Search Results

1 A novel analysis approach called “Regression Density method” was developed for better understanding of fuel property effects on exhaust emission. The approach was applied to diesel emission data obtained in JCAP programs and emission models were conducted to analyze the effects of fuel properties and engine conditions on emissions. By introducing this analysis method, the relationship between density factor and aromatics factor (chemical composition factor) was identified, however, they have been reported previously as dominant factors in fuel properties. The effects of engine conditions and fuel properties on emissions were investigated quantitatively based on the statistically conducted emission models to clarify universal ways to emission reduction. The mechanism of emission formation of vehicles and engines with characteristic behavior was also examined.

The differences between spray models are investigated by comparing calculation results with experimental data. The calculations are performed using the KIVA-II code. The spray models TAB, which is the original model of KIVA-II, and the model developed by Reitz are calculated and compared. A semi-empirical spray model based on the TAB model is also formulated and compared with the other models. The penetration and droplet size distribution are compared with data from constant pressure bomb tests. The calculated ignition delay is compared with actual engine operating data- Each spray model has different characteristics influencing the atomization process. These differences result in discrepancies during the penetration, evaporation, and ignition.

Since in-cylinder flame temperature has a direct effect on an engine's NOx characteristics, this phenomena has been studied in detail in a multi-cylinder DI diesel engine using a new method allowing the in-cylider temperature distribution to be measured by the two color method. An endoscope is installed in the combustion chamber and flame light introduced from the endoscope is divided into two colors by filters. The images of combustion phenomena using the two wavelengths are recorded with a framing streak camera which includes a CCD camera. The flame temperature and KL factor are immediately calculated by a computer using the two color images from the CCD camera. In the case of EGR, the test was conducted under 75% load conditions. The flame temperature was reduced according to an increase of EGR rate.

In order to reduce particulate and NOx emission from the direct injection diesel engine, most researchers have been expecting the utilization of higher injection pressure and injection rate for improvement of diesel combustion. In the case of pump-line-nozzle system, the injection pipe line is very important with regard to the high injection pressure. Namely, the pipe line must be able to resist not only high pressure but also cavitation erosion. In this paper, the effect of high injection pressure, injection rate and sharp cutting at the end of fuel injection are discussed along with cavitation phenomena on the injection pipe line. And durability tests on the pipe line system under high injection pressure using a test rig are also described. Regarding durability tests, several measures have been taken for the injection pipe. As a result, the authors have found that the best solution for the injection pipe is a composite pipe made with SUS and steel.