S. Stournas

AN INVESTIGATION OF USING BIODIESEL/MARINE DIESEL BLENDS ON THE PERFORMANCE OF A STATIONARY DIESEL ENGINE

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.

Investigation of the effectiveness of absorbent materials in oil spills clean up

The present study examines the absorption capacity of five different types of materials for oil spills clean up. The absorbents were a commercial cellulosic material from processed wood, a commercial synthetic organic fiber from polypropylene and three commercial types of local expanded perlite from the island of Milos. The absorption capacities of the above materials were evaluated in a wet as well as a dry environment with different types of petroleum products. The results showed that commercial types of perlite, in some cases, have absorption capacities comparable to natural and synthetic organic materials used for clean-up applications. The enhancement of the hydrophobic properties of perlite can result in better performance in a water bath. The nature of the spilled oil proved to play an important role in the selection of the proper absorbing material. Overall, the results suggested that partial substitution of commercial synthetic sorbents by mineral materials widely produced in Greece for oil spill clean-up operations is possible, given their friendliness to the environment and their local abundancy.

Desulfurization of petroleum fractions by oxidation and solvent extraction

Abstract The known ability of several solvents to extract sulfur compounds selectivity from petroleum fractions can be dramatically improved by oxidizing the sulfur from the divalent state (sulfide) to the hexavalent (sulfone). The oxidation process itself leads to the removal of a substantial portion of the existing sulfur and makes the remaining sulfur compounds amenable to efficient removal even by solvents such as methanol which are not effective in selective extraction of the unoxidized sulfur compounds. Thus this combination process is capable of removing up to 90% of the sulfur compounds in petroleum fractions at acceptable yields. The oxidation process has no deleterious effects on the distillation profile and other characteristics of the middle distillate fractions that were examined.

Tobacco seed oil as an alternative diesel fuel: physical and chemical properties

Abstract 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.

Light vehicle regulated and unregulated emissions from different biodiesels.

In this study, the regulated and unregulated emissions profile and fuel consumption of an automotive diesel and biodiesel blends, prepared from two different biodiesels, were investigated. The biodiesels were a rapeseed methyl ester (RME) and a palm-based methyl ester (PME). The tests were performed on a chassis dynamometer with constant volume sampling (CVS) over the New European Driving Cycle (NEDC) and the non-legislated Athens Driving Cycle (ADC), using a Euro 2 compliant passenger vehicle. The objectives were to evaluate the impact of biodiesel chemical structure on the emissions, as well as the influence of the applied driving cycle on the formation of exhaust emissions and fuel consumption. The results showed that NO(x) emissions were influenced by certain biodiesel properties, such as those of cetane number and iodine number. NO(x) emissions followed a decreasing trend over both cycles, where the most beneficial reduction was obtained with the application of the more saturated biodiesel. PM emissions were decreased with the palm-based biodiesel blends over both cycles, with the exception of the 20% blend which was higher compared to diesel fuel. PME blends led to increases in PM emissions over the ADC. The majority of the biodiesel blends showed a tendency for lower CO and HC emissions. The differences in CO(2) emissions were not statistically significant. Fuel consumption presented an increase with both biodiesels. Total PAH and nitro-PAH emission levels were decreased with the use of biodiesel independently of the source material. Lower molecular weight PAHs were predominant in both gaseous and particulate phases. Both biodiesels had a negative impact on certain carbonyl emissions. Formaldehyde and acetaldehyde were the dominant aldehydes emitted from both fuels.

Biodiesel emissions profile in modern diesel vehicles. Part 2: Effect of biodiesel origin on carbonyl, PAH, nitro-PAH and oxy-PAH emissions

In the present study, the effects of different biodiesel blends on the unregulated emissions of a Euro 4 compliant passenger car were examined. Two fresh and two oxidized biodiesel fuels of different source materials were blended with an ultra low sulphur automotive diesel fuel at proportions of 10, 20, and 30% v/v. Emission measurements were conducted on a chassis dynamometer with a constant volume sampling (CVS) technique, over the New European Driving Cycle (NEDC) and the Artemis driving cycles. The experimental results revealed that the addition of biodiesel led to important increases in most carbonyl compounds. Sharp increases were observed with the use of the oxidized biodiesel blends, especially those prepared from used frying oil methyl esters. Similar to carbonyl emissions, most PAH compounds increased with the addition of the oxidized biodiesel blends. It can be assumed that the presence of polymerization products and cyclic acids, along with the degree of unsaturation were the main factors that influenced carbonyl and PAH emissions profile.

