This paper presents the lubricity measurements of the three commercial gasoline types, unleaded gasoline (95 RON), new super or LRP (96 RON) and super unleaded gasoline (98 RON) and the effects of ...various physico-chemical properties on lubricity. The results indicate that the nature of the fuel is an important factor for the lubrication properties of each type of gasoline fuel. The potassium content takes an active part in this and the amount that is added to the fuel doesn't seem to affect the final result of CWSD1.4 proportionally. A careful statistical approach to the data identified that, the composition, the sulfur and nitrogen contents, the oxygen content that is mainly contributed from the MTBE content and the viscosity, do affect the lubricity but in a different degree for each type of fuel. This differentiation of the properties' effect on lubricity, reinforces the idea of the complicated wear mechanism that takes place under the specific conditions of the experiments and the important role of the compositional characteristics of the fuel. Oxygen content and MTBE seem to maintain or even increase the wear mechanism. Chlorine was also detected on the metal surface of the specimens after scanning with electron microscopy (SEM).
In recent years, the acceptance of fatty acid methyl esters (biodiesel) as a substitute to petroleum diesel has rapidly grown in Greece. The raw materials for biodiesel production in this country ...mainly include traditional seed oils (cotton seed oil, sunflower oil, soybean oil and rapeseed oil) and used frying oils. In the search for new low-cost alternative feedstocks for biodiesel production, this study emphasizes the evaluation of pumpkin seed oil. The experimental results showed that the oil content of pumpkin seeds was remarkably high (45%). The fatty acid profile of the oil showed that is composed primarily of linoleic, oleic, palmitic and stearic acids. The oil was chemically converted via an alkaline transesterification reaction with methanol to methyl esters, with a yield nearly 97.5
wt%. All of the measured properties of the produced biodiesel met the current quality requirements according to EN 14214. Although this study showed that pumpkin oil could be a promising feedstock for biodiesel production within the EU, it is rather difficult for this production to be achieved on a large scale.
Vegetable oils are produced from numerous oil seed crops. While all vegetable oils have high-energy content, most require some processing to assure safe use in internal combustion engines. Some of ...these oils already have been evaluated as substitutes for diesel fuels. With the exception of rape seed oil which is the principal raw material for biodiesel fatty acid methyl esters, sunflower oil, corn oil and olive oil, which are abundant in Southern Europe, along with some wastes, such as used frying oils, appear to be attractive candidates for biodiesel production. In this paper, fuel consumption and exhaust emissions measurements from a single cylinder, stationary diesel engine are described. The engine was fueled with pure marine diesel fuel and blends containing two types of biodiesel, at proportions up to 50%. The two types of biodiesel appeared to have equal performance, and irrespective of the raw material used for their production, their addition to the marine diesel fuel improved the particulate matter, unburned hydrocarbons, nitrogen oxide and carbon monoxide emissions.
Two different options for the autonomous power supply of rural or/and remote buildings are examined in this study. The first one involves a PV – diesel based power system, while the second one ...integrates RES and hydrogen technologies for the development of a self – sustained power system. The main objective is the replacement of the diesel generator and a comparison between these two options for autonomous power supply. Model simulations of the two power systems before and after the replacement, an optimization of the component sizes and a techno – economic analysis have been performed for the purpose of this study. A sensitivity analysis taking into account future cost scenarios for hydrogen technologies is also presented. The results clearly show that the Cost of Energy Produced (COE) from the PV – hydrogen technologies power system is extremely higher than the PV – diesel power system. However, the adopted PV – hydrogen technologies power system reduces to zero the Green – House Gas (GHG) emissions. Moreover, the sensitivity analysis indicates that COE for the latter system can be further reduced by approximately 50% compared to its initial value. This could be achieved by reducing critical COE’s parameters, such as PEM electrolyser and fuel cell capital costs. Hence, a possible reduction on the capital costs of hydrogen energy equipment in combination with emissions reduction mentioned above could make hydrogen – based power systems more competitive.
► The 95% coverage interval of the measurement of Gross Heat of Combustion of fuel is estimated. ► Two approaches are used, GUM approach and the adaptive Monte Carlo method (MCM). ► The results of ...the two approaches differ considerably. ► The GUM approach underestimates the calculated uncertainties and coverage intervals by up to 7–12%.
