ozone layer depletion. This has necessitated the search for an alternative eco-friendly fuel for internal combustion engine with the view to reduce the emission of gases generated by the inevitable use of diesel engine and also to increase the engine performance. The use of bio-fuels is an effective measure to substitute fossil fuels and reduce particulate matters for diesel engines. Many researchers suggest the use of biodiesel blends of between 6 to 20 percent volume of biodiesel. In this study, biodiesel which was used as the alternative fuel was produced by conversion of the groundnut oil through alkali-based transesterification with potassium hydroxide (KOH) as catalyst. The blending was carried out in the following percentage by volume of the biodiesel 10 percent, 20 percent, 30 percent and 100 percent corresponding to B10, B20, B30 and B100 respectively. Experimental analysis was carried out using biodiesel blends and the characterization of the blend was tested for properties such as: specific gravity (density), flash point, viscosity, and so on, the results compared with available standards. The density was found to be between 830.9kg/m3 and 867.4kg/m3 , the viscosity falls within 1.76mm/s2 and 2.1mm/s2 while the flash point was between 60oC and 160oC, increasing as the quantity of biodiesel increases. The results of the blends show that the biodiesel blend B30 can be used without altering the engine configuration.
... Hence ULSD loses its lubricity property, so fuel pump system experiences friction which leads to the failure of engine by tear and wear. Adding a lubricity improver helps to reduce friction between the metallic parts of fuel pump, that lessens the impact of lubricity loss [6][7][8]. In the past two decades several attempts have been made to prepare efficient lubricity additives and compounds, such as carboxylic acids, nitrogen containing compounds such as amines and amides of fatty acids, and natural or synthetic esters are reported as good lubricity enhancers for ULSD [9][10][11]. ...
... [10][11][12] However, in the absence of such components, the direct usage of ULSD in motor vehicles causes a negative impact on the fuel injection system of the engine and leads to engine damage. 13,14 Hence ULSD has to be blended with appropriate lubricity additives in order to enhance its lubricity. 13 According to the literature, additives possessing polarity-imparting hetero atoms or functional groups such as carboxylic esters (-COOR) improve the lubricity of the fuel. ...
A new route for the conversion of refinery light cracked naphtha (LCN) stream into lubricity improvers for ultra-low sulphur diesel (ULSD) was developed through a simple chemical process involving olefin epoxidation and esterification reactions. Two different methods viz., H2O2/glacial acetic acid and m-chloroperbenzoic acid (m-CPBA), were found to be suitable for the epoxidation of LCN. The LCN epoxide was subjected to an esterification reaction via epoxide ring opening using different long chain (C4 - C18 alkyl groups) organic acids to get the hydroxy ester derivatives of LCN. The lubricating property of the newly synthesized hydroxy esters was studied by dosing them with ULSD at 300 and 150 ppm (wt/vol) concentrations. Amongst them, LCN hydroxy ester derived from stearic acid showed the best lubrication-enhancing property at both dosage levels. The scanning electron microscope (SEM) image and energy dispersive spectra (EDS) of the high-frequency reciprocating rig (HFRR) specimen support the lubricating action of the LCN esters through the formation of a protective layer between the metallic surfaces. The synergy of simple chemical processes and efficient lubricity action makes these LCN esters as promising materials for low-cost and scalable additives for ULSD.Graphical abstractThe olefin-rich light cracked naphtha obtained from the fluidized catalytic cracker unit of the oil refinery was converted into hydroxy esters through an epoxidation reaction followed by the esterification with different carboxylic acids. The hydroxy esters at low dosage levels (150/300 ppm) enhance the lubricating property of ultra-low sulfur diesel.
... 10−12 However, the direct usage of ULSD in motor vehicles causes friction between the metal surfaces of fuel injection system which leads to the engine damage. 13,14 In the absence of lubricity imparting components such as sulfur and other polar components, the diesel fuel must get its lubricity property by an alternative source. The lubricity of ULSD can be improved by adding lubricity additives. ...
Light cracked naphtha (LCN) is one of the olefin streams obtained from oil refinery in the petrochemical fluidized catalytic cracking unit. In this communication, we report a new method for the conversion of LCN into lubricity improvers for ultra-low sulfur diesel (ULSD) through a feasible two-step synthetic procedure. In the first step, olefins of LCN were subjected to the hydroboration reaction using BH3 to get the hydroxy LCN derivative which was then subjected to the esterification reaction with different organic acids to get the final LCN esters (6a-j). The lubricating property of the LCN esters was studied at two blending concentrations (300 and 150 ppm, wt/vol) with ULSD. Interestingly, ester (6a) derived from stearic acid showed the tiniest wear scar diameter in both dosage levels. The mechanism of lubricity action of LCN esters on metallic surfaces was studied by analyzing the worn surfaces using scanning electron microscopy and energy-dispersive X-ray spectroscopy techniques. The studies reveal that the lubricity additives derived from cracked naphtha through a simple chemical reaction strategy are promising precursors in enhancing the lubricity of ULSD.
... Further, fuel lubricity is a growing concern owing to the usage of ultra-low sulfur diesel as per stringent regulation by almost every country nowadays (Knothe and Steidley 2005;Wu et al. 2022). The inability of lubricant properties by fuel made it cause a plethora of problems in fuel injector, and fuel pump consequently leads to engine failure (Barbour, Rickeard, and Elliott 2000). However, the poor lubricity is not only due to the removal of sulfur but also due to low the level of oxygen or nitrogen-based polar compounds. ...
