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Alcohol-based fuels are a viable alternative to fossil fuels for powering vehicles. As a drop-in fuel, an oxygenated fuel blend containing the C8 alcohol 2-ethylhexanol (isomer of octanol), hydrotreated vegetable oil (HVO) and rapeseed methyl ester (RME) can reduce soot and NOx emissions whilst maintaining engine performance. However, fuel injection strategy significantly affects combustion and hence has been investigated with a view to reducing emissions whilst maintaining engine efficiency. In a single cylinder light-duty compression ignition research engine, the effect of different injection strategies (main, main/post, double pre/main, double pre/main/post injection) and EGR levels (0%, 19%) on specifically NOx, soot emissions and particle size distribution was investigated for three different fuels: fossil diesel fuel, HVO and the oxygenated blend. The blend was designed to have diesel-like combustion properties (cetane number of 52) and had an oxygen content of 5.4% by mass. The crank angle used when measuring MFB50, fuel consumption and IMEP was kept constant. The engine efficiencies were similar for all tested fuels and injection strategies. Heat release analysis revealed a strong influence of the cetane number on main and main/post injection strategy. However, when using double pre-injection, the start of combustion was similar for all fuels. Combustion characteristics, particle mass and number were more affected when using double pre-injection rather than post-injection. With 19% EGR and double pre-injection, soot mass increased as agglomerated particle mode increased in the PSD. Further, the in-cylinder temperature and pressure were lower compared to combustion without EGR, leading to a reduction of NOx emissions by a factor of 2.5 while soot emissions increased by a factor of 10. There were just minor differences in NOx emissions with variations in injection strategy. The PSD moved towards smaller particle diameters without EGR. In conclusion, the soot reduction potential of all fuels tested was coupled to the use of double pre-injection and EGR rather than post-injection.

Recently introduced sulfur caps on marine fuels in so-called sulfur emission control areas (SECAs) are forcing shipping companies to sail on more or less automotive grade diesel in lieu of the considerably less expensive, but sulfur-laden heavy fuel oil (HFO) to which they were accustomed. This development is an opportunity for a bio-based substitute, given that most biomass is sulfur free by default. Moreover, given that biomass is typically solid to start with, cracking it to an HFO grade, which is highly viscous in nature, will involve fewer and/or less harsh process steps than would be the case if an automotive grade fuel were to be targeted. In this study, a renewable low sulfur heavy fuel oil (LSHFO) has been produced by means of subcritical water assisted lignin depolymerization in the presence of a short length surfactant, ethylene glycol monobutyl ether (EGBE). The resulting oil contains a lignin derived content of 75 wt.-%, with the remainder consisting of EGBE and water (reusable). The derived LSHFO has a 20% higher heating value than the lignin feedstock. It is still roughly 20% and 30% lower when compared to the HFO and low sulfur marine gas oil (LSMGO) benchmarks, respectively. The lower heating value can be attributed to the fuel bond oxygen (10%) and water present in the LSHFO. Viscosity and sulfur levels, however, are within the HFO and LSMGO range and target respectively. Future work will examine what impact lignin particle size and surfactant type/concentration will have on the results.Graphical abstract

Although waste animal fats such as chicken fat are promising alternative energy sources, biodiesels produced from these type of feedstocks hardly satisfies the EN14214 biodiesel standards. In this study, biomixtures were prepared by blending cottonseed biodiesel and chicken rendering fat biodiesel which were produced via transesterification method. Biodiesels were blended with each other at 60/40, 50/50 and 30/70 volume ratios to produce CO60CH40, CO50CH50 and CO30CH70 fuels. First, fuel properties of the neat biodiesels and novel biomixtures were measured and compared to European biodiesel standards and diesel. Then, the engine performance, combustion characteristics and exhaust emissions of these novel biomixture fuels were measured in a three-cylinder indirect injection diesel engine under various engine loads and at constant speed of 1500 rpm. The fuel characterisation showed that CO60CH40 and CO50CH50 biomixtures met the European standards. The Brake Specific Energy Consumption (BSEC) and Brake Thermal Efficiency (BTE) of all biomixtures were comparable with CO100, CH100 and diesel at the full engine load. The combustion results revealed that the maximum in-cylinder pressure and energy release values of the CO50CH50 were 4.2% and 4.4% higher than the diesel at full engine load because of optimised fuel properties of biomixture such as molecular structure, viscosity, cetane number and iodine value. CO50CH50 had 2.9% reduced CO 2 and comparable CO emission compared to diesel, which were also 5.6% and 13% lower than cottonseed biodiesel respectively. However, NO emission of CO50CH50 was found 3.8% and 5.8% higher than diesel and cottonseed biodiesel. A 6.5% reduction on NO emission was observed when CO60CH40 biomixture fuel was used instead of diesel. To conclude, this research showed that blending of cottonseed and chicken fat biodiesels is a promising approach to meet the EN14214 standards, improve in-cylinder pressure, optimise energy release and reduce exhaust emissions. Blending of different biodiesels will be tested as a future work.

