Search Results

NO2 is an effective soot oxidizer operating at lower temperatures than O2. The effect of pure NO2 on soot oxidation was evaluated and compared with the gas treated by plasma, which initially consisted of NO, O2, and hydrocarbons. The cutout of a commercial DPF was used and the pressure difference across the DPF was monitored for an hour. The concentration of NO/NO2, CO, CO2 at the outlet of the DPF was measured as a function of time. CO and CO2 concentration was measured periodically by gas chromatography. The experiment was performed at 230, 250, 300, 350°C. When NO2 only was used as an oxidizing agent, there was a close relationship between the decrease of the pressure difference across the DPF, the CO and CO2 concentration at the outlet of the DPF, and the back conversion of NO2 to NO.

In this study, spark-ignition engine knock was studied experimentally. Cylinder pressure and cylinder block vibration of a four cylinder SI engine were measured. Knock characteristics, such as knock intensity, knock cycle percentage, knock occurrence crank angle, were determined from pressure and vibration signals using different analysis methods. Methods using band-pass filter, third derivative and step method, which was developed in this study, were shown to be the most suitable. The step method only used signals above threshold value during knocking and, as a result, both pressure and vibration signal analysis results with this method showed good signal-to-noise ratio. The knock intensities calculated from cylinder pressure and block vibration were proportional to each other over a wide range. It was confirmed in this study that vibration signals were useful in knock detection.