Biodiesel is an emerging solution to petrodiesel owing to its high flash point, low toxicity, biodegradability, and less greenhouse gas (GHG) emissions. It is still a problem for end-users due to poor oxidation stability and cold flow properties. However, biodiesel can be used as a lubricity improver in petrodiesel, but high dosages of biodiesel may be cost-intensive. Multifunctional additives can provide a robust solution to the said challenge. We report herein the Schiff base ethyl levulinate coupled with N-phenyl-p-phenylenediamine (EL-NPPD) as multifunctional additive, viz. antioxidant and lubricity enhancer for the biodiesel. The additive was synthesized in two steps: ethyl levulinate (EL) production followed by imine formation. The final product was characterized using thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) spectroscopy. The antioxidant properties of the synthesized additive were checked in terms of induction time using Rancimat as per EN14112 methods. At the 1000 ppm concentration, the induction period value of 7.94 ± 0.6 was observed. Further, as the concentration increased, induction time got increased. Furthermore, the antioxidant potential was checked with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical inhibition-based method in which different concentrations of additive ranging from 1000 to 5000 ppm were used against commercial antioxidants. As concentration increased to 4000 ppm, % inhibition values got increased by 15%, which showed better antioxidant activity of EL-NPPD. Similarly, the lubricity tests were performed using the HFRR test in which additive ranging from 1000 to 2000 ppm was used, and the average wear scar diameter (AWSD) was significantly reduced from 258 ± 11 to 248 ± 10, i.e. around 5% reduction than neat biodiesel sample.
... Table 4 Engine performance, combustion and emission characteristics in the case of using MF and its blends. [398,399]. Similar observations were made in the case of gasoline. Besides fuel viscosity, the availability of sulfur, nitrogen, and oxygenated content in gasoline has a considerate impact on its lubricity [400]. ...
Currently, the development of alternative and green energy sources has been being strongly pushed aiming to recoup the lack of fossil energy, to meet the ever-increasing demand of energy use in modern society, and to palliate concerns regarding environmental pollution and global climate change. Therefore, producing energy from biomass sources has recently been of great interest because biomass is considered as a reliable and ubiquitous source. Indeed, the conversion of biomass into furan derivatives through the catalytic production process is emerging as a fascinating and promising method. Being one of the furan-based compounds, 2-Methylfuran (MF) is known as a critical platform substance and an ideal green solution on the pathway of finding alternative fuels because the MF properties are similar to those of fossil fuels and MF could be generated from renewable biomass source. In this review paper, the process of MF synthesis from biomass through catalyst reactions was thoroughly analyzed. More importantly, the pyrolysis and oxidation progress of MF was also critically presented aiming to clarify the applicability of MF to internal combustion engines. Finally, the performance, the characteristics of combustion, and pollutant formation of internal combustion engines fueled with MF were discussed in detail. In general, MF could become a promising alternative fuel for internal combustion engines although studies on the engine durability, compatibility to materials, tribology behaviors should be further carried out in the future.
... B10 (Diesel) has a higher average coefficient of friction (0.0676) and lower lubricity among other fuel samples due to the presence of higher Sulfur content. In diesel engines, fuel lubricity is important because it provides lubrication during rotating pumps and fuel injection (Barbour et al., 2000). B100 biodiesel and B30 fuel sample showed good lubricity and low coefficient of friction compared to alcoholic additives (B30 + DMC and B30 + Eth) and B10 (Diesel). ...
This study focused on evaluating the lubricity of diesel–biodiesel fuel with oxygenated alcoholic and nano-particle additives. Fuel injection system lubrication depended primarily on the fuel used in the diesel engine. Palm–sesame oil blend was used to produce biodiesel using the ultrasound-assisted technique. B30 fuel sample as a base fuel was blended with fuel additives in different proportions prior to tribological behavior analysis. The lubricity of fuel samples measured using HFRR in accordance with the standard method ASTM D6079. All tested fuels’ Tribological behavior examined through worn steel balls and plates using scanning electron microscopy (SEM) to assess wear scar diameter and surface morphology. During the test run, the friction coefficient was measured directly by the HFRR tribometer system. The results exhibited that B10 (diesel) had a very poor coefficient of friction and wear scar diameter, among other tested fuels. The addition of oxygenated alcohol (ethanol) as a fuel additive in the B30 fuel sample decreased the lubricity of fuel and increased the wear and friction coefficient, among other fuel additives. B30 with DMC showed the least wear scar diameter among all tested fuels. B30 with nanoparticle TiO2 exhibited the best results with the least wear scar diameter and lowest friction coefficient among all other fuel samples. B30+DMC demonstrated significant improvement in engine performance (BTE) and carbon emissions compared to different tested samples. B30+TiO2 also showed considerable improvement in engine characteristics.
... Most diesel engine components are self-lubricated with diesel fuel, Table 8 Physicochemical properties of POME, SOME and P50S50 biodiesels. such as (fuel injectors, fuel pumps, etc.) [51]. Wear scar diameter (WSD) of tested fuels that are measured by SEM micrographs of metal balls. ...
The purpose of this study was the improvement of cold flow and lubricity characteristics of biodiesel produced from the palm-sesame oil blend. Extreme learning machine (ELM) and response surface methodology (RSM) techniques were used to model the production process and the input variables (time, catalyst amount, methanol to oil ratio, and duty cycle) were optimized using cuckoo search algorithm. The mean absolute percentage error (MAPE), coefficient of determination (R²), mean square error (MSE), root mean square error (RMSE), and standard error of prediction (SEP) were calculated to evaluate the performance of RSM and ELM. The results showed that ELM model had better performance in prediction than RSM model. The optimum yield of P50S50 biodiesel obtained was 96.6138% under operating parameters of time (38.96 min), duty cycle (59.52%), methanol to oil ratio (60 V/V %) and catalyst amount (0.70 wt%). The cold flow characteristics of P50S50 biodiesel are significantly improved like cloud point (7.89 °C), pour point (3.80 °C), and cold filter plugging point (- 1.77 °C) with better oxidation stability 6.89 h. The average coefficient of friction P50S50 biodiesel was lower than palm biodiesel (B100) and B10 commercial diesel by 2.29% and 12.37% respectively.
... It is also a precursor to particulate matter (PM) and acid rain. Hydroprocessing is a refinery process for removing heteroatomic molecules containing sulphur, nitrogen and oxygen, as well as saturating aromatic molecules [1]. Hydroprocessing is known to reduce the naturally-occurring lubricity in diesel fuels [2,3]. ...
Lubricity improver additives are adsorbed on sliding surfaces and form boundary films. Although for most additives, the films are monolayers, multilayer adsorption does occur in tribological contacts. However, to date, the isotherms adopted to study the adsorption thermodynamics for tribological systems are limited to monolayer films.
