Study of Combustion and Emission Characteristics of Gasoline Engine with Miller Cycle

2014 ◽  
Vol 960-961 ◽  
pp. 1411-1415 ◽  
Author(s):  
Jian Wu ◽  
Wei Fan ◽  
Yang Hua ◽  
Yun Long Li ◽  
Shao Zhe Zhang ◽  
...  
Keyword(s):  
Heat Release ◽  
Compression Ratio ◽  
Gasoline Engine ◽  
Control Technology ◽  
Miller Cycle ◽  
High Compression Ratio ◽  
Combustion Heat ◽  
Geometry Compression ◽  
Cam Profile ◽  
Hc Emissions

On the basis of original engine, high compression ratio miller cycle can be realized, through perfecting the inlet cam profile, using higher geometry compression ratio, combining VVT control technology. The results indicate that the miller cycle achieved by VVT control technology can reduce pumping loss, and improve the effect utilization of energy. The combustion heat release rate is lower than the original engine, and combustion heat release are mainly concentrated on TDC later, lower the burning temperature. Compared with the original engine, NOX emissions decrease significantly, but CO and HC emissions increase somewhat.

scholarly journals Nissan gasoline engine strategy for higher thermal efficiency

2017 ◽  
Vol 169 (2) ◽  
pp. 141-145 ◽  
Author(s):  
Hideaki MIZUNO
Keyword(s):  
Heat Capacity ◽  
Energy Loss ◽  
Compression Ratio ◽  
Thermal Efficiency ◽  
Gasoline Engine ◽  
Loss Reduction ◽  
Miller Cycle ◽  
High Compression Ratio ◽  
Gasoline Engines ◽  
Evolution Trend

Rising highly concern about the environment has led to demands for the improvement of the efficiency of gasoline engines. Engine thermal efficiency will reach about 40% by technologies as boosted EGR, miller cycle and so on. This evolution trend will be continuously required to survive engines for the future. In this background, further improvement based on theoretical thermal efficiency of high compression ratio and specific heat capacity should be promoted. In addition, energy loss reduction such as represented by cooling loss and friction is also very important for the efficient and effective improvement. NISSAN’s challenges will be introduced to solve these propositions.

Controlled ASSCI With Moderate Auto-Ignition for Engine Knock Suppression in a GDI Engine With High Compression Ratio

2014 ◽  
Author(s):  
Hui Liu ◽  
Zhi Wang ◽  
Jianxin Wang ◽  
Mengke Wang ◽  
Wanli Yang
Keyword(s):  
Heat Release ◽  
Compression Ratio ◽  
High Compression Ratio ◽  
Two Stage ◽  
Second Stage ◽  
High Compression ◽  
Auto Ignition ◽  
Crank Angle ◽  
Engine Knock ◽  
Gdi Engine

This paper presents an experimental study on controlled ASSCI (Assisted Spark Stratified Compression Ignition) for engine knock suppression in a GDI engine with high compression ratio. The direct injection is used for forming desired stoichiometric stratified mixture at WOT condition without turbo-charging. The engine is filled with 20% cooled external EGR and the ignition timing is maintained at MBT point. The combustion characteristics of the desired stoichiometric stratified mixture show two-stage heat release, where the first stage is caused by spark ignition and the second stage is due to moderate auto-ignition. Compared with engine knock, the second stage heat release of controlled ASSCI shows smooth pressure curve without pressure oscillation. This is due to the low energy density mixture around the cylinder wall caused by cooled external EGR. The stratified mixture could suppress knock. Fuel economy and combustion characteristics of the baseline and the controlled ASSCI combustion were compared. The baseline GDI engine reaches a maximum of 8.9 bar BMEP with BSFC of 291 g/(kWh), the controlled ASSCI combustion achieves a maximum of 8.3 bar BMEP with BSFC of 256 g/(kWh), improving the fuel economy over 12% while maintaining approximately the same power. CA50 (the crank angle of 50% heat release) of the controlled ASSCI is detected at 8.4° CA ATDC, which is 17.4° CA advanced than that of the baseline while the combustion duration of the controlled ASSCI is 52.84dG CA, 16.6° CA longer than that of the baseline caused by diluted mixture and two-stage heat release. The COV of the controlled ASSCI is 1.4%, 2.1% lower than that of the baseline. The peak pressure (Pmax) and the maximum pressure rise rate (PRRmax) of the controlled ASSCI are 59.7 bar and 2.2 bar/° CA, 22.9 bar and 1.5 bar/° CA higher than that of the baseline respectively. The crank angle of Pmax and PRRmax of the controlled ASSCI are 11° CA ATDC and −1° CA ATDC, 15.4° CA and 17.2° CA earlier than that of the baseline. The results show that controlled ASSCI with two-stage heat releases is a potential combustion strategy to suppress engine knock while achieving high efficiency of the high compression ratio gasoline engine.

Effects of Different LPG Fuel Systems on Performances of Variable Compression Ratio Single Cylinder Engine

2002 ◽  
Author(s):  
G. H. Choi ◽  
J. H. Kim ◽  
Christian Homeyer
Keyword(s):  
Liquid Phase ◽  
Heat Release ◽  
Compression Ratio ◽  
Power Output ◽  
Alternative Fuels ◽  
Gasoline Engine ◽  
Cylinder Pressure ◽  
Maximum Heat ◽  
Spark Timing ◽  
Test Engine

Since the early 20th century, most ground vehicles are driven with gasoline and diesel. The degradation of the environment affects human on earth unless the quality of the air is improved. One of the alternative fuels, LPG, is potentially capable of lowering vehicular emissions when compared to gasoline or diesel. There is a penalty in power output resulting from the use of LPG because the engine can induce less amount of air with Mixer system comparing with gasoline engine. Currently, the liquid-phase LPG is injected into the intake port of the engine, the fuel vaporizes enroute to the combustion chamber. Therefore, the performance and combustion processes of the tested engine are investigated with different LPG fuel systems. The test engine was developed and named heavy-duty VACRE. The test engine for this work operates 1400rpm with MBT conditions. The major conclusions of the work include; 1) The power output of LPi system with liquid-phase is approximately 17% higher than that of vapor-phase Mixer system due to increases of volumetric efficiency. And the MBT spark timing of LPi system is approximately 25% more advanced than that of Mixer system at λ value 1.0; 2) The LPi system shows both the maximum heat release rate and the cumulative heat release to be approximately 20% higher than the Mixer system; 3) Maximum cylinder pressure decrease with increase of compression ratio and a point of maximum cylinder pressure is delayed with high compression ratio.

209 Effects of combustion systems and various hydrocarbons on performance of high compression ratio gasoline engine

2012 ◽  
Vol 2012.51 (0) ◽  
pp. 55-56
Author(s):  
Takahiro KAWADA ◽  
Shingo OKAYA ◽  
Jin KUSAKA ◽  
Takashi YOUSO ◽  
Masahisa YAMAKAWA ◽  
...  
Keyword(s):  
Compression Ratio ◽  
Gasoline Engine ◽  
High Compression Ratio ◽  
High Compression ◽  
Combustion Systems
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