Combustion of Fischer-Tropsch, RME and Conventional Fuels in a Heavy-Duty Diesel Engine

This investigation includes a comparison of two Fischer-Tropsch (FT) fuels derived from natural gas and a Rapeseed Methyl Ester (RME) fuel with Swedish low sulfur Diesel in terms of emissions levels, fuel consumption and combustion parameters. The engine used in the study was an AVL single cylinder heavy-duty engine, equipped with a cylinder head of a Volvo D12 engine. Two loads (25% and 100%) were investigated at a constant engine speed of 1200 rpm. The engine was calibrated to operate in different levels of EGR and with variable injections timings. A design of experiments was constructed to investigate the effects of these variables, and to identify optimal settings. The results showed that the soot emissions yielded by FT and RME fuels are up to 40 and 80 percent lower than those yielded by the Swedish Diesel. In addition the FT fuel gave slightly lower, and the RME significant higher NOx emissions than the Swedish Diesel. Due to the low heating value of the RME fuel, the fuel consumption was increased by 10% compared with the Swedish Diesel. The fuel consumption with the FT fuel, which has a similar heating value to conventional fuels, was not significantly different from that obtained with the Diesel.