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Engine fuel tests were conducted with two oxygenates blended with conventional diesel and a synthetic Fisher-Tropsch (F-T) diesel to determine their emissions reduction potential. The oxygenated additives evaluated were dimethoxy methane (DMM) (also known as methylal) and diethyl ether (DEE). Blends of 5, 10, 20 and 30% by volume were investigated. The test engine was a 1993 Cummins B5.9 diesel, and data was collected for steady state operation at nine engine speed-load conditions. Experimental results show that all of the test fuels reduce PM when data is averaged across the nine engine operating modes. The largest reductions in PM were observed with a blend of 30% DMM in diesel, which yielded a 35% reduction compared to the baseline diesel fuel. Lower DMM blend levels also resulted in PM reductions, but to a lesser extent. On a modal averaged basis, F-T diesel reduced PM emissions by 29%, and DEE in concentrations of 10 to 30% reduced PM emissions by between 13 and 24%.

“Gas-to-liquids” catalytic conversion technologies show promise for liberating stranded natural gas reserves and for achieving energy diversity worldwide. Some gas-to-liquids products are used as transportation fuels and as blendstocks for upgrading crude-derived fuels. Methylal (CH3-O-CH2-O-CH3), also known as dimethoxymethane or DMM, is a gas-to-liquid chemical that has been evaluated for use as a diesel fuel component. Methylal contains 42% oxygen by weight and is soluble in diesel fuel. The physical and chemical properties of neat methylal and for blends of methylal in conventional diesel fuel are presented. Methylal was found to be more volatile than diesel fuel, and special precautions for distribution and fuel tank storage are discussed. Steady state engine tests were also performed using an unmodified Cummins B5.9 turbocharged diesel engine to examine the effect of methylal blend concentration on performance and emissions.

A method for determining the flame contour based on the flame arrival time at the fiber optic (FO) spark plug and at the head gasket ionization probe (IP) locations has been developed. The experimental data were generated in a single-cylinder Ricardo Hydra spark-ignition engine. The head gasket IP, constructed from a double-sided copper-clad circuit board, detects the flame arrival time at eight equally spaced locations at the top of the cylinder liner. Three other IP's were also installed in the cylinder head to provide additional intermediate data on flame location and arrival time. The FO spark plug consists of a standard spark plug with eight symmetrically spaced optical fibers located in the ground casing of the plug. The cylinder pressure was recorded simultaneously with the eleven IP signals and the eight optical signals using a high-speed PC-based data acquisition system.