To address this, the original Brunauer–Emmett–Teller (BET) gas adsorption isotherm was modified for use in dilute liquid solutions. The modified BET isotherm was used to fit experimental wear data collected using high frequency reciprocating rig (HFRR) for ultra-low sulphur diesel (ULSD) fuels containing trace levels of commercial lubricity improving additives. The results suggested that for certain additives in ULSD, the boundary film is multilayer.
... Available complex polar substances, which created protective layers on the metal surfaces, are as a natural lubricant. Among them oxygen-, nitrogen-, aromatics, and olefinic contents are listed [1,3,11]. Vegetable oils that are mainly consist of triacylglycerides and small amounts of nondiacylglycerol compounds such as phospholipids, free fatty acids, sterols, tocopherols, dyes, flavonoids and glycolipids. ...
The aim of the study was to determine the sulphur content in 33 samples of oils pressed from different species of vegetable. The unconventional oil samples were purchased from commercial store. Oils was analysed in terms of sulphur content according to the method using X-ray fluorescence spectrometry with wave dispersion, that is described in the PN-EN ISO 20884, 2012 standard. Obtained results of sulphur analysis were presented as the arithmetic mean ± standard deviation (from three replicates) and statistically analysed using the Statistica 13.0 PL program. In order to indicate significance of differences between oils analysis of variance (ANOVA) with Tukey's test of p ≤ 0.05 significance level was used. The statistical analysis indicated significant differences in the content of sulphur content in the analysed vegetable oils, which could affect the lubricity of prepared fuel blends and in some cases significantly, increase the sulphur content above acceptable value 10 ppm. It was concluded that vegetable oils could be a suitable raw material improving the lubricating properties of low-sulphur diesel oils. However, due to significant differences in the sulphur content in the analysed samples, the content of this element should be analysed beforehand in order to eliminate the possibility of exceeding the permissible level of sulphur in transport fuels.
... In a diesel engine, fuel is sprayed into compressed air and atomized into small drops in proximity to the nozzle exit. A high viscosity leads to inferior atomization, disrupting the crucial oxygen and fuel mixture, resulting in incomplete combustion, increasing the engine deposits, and the energy required to pump the fuel, consequently wearing the fuel pump elements and injectors [28]. Hence, the viscosity has to conform within the range of specification limits. ...
... Traditionally fuel viscosity was used as an indicator of a fuel's ability to provide wear protection, but since the introduction of low sulfur diesel fuels, even some fuels of higher viscosity have been found capable of producing wear [7]. It is true to say that, as viscosity reduces, lubrication will move from a hydrodynamic regime, through a mixed lubrication regime and then to a boundary regime where lubricity is critical. ...
... This rule is not applicable since the introduction of low-sulfur marine fuels. It was proved that even low-sulfur marine fuels with high viscosity have the ability to produce wear problems[7]. Polar compounds which were formed through the production process provide a protection layer between the working metal surfaces. ...
In this study, seven mixtures of diisopropanolamides that were synthesized from various vegetable oils (sunflower oil, soybean oil, cotton seed oil, olive oil, tobacco seed oil, coconut oil, used frying oil) were used as lubricating additives in a low-sulfur marine gas oil. All tribological measurements were carried out by using the high-frequency reciprocating ring (HFRR) test procedure, according to EN ISO 12156-1. The obtained wear results showed that all mixtures of diisopropanolamides used provide satisfactory a mean wear scar diameter (WS 1.4) of less than 520 µm, at concentration levels of 60–120 ppm. The concentrations below 60 ppm had no effect on the fuel lubricity. An increase in the concentration of the diisopropanolamide mixtures led to an insignificant increase of the lubrication effectiveness.
... The background is that hydrodesulfurization of petrodiesel reduces or eliminates the inherent lubricity of this fuel [308][309][310][311], which is essential for proper functioning of vital engine components such as fuel pumps and injectors. Hydrodesulfurization reduces not only the sulfur content of diesel fuel but also removes oxygen-and nitrogen-containing compounds which were responsible for its inherent lubricity [311,312]. The effect of heteroatoms on lubricity was confirmed by an investigation of neat C3 compounds with OH, NH2, and SH groups leading to the sequence of lubricity improvement OH > NH2 > SH [313]. ...
The mono-alkyl esters, most commonly the methyl esters, of vegetable oils, animal fats or other materials consisting mainly of triacylglycerols, often referred to as biodiesel, are an alternative to conventional petrodiesel for use in compression-ignition engines. The fatty acid esters that thus comprise biodiesel largely determine many important fuel properties. In turn, the composition of the biodiesel depends on the composition of the parent feedstock because feedstocks with widely varying fatty acid composition can be used for biodiesel production. The use of different feedstocks is also significant under aspects of increasing biodiesel supply and socio-economic issues. In this article, biodiesel production is briefly described, followed by a discussion of biodiesel fuel properties and the influence of varying fatty acid profiles and feedstocks. It is shown that the properties of biodiesel least influenced by minor components can be determined by a straightforward equation in which the properties of the biodiesel fuel are calculated from the amounts of the individual component fatty esters and their properties. Optimizing biodiesel composition is also addressed.
... High levels of lubricity imply in low wear scar, ensuring the formation of effective interfacial lubricant film that implies in the separation of contact surfaces 5 . The allowed maximum values of WSD have been established by American and European standards as 520 µm (ASTM D 975) and 460 µm (EN 590) at 60 °C, respectively 6 . ...
During the contact between metallic surfaces in mechanical systems, some dynamic characteristics present significant changes as the vibration signal patterns. The acquisition and characterization of these signals, by the use of Fourier Transform (FT), are non-intrusive tools in the evaluation of lubricity. This study aimed to evaluate dynamically the fuels lubricity (diesel S50, biodiesel and its blends) by the reciprocating sliding of a ball against a flat disc (AISI 52100 steel). After that, the vibration signals were evaluated by statistical test and FFT (Fast Fourier Transform) and STFT (Short-Time Fourier Transform) analyses and verified their associations with parameters supplied by ASTM D6079. The results present a correlation between lubricity, frequency spectrum and the parameters of profiles from the worn disc surface. In addition, the evolution of wear scars presented an influence of the biodiesel content in these fuels.
