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Kobashi Y.,Kanazawa Institute of Technology | Fujimori K.,Kanazawa Institute of Technology | Maekawa H.,Kanazawa Institute of Technology | Kato S.,Kanazawa Institute of Technology | And 2 more authors.
SAE International Journal of Engines | Year: 2011

Auto-ignition and combustion processes of dual-component fuel spray were numerically studied. A source code of SUPERTRAPP (developed by NIST), which is capable of predicting thermodynamic and transportation properties of pure fluids and fluid mixtures containing up to 20 components, was incorporated into KIVA3V to provide physical fuel properties and vapor-liquid equilibrium calculations. Low temperature oxidation reaction, which is of importance in ignition process of hydrocarbon fuels, as well as negative temperature coefficient behavior was taken into account using the multistep kinetics ignition prediction based on Shell model, while a global single-step mechanism was employed to account for high temperature oxidation reaction. Computational results with the present multi-component fuel model were validated by comparing with experimental data of spray combustion obtained in a constant volume vessel. The results showed a good agreement in terms of spray tip penetration, liquid length, ignition delay and so on, for several kinds of dual-component fuels. Additional investigation into a combustion control methodology using dual-component fuel, which aims to mitigate combustion rate of premixed charge, was performed. Consequently, the feasibility of this approach was confirmed. © 2011 SAE International. Source

Mizushima N.,National Traffic Safety and Enviro Laboratory | Murata Y.,Waseda University | Suzuki H.,National Traffic Safety and Enviro Laboratory | Ishii H.,National Traffic Safety and Enviro Laboratory | And 2 more authors.
SAE International Journal of Fuels and Lubricants | Year: 2010

The use of biomass fuels for vehicles has been a focus of attention all over the world in terms of prevention of global warming, effective utilization of resources and local revitalization. For the purpose of beneficial use of unused biomass resources, the movement of the use of bioethanol and biodiesel made from them has spread in Japan. In Japan, biodiesel is mainly made from waste cooking oil collected by local communities or governments, and in termsof local production for local consumption, it is used as neat fuel (100% biofuel) or mixed with diesel fuel in high concentration for the vehicles. On the other hand, extremely low emission level must be kept for not only gasoline vehicles but also diesel vehicles in the post new long-term regulation implemented from 2009 in Japan. It is necessary for diesel vehicles to equip an advanced type of aftertreatment such as Urea-Selective Catalytic Reduction (SCR) system or lean NOx trap (LNT) catalyst system in order to comply with this regulation. In this study, engine bench tests were conducted to understand the emission characteristics in the use of high concentration of biodiesel for an engine system with the urea-SCR system which is expected to be equipped for a lot of heavy-duty vehicles in the near future. The results indicated that NOx emission in biodiesel operation increased compared with that in conventional diesel operation under Japanese JE05 mode test. This is because of the NOx emission increasing in the engine out and the NOx reduction efficiency decreasing in the urea-SCR system. Especially, B100 (Neat biodiesel) increased NOx emission over the New Long-Term regulation limit, even though this engine system complied with the new long-term regulation level enough. This was mainly affected by the decrease of NOx reduction efficiency in urea-SCR system due to the decrease of NO2 /NOx ratio at the inlet of urea-SCR. The factor of the decrease in NO2 /NOx ratio was considered to be the decrease in NO2 concentration derived from thereduction of engine-out NO 2 emission and the deterioration of oxidizability of diesel oxide catalyst (DOC). As for the deterioration of oxidizability of DOC, it was thought to be due to the decrease in exhaust gas temperature, catalyst poisoning and reduction action by SOF adhered in DOC. Therefore, it was necessary to improve oxidizability of DOC in order to decrease NOx emissions. © 2010 SAE International. Source

Kobayashi M.,New ACE Institute Company Ltd | Aoyagi Y.,New ACE Institute Company Ltd | Adachi T.,New ACE Institute Company Ltd | Murayama T.,New ACE Institute Company Ltd | And 3 more authors.
SAE Technical Papers | Year: 2011

