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Technical Paper

Octane Appetite Studies in Direct Injection Spark Ignition (DISI) Engines

The anti-knock or octane quality of a fuel depends on the fuel composition as well as on the engine design and operating conditions. The true octane quality of practical fuels is defined by the Octane Index, OI = (1-K)RON + KMON where K is a constant for a given operating condition and depends only on the pressure and temperature variation in the engine (it is not a property of the fuel). RON and MON are the Research and Motor Octane numbers respectively, of the fuel. OI is the octane number of the primary reference fuel (PRF) with the same knocking behaviour at the given condition. In this work a wide range of fuels of different RON and MON were tested in prototype direct injection spark ignition (DISI) engines with compression ratios of 11 and 12.5 at different speeds up to 6000 RPM. Knock Limited Spark Advance (KLSA) was used to characterize the anti-knock quality of the fuel. Experiments were also done using two cars with DISI engines equipped with knock sensor systems.
Technical Paper

Feasibility Study of Exhaust Emissions in a Natural Gas Diesel Dual Fuel (DDF) Engine

The Diesel Dual Fuel (DDF) vehicle is one of the technologies to convert diesel vehicles for natural gas usage. The purpose of this research was to study the possibility of a DDF vehicle to meet emission standards for diesel vehicles. This research was done for small passenger vehicles and commercial vehicles. The exhaust emissions compliance of such vehicles in a New European Driving Cycle (NEDC) mode which was composed of Urban Driving Cycles (UDC) and an Extra Urban Driving Cycle (EUDC) was evaluated. (see APPENDIXFigure A1) In this study, the passenger vehicle engine, compliant with the EURO4 standard, was converted to a DDF engine. Engine bench tests under steady state conditions showed similar result to previous papers. Total hydrocarbon (HC) emission was extremely high, compared to diesel engine. The NEDC mode emissions of the DDF vehicle were estimated based on these engine bench test results.
Technical Paper

Effects of Next-Generation Bio Diesel Fuel on the Engine Performance

Hydrotreated Vegetable Oil (HVO) and Sugar-to-Diesel as next-generation bio diesel fuels consist of normal and iso-paraffin, and those carbon number of paraffinic hydrocarbons and distillation characteristics are narrow distribution. These characteristics would cause to deteriorate the evaporation and mixture with air and fuel. Therefore, in this study, the effects of normal paraffin (Tridecane) and iso-paraffin (HVO) on emission characteristics and cold start performance in a diesel engine were investigated by engine dynamometer tests, cold start vehicle tests, and spray analyzer tests. From the results, it was found that normal and iso-paraffin are beneficial for HC, CO, Smoke emission reduction. In addition, isomerization is effective for the diesel engine to fulfill cold start performance, since normal paraffin of narrow carbon number distribution became solidified under low temperature and high pressure condition in a common rail system.