NOx Reduction Strategy using Direct Water Injection in a Diesel Engine (First Report)
-Proposal of an In-Cylinder Water Stratification Concept at a Medium-Low Load-

Kazuhisa Inagaki (Toyota Central R&D Labs.)･Tsutomu Kawae (Toyota Industries)･Teruaki Kondo･Kazuaki Nishikawa (Toyota Central R&D Labs.)･Yo Usui (Toyota Industries)

We propose a concept of stratifying water within the combustion chamber to significantly reduce NOx emissions, and we have validated the performance with an actual prototype. The results are as follows:Through Computational Fluid Dynamics (CFD), we found that stratifying water along the fuel injection axis in the upper part of the cavity is more effective in reducing NOx emissions compared to homogeneity.The stratification of water distribution within the chamber not only reduces NOx but also decreases soot. When the mass ratio of water to fuel is 50%, under conditions of equal soot, NOx decreased to 1/4 compared to the case without water injection.

Study of Improving Indicated Thermal Efficiency with Higher Supercharging and Optimized Supercharging System on Heavy Duty Diesel Engine

Hiroaki Saito･Munemasa Hashimoto･Yoshinori Ishii (Isuzu Advanced Engineering Center)

In order to achieve high thermal efficiency in heavy duty diesel engines, high supercharging is an important method. In this study, combustion and heat balance analysis were carried out under different excess air ratio (lambda) condition using single cylinder testing engine, which is provided two-stage superchargers and can be controlled supercharging and exhaust pressure independently. This paper reports the lambda conditions and realizing constitution in actual engines which can achieve maximum indicated thermal efficiency, and the disadvantage of excessive high lambda operation.

Development and Application of Piston Temperature Estimation Method for a Diesel Engine

Takuro Mita (Isuzu Advanced Engineering Center)･Yorimasa Tsubota (Isuzu Motors)

A method to estimate the temperature of a piston made of aluminum alloy for diesel engines was developed. This method is simple and has a low computational cost, and accurately estimate the piston temperature during transient operations. Using this estimation method, it was possible to understand the stress that the piston and reduce fuel consumption when combined with oil path circuit control.

Development of High-Response Heat Insulation Material Technology in Engine Combustion Chamber to Improve the Fuel Economy (3rd Report)
-Development of Paint Model of Heat Insulation Coating and Confirmation of the Heat Insulation Effect of a Diesel Engine-

Masaya Minato･Ken Sakamoto･Yoshitaka Wada･Shinji Kadoshima･Yuki Nakanishi･Tsutomu Shigenaga･Takuya Noda･Kiyotomo Igawa･Kengo Nakashima･Sangkyu Kim (Mazda)

To decrease cooling loss of engines and improve fuel economy, we are developing heat insulation material technology. In order to uniformly and efficiently apply the heat-insulation coating to pistons with a complex shape, we constructed paint model that can visualize the spraying and coating conditions and accurately predict the required characteristics such as coating thickness.We report about this model and the heat insulation effect of the actual engine.

Combustion Process Analysis of Hydrogen/Diesel Dual-Fuel Engine by Numerical Simulation

Takafumi Kamino･Kenji Hiraoka･Takafumi Tentora･Gin Morita (Yanmar Holdings)

Hydrogen is mentioned as a power source toward carbon newtrality. In order to improve performance of hydrogen engines, it is necessary to clarify the combustion forms. In this study, 3D-CFD calculation and the combustion process analysis were carried out based on experimental results of pilot ignition hydrogen engine.

Combustion Analysis of the Hydrogen/Diesel Dual Fuel Engine with the Single Cylinder Engine Testing

Gin Morita･Takafumi Tentora･Kenji Hiraoka･Takafumi Kamino･Toru Takemoto (Yanmar Holdings)

Combustion characteristics of a diesel fuel ignited hydrogen engine were investigated with the single cylinder engine testing.
In the case of the homogeneous distribution of hydrogen, combustion parameters such as hydrogen-diesel fuel energy ratio, excess air ratio, and so on were changed and the effects of these parameters on the combustion were revealed.
Additionally, with the CFD calculation, the characteristics of the pilot diesel ignited hydrogen combustion were analyzed, and the results were reported in this paper.

A Study on the Optimization of Low-Temperature Low Pressure Circuit (LPC) Performance of Diesel Vehicles

Keun Soo Kim･Jung Hoon Park･Cheol Lee･Seung Yub Lee (Hyundai Motor)

The cooling and lubrication of the high-pressure pump in the diesel system is carried out by the fuel, so it is necessary to satisfy the required fuel flow of the high-pressure pump. In addition, the high pressure pump inlet pressure formation is important to prevent the generation of the high pressure pump internal cavitation, and the return pressure of the engine affects the operation of the injector, so the return pressure requirement is also very important. The performance of the heater in the fuel filter is an important for LPC performance development, as diesel fuel has the characteristics of reduced liquidity due to paraffin generation at low temperature, which may prevent the fuel filter from forming enough pressure.
This study aims to analyze the influence of each factor through vehicle testing on factors to be considered in developing cold LPC performance on diesel vehicles.