... Traditionally fuel viscosity was used as an indicator of a fuel's ability to provide wear protection, but since the introduction of low sulfur diesel fuels, even some fuels of higher viscosity have been found capable of producing wear [7]. It is true to say that, as viscosity reduces, lubrication will move from a hydrodynamic regime, through a mixed lubrication regime and then to a boundary regime where lubricity is critical. ...
In this study, seven mixtures of diethanolamides that were synthesized from various vegetable oils (Sunflower oil, Soybean Oil, Cotton Seed Oil, Olive oil, Tobacco seed oil, Coconut oil, used frying oil) were used as lubricating additives on a low sulfur MGO, at eight different concentrations of 20, 50, 80, 110, 140, 170, 200 and 230 ppm. All tribological measurements were carried out by using the HFRR test procedure, according to ISO 12156-1. The relative humidity in the laboratory was kept between 52 % and 57 %, while the mean ambient temperature was approximately constant at 23 °C. The obtained wear results showed that all mixtures of diethanolamides used provide satisfactory a mean wear scar diameter (WS 1.4) of less than 520 μm, at concentration levels of 80-170 ppm. The concentrations below 80 ppm had no effect on the fuel lubricity. A further increase in the concentration of the diethanolamide mixtures higher than 170 ppm, led to an insignificant increase of the lubrication effectiveness.
... Because, the naturally available trace level complex polar substances (e.g. oxygen-, nitrogen-, aromatics, and olefinic contents) which used to be in the diesel fuel and created protective layers on the metal surfaces as a natural lubricant are also destroyed in the hydro-desulfurization process [6,11]. ...
Ultra-low sulfur diesel fuel is essential requirement as per the emission regulation. With the adoption of hydrodesulfurization (HDS) process, the diesel fuel loses its inherent lubricity, however certain amount of lubricity of diesel fuel is needed to save several engine components from wear and failure. Though the loss of lubricity of the diesel fuel is observed with the removal of sulfur, it is mainly due to the loss of nitrogen and oxygen based polar trace compounds which are also removed in the HDS process. Unrefined biodiesels having little amount of monoglycerides (<0.8%) and free fatty acids also show better lubricity and fuel properties to be used as fuel lubricant. Biodiesel are also considered as the suitable blending compound with the diesel. This study found that the biodiesel blends up to 20% with the diesel fuel can effectively reduce both the wear of the tribo-contact surfaces as well as the friction coefficient. The use of biodegradable fuel lubricant has set away the threat of environment pollution by the diesel additives which are derived chemically. The oxidation stability and the low temperature properties of both the biodiesel and the vegetable oils can be improved with some chemical modification. It can be concluded that the use of biodiesel with the diesel fuel can be an appropriate option for effective engine lubrication system where only the fuel has to provide the required lubricity.
... Interestingly, investigators used enzyme catalyst along with homogeneous acid and base catalysts for transesterification of waste cooking oil. Researchers [16] used immobilized lipase based on Rhizopus orzyae and focusing on optimization of several parameters and adding method, reaction temperature, and water content. Authors observed that methanol/oil ratio of 411, immobilized lipase/oil of 30 wt% and 40°C were suitable for waste oils under 1 atm. ...
Ahstract-The energy demand has increased tremendously due to world population growth and increase in industrial development activity. To meet energy demand, petroleum fuel has been serving the world. The excess use of petroleum sourced fuels would lead to unsustainable situation because of depleting supplies and all the environmental issues which would be responsible for a major deficit in the future. Critical need for looking into new alternative renewable energy resources have resulted in increased interest in the study of alternative fuels such as biodiesel. Consequently, biodiesel is a very promising alternative to petroleum diesel oil and renewable which has the similar properties petroleum diesel. Biodiesel actually is a trans-esterified fuel which is produced from vegetable oils and animal lipids which has properties similar or better than diesel fuel. Based on various research and demonstration projects it has proven that biodiesel can be used as pure or in blends with conventional diesel fuel in diesel engines without any modifications. The aim of this paper is to review the studies done earlier and to observe the production and fuel characteristics of biodiesel produced from various feed stocks like vegetable oils and waste oils and their effect on CI engine from the viewpoint of performance, combustion and emissions and its sustainability.
... This thin film is formed by adsorption of polar molecules of fuel on metal surfaces, i.e., there is a high affinity to metallic surfaces forming a thin protective metal-metal contact. The maximum permitted WSD by American and European standards is 520 µm (ASTM D 975-10) to 460 μm (EN 590 -10) to 60° C, respectively 11 . ...
The contact of diesel fuel with engine subsystems demands a good wear resistance. Lubricity is an important feature for integrity of injection system and the sulphur composites are primarily responsible for lubrication of the injector nozzle. Biodiesel is responsible for partially restoring the lubricity of diesel fuel that presents low levels of sulphur composites and, furthermore, it causes less pollution than diesel fuel. The lubricity is measured through the wear scar diameter following the ASTM D 975 standards. However, the friction and wear with light loads of micro/nanocomponents are highly dependent on surface interactions that can be evaluated by microscopy techniques. This study aimed to measure and to analyze the biodiesel lubricity and their blends (B5, B20) with diesel by observing the wear scars of discs using the scanning electronic microscopy (SEM), atomic force microscopy (AFM) and micro roughness techniques. The fuels performance was evaluated using HFRR tribometer. The tests conditions were based on standard ADTM D-6079-04. The coefficient of friction was measure during the test. After the test, the worn ball and disc were analyzed by SEM, AFM and profilometer. The results showed that the addition of biodiesel in diesel improve the tribological performance of fuel. Also, the just WSD value is not sufficient to evaluate the lubrication ability of a fuel. Analysis of the worn disc surfaces proved to be compatible with WSD number and also more sensitive to these kinds of fuels, showing mainly the form and intensity of the wear.
... The carboxyl group is likely to be most effective in improving the lubricity [4]. Electrons of double bonds at the end of the carbon chain are also very effective in improving lubricity [6]. The sequence of oxygenated groups to improve lubricity according to [4] is as follows: COOH> CHO> OH> COOCH 3 > C=O> C-O-C. ...
