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In 2004 the European Parliament ratified the Euro III and IV standards limiting the pollutant emission of, among others, rail and marine diesel engines. In these sectors, it is particularly important to keep any fuel consumption penalty, when reducing emissions, to a strict minimum. Furthermore, exhaust gas after treatment is mostly avoided for cost reasons. Thus, manufacturers are looking to pretreatment of fuels, alternative fuels, and limiting engine-out emissions as ways to attain the required emission levels. This paper discusses the experimental work done on a 1324 kW, 1000 rpm six cylinder marine diesel engine equipped with mechanical unit injectors. The aim was to determine the influence of compression ratio and fuel injection parameters on engine-out emissions, with emphasis on NOx emissions. A range of fuel injection parameters were examined, varying the start of injection, pump plunger diameter, injection pressure, and injector nozzle geometry.

There is a growing consensus that there will not be a single alternative to fossil fuels, but rather different fuels, fuel feedstocks, engine types and operating strategies. For stationary diesel engines, straight vegetable oils are an interesting alternative to fossil diesel, because of their potential for lower life cycle greenhouse gas emissions. Using animal fats is also compelling, as it does not imply the cultivation of oil-bearing seeds and related emissions, not to mention the ‘food versus fuel’ debate. The aim of the present work is to correlate engine performance and durability with the properties (composition) of these alternative fuels, to provide a basis from which standards can be formulated for the properties of oils and fats to be used as engine fuel. Tests on different oils and fats are reported.

Medium speed diesel engines are well established today as a power source for heavy transport and stationary applications and it appears that they will remain so in the future. However, emission legislation becomes stricter, reducing the emission limits of various pollutants to extremely low values. Currently, many techniques that are well established for automotive diesel engines (common rail, after treatment, exhaust gas recirculation - EGR, …) are being tested on these large engines. Application of these techniques is far from straightforward given the different requirements and boundary conditions (fuel quality, durability, …). This paper reports on the development and experimental results of cooled, high pressure loop EGR operation on a 1326kW four stroke turbocharged medium speed diesel engine, with the primary goal of reducing the emission of oxides of nitrogen (NOx). Measurements were performed at various loads and for several EGR rates.