Effect of anti‐oxidants on the lubricity of B30 biodiesel–diesel blend

Biodiesel is used in many countries as blends with diesel fuel. However, the main obstacle in biodiesel/diesel blends acceptance, commercialization worldwide and using higher blends seems to be its ability to oxidise and increase wear and friction of automotive parts. An experimental investigation has been carried out to analyse the effect of three different anti‐oxidants on the lubricity of palm biodiesel–diesel blend (B30) and to optimise anti‐oxidant concentration based on the performance. The three phenolic anti‐oxidants, butylated hydroxytoluene, propylgallate and pyrogallol, were tested using four‐ball tribotester for 1 h with 1500 rpm and 40 kg load, at ambient temperature. These three anti‐oxidants were used in varying concentrations of 200, 400 and 600 ppm. Propylgallate anti‐oxidant showed most effective results by enhancing the lubricity of the blend in terms of reduced wear and friction. Copyright © 2016 John Wiley & Sons, Ltd.     

Development of laboratory tests to predict the lubricity properties of diesel fuels and their application to the development of highly refined diesel fuels

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.     

Boundary lubrication of low‐sulphur diesel fuel in the presence of fatty acids

This paper presents an overview of the effect of aliphatic acids on the tribological properties of selected hydrocarbons and petroleum fractions. The major experimental part of the work focuses on improvements to the lubricity of low‐sulphur diesel fuel. Experiments were carried out using a pin‐on‐disc friction machine and HFRR test rig. The wear results obtained clearly show a specific effect of the test acids dissolved in hydrocarbons in the concentration range 0.005–0.1% (50–1000 ppm). Although the overall picture presented by these results is very complex, it can be concluded that a very small amount of the selected acids dramatically improves low‐sulphur diesel fuel lubricity.     

The Lubricity of Gasoline

A study has been made of the lubricating properties of gasoline fuel. A conventional HFRR diesel fuel lubricity tester has been modified to measure gasoline wear. Using this test equipment, a number of features of gasoline lubricity have been investigated, including the comparative lubricating behavior of gasoline, the influence of detergent additives and oxygenates on wear and the wear behavior of a series of refinery streams employed in gasoline blending.

The lubricity of a range of pure organic chemicals known to be present in gasoline has also been studied. From these measurements it has been shown that, except for components such as dienes and diaromatics, the HFRR lubricating properties of most gasoline hydrocarbon constituents are broadly independent of chemical structure bur depend significantly on viscosity. Using these measurements, predictive wear equations based on gasoline group analysis have been developed.

Because it has been found that viscosity plays a role in determining the wear properties of gasoline, the elastohydrodynamic (EHD) film-forming and friction properties of gasoline have been measured and compared to those of diesel fuels. This shows that the combination of gasoline's very low viscosity and low pressure-viscosity coefficient results in very thin EHD film thickness generation and also very low friction in full-film EHD conditions.     

Tribological performance of ionised vegetable oils as lubricity and fatty oiliness additives in lubricants and fuels

Lubricity and fatty oiliness additives, also known as friction modifiers in the tribological vocabulary, are steadily gaining acceptance from lubrication engineers and lubricant formulators. The present communication describes how such additives function in various tribosystems and which parameters control lubricity of finished formulations. Extensive experimental data are presented to demonstrate the outstanding tribological performance of bio‐based lubricity and fatty oiliness additives produced by Elektrionization^TM of vegetable feedstocks. Featuring a unique combination of viscosity and polarity, ionised vegetable oils form sufficiently thick and resilient protective layers by adsorption to rubbing surfaces. It is shown that, unlike extreme pressure additives, which act when a direct asperity–asperity contact occurs in the boundary lubrication regime, ionised vegetable oils function by postponing the onset of the boundary lubrication regime. Copyright © 2009 John Wiley & Sons, Ltd.     