The paper presents the research results of lubricity of selected vegetable oils, rapeseed oil methyl esters, and esters with addition of oleic acid. Higher wear of samples during lubrication by rapeseed oil methyl esters in comparison to the tested vegetable oils was obtained. The addition of oleic acid to esters resulted in the improvement of their lubricating properties.
... Earlier, the fuel viscosity was considered to be the fuels ability for protection against engine wear. By the introduction of low sulfur diesel, some fuels found to produce engine wear even though they had relatively high viscosity compared to diesel (Barbour et al., 2000). Lubricators or the lubricity additives were added to low sulfur diesel to provide lubricity to the fuels. ...
... shown that minor components with oxygen and nitrogen promote lubricity [32]; Sasol now enhances their diesel fuel with a lubricity additive [33]. ...
... During the desulfurization process, nonpolar compounds are also eliminated from petrodiesel, which leads to the loss of lubricity. 6 The poor lubricity of ultra-low-sulfur diesel is mainly due to the removal of heterocyclic nitrogen and oxygen, which are responsible for the lubricity during hydro-treatment along with sulfur. 7 Biodiesel addition at levels of 1−2% in diesel blends has the beneficial impact of restoring lubricity through an antiwear action on engine injection systems. ...
The major objective of this study was to analyze the effectiveness of Indian wild castor oil and methyl/ethyl ester as an additive to enhance the lubricity of low lubricity diesel fuel. The methyl and ethyl ester of castor oil were formulated by transesterification reaction using homogeneous acid–base catalyst. The conformity of the ester was carried out by gas chromatograph (GC) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The lubricity, wear scar diameter (wsd), and film thickness (%) of the oil and its esters were tested alone and as an additive in low lubricity diesel fuel and compared. The lubricity of the test samples were analyzed by high-frequency reciprocating rig (HFRR). The test results shows that even less than 1% of castor oil, methyl and ethyl ester are enough to regain the lubricity of the low lubricity diesel fuel. In the study, it was observed that the ethyl ester has comparatively better lubrication than their methyl counterpart and fresh oil. An additive dose of even 0.2% is enough to bring the wsd down to below the maximum allowable limit of 450 μm. The wsd of low lubricity diesel fuel (LLDF) was 654 μm. The wsd of LLDF was appreciably reduced with the addition of 1% of castor oil (CO), castor oil methyl ester (CM), and castor oil ethyl ester (CE). The percentage reduction in the wsd was observed to be 70.03%, 70.48%, and 75.69%, respectively, with the addition of 1% of additive.
The present study aims to show the tribological properties of soybean oil's ethylene glycol ester (SOEGE) and its effect on low-sulfur diesel fuel lubrication. The SOEGE or 2-hydroxyethyl ester was synthesized by a transesterification reaction of soybean oil and ethylene glycol with a potassium carbonate catalyst. The product was characterized using Gas Chromatography-Mass Spectrometry (GC-MS). Then, the lubricity of commercial diesel fuel (Pertadex) and SOEGE were tested alone using the High-Frequency Reciprocating Rig (HFRR) machine. Its mixture form with various product doses in Pertadex (0.2, 0.4, 0.6, 0.8, and 1% v/v) was also tested with the same apparatus. This study showed that the product's coefficient of friction and Wear Scar Diameters (WSD) were 0.057 and 154.4 m, respectively. This value is lower than Pertadex and Fatty Acids Methyl Ester (FAME) of Soybean oil from the literature. Furthermore, adding products into Pertadex can reduce the coefficient of friction and WSD of Pertadex. The Pertadex coefficient of friction was reduced from 0.161 to 0.135 after the addition of 0.8% product. At a concentration of 1% product, WSD Pertadex was successfully reduced by 39.42%. These phenomena imply that ester ethylene glycol has an excellent lubricating effect on low-sulfur diesel. This work's findings open opportunities for other researchers to develop alternative lubricating bio-additives for low-sulfur diesel through the in-depth study of tribochemistry or tribosurface.
The COP26 goals rapidly accelerate the shift of road transport to electric vehicles (EVs). However, the global transition to EVs should be assessed carefully. A forced transition to electric mobility without tailored solutions for each case can increase greenhouse gas (GHG) emissions. In this context, low-carbon fuels can be considered a promising short-term solution to efficiently reach the carbon neutrality target. This manuscript aims to highlight the competitive advantages of hydrotreated vegetable oil (HVO) over commercial diesel fuel. Recent works on HVO are considered, ranging from exploring the production processes and spray evolution characteristics to the various engine strategies to highlighting the potential. Greater emphasis was placed on environmental impact assessment, considering the results available for Life Cycle Assessment (LCA) and Well-To-Wheel. The main characteristics and influences of HVO in CI engines are assessed on the combustion process, GHGs, and pollutants emissions. The results show the high potential of the HVO to reduce the impact of the road transport sector actively. It is highly compatible with existing engines and fueling systems while ensuring lower CO2, CO, THC, PM emissions, and combustion noise levels with similar efficiency and fuel consumption. Additionally, the residual feedstock can assure up to 75% GHG over the whole life cycle. Therefore, sustainable fuels, such as HVO, combined with advanced technologies could not only support the reduction of tailpipe emissions but also benefit the overall CO2 assessment.KeywordsHydrotreated vegetable oils (HVO)Renewable fuelsCompression ignition engineLife cycle assessmentGreenhouse gas
To achieve carbon neutrality in the near future, there is a need for a solution to sustainable mobility with a high technology readiness level. One option is to use biofuels in existing vehicles powered by internal combustion engines. This review aims to present the competitive edge of hydrotreated vegetable oil (the second generation biosourced fuel used in compression ignition engines) over fatty acid methyl ester (the first generation counterpart) and fossil diesel. Emphasis is placed on the comparison between neat hydrotreated vegetable oil and fossil diesel. Recent works on hydrotreated vegetable oil are covered, ranging from the explorations of spray-combustion characteristics with various forms of combustion chambers to the analysis of the performance and emissions of compression ignition engines. Structural presentation is adopted rather than just stacking data found in various publications to help readers conceptualize the performance and emissions of hydrotreated vegetable oil used as a fuel in compression ignition engines as well as its fundamental chemical and physical properties. The discussion of works involving engines is divided into two sections for engines with pump-line-nozzle injection and modern injection technologies because of the vast differences in combustion environment and the trends of experimental results. Also, the production and lubricity issue of hydrotreated vegetable oil are briefly discussed.