The Guide to Uncertainty of Measurement (GUM) approach and the adaptive Monte Carlo method (MCM) provide two alternative approaches for the propagation stage of the uncertainty estimation. These two approaches are implemented and compared concerning the 95% coverage interval estimation of the measurement of Gross Heat of Combustion (GHC) of an automotive diesel fuel by bomb calorimetry. The GUM approach, which assumes either a Gaussian or a
t-distribution for the output quantity (GHC) gives half width intervals of 0.28
MJ
kg
−1 (Gaussian distribution) or 0.29
MJ
kg
−1 (
t-distribution). On the other hand, MCM, which provides a reliable probability density function of GHC through numerical approximation, gives a half width interval of 0.32
MJ
kg
−1. Thus, the GUM approach underestimates the calculated uncertainties and coverage intervals by up to 7–12%. The main reasons of these differences are the approximations and the assumptions introduced by GUM approach, i.e. assumption for the GHC probability distribution and overestimation of effective degrees of freedom by the Welch-Satterwaite formula. Moreover, the estimation and the use of sensitivity coefficients and uncertainty budget within GUM and MCM approaches are examined.
This paper presents the impact of essential oils on the lubricity of automotive diesel. Nine essential oils were used as lubricating additives on two low sulfur diesel fuels, at the concentration ...range of 200–5000
ppm. Tribological experiments carried out on the high frequency reciprocating rig showed that five of nine essential oils used provide satisfactory mean wear scar diameter (WS 1.4) of less than 460
μm, at the concentration levels of 200–5000
ppm. Among the essential oils, those having the higher density and viscosity appeared to have better lubrication performance, exhibiting smaller wear scar diameter (WS 1.4) than the limit of 460
μm. Overall, the five essential oils seem to be better lubricants than others, maybe due to their chemical structure characteristics.
This paper presents the impact of oxygen and nitrogen compounds on the lubrication properties of low sulfur diesel fuels. It discusses the most recent results, concerning the influence of adding low ...amounts of 4 specific types of biodiesel, 5 aliphatic amines, 2 tertiarty amides, 10 mono-carboxylic acid esters, 3 acetoacetates and 7 esters of di-carboxylic acids on the tribological behaviour of the steel-on-steel systems, lubricated with low sulfur automotive diesel fuel. Experiments were carried out on the HFRR (high frequency reciprocating rig). The obtained wear results showed that all the various classes of additives improved fuel lubricity.
Tobacco seed is a byproduct of tobacco leaves production in Greece. This oil seed was evaluated in the present study, as a renewable and potential source of energy. Successive tobacco seed oil ...extraction indicated that almost 38% of the seed was oil. The major constituents observed by GC analysis were linoleic acid (18:2), oleic acid (18:1) and palmitic acid (16:0). The physical, chemical and fuel related properties of tobacco seed oil were investigated in this work. These properties were comparable to those of other vegetable oils and to current European specifications for automotive diesel fuel. This study suggests that this non edible oil may be an appropriate substitute for diesel fuel. The environmental advantages of tobacco seed oil as a fuel can be exploited for specific niche markets such as inner city vehicles or tractors. On the other hand, tobacco seed oil as a fuel represents one possible hope for the future of EU tobacco agriculture.
In this study, fatty acid ethyl esters (FAEE) were produced from four different vegetable oils (sunflower, cotton seed, olive oil, and used frying oil) using calcium ethoxide as a heterogeneous solid ...base catalyst. The ester preparation involved a two-step transesterification reaction, followed by purification. The effects of the mass ratio of catalyst to oil, the molar ratio of ethanol to oil, and the reaction temperature were studied on conversion of sunflower oil to optimize the reaction conditions in both stages. The rest of the vegetable oils were converted to ethyl esters under optimum reaction parameters. The optimal conditions for first stage transterification were an ethanol/oil molar ratio of 12:1, catalyst amount (3.5%), and 80°C temperature, whereas the maximum yield of ethyl esters reached 80.5%. In the second stage, the yield of ethyl esters showed signs of improvement of 16% in relation with the one-stage transesterification, which was obtained under the following optimal conditions: catalyst concentration 0.75% and ethanol/oil molar ratio 6:1. Property analysis of prepared ethyl ester samples was done, in order to examine their quality parameters. The results obtained showed that the density, viscosity, and calorific value of the produced ethyl esters had values close to those of a no. 2 diesel. On the contrary, the cold filter plugging points were higher than the conventional diesel fuel.
To reduce their fuel related logistic burden, North Atlantic Treaty Organization (NATO) Armed Forces are advancing the use of a single fuel for both aircraft and ground equipment. To this end, F-34 ...(the commercial equivalent is Jet A-1) is replacing distillate diesel fuel in many applications. However, tests conducted with this kerosene type on high frequency reciprocating rig showed that this type of fuel causes unacceptable wear. This excessive wear is caused by the poor lubricity of aviation fuel. In order to make this type of fuel compatible with direct injection compression engines, seven di-carboxylic acid esters have tested to improve the lubricity of kerosene. Tribological results showed that all esters tested in this series of experiments seem to be suitable for increasing the kerosene lubricity to a satisfactory level.
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