Presentations

One of the numerous ways of overcoming knocking is to deliberately create fuel inhomogeneities within the combustion chamber, since it has proved to lengthen combustion duration and to drastically reduce maximum pressure rise rate (PRR). Thus, the goal of this paper is to investigate in details the reason why the whole combustion duration tends to enlarge, according to the fuel inhomogeneities. To make this analysis, a 4 stroke optically accessible engine provided with two different chemiluminescence measuring systems have been used. The first system is a chemiluminescence intensifier, mostly to investigate the fuel properties, and the second one is a chemiluminescence imaging system, with a high-speed camera rather for close and precise observations.

In HCCI Engine, combustion is affected by change of compression speed corresponding to engine speed or compression ratio. The purpose of this study is to investigate the mechanism of influence of engine speed on HCCI combustion characteristics by using numerical analysis. At first, the influence of engine speed was shown. And then, in order to clarify the mechanism of influence of engine speed, results of kinetics computations were analyzed to investigate the elementary reaction path for heat release at transient temperatures by using contribution matrix.

Stratified charge has been thought as one of the ways to avoid the sharp pressure rises of HCCI combustion. The purpose of this study is to evaluate the potential of EGR Stratifications to reduce Pressure Rise Rate on HCCI combustion. Pre-mixture with EGR stratifications is charged into Rapid Compression Machine. After that, the pre-mixture is compressed and in that process, in-cylinder gas pressure and temperature are analyzed. Additionally numerical calculation with multi-zones model is run to know the potential of EGR Stratifications for reducing Pressure Rise Rate.

--continued-- And concerning to both vehicles, simultaneously vehicle position by GPS, vehicle dynamics, engine dynamics, driver’s operation and road environment were measured. Adopting for transient mode regulation, Japanese JE05 mode, average NOx emission rates became lower by 57.4%, average distance based NOx emission became lower by 46%. And frequency of spot of distance based NOx emission was also lower. But concerning to Vehicle adopted for New Long Term Regulation, Hot-spots occupied 0.70% of route, this is high compared to 0.19% of Vehicle adopted for Long Term Regulation, so that 46% reduction of averaged distance based NOx emissions are not directly leads to 46% reduction of area of Hot-spots.

The purpose of the research is to investigate of diesel spray combustion for simultaneously reduce way NOx and PM．The pressure diesel injection were done into intermediates that are generated by very lean DME HCCI combustion using a RCM. The concentration of intermediate could not be directly measured; we estimated it by CHEMKIN calculation. DME HCCI characteristic is surveyed. Validations of the CHEMKIN calculation were confirmed pressure rise of an experiment and pressure rise of a calculation．Using a framing streak camera captured two dimensional spontaneous luminescence images from chemical species at low temperature reaction(LTR) and high temperature reaction (HTR). Also, the combustion events were observed by high-speed direct photography， the ignition and combustion were analyzed the combustion chamber pressure profiles

It is widespread knowledge that deliberately creating fuel inhomogeneities in HCCI combustion brings about a reduction in the maximum PRR. Investigating this phenomenon with an optical accessible engine, fueled with DME and equipped with Photomultiplier and Image Intensifier.

We measured emissions behavior using on-board measurement system of the engine and vehicle behavior target on-road driving truck. In particular, it deals with the parameters of the engine and vehicle behavior that affect roadside pollutions due to locally high concentrated NOx emissions. Then, it shows emission estimation models using the parameters as variables.

CNG/Diesel dual-fuel engine is using CNG as a main fuel, and injects diesel only a little as a ignition priming. In this study, remodeling a existing diesel engine into dual-fuel engine that can injects diesel with high pressure by CRDi(Common Rail Direct injection), and injecting CNG at intake port for premixing. The results show that CNG/Diesel dual-fuel engine satisfied coordinate torque and power with conventional diesel engine. And CNG alternation rate is over 89% in all operating range of CNG/diesel dual-fuel engine. PM emission is lower 94% than diesel engine, but NOx emission is higher than diesel engine.

The gas emission of diesel vehicle consists of mainly N2, CO2, H2O, and additionally, it consists of CO and THC, results in incomplete combustion of fuel, NOx (nitrogen oxide), it results in high temperature combustion in engine, and PM (particulate matter). Of those emissions, NOx accumulated by the roadside results in harmful influence to pedestrian and resident by the roadside. This roadside partial pollution of NOx consists of driver’s operation, engine dynamics, vehicle’s dynamics and road infrastructures. In this research, it was investigated the influence of driver, driver’s operation to the exhaust gas emission of diesel vehicle, and also it was compared between vehicle adopted for new long term regulation and vehicle adopted for long term regulation by on-board measurement system.

Cooled exhaust-gas recirculation (Cooled EGR) is known as the effective way to mitigate knock in HCCI engines, which helps to extend operating range to high-load limits. However, the misfire is caused easily in low-load limits with high CO. Fuel stratification is combined with EGR to compensate those problems. CO2 is used in order to simulate the effects of cooled EGR in numerical analysis. A combination of cooled EGR and fuel stratification shows extended operating ranges to high-load limits. However, high CO is produced in operating point due to the low combustion temperature with significantly low NOx.