Biodiesel Emissions from a Baseline Engine Operated with Different Injection Systems and Exhaust Gas Recirculation (EGR) Strategies during Transient Sequences

This work is focused oil the measurement and analysis or biodiesel emissions resulting from two commercial diesel engines derived from the same baseline engine. One of the engines was equipped with a rotary fuel injection pump electronically controlled. Another engine was equipped with a common-rail injection system. Both engines were tuned by the manufacturer with diesel fuel, and each of them was optimized with different exhaust gas recirculation (EGR) strategies. Both engines were tested under several transient conditions. A methyl ester obtained from unused Sunflower oil was tested as diesel fuel, pure and blended with 30 and 70% of a commercial diesel fuel, which was also used pure. The engines were mounted in a test bench prepared for operating under transient conditions. Ail AVL 439 smoke meter and all Environnement gas analyzer allowed for the study of the effect of these fuels oil the variations of the engine emissions with time. The consideration of the thermochemical properties of the tested fuels and the engine parameters, such as fuel/air ratio or EGR ratio, were used for the analysis of the results. The studied engine transient processes were (a) a load increase at constant engine speed and (b) an engine speed decrease at constant torque. The obtained results proved that the biodiesel effect oil pollutant emissions during transient conditions depends upon the fuel injection system and EGR strategy used during the engine tuning.