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The paper presents a comparative analysis of the operational parameters, smoke emission and the content of toxic components in exhaust gases of a compression ignition engine fuelled with fossil diesel, commercially available biodiesel (fatty acid methyl ester) and their 50%/50% blend. The study was carried out using a diesel engine equipped with an in-line injection pump used in delivery vans. An indirect injection, considerably worn engine was chosen because such engines are very often fuelled with the less expensive biodiesel. Measurements were made on an engine operated at different rotational speeds under full load as well as using the European Stationary Cycle (ESC) test. Emissions of regulated and non-regulated compounds were measured with the use of the Fourier-Transform Infrared (FTIR) analytical system, which provided concentrations of 23 exhaust gas components.

The paper presents results of research of a gasoline engine capable of controlled auto-ignition (CAI) mode of combustion. The experiments were conducted on a single cylinder research engine equipped with direct fuel injection and a fully variable valvetrain. CAI operation was obtained with the use of the negative valve overlap (NVO) technique. The engine was operated at variable rotational speed and load. Comparative analysis of performance, fuel consumption and exhaust emissions was made for both SI and CAI combustion modes. Combination of variable valvetrain settings and variable excess air ratio allowed loads between 0.2 and 0.42 MPa IMEP in CAI combustion mode. Direct fuel injection provided the possibility to control the heat release rate via injection angle.