Study On The Characteristics Of Unregulated Exhaust Emissions From A Modern Diesel Engine Fueled With Direct Coal-to-liquid Fuel

With the fast increasing demand in liquid transportation fuels, limited petroleum resources, and volatile petroleum prices, coal liquefaction technologies have received the world’s attention. This paper has mainly investigated on the unregulated emission characteristics of a common rail diesel engine by fuelling with blends of coal-to-liquid (CTL) fuel and conventional diesel fuel in different volume ratios with or without additives. The main subjects invested are as follows: First, the typical gaseous unregulated emission characteristics from different fuel formulas; Second, the effects of different formulas on the particulate matters and SOF; Third, the characteristics of PAHs in the PM from different formulas. According to the experimental results, the main conclusions can be drawn as follows:1. The brake specific unregulated emissions of different formulas are sharply declined and then level off or increase slightly with increasing the engine load at a constant engine speed.2. Compared to the reference diesel fuel, most of the gaseous PAHs derived from CTL are slightly enhanced, while the total carbonyls show a negligible reduction.3. CTL is sensitive to the oiliness additive, which can cause a great enhancement of brake specific unregulated emissions of CTL, especially at the case of low engine load conditions. However, by blending with the conventional diesel fuel and the cetane additive, the higher brake specific emissions caused by the oiliness additive can be significantly reduced.4. In comparison to the convention diesel fuel, the mass of PM emissions of the CFT shows no distinct differences, but the SOF proportion in the PM of CFT is slightly reduced. The additives have a weak impact on the proportions of SOF in the PM.5. The brake specific emissions of the PAHs in particle phase obtained from the neat CTL are slightly lower than that of conventional diesel fuel. The introduction of oiliness additive causes the increment of PAHs in particle phase, but this can be compensated by blending with the conventional diesel fuel and centane additive. The experimental result shows that naphthalene accounts for the most percent in the PAHs in particle phase, followed by acenaphthylene, acenaphthene and phenanthrene, however, the oncofetal substance of benzopyrene and indeno(1,2,3-cd) pyrene accounts for a very small percentage.