The study and evaluation of chemical and physical NOX formation routes inform of the kinematics behind NOX emissions. The NOX emissions are a product of conventional combustion of petroleum and by extension biodiesel blends and fuels in internal combustion processes especially compression ignition engines. The understanding of these mechanisms and kinematics help in developing advanced controls and the reduction of NOX emissions. There are a number of studies presented and reviewed in this chapter to enhance modern arguments on NOX formation routes. This chapter deals thus with the five main mechanisms referred as to the formation routes and their reaction equations. However, the dominant routes of NOX formation are the Zeldovich and Fenimore routes. Secondly, this chapter underscores the influence and role of atmospheric nitrogen in combustion and subsequent formation of NOX emissions. Atmospheric nitrogen also known as molecular nitrogen is the main source nitrogen in the combustion of fuels in internal compression ignition engines. Thirdly, this chapter also emphasizes the importance and critical role of factors of the formation such as temperature and others.
This book focuses on biodiesel combustion, including biodiesel performance, emissions and control. It brings together a range of international research in combustion studies in order to offer a comprehensive resource for researchers, students and academics alike.
The book begins with an introduction to biodiesel combustion, followed by a discussion of NOx formation routes. It then addresses biodiesel production processes and oil feedstocks in detail, discusses the physiochemical properties of biodiesel, and explores the benefits and drawbacks of these properties. Factors influencing the formation of emissions, including NOx emissions, are also dealt with thoroughly. Lastly, the book discusses the mechanisms of pollution and different approaches used to reduce pollutants in connection with biodiesel. Each approach is considered in detail, and diagrams are provided to illustrate the points in line with industry standard control mechanisms.
Biodiesel fuel properties both physical and chemical have significant impact on combustion performance and emission characteristics of compression ignition engines and the production of NOx gases. The physicochemical properties of biodiesel except for the viscosities of ethyl esters and ethyl esters are comparable. However, the pour point and viscosity of methyl ester compared to ethyl esters differ largely. For example, methyl esters produce more torque per unit of biodiesel used compared to ethyl esters. It is also interesting to note that in biodiesel physicochemical properties, the heat value of combustion could be similar or identical but find different combustion, performance and emission characteristics behaviour. One of the critical physicochemical properties of biodiesel is viscosity especially in compression ignition engines. This chapter looks critically at the influence of biodiesel physicochemical properties and the role they play in the combustion process. Secondly, this chapter looks at the role of different influencing factors with a physicochemical property under discussion such factors which affect the kinematic viscosity of biodiesel could be interlaced with other properties yet unique to a property. Thirdly, this chapter will look at the equations related to physicochemical properties of biodiesel and their use in analysis and calculation of different biodiesel properties.
It is inevitable in time that the lubrication oils used in the marine diesel generators are contaminated with fuel leakages from the combustion chamber, injector, fuel pumps. Due to this contamination, the lubricating properties of the lubricating oil will decrease, resulting in friction losses and wear in the piston ring-cylinder liner area on the engine.
In such cases, it will not be easy to change or clean (separate) the lubricating oil, which will cause an additional cost. For this purpose, in this study, friction forces of %10, %20, %30 diesel fuel mixed in the
lubricating oil are determined in the piston ring-cylinder liner area. Improvement of these negative effects with tall oil fatty acid in different ratios was investigated by using Taguchi design method.
Fatty acid methyl esters (FAME) derived from plant oils are excellent lubricant improvers, but they do not have desirable oxidative stability and cold flow properties. This study investigated phenol hydrodeoxygenation in hexadecane and aromatic alkylation of FAME over a K30 montmorillonite catalyst to give phenyl-branched FAME (PBFAME) as a potential lubricant improver. The high selectivity to aromatic hydrocarbons during hydrodeoxygenation over Pd/C was likely due to the slow hydrogenation rate of phenols in hexadecane, absence of hydrogen bonding in non-polar solvents allowing hydroxyl groups to participate in dehydration reactions, and limited diffusion of hydrogen from bulk solution to Pd sites. Isomers of methyl (methylphenyl)octadecanoate (n-MMPO) were produced during toluene alkylation of methyl oleate. The presence of both Brønsted and Lewis acid sites in K30 facilitated selective synthesis of n-MMPOs. The oxidative stability and cold flow properties of n-MMPO were better than that of canola biodiesel.
The purpose of this work was to study the influence of soybean biodiesel addition in ultra-low sulfur diesel (ULSD) on its tribological behavior under low-amplitude reciprocating conditions, simulating the operation of a fuel injector system. The methodology was divided into three parts: the first was the fuel preparation and its physicochemical characterization, where were studied four fuels (diesel, soybean biodiesel, and mixtures of them).The following step was the evaluation of the fuel tribological properties, using the high-frequency reciprocating rig (HFRR) test. These tests were carried out by steel ball-on-disk lubricated contact, on which the friction coefficient of friction (COF), the film percentage, and the wear scar diameter (WSD) were measured, according to ASTM D6079-11. In the end, the analysis of the damages presented on the worn disk surfaces was characterized by scanning electronic microscopy (SEM) and atomic force microscopy (AFM) techniques. Results showed that the addition of biodiesel to ULSD is an excellent option to restore the lubricating ability of this fuel. The biodiesel incorporation reduces the friction coefficient and improves the film formation. Besides, the evaluation of worn disk surfaces using SEM and AFM techniques showed that biodiesel avoids damages to surface through protective film formation and reduces the superficial roughness.
This work is proposing a catalyzed Continuous Stirred Tank Reactor (CSTR) model equations as an extension of the work of Abowei et.al., (2013) exploiting the transesterification kinetic of Olatunji et. al., (2012) at an isothermal condition. The Kinetic model of Olatunji et. al., (2012) was obtained through laboratory experiment of which ester was produced using alcohol to oil molar ratios of 6:1, 9:1 and 12:1 at isothermal reaction temperature of 50 0 C. The model equations proposed were capable of simulating reactor dimensions as a function of Olatunji et.al (2012) kinetic parameters. The model equations were further analyzed with MATLAB programming techniques, and results obtained for reactor dimensions, length (L r) volume of the reactor, (V R), heat generation per unit volume, (qr), space velocity, (S v),and space time, (S r), demonstrated high dependency functionality of Olatunji et. al., (2012) proposed kinetic model parameters.