柴油润滑性的机制研究

利用作者从事柴油润滑性研究与检测工作十年来积累的大量数据,将柴油的常规理化分析指标以及质谱分析结果与柴油润滑性的相关性进行归纳总结,探讨柴油润滑性的机制。结果表明:脱硫工艺过程与柴油的润滑性有很好的相关性;磨损对某些含硫物质的多少并不敏感;柴油中氮含量越高,润滑性越好;柴油的黏度和密度越大,润滑性越好;馏出点温度越高,馏分的润滑性越好;饱和烃中的链烷烃和环烷烃对润滑性起负作用,而非饱和烃对润滑性有贡献,在芳烃组分中,多环芳烃比单环芳烃对提高润滑性的贡献大。     

HFRR lubricity response of an additized aviation kerosene for use in CI engines

To reduce their fuel related logistic burden, NATO Armed Forces are advancing the use of a single fuel for both aircraft and ground equipment. To this end, F-34 is replacing distillate diesel fuel in many applications. However, tests conducted with kerosene on High Frequency Reciprocating Rig, showed that it causes unacceptable wear due to the poor lubricity of aviation fuel. In order to make this type of fuel compatible with direct injection compression engines, tests were carried out with ten mono–carboxylic acid esters to improve the lubricity of kerosene. Tribological results showed that all esters tested, were suitable for increasing the kerosene lubricity to a satisfactory level. Among the esters of the same molecular type, those having the ester group around the middle of the molecule appear to have better lubrication performance.     

Evaluation of ball and disc wear scar data in the HFRR lubricity test

The high‐frequency reciprocating rig (HFRR) lubricity tester has become a widespread method for determining the lubricity of diesel fuels. The test is a ball‐on‐disc method, in which a steel ball scrapes over a steel disc immersed in the liquid to be tested. According to standards, the wear scar generated on the ball, in the form of the average of the x‐ and y‐axes, is used for evaluating the lubricity of the sample. Generally, the smaller the wear scar, the greater the lubricity of the sample. However, a wear scar is also generated on the disc. The size of the wear scar on the disc also depends on the lubricity of the sample. In this work, the wear scar data of the balls and discs of 230 samples related to the testing of biodiesel and related compounds with petrodiesel were evaluated. Data comparisons for all wear scar combinations correlated well by linear regression. Although correlations are slightly better when using only ball wear scar data (r² > 0.99), other wear scar data, including those generated on the disc, appear just as useable (r² ≈ 0.97–0.99) for evaluating lubricity by the HFRR test. The wear scars on the disc have the advantage of being more easily measurable and recognisable under the microscope, especially if the wear scars are small. Limits for all wear scar values corresponding to current limits for average ball wear scar data in standards are presented. Published in 2007 by John Wiley & Sons, Ltd.     

Preparation and evaluation of vegetable oil derived biodiesel esters as lubricity additives

Various vegetable‐oil derived esters using methyl, ethyl, butyl, and 2‐propyl alcohols were prepared and tested as diesel fuel lubricity additives in a roller‐on‐cylinder lubricity evaluator. At1% additive treat rate, the canola methyl and 2‐propyl esters, the best‐performing esters, increased the lubricity number of a reference fuel by 60%. Statistical analyses indicated strong effects of fatty acids and alcohols on the wear, friction, and lubricity number of the fuel. While no single fatty acid was identifiably responsible for the wear reduction, certain non‐linoleic compounds correlated with the wear data in a semi‐log relationship. The low‐temperature behaviour of the biodiesel was studied using differential scanning calorimetry. The major transitional peak temperature of the biodiesel esters changed with the melting points of their primary fatty acids, and decreased with the lengthening and branching of the tail alkyl groups.     

柴油成膜润滑机制探讨

柴油是发动机燃料供给系统的润滑剂,其润滑性非常重要。在高频往复试验机上对不同柴油样品进行了润滑性评价,对试验后的金属件进行磨斑表面分析,通过对比研究,探讨了柴油成膜润滑机制。结果表明,柴油成膜组分少,不能形成良好润滑保护膜,或者因腐蚀反应不能形成有效润滑保护膜,是柴油润滑性差并导致偶件磨损的原因。     

影响柴油润滑性检测结果的因素

利用作者多年来从事柴油润滑性检测工作的经验积累,对影响柴油润滑性检测结果的诸多因素进行探讨,介绍柴油抗磨剂以及生物柴油的检测情况,这对即将在全国范围开展的柴油润滑性检测工作具有一定的指导意义.     

The lubricity of diesel fuels

The main chemical factors influencing the lubricity of diesel fuels have been investigated by carrying out wear tests on diesel fuels, diesel fuel fractions and model fuels.It has been found that, under the test conditions used, sulphur-containing components were pro-wear. Nitrogen-containing components tended to reduce wear but only at concentrations in excess of those normally found in diesel fuels. Polyaromatic species and, in particular, oxygen-containing components, were found to reduce wear significantly at concentrations normally found in fuels.     