A set of additives was selected to improve the durability of the physical-chemical and biological characteristics of mineral diesel and its blend with biodiesel. Two biodiesels were used: soybean (SME) and rapeseed (RME). Both physical-chemical properties and fuel dispersion of fuel blends and their mixtures with additives were measured that could have effects on the combustion process in diesel engines. The dispersion of the fuel is affected by the injection nozzle integrity, influencing the capacity of the fuel to vaporize, while the modification of the fuel molecular structure can cause changes in combustion reaction. A 7 hole Common Rail (CR) 2nd generation injector, 136 ?m in diameter, was used at 80 MPa and 1.0 ms injection pressure and duration, respectively. The injection rate was determined using the Bosch's Method, while the fuel dispersion was measured by analyzing the images of spray evolving in an optical accessible quiescent vessel. The results showed that the additives have a great influence on the stability of the blends. Adding the biocide "P", antioxidant "AN" and pour point depressant "D", an increase of the oxidation stability of 390 % of the B20SME samples compared to B20 without additives. For B20SME containing "P", "AS" and "D", the oxidation stability increased of 810%. The injection rate data showed that a slight reduction in the rate of injections (9.91% for Diesel B5RME, 8.13% relative to B20RME and 12.84% relative to B20SME) was registered when additives were used. Finally, the inclusion of the additives did not produce particular variations on the fuel spray tip penetration.

A burning process in a combustion chamber of an internal combustion engine is very important to know the maximum temperature of the gases, the speed of combustion, the ignition delay time of fuel and air mixture exact moment at which ignition will occur. The automobilist industry has invested considerable amounts of resources in numerical modeling and simulations in order to obtain relevant information about the processes in the combustion chamber and then extract the maximum engine performance control the emission of pollutants and formulate new fuels. This study aimed to general construction and instrumentation of a shock tube for measuring shock wave. As specific objective was determined reaction rate and ignition delay time of diesel and ethanol doped with different levels of additive enhancer cetane number. The results are compared with the delays measured for the ignition diesel and biodiesel.

Acetone-Butanol-Ethanol (ABE), an intermediate product in the ABE fermentation process for producing bio-butanol, is considered a promising alternative fuel because it not only preserves the advantages of oxygenated fuel which typically emit less pollutants compared to conventional diesel, but also lowers the cost of fuel recovery for each individual component during the fermentation. With the development of advanced ABE fermentation technology, the volumetric percentage of acetone, butanol and ethanol in the bio-solvents can be precisely controlled. In this respect, it is desirable to estimate the performance of different ABE blends to determine the best blend and optimize the production process accordingly.

Forthcoming on-highway 2005/2007 European and North American emission regulations will require modern diesel engines to be equipped with Diesel Particulate Filters (DPF) capable of trapping up to 99% of the exhaust particulate matter. Since diesel particulates (soot) accumulate in the filter over time, the overall system needs to be regenerated by attaining the ignition temperature of soot, which in the presence of oxygen is >600 °C. Catalyzed DPFs regenerate at temperatures as low as ∼300 °C. One of the major issues facing OEMs, aftertreatment system manufacturers, and lubricant formulators is the potential effects of the lubricant-derived ash deposits and their impact on a pressure increase across filters, as well as overall filter performance and its service characteristics. In the present study, several lubricant-formulating additive variables, metal detergent type, antiwear additive (ZDP) type and level, the presence of boron as well as the effect of noble metal concentration in catalyzed DPF were examined. The paper explores ramifications of these formulation variables, especially the effects of lubricant chemistry, on DPF balance point temperature, ash deposits distribution and recovery. Findings identify the impact of lubricant derived species on soot combustion, ash type and presence of volatile components within the filter deposits.

