Fuel economy and emission characteristics of Gas-to-Liquid (GTL) and Rapeseed Methyl Ester (RME) as alternative fuels for diesel engines

The effect of RME (Rapeseed Methyl Ester) biodiesel and GTL (Gas-to-Liquid) fuels on the fuel consumption and emission characteristics including particulate matter of diesel engine was investigated. The engine tests were carried out based on the ESC 13-mode test procedure. Particulate Matter (PM) distribution was analyzed using the scanning mobility particle seizer (SMPS). Compared to the base line diesel fuel;biodiesel (RME) emitted up to 70% less specific CO;up to 50% less specific HC;and 60% less specific PM emissions. For RME fuel;the majority of the particle numbers were in the diameter range of 10–30 nm. For the conventional diesel and GTL fuels;the majority of PM emissions were in the diameter range of 30–200 nm. The GTL fuel emitted slightly less specific CO;HC;NOx;and PM than the conventional diesel fuel. The major deficit of the biodiesel fuel was its higher specific fuel consumption rate that was in the range up to 15% (by weight) higher than the other fuels. A relatively higher NOx and CO2 emission at most of the engine loads was encountered for biodiesel fuel. The CO2 emission of the GTL fuel was up to 5% lower than the specific CO2 emission of the other two fuels.