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In order to discuss future technical issues for urea SCR (selective catalytic reduction) system, it is necessary to assess various technical possibilities that would be applied to urea SCR systems which is capable of complying with future emission level requirements, for example Japanese 2009 emission regulation. In this paper, three measures (enhanced insulation on a DOC (diesel oxidation catalyst), aggressive urea solution injection and idling stop) are installed on a urea SCR system of a commercial engine system in order to achieve further NOx (nitrogen oxide) reductions. With combination of these three measures, NOx is drastically reduced to the levels lower than 0.7 g/kWh, which is a NOx limit value of the Japanese 2009 emission regulation. NH3 (ammonia) and HCN (hydro cyanide) are also measured as unregulated harmful components.

The Poly-Aromatic Hydrocarbon (PAH) formation process from benzene was studied using a laminar flow reactor and GC-MS. In addition to PAH, acetylene and ethylene were observed. Without oxygen at temperatures over 1070 K, the amount of PAH and C2 species increased as the benzene concentration decreased. Addition of oxygen caused a linear decrease in the benzene concentration, and almost all of the benzene was consumed under stoichiometric conditions at all temperatures. At 1053 K, the concentrations of PAH and C2 species were not affected by the addition of oxygen. On the other hand, when the temperature was greater than 1070 K, the amount of PAH formed increased as the equivalence ratio increased, until the equivalence ratio was about 4. Above this equivalence ratio, the amounts decreased. Amounts of phenanthrene and biphenyl were large compared to those of other PAHs, which indicated that the dominant PAH formation path is the formation of phenanthrene via biphenyl.

The purpose of this study is to improve low-temperature flow-properties of biodiesel fuels (BDF) by blending with ethanol and to analyze the combustion characteristics in a diesel engine fueled with BDF/ethanol blended fuel. Because ethanol has a lower solidifying temperature, higher oxygen content, lower cetane number, and higher volatility than BDF, ethanol blending would have a large effect on cold flow performance, mixture formation, ignition, combustion, and exhaust emissions. The engine experiments in the study were performed with a diesel engine and blends of BDF and ethanol at different blending ratios. The cold flow performance of the blended fuels was evaluated by determining the fuel cloud point. The experimental results show that the ethanol blending lowers the cloud point of the blended fuel and significantly reduces smoke emissions from the engine without deteriorating other emissions or thermal efficiency.