The purpose of this work was to investigate the impact of marine gas oil (MGO)/biodiesel blends on the exhaust emissions and fuel consumption in a single cylinder, stationary, diesel engine. Three different origins of biodiesel were used as the blending feedstock with the reference MGO, at proportions of 5 and 10% by volume. Methyl esters were examined according to the automotive FAME standard EN 14214. The baseline MGO and biodiesel blends were examined according to ISO 8217:2005 specifications for the DMA category. Independently of the biodiesel used, a decrease of PM, HC, CO and CO(2) emissions was observed. Emissions of NO(x) were also lower with respect to MGO. This reduction in NO(x) may be attributed to some physicochemical properties of the fuels applied, such as the higher cetane number and the lower volatility of methyl esters. Reductions in PM for biodiesel blends were lower in the exhaust than those of the reference fuel which was attributed to the oxygen content and the near absence of sulphur and aromatics compounds in biodiesel. However, a slight increase in fuel consumption was observed for the biodiesel blends that may be tolerated due to the exhaust emissions benefits. Brake thermal efficiency was also determined. Unregulated emissions were characterized by determining the soluble organic fraction content of the particulate matter.

The EU Directives and legislation by worldwide environmental authorities impose constantly lower levels for the airborne pollutant emissions of internal combustion engines towards the goal of zero emission vehicles. During the last decade, engine manufacturers, refiners and fuel companies invest highly in order to comply with the increasingly severe emission requirements.The diesel engine is widely used for transportation, manufacture, power generation, construction and farming operations. There are different kinds of diesel engine depending on their application: small, high speed, indirect-injection engines or low speed, direct -injection behemoths with cylinders more than one meter in diameter. Their main advantages are the efficiency, economy and reliability. The physicochemical properties of the diesel fuels and the engine design affect the operability, the efficiency and the performance of the diesel engine and they correlate to the exhaust emissions.In Greece, the diesel fuel market steadily increases during the last years. 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 (i.e. contamination with water, tank sludge and residues) or adulteration with lower value and taxation fuels (heating oil, marine diesel or industrial solvents).The transportation sector is a major source of air pollution. It contributes to harmful exhaust emissions, such as greenhouse gas emissions, carbon monoxide, sulfur oxides (SO x ), nitrogen oxides (ΝΟ x ), unburned hydrocarbons (HC) and particulate matter (PM) emissions.In this paper, PM and exhaust emissions from a stationary single cylinder diesel engine were examined. For comparison purposes, tests were carried out with a typical automotive diesel fuel of the Greek market and with adulterated fuels with heating oil or white spirit. The noncomplying diesel fuels gave increased emissions in all cases with only exception the PM emissions due to adulteration with white spirit. More specifically, the experimental results for the adulterated fuels with heating diesel showed an increase of the nitrogen oxide emissions up to 73.9%, of the unburned hydrocarbons up to 29.6% and of PM up to 121% compared to the baseline diesel fuel emissions.KEYWORDS: Air quality, exhaust emissions, automotive diesel fuel, industrial solvents, adulterated fuels, white spirit, particulate matters 292 MATTHEOU et al.