Presentations

EGR realizes low temperature combustion and reduces heat loss, on the other hand, thermal efficiency decreases by　burning velocity deterioration under heavy EGR operation. T.Alger et al. in SwRI proposed ”Dedicated EGR”(d-EGR) that is running one or more cylinders rich and routing 100% of that cylinder’s exhaust directly into others, and it generates significant amount of CO and H2 that promote burning velocity. This research aims to improve thermal efficiency and inspect fuel ignitability by advancing ignition timing, and clarify the operable conditions of the natural gas SI engine using d-EGR.

This paper outlines single diesel injection model for model-based engine control system. For reducing calculation load, the model is discretized one cycle into six stages. In order to develop the single injection model to multiple-injection model, new ignition delay prediction model has been developed. The new model can express advanced ignition for pilot and pre injections. Applying new ignition delay model to single injection model, the improvement of the ignition delay prediction accuracy for advanced ignition has been confirmed.

PCCI engine is expected that can reduce PM and the NOx emissions. Furthermore, a new combustion concept that also reduces hydrocarbon emissions and the combustion noise by split fuel injection is reported. In this paper, we analyzed the influence that split fuel injection in the PCCI engine gave in combustion phase using elementary reaction numerical calculation. In addition, we tried the identification of the chemical species and elementary reactions which became the big factor to affect the heat release. The results show that the ignition timing become earlier so that there is much fuel which reacted during  low temperature oxidation reaction period.

HCCI (Homogeneous Charge Compression Ignition) engine has a problem that knocking occurs by the sharp pressure rising at the time of high IMEP driving. Knocking can be avoided by retarding combustion phasing. But when　the phase was delayed excessively, combustion become unstable.This study is researching the cycle-to-cycle IMEP variation by retarding CA50, using system of Rebreathing EGR and External EGR. Fluctuation of REGR gas temperature and mass is the factor of the IMEP variation. And the reintroduction period of EEGR gas have relation to the cyclical variation.

Steam reforming is an endothermic reaction and needs high-temperature heat source. SOFC can make direct internal reforming possible, since its operation temperature is very high as 973.15 to 1273.15K and it brings out steam reforming inside the fuel cell using exhaust heat. However the direct internal reforming has a problem that the carbon deposition occurs at the anode, and it causes lowering of operating voltage. In this study, we reproduce the microstructure of the SOFC anode theoretically, and find out the condition for the carbon deposition by reproducing steam reforming on the Ni surface using numerical calculation with elementary reactions.

HCCI engine has a problem that knocking rises at high load. It is necessary to scatter reaction time of the pre-air-fuel mixture every local site in the combustion chamber as this solution technique.As the technique, heterogeneous aeration of the fuel has been performed and a reduction effect of the pressure rate of climb at the time of the HCCI combustion has been inspected. LIF method has been performed for a measurement of the fuel levels distribution in this study and investigated fuel density distribution from intensity of fluorescence in the fuel homogeneous technique, fuel heterogeneity aeration technique and performed the comparison with the firing combustion process.

The supercharge downsizing of the engine become easy to raise a Low Speed Pre-Ignition at the time supercharge and high compression ratio. Therefore it jets the fuel which is in a liquid directly in a combustion chamber, and a technique to lower gas temperature by evaporation latent heat, and to prevent a Low Speed Pre-Ignition is important. Direct injection system makes heterogeneous air-fuel mixture This study show that investigation of the influence that the heterogeneous air-fuel mixture gives for auto-ignition and the relationship between heterogeneous air-fuel mixture and the Low Speed Pre-Ignition.

Homogeneous Charge Compression Ignition (HCCI) engine has attracted considerable interest as a new combustion concept for internal engines in recent years because of high efficiency and clean combustion. However its operation range is limited by the knocking at high load, which results from an excessive pressure rise rate(PRR). And, exhaust gas recirculation(EGR) is good method to achieve Low Temperature Combustion. The purpose of this study is to investigate the effects of EGR and CH2O addition under constant amount of fuel on PRR . To do so, numerical analysis combustion experiment with rapid compression machine(RCM) were done. The results show that EGR under constant amount of fuel on PRR had an effect on PRR because of increasing heat capacity, and CH2O addition under constant amount of fuel had not an effect on PRR but had an effect on combustion timing.

It was known that the engines with existing combustion systems had a lot of advantages like exhaust gas cleanness etc, when the DEM was applied as a fuel to the internal combustion engine. In this thesis. The new engine with HCCI combustion sytem whidh is the latest engine combustion method in the world, was developed. The potential as a fuel of DME with an excellent ignition combustion characteristic is inroduced.