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Many incidents associated with filter plugging have extensively been reported in microbially contaminated diesel and biodiesel fuel systems, especially under long term storage conditions. In this study a quantitative assessment of the undesirable insoluble solids produced in contaminated biodiesel fuels was carried out in order to evaluate their evolution rate during biodeterioration. For this purpose, a series of contaminated biodiesel fuel microcosms were prepared and stored for six months under stable conditions. The quantity of the particulate contaminants was monitored during storage by a multiple filtration technique which was followed at the end by a comparison with the active bioburden per ATP bioluminescence protocol. Additionally, identical microcosms were treated with a commercially available biocide in order to examine the latter’s activity both on solids formation and the microbial proliferation.

The aim of this study is to investigate the lubricity of hydrocarbons that constitute components of petroleum diesel fuel. A number of typical hydrocarbon compounds were selected as representative of the group types of alkanes (paraffins), cycloalkanes (naphthenes) and aromatics, similar to those that are present in diesel fuel. The lubricity of these substances was examined in a High Frequency Reciprocating Rig (HFRR) apparatus according to the ISO 12156-1 standard method. Thereafter, a series of diesel surrogate fuel were prepared from the above substances based on literature data for diesel fuel composition and on the previously obtained results. These model fuels were assessed regarding their lubricating performance in order to evaluate how each individual component can affect the lubricity of the final fuel.

FAME is the most common renewable component of conventional automotive diesel. Despite the advantages, biodiesel is more susceptible to oxidative deterioration and due to its chemical composition as well as its higher affinity to water, is considered to be a favorable substrate for microorganisms. On the other hand, apart from biodiesel, alcohols are considered to be promising substitutes to conventional diesel fuel because they can offer higher oxygen concentration leading to better combustion characteristics and lower exhaust emissions. More specifically, n-butanol is a renewable alcohol demonstrating better blending capabilities and properties when it is added to diesel fuel, as its composition is closer to conventional fuel, when compared ethanol to for example. Taking into consideration the alleged disinfectant properties of alcohols, it would be interesting to examine also the microbial stability of blends containing n-butanol in various concentrations.

Air pollution caused by diesel emissions, especially NOx, particulate matter, carbon monoxide and unburned hydrocarbons, has been a noteworthy matter. In Europe and the United States, legislative efforts towards improving air quality not only lead manufacturers to develop and introduce further improved emission control systems, but also the trigger demanding requirements on the oil industry towards producing advanced fuels. Therefore, much work on the effects of fuel properties on the emissions and engine performance has been performed worldwide. The fuels produced by the refineries usually comply with the existing specifications. However, alterations in the fuel properties may occur through the supply chain to the service stations due to failures of the distribution system or adulteration with lower value and taxation fuels (heating oil, marine diesel or industrial solvents).

The objective of this paper was to evaluate the performance and airborne emissions of a diesel-water emulsion in 4 public buses operated in the area of Athens. The fuels used were a typical automotive diesel from the Greek market, a low sulfur diesel and a diesel-water emulsion of 13 % v/v water in low sulfur diesel. The fuels were characterized by exposing their physicochemical properties according to EN 590. The measurements of emissions of carbon monoxide, unburned hydrocarbons and carbon dioxide did not show any significant differences among the three fuels. The effects on NOx emissions can be termed as mixed, bearing also in mind that they represent engine operation at no load. The beneficial effect of the emulsified diesel fuel could be readily observed in the case of smoke opacity emissions.

In this paper, two diesel fuels were examined in a single cylinder diesel engine under an emissions measurement test of 72 hours total duration. The test cycle included steady state measurements and transient measurements. The two test fuels were a typical automotive diesel fuel, complying with the specifications of the EN 590 European standard for the year 2004 (sulfur content 350 mg/kg), and an ultra low sulfur diesel fuel containing 15% GTL, complying with the specifications of the EN 590 European standard for the year 2008 (sulfur content 10 mg/kg). Exhaust emissions measurements included gaseous pollutants (carbon monoxide, hydrocarbons, nitrogen oxides), and particulate matter emissions. In all cases carbon monoxide and hydrocarbons emissions were very low. Nitrogen oxides emissions did not show a clear trend, indicating that this pollutant is affected mainly by the engine and less by the fuel.