Effects of low concentration biodiesel blends application on modern passenger cars. Part 3: Impact on PAH, nitro-PAH, and oxy-PAH emissions

This study explores the impact of five different types of methyl esters on polycyclic aromatic hydrocarbon (PAH), nitrated-PAH and oxygenated PAH emissions. The measurements were conducted on a chassis dynamometer, according to the European regulation. Each of the five different biodiesels was blended with EN590 diesel at a proportion of 10-90% v/v (10% biodiesel concentration). The vehicle was a Euro 3 compliant common-rail diesel passenger car. Emission measurements were performed over the NEDC and compared with those of the real traffic-based Artemis driving cycles. The experimental results showed that the addition of biodiesel led to some important increases in low molecular-weight PAHs (phenanthrene and anthracene) and to both increases and reductions in large PAHs which are characterised by their carcinogenic and mutagenic properties. Nitro-PAHs were found to reduce with biodiesel whereas oxy-PAH emissions presented important increases with the biodiesel blends. The impact of biodiesel source material was particularly clear on the formation of PAH compounds. It was found that most PAH emissions decreased as the average load and speed of the driving cycle increased. Cold-start conditions negatively influenced the formation of most PAH compounds. A similar trend was observed with particulate alkane emissions.

Effects of fatty acid derivatives on the ignition quality and cold flow of diesel fuel

The biodiesel that is considered as a possible substitute or extender of conventional automotive diesel fuel is commonly composed of fatty acid methyl esters that are prepared from the glycerides in vegetable oils by transesterification with methanol. This form of biodiesel is compatible with diesel fuel but offers no improvement in its ignition quality. This work describes the results of a series of experiments aimed at assessing other common fatty acid derivatives that could provide the desired biofuel component and, at the same time, improve the performance of the fuel. It was found that tertiary fatty amines and amides are significantly more effective than methyl esters in enhancing the ignition quality of the finished diesel fuel without having any negative effect on its cold flow properties.

Effects of low concentration biodiesel blend application on modern passenger cars. Part 1: Feedstock impact on regulated pollutants, fuel consumption and particle emissions

Five biodiesels from different feedstocks (rapeseed, soy, sunflower, palm, and used fried oils) blended with diesel at 10% vol. ratio (B10), were tested on a Euro 3 common-rail passenger car. Limited effects (-2% to +4%) were observed on CO(2) emissions. CO and HC emissions increased between 10% and 25% on average, except at high speed - high power where emissions were too low to draw conclusions. NOx emissions increased by up to 20% for two out of the five blends, decreased by up to 15% for two other blends, and remained unchanged for one blend. Particulate matter (PM) was reduced for all blends by up to 25% and the reductions were positively correlated with the extent of biodiesel saturation. PM reductions are associated with consistent reductions in non-volatile particle number. A variable behaviour in particle number is observed when volatile particles are also accounted.

Effects of low concentration biodiesel blends application on modern passenger cars. Part 2: Impact on carbonyl compound emissions

Today in most European member states diesel contains up to 5% vol biodiesel. Since blending is expected to increase to 10% vol, the question arises, how this higher mixing ratio will affect tailpipe emissions particularly those linked to adverse health effects. This paper focuses on the impact of biodiesel on carbonyl compound emissions, attempting also to identify possible relationship between biodiesel feedstock and emissions. The blends were produced from five different feedstocks, commonly used in Europe. Measurements were conducted on a Euro 3 common-rail passenger car over various driving cycles. Results indicate that generally the use of biodiesel at low concentrations has a minor effect on carbonyl compound emissions. However, certain biodiesels resulted in significant increases while others led to decreases. Biodiesels associated with increases were those derived from rapeseed oil (approx. 200%) and palm oil (approx. 180%), with the highest average increases observed at formaldehyde and acroleine/acetone.