Increased environmental awareness and depletion of fossil fuel resources are driving industry to develop alternative fuels that are environmentally more acceptable. Vegetable oils are potential alternative fuels. Vegetable oils in India are produced from numerous oilseed crops. While all vegetable oils have high energy content, most require some processing to ensure safe usage in internal combustion engines. Most detrimental properties of oils are its high viscosity, low volatility and polyunsaturated character. The most widely used method is to convert vegetable oils into biodiesel. Biodiesel fuels are primary esters, which are produced by transesterifcation of vegetable oils. Several vegetable oil esters have been investigated so far in different parts of the world and found suitable to be used in diesel engines. In present investigation, methyl esters of some non-edible vegetable oils of Indian origin (castor, linseed and ricebran) are prepared and their properties have been evaluated. The effect of temperature on the viscosity of vegetable oils and their esters was studied. Viscosity of vegetable oils drastically decreases after transesterification. Flash point and specific gravity of neat ricebran and linseed oil and their esters were also evaluated in this investigation. Introduction Increased environmental concerns, tougher clean air standards, increasing prices and uncertainties concerning petroleum availability necessitate the search for a viable alternative fuel, which is more environment friendly, hence vegetable fuel studies have become prominent among various potential alternatives. The idea of using vegetable oils as fuel for diesel engine is not new. When Rudolf diesel first invented t he diesel engine, he demonstrated it at the 1900 world exhibition in Paris, employing peanut oil and said “The use of vegetable oils for engine fuels may seem insignificant today, but such oils may become in course of time as important as petroleum and the coal tar products of the present time” [1]. In the 1930’s and 1940’s, vegetable oils were used as diesel fuels from time to time, but usually only in emergency situations. Recently, because of increase in crude oil prices, limited resources of fossil fuels and environmental concerns, there has been a renewed focus on vegetable oils and animal fats to make biodiesel fuels. Biodiesel is biodegradable, non-toxic and essentially free from sulphur. It is renewable and can be produced from agriculture & plant resources. While short-term tests are positive, long-term usage of neat vegetable oils or their blends with diesel leads to various engine problems such as injector coking, ring sticking, injector deposits etc. [2,3]. High viscosity, low volatility and a tendency to polymerize within the cylinder are the root cause of many problems associated with direct usage of these oils as fuels [2]. The process of transesterification yields vegetable oil esters, which have shown promise as alternative diesel fuel as a result of improved viscosity & volatility characteristics. Several researchers investigate the different vegetable oil esters [3-7] and found esters comparable to diesel fuel. Muniyappa et. al., optimized the transesterification process for Soyabean oil, [3] . Freedman et. al. investigated the effect of various parameters on vegetable oil yield [4]. Several researchers transesterified the vegetable oils and found that properties are quite comparable to mineral diesel and performance and emission characteristics of CI engines using biodiesel in different proportion as a blend with mineral diesel improves [5-10]. Agarwal et.al. developed linseed oil methyl esters and found it comparable to diesel with improved emission characteristics compared to diesel [5,6]. Physical wear of various vital parts, injector coking, carbon deposits etc. were found to be substantially lower in case of 20% biodiesel fuelled engines [11]. The objective of this study is to investigate the effect of transesterifcation on the viscosity and other properties of non-edible vegetable oils of Indian origin and to evaluate the effect of temperature on the viscosity of neat vegetable oil and their methyl esters. Detailed results on the viscosity and other properties of oils and their esters are presented in this paper. Composition of Vegetable Oils Petroleum diesel fuel is a complex mixture of hydrocarbons with carbon atoms ranging between 12-18, whereas vegetable oils are mixture of organic compounds ranging from simple straight chain compound to complex structure of proteins and fat-soluble vitamins and are commonly referred as triglycerides. Vegetable oils are usually triglycerides, generally with number of branched chains of different length, and have structural notation as shown.

Exhaust gas recirculation (EGR) cooler fouling has emerged as an important issue in diesel engine development. Uncertainty about the level of impact that fuel chemistry may have upon this issue has resulted in a need to investigate the cooler fouling process with emerging non-traditional fuel sources to gage their impact on the process. This study reports experiments using both ultra-low sulfur diesel (ULSD) and 20% biodiesel (B20) at elevated exhaust hydrocarbon conditions to investigate the EGR cooler fouling process. The results show that there is little difference between the degradation in cooler effectiveness for ULSD and B20 at identical conditions. At lower coolant temperatures, B20 exhibits elevated organic fractions in the deposits compared with ULSD, but this does not appear to lead to incremental performance degradation under the conditions studied. Comparisons with a previous study conducted at low HC levels shows that the presence of increased volatiles in the deposit does not impact the degradation in effectiveness significantly. Moreover, the effectiveness loss divided by the deposit mass gain for both low- and high-HC conditions seems to indicate that the HC fraction in the deposit does not significantly alter the overall thermal properties of the deposit layer.

Vegetable oils have energy content suitable to be used as compression ignition (CI) engine fuel. However, several operational and durability problems of using straight vegetable oils in CI engines are reported in the literature, which are primarily caused by their higher viscosity and low volatility compared to mineral diesel. The viscosity can be brought in acceptable range by (i) chemical process of transesterification, (ii) blending of oil with mineral diesel or (iii) by heating the vegetable oil using exhaust gas waste heat. Reduction of viscosity by blending or exhaust gas heating saves the chemical processing cost of transesterification. Present experimental investigations were carried out for evaluating combustion, performance and emission behavior of Jatropha oil blends in unheated conditions in a direct injection CI engine at different load and constant engine speed (1500 rpm). Analysis of in-cylinder pressure rise, instantaneous heat release and cumulative heat release was carried out. All test blends exhibited similar combustion stages as mineral diesel; however, Jatropha oil blends showed earlier start of combustion but lower heat release rate during premixed combustion phase for all engine loads. The crank angle position of peak cylinder pressure for vegetable oil blends shifts towards top dead center compared to baseline diesel. Combustion duration was found to be comparable with diesel up to 20% concentration of Jatropha oil in the fuel. HC, CO and NO emissions were found to slightly increase with increase in Jatropha oil content in the fuel blends.