The drive to improve efficiency and to reduce emissions (including greenhouse gases) from internal-combustion engines has significant ramifications for fuel properties. Deployment of improved engines is aided by the wide availability of well-defined fuels, sometimes with more stringent specification of properties such as the sulphur content and the vaporisation and combustion characteristics (e.g. the octane rating). Fuel regulation has also led to the inclusion of low-carbon fuel components such as ethanol and biodiesel in mainstream road fuels. These trends will probably continue over the next few decades, and so it is important to understand their implications for commercial-scale fuel production and distribution. This paper provides a technical explanation of the linkages between the properties of commercial-scale fuels, the technologies used to make them and the ‘landscape’ of the fuels industry (e.g. the distribution systems and the interlinked markets for non-fuel products and energy). Industrially relevant examples are used to explain how the refining industry has adapted, and is still adapting, to the changes in the sulphur and volatility specifications, the mandated biocontent and the changes in engine technology. This paper is not intended to make a case for any specific type of fuel but does aim to explain the principles by which refined fuels can be adapted to meet future specifications or to work in conjunction with alternative fuel components. It covers current issues such as the lower sulphur content, the increased biocontent and the emerging theme of higher-octane-number gasoline as a route to a higher engine efficiency.
The energy demand has increased tremendously due to world population growth and increase in industrial development activity. To meet energy demand, petroleum fuel has been serving the world. The excess use of petroleum sourced fuels would lead to unsustainable situation because of depleting supplies and all the environmental issues which would be responsible for a major deficit in the future. Critical need for looking into new alternative renewable energy resources have resulted in increased interest in the study of alternative fuels such as biodiesel. Consequently, biodiesel is a very promising alternative to petroleum diesel oil and renewable which has the similar properties petroleum diesel. Biodiesel actually is a transesterified fuel which is produced from vegetable oils and animal lipids which has properties similar or better than diesel fuel. Based on various research and demonstration projects it has proven that biodiesel can be used as pure or in blends with conventional diesel fuel in diesel engines without any modifications. The aim of this paper is to review the studies done earlier and to observe the production and fuel characteristics of biodiesel produced from various feed stocks like vegetable oils and waste oils and their effect on CI engine from the viewpoint of performance, combustion and emissions and its sustainability.
Ethanol, used widely as a spark-ignition (SI) engine fuel, has seen minimal success as a compression ignition (CI) engine fuel. The lack of success of ethanol in CI engines is mainly due to ethanol's very low cetane number and its poor lubricity properties. Past researchers have utilized nearly pure ethanol in a CI engine by either increasing the compression ratio which requires extensive engine modification and/or using an expensive ignition improver. The objective of this work was to demonstrate the ability of a hydrogen port fuel injection (PFI) system to facilitate the combustion of ethanol in a CI engine. Non-denatured anhydrous ethanol, mixed with a lubricity additive, was used in a variable compression ratio CI engine. Testing was conducted by varying the amount of bottled hydrogen gas injected into the intake manifold via a PFI system. The hydrogen flowrates were varied from 0 - 10 slpm. The engine was operated at compression ratios varying from 19:1 to 24:1 and intake air temperatures ranging from 80°C to 120°C. To prevent injection system lubrication failure, castor oil and lauric acid were tested in various blends with ethanol according to ASTM D975. It was found that 2% by volume of lauric acid provided a wear scar diameter of 200 μm, very close to the diesel fuel wear scar diameter of 195 μm at 25°C, and was chosen as the lubricity additive. Small amounts of hydrogen enabled ethanol operation at a compression ratio of 19:1 and an intake temperature of 80°C. This was a condition that was not sustainable without hydrogen injection. Adding hydrogen with the intake air advanced the start of combustion (SOC) timing for many of the conditions tested. The relatively small amounts of hydrogen necessary could be provided by an onboard ethanol reformer. Further work is necessary to determine why the hydrogen injection causes this SOC advance.
The interactions of new biofuels and standard engine components are being investigated at the Institute for Fluid Power Drives and Controls (IFAS) at RWTH Aachen University as part of the research of the cluster of excellence “Tailor-Made Fuels from Biomass”. Since modern common rail fuel pumps are fuel lubricated special interest lays on the lubricity of new fuels. At IFAS a High Frequency Reciprocating Test Rig (HFRR) is used to screen possible biofuel candidates with regard to this property. Most of these substances show lubricating abilities similar to those of modern diesel fuels. Nevertheless with 2-Methyltetrahydrofuran a remarkable outlier can be found among the favoured fuel candidates. To unravel the influences of certain molecule structures additional substances were included into the experimental research. By comparing the wear scars of linear alkanes, alkenes and alcohols produced in the HFRR the influence of the molecules chain length and functional group is analysed. This paper gives an introduction to the HFRR test set up and presents the experimental results of the recently screened biofuel candidates.
In this research work, a mathematical model was simulated for Continuous Stirred Tank Reactor (CSTR) as an extension of the work of Abowei et al., (2013) exploiting the transesterification kinetic of Olatunji et. al., (2012) at an isothermal condition. The Kinetic model of Olatunji et. al., (2012) was obtained through laboratory experiment on which ester was produced using alcohol to oil molar ratios of 6:1, 9:1 and 12:1 at isothermal reaction temperature of 50 o C. The simulated model equations was able show reactor dimensions as a function of Olatunji et. al., (2012) kinetic parameters. The model equations were further analyzed with MATLAB programming technique, and results obtained for reactor dimensions can be used to predict the volume to be produced at different time intervals and reaction rate which demonstrated high dependency functionality of Olatunji et. al., (2012) proposed kinetic model parameters.