Reduction of exhaust emissions and BSFC was studied for high pressure, wide range, and high EGR rates in a Super-clean Diesel six-cylinder heavy duty engine. The GVW 25-ton vehicle has 10.52 L engine displacement, with maximum power of 300 kW and maximum torque of 1842 Nm. The engine is equipped with high-pressure fuel injection of a 200 MPa level common-rail system. A variable geometry turbocharger (VGT) was newly designed. The maximum pressure ratio of the compressor is about twice that of the previous design: 2.5. Additionally, wide range and a high EGR rate are achieved by high pressure-loop EGR (HP-EGR) and low pressure-loop EGR (LP-EGR) with described VGT and high-pressure fuel injection. The HP-EGR can reduce NOx concentrations in the exhaust pipe, but the high EGR rate worsens smoke. The HP-EGR system layout has an important shortcoming: it has great differences of the intake EGR gas amount into each cylinder, worsens smoke. The system layout can eliminate large differences of intake EGR gas amounts into each cylinder. The improved HP-EGR system layout achieves a wide range and high EGR more than the previous system. For engine speed of 1200 rpm and 40% load (BMEP0.83 MPa), the combined EGR of HP-EGR and LP-EGR can increase about twice EGR rate compared with the case of HP-EGR only and improve NOx to around half without BSFC deterioration. This system was evaluated practically to improve exhaust emissions in both steady-state and transient test conditions. Finally, the super-clean diesel engine is used with this system and checked experimentally using the JE05 transient test mode to meet the target performance. Copyright © 2011 SAE International. Source

Hashimoto M.,New ACE Institute Company Ltd | Aoyagi Y.,New ACE Institute Company Ltd | Kobayashi M.,New ACE Institute Company Ltd | Murayama T.,New ACE Institute Company Ltd | And 2 more authors.
SAE Technical Papers | Year: 2012

Reduction of exhaust emissions and BSFC has been studied using a high boost, a wide range and high-rate EGR in a Super Clean Diesel, six-cylinder heavy duty engine. In the previous single-turbocharging system, the turbocharger was selected to yield maximum torque and power. The selected turbocharger was designed for high boosting, with maximum pressure of about twice that of the current one, using a titanium compressor. However, an important issue arose in this system: avoidance of high boosting at low engine speed. A sequential and series turbo system was proposed to improve the torque at low engine speeds. This turbo system has two turbochargers of different sizes with variable geometry turbines. At low engine speed, the small turbocharger performs most of the work. At medium engine speed, the small turbocharger and large turbocharger mainly work in series. At high engine speed, the small turbocharger does no work at all, but the large turbocharger works mainly using a small turbocharger bypass. The basic engine, with six cylinders in-line and displacement of 10.5 L, is equipped with a high-pressure fuel injection system and a high- and low-pressure loop EGR system for using the high boosting and high EGR rate to reduce BSNOx and PM. Experimentally obtained results show that the sequential and series turbocharging system has 50% higher torque than the conventional, with improved fuel consumption achieved in the low-speed region. Copyright © 2012 SAE International. Source

Osada H.,New ACE Institute Company Ltd | Aoyagi Y.,New ACE Institute Company Ltd | Shimada K.,New ACE Institute Company Ltd | Goto Y.,National Traffic Safety and Enviro Laboratory | Suzuki H.,National Traffic Safety and Enviro Laboratory
SAE Technical Papers | Year: 2010

For reducing NOx emissions, EGR is effective, but an excessive EGR rate causes the deterioration of smoke emission. Here, we have defined the EGR rate before the smoke emission deterioration while the EGR rate is increasing as the limiting EGR rate. In this study, the high rate of EGR is demonstrated to reduce BSNOx. The adapted methods are a high fuel injection pressure such as 200 MPa, a high boost pressure as 451.3 kPa at 2 MPa BMEP, and the air intake port that maintains a high air flow rate so as to achieve low exhaust emissions. Furthermore, for withstanding 2 MPa BMEP of engine load and high boosting, a ductile cast iron (FCD) piston was used. As the final effect, the installations of the new air intake port increased the limiting EGR rate by 5%, and fuel injection pressure of 200 MPa raised the limiting EGR rate by an additional 5%. By the demonstration of increasing boost pressure to 450 kPa from 400 kPa, the limiting EGR rate was achieved to 50%. At the same time, BSNOx was reduced to 1.0 g/kWh from 3.5 g/kWh at 2 MPa BMEP with no increase in smoke emission and particulate matter (PM). The technologies developed in this study are not only to reduce exhaust emissions but also useful and available to improve brake-specific fuel consumption for both single-cylinder and multi-cylinder heavy duty diesel engines. Copyright © 2010 SAE International. Source

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