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Simultaneous crank-angle-resolved measurements of gasoline concentration and gas temperature were made with two-color mid-infrared (mid-IR) laser absorption in a production spark-ignition engine (Nissan MR20DE, 2.0L, 4 cyl, MPI with premium gasoline). The mid-IR light was coupled into and out of the cylinder using fiber optics incorporated into a modified spark plug. The absorption line-of-sight was a 5.3 mm optical path located closely adjacent to the ignition spark providing spatially resolved absorption. Two sensor wavelengths were selected in the strong bands associated with the carbon-hydrogen (C-H) stretching vibration near 3.4 μm, which have an absorption ratio that is strongly temperature dependent. Fuel concentration and temperature were determined simultaneously from the absorption at these two wavelengths.

Plasma burner of a new concept is suggested, developed and characterized as a unique SCR catalyst warm-up technology. This study shows a promising potential of using a plasma burner for rapid warm-up performance, minimizing fuel consumption and maximizing flame stability regardless of the temperature, oxygen concentration and flow velocity of exhaust gas in diesel engines. Since the oxygen and fuel source of the plasma burner are separated from the exhaust gas line, the performance of the plasma burner can be used regardless of engine conditions, such as engine speed and oxygen concentration. This study shows that the plasma burner can be used as an effective and promising tool for clean and energy efficient NOx and HC aftertreatment system for diesel engines.