ABSTRACT
In this research work, a mathematical model was simulated for Continuous Stirred Tank Reactor (CSTR) as an extension of the work of Abowei et al ., (2013) exploiting the transesterification kinetic of Olatunji et. al.,(2012) at an isothermal condition. The Kinetic model of Olatunji et. al., (2012) was obtained through laboratory experiment on which ester was produced using alcohol to oil molar ratios of 6:1, 9:1 and 12:1 at isothermal reaction temperature of 50oC. The simulated model equations was able show reactor dimensions as a function of Olatunji et. al.,(2012) kinetic parameters. The model equations were further analyzed with MATLAB programming technique, and results obtained for reactor dimensions can be used to predict the volume to be produced at different time intervals and reaction rate which demonstrated high dependency functionality of Olatunji et. al., (2012) proposed kinetic model parameters.
It is not practical to separate a diesel fuel thoroughly into its pure individual components and then to collect samples large enough to assess their contribution to wear reduction individually. In this study model compounds are used instead. The purpose of this work is to clarify the conflicting literature results on the effect of aromatics, partial aromatics, and sulfur compounds on wear performance of fuels and to examine the effect of nitrogen compounds and oxygen compounds on diesel fuel lubricity. Attention was particularly given to the behavior of these compounds at low concentrations comparable to those found in diesel fuels.
The sulfur content of diesel gas oil will be regulated to a maximum of 0.05 mass% from July 1997. However, deeply desulfurized diesel gas oil has poor lubricity for distributor type injection pumps of diesel engines that use the gas oil for lubrication of their moving parts. In order to investigate the reason for poor lubricity of low sulfur diesel gas oil, the polar compounds in diesel gas oil were extracted and their effects were studied. Among the Polar compounds, phenols and carboxylic acids had good effects on lubricity of diesel gas oil, but since these acidic compounds were reduced with desulfurization, the low sulfur diesel gas oil had poor lubricity. On further investigation, it was observed that catechols and naphthenic acids also had good effects on lubricity of diesel gas oil.
Severe refinery practices to remove naturally occurring sulfur compounds affect fuel lubricity, and a laboratory wear test that accurately defines the lubricating qualities of diesel and kerosene fuels is urgently needed. This paper details the development of two closely related laboratory test procedures that predict fuel-related wear, cognizant of the the contact conditions in full-scale equipment. Most preceding methodologies measure the wear scar produced under conditions of boundary lubrication in continuous sliding. In contrast, the tests described in the present study rely on the transition from mild boundary-lubricated wear to adhesive scuffing to define the lubricating qualities of the fuel. The resulting procedures allow the fuels to be either ranked using a continuous scale, or separated using a simple pass/fail criteria. Careful selection of the test parameters produced a sharp change in both friction and a wear at the mechanism transition and wide separation between acceptable and unacceptable fluids. Both procedures were sensitive to the addition of trace quantities of lubricity additives and also showed directional correlation with refinery severity, as measured by sulfur and aromatic content. As a result, excellent correlation was achieved with full-scale equipment tests performed at a number of locations. However, the correlation achieved between laboratory wear tests and full-scale equipment fell below a critical viscosity. 24 refs., 10 figs., 3 tabs.
A review of adsorption chromatography in coal liquids analyses reveals a multitude of closely related methods. This paper makes use of the distribution coefficient measurement (K /SUB D/ ) as a tool for systematically evaluating chromatographic separations. The K /SUB D/ for model compounds can be used to select adsorbents, optimize elution solvents, and standardize activity. Such K /SUB D/ measurements have been used to design a scheme for separating coal liquids into five well defined fractions.
In the last few years there has been an increasing requirement for the provision of environmentally benign diesel fuels. However, the introduction of such fuels into service has been associated with high levels of field failure of rotary distribution fuel pumps due to wear. This is because the refining processes necessary to produce ecologically acceptable fuels result in greatly reduced levels of sulphur compounds, aromatics, and polar material, many of which are potential lubricity agents.
This paper describes the development of bench test methods to evaluate diesel fuel lubricity and thus enable the identification of appropriate ‘solutions’.
It has been found that the key to obtaining good correlation between field experience and bench tests is (1) to reproduce the thermal conditions present in operating pump contacts and (2) to ensure that the same mechanisms of wear operate in the bench test as in the pump environment. The physical and chemical processes involved in the lubrication of fuel pumps and the influence of temperature on these processes are outlined.
As a result of the work described in this paper, effective additive solutions have been discovered for controlling the failure of diesel fuel pumps in the field and a provisional ISO (ISO/TC 22 / SC 7 M595: ‘Diesel engines - diesel fuel - performance requirement and test method for assessing fuel lubricity’) and CEC test method for assessing diesel fuel lubricity has also been developed.
Certain nitrogen compounds and their derivatives used as antiwear additives in base stocks have been tested on a four-ball machine and an HQ-1 tester for their relative antiwear effectiveness. The preliminary results indicate that the heterocyclic nitrogen compounds, in general, have a beneficial effect on the antiwear performance of base stocks. Hydroxy groups involved in some nitrogen-containing compounds have been found to improve their antiwear performance significantly. In particular, one of the hydroxy-substituted benzothiazoles is most effective in wear reduction and anti-scuffing. However, the beneficial effect of a hydroxy group has not been observed for short-chain amines.
Since the beginning of October 1993, environmental legislation in the USA has required the sulphur content of diesel fuel to be reduced to less than 0.05 wt.% for road vehicles. Pressure for such reductions to be adopted in other markets is growing: notably, sulphur levels as low as 10 ppm are being encouraged in Sweden by the use of tax incentives. However, it is suspected that fuel pumps suffer from lubrication problems with the use of low sulphur diesel (LSD). Additive treatment of fuels and fuel blending is thought to mitigate such problems but there is a need for an industrial method of screening candidate fuel treatments prior to expensive service or rig trials.
This paper outlines a test procedure based on the Plint TE-77 reciprocating test rig. Initial investigations have enabled fuels of known pump performance to be ranked correctly through an assessment of scuffing wear. In this test, scuffing is evaluated by surface profilometry of the flat specimen and the mechanism is verified by the detection of ‘white’ etching layers on surfaces. The test also allows the separate evaluation of mild wear by measurement of the width of the scar generated on the roller by the line contact configuration.