柴油润滑性添加剂研究

针对柴油的低硫化引起的喷油泵磨损问题,研制了一种酯类柴油润滑性添加剂。经实验室分析研究,表明研制产品具有优异的润滑性能外,同时还具有一定的抗氧、防腐作用,且具有良好的贮存稳定性以及与柴油其它添加剂的配伍性;苛刻条件下BOSCH高压油泵台架试验后,其润滑性能无明显变化,油泵无明显磨损现象,泵的输出性能没有损失,没有任何有关燃油或者润滑剂的兼容性问题。加入量仅为150~250mg/kg。     

Phase Behavior and Lubricity of Aqueous PEO-PPO-PEO and PPO-PEO-PPO Triblock Copolymer Solutions

Aqueous triblock copolymer solutions are potential low-cost, eco-friendly lubricants. However, as a solution, their phase changes with copolymer concentration and solution temperature, raising the question, “Does the phase change affect the formation of adsorbed layer and the lubrication performance?” This article studies the copolymer solution phase behavior and lubricity in response to the copolymer structure, concentration, and solution temperature. Four different triblock copolymers, two normal PEO-PPO-PEO and two reverse PPO-PEO-PPO composed of PEO poly(ethylene oxide) and PPO poly(propylene oxide), have been investigated. From cloud point and surface tension measurements, phase change and micellization are shown to depend on copolymer type, number of hydrophilic PEO blocks, and temperature. Furthermore it is found that the phase and the presence of micelles lead to significant variation in adsorbed copolymer mass and lubricity. Based on the observed phase behaviors, the lubricity of copolymer solutions is discussed with regard to aggregation and adsorption on the solid–liquid interface.     

The impact of biofuels on engine oil performance

The dilution of biogenic fuels into lubricating engine oils often leads to a shortening of the recommended oil drains (between 30% and 60%) and an increase in wear. The large number of overlapping and influencing factors, of which dilution and polymerization of fuel components in the engine oil are emphasised, makes it difficult to find a uniform solution to prevent failures in the various applications. Insofar single solutions for the different types of biofuels are needed. The contribution of base oil chemistry and additives as well as triboactive materials is featured to deal with the adverse effects of biofuels. In the frame of the European Commission (EC)‐funded project ‘cleanengine’, tentative engine oils based on esters with a content of renewables and polyglycols are formulated to increase the lubricant's tolerance in engines fuelled with biofuel‐based blends, with the aim of ensuring required lubricating and wear protection performance while keeping oil drain intervals unchanged. The present paper focuses on four‐stroke diesel applications, fuelled by biodiesel (fatty acid methyl ester — FAME) as well as by rapeseed oil and Jatropha oil (pure vegetable oils, triglycerides), together with relevant blends of those biofuels and conventional diesel fuel. This paper screens the functional profile (in particular rheological, toxicological, bio‐compatibility, tribological and biofuels affinity) of lube families with respect to biofuel contamination. Moreover, this is followed by the contributions of piston ring and liner materials as well as thin film coatings. Copyright © 2011 John Wiley & Sons, Ltd.     

Analysis of Tribological Properties of Palm Biodiesel and Oxidized Biodiesel Blends

Biodiesel has become an increasingly significant alternative fuel to replace conventional diesel completely or partially. Although biodiesel has several advantages, such as environmental friendliness, renewability, and reduced emissions, it also has major drawbacks. Tribology is one of the major concerns for biodiesel usage, in which biodiesel lubricity deteriorates by usage and/or by storage because of its oxidative nature. The present study aims to investigate the lubrication behavior of oxidized and pure palm biodiesel blends by using a four-ball tribotester machine. Tests were carried out in diesel, pure biodiesel (B100), their blends (B10 [10% biodiesel in diesel], B20, B30, and B50), and oxidized biodiesel (Oxd B100) and its blends (Oxd B10, Oxd B20, Oxd B30, and Oxd B50). Tests were conducted at room temperature under a normal load of 40 kg for 1 h at 1,200 rpm. Surface analyses were carried out by scanning electron microscopy, energy-dispersive spectrometry, and optical microscopy, and fuel analysis was performed by gas chromatography–mass spectroscopy. Diesel fuel showed the highest wear and friction. Surface deformation, wear, and friction decreased as the biodiesel concentration increased in the blend. Oxidized biodiesel blends showed improved lubricity compared to pure biodiesel and blends. However, Oxd B100 showed higher wear than Oxd B50.     

