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In this study, engine performances and exhaust emissions characteristics of compression ignition engine fueled with GTL were investigated by comparison with diesel fuel. Diesel engine could be operated fueled with GTL without any special modify for the test engine. With the high cetane number of GTL, the ignition lag was shorter, and the combustion started earlier than that of diesel fuel. Brake thermal efficiency operated with GTL increased at middle load conditions due to incomplete combustion emission such as CO and THC were lower than that of diesel fuel operation. NOx emission with GTL was comparable to diesel fuel, and there was a little decrease at high load. With GTL, soot emission was lower than with diesel fuel at above middle load condition. It seemed to be a reason of soot reduction that there was little sulphur contained in GTL.

For better understanding of the in-cylinder combustion characteristics of DME, combustion radicals of a direct injection DME-Fueled compression ignition engine were observed using a spectroscopic method. In this initial report, the emission intensity of OH, CH, CHO, C2 and NO radicals was measured using a photomultiplier. These radicals could be measured with wavelength resolution (half-width) as about 3.3 nm. OH and CHO radicals appeared first, and then CH radical emission was detected. After that, the combustion radicals were observed using a high-speed image intensified video camera with band-pass filter. All of radicals were able to observe as images with half-width as 6 or about 10 nm. Rich DME leaked from nozzle was burning at the end of combustion. Therefore, the second light emission of C2 radical after the main combustion was observed.