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Emissions and performance parameters of a medium size, medium speed D.I. diesel engine with increased charge air pressure and reduced but fixed inlet valve opening period have been measured and compared to the standard engine. While power output and fuel consumption are slightly improved, nitric oxide emissions can be reduced by up to 20%. The measurements confirm the results of simulations for both performance and emissions, for which a quasidimensional model including detailed chemistry for nitric oxide prediction has been developed.

In view of the large (and further increasing) range of fuels applied in marine diesel engines, there is a clear need for obtaining a better understanding of the effect of those fuels on the key in-cylinder processes governing the combustion characteristics of these engines. For this purpose, a constant volume chamber representative of the combustion system of large marine diesel engines has been complemented with a device allowing the investigation of small fuel quantities and the resulting setup has been used for studying the combustion behaviour of typical marine diesel fuels at conditions relevant for large marine two-stroke diesel engines. Specifically, two clearly distinct heavy fuel oils have been compared to a light fuel oil. Two optical measurement techniques were used to complement the findings made on the basis of rate of heat release analysis.