Vegetable oil derivatives: environment‐friendly lubricants and fuels

A critical appraisal is made of the applications of vegetable oils, the fatty esters complex and synthetic esters as rapidly biodegradable and non‐toxic lubricants and fuels in the developed countries of America, Europe and Asia. The criteria employed for assessing the toxicity and biodegradability of the various fluids and limits set by various state and regional organizations are reviewed. The properties of vegetable oils, fatty esters, chemically modified esters and synthetic esters relevant for performance as lubricants in various applications such as hydraulic oils, refrigeration oils, chainsaw lubricants, metalworking fluids, engine oils, two‐stroke oils, mould release lubricants, greases, gear and transmission oils vis‐à‐vis conventional mineral oils and greases for corresponding applications are compared. The advantages, such as high lubricity, viscosity–temperature relationship, low lubricant consumption, energy efficiency combined with public health, safety and environmental contamination, more than offset the disadvantages of initial costs in most of these applications. It has been suggested that modified and stabilized oils of wasteland and forest origin and other non‐edible oils and their chemically modified derivatives can be produced at relatively cheaper cost than similar oils marketed in the developed world and can be introduced in India with immense environmental and performance benefits, particularly in applications involving high environmental contamination safety and public health. When blended with highly refined diesel fuels, methyl esters can work as highly efficient environment‐friendly fuels particularly for applications in passenger transport, light commercial vehicles and generators. Copyright © 2006 John Wiley & Sons, Ltd.     

Tribological effects of Cu,Fe and Zn nano‐particles,suspended in mineral and bio‐based oils

Many studies focus on nanoparticles as lubricity additives but overlook the fact that wear produces nanosized debris during the field use. In order to simulate the fine metal contaminants, which are the most widespread in various field applications, prefabricated Fe, Cu and Zn nanoparticles were used. Their 0.01–1% suspensions in vegetable and mineral oils with or without ZDDP and ashless AW package were tested on four‐ball AW under 150‐N load. Tribological effects of nanoparticles were not significant in formulations without AW additives. However, nanoFe addition produced notable lubricity improvement in already excellently performing rapeseed formulation with ZDDP, while such addition reduced performance of the ashless AW pack. Results show that metal nanoparticles can play both positive and negative roles on additive effectiveness and nanosized contaminants can significantly affect the lubricant performance. Copyright © 2015 John Wiley & Sons, Ltd.     

Metalworking emulsions from industrial vegetable oils

In the present work, an attempt has been made to develop the indigenous formulation for metalworking lubricants by replacing mineral oils partially with non‐edible industrial oils like rapeseed and karanja oil. Metalworking formulations consist of vegetable oil, mineral oil, an emulsifier and commercial additives for better performance. Non‐edible vegetable oils such as karanja and rapeseeds are renewable, biodegradable and cheaper than synthetic fluids. The constituent vegetable oils and mineral oils were evaluated for physico‐chemical characteristics and blended as per the saponification value and viscosity requirements of the reference oils. The so formulated oils are taken as 5% oil‐in‐water emulsion and tested for lubricity, load bearing capacity, particle size distribution, wear test, weld load test and plate‐out test. Performance of all formulated oils was compared with that of the reference oils, and optimized to meet the market requirements. Copyright © 2008 John Wiley & Sons, Ltd.     

Effect of oxygen enrichment on the performance,combustion, and emission of single cylinder stationary CI engine fueled with cardanol diesel blends

We investigated the effect of intake air enrichment on the performance, combustion, and emission characteristics of a single cylinder direct-injection stationary diesel engine fueled with non- edible alternative fuel, namely, cardanol — diesel — methanol blend (B20M10). The results were compared with baseline diesel operations under standard operating conditions. The bio-fuel blend B20M10 (20% cardanol, 10% Methanol, and 70% diesel) was used as fuel and the combustion, performance, and emission characteristics were investigated by oxygen enriching of intake air with 3, 5, and 7 percentage by weight. With the increase of intake air oxygen concentration, CO, HC, and smoke were found to be decreased. But BTE and NOx emission were considerably increased. The blended fuel B20M10 with 7% oxygen enrichment of intake air was compared with diesel operation. The results show a 0.5% lesser BTE, 28% more NOx emission at full load condition. There is not much variation of smoke emission to be noticed for this fuel combination compared to diesel.