Limitations of Sector Mesh Geometry and Initial Conditions to Model Flow and Mixture Formation in Direct-Injection Diesel Engines

2019 ◽  
Author(s):  
Federico Perini ◽  
Stephen Busch ◽  
Eric Kurtz ◽  
Alok Warey ◽  
Richard C. Peterson ◽  
...  
Keyword(s):  
Diesel Engines ◽  
Initial Conditions ◽  
Direct Injection ◽  
Mixture Formation ◽  
Model Flow

Effect of n-heptane and n-decane on exhaust odour in direct injection diesel engines

2005 ◽  
Vol 219 (4) ◽  
pp. 565-571 ◽  
Author(s):  
M M Roy
Keyword(s):  
Direct Effect ◽  
Diesel Fuel ◽  
Diesel Engines ◽  
Ignition Delay ◽  
Boiling Point ◽  
Alternative Fuels ◽  
Direct Injection ◽  
Cetane Number ◽  
Mixture Formation ◽  
Incomplete Combustion

This study investigated the effect of n-heptane and n-decane on exhaust odour in direct injection (DI) diesel engines. The prospect of these alternative fuels to reduce wall adherence and overleaning, major sources of incomplete combustion, as well as odorous emissions has been investigated. The n-heptane was tested as a low boiling point fuel that can improve evaporation as well as wall adherence. However, the odour is a little worse with n-heptane and blends than that of diesel fuel due to overleaning of the mixture. Also, formaldehyde (HCHO) and total hydrocarbon (THC) in the exhaust increase with increasing n-heptane content. The n-decane was tested as a fuel with a high cetane number that can improve ignition delay, which has a direct effect on wall adherence and overleaning. However, with n-decane and blends, the odour rating is about 0.5-1 point lower than for diesel fuel. Moreover, the aldehydes and THC are significantly reduced. This is due to less wall adherence and proper mixture formation.

Experimental Validation for Control-Oriented Modeling of Multi-Cylinder HCCI Diesel Engines

2006 ◽  
Author(s):  
Marcello Canova ◽  
Shawn Midlam-Mohler ◽  
Yann Guezennec ◽  
Giorgio Rizzoni ◽  
Luca Garzarella ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Diesel Engines ◽  
Soot Formation ◽  
Direct Injection ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Injection System ◽  
Compression Ignition ◽  
Mixture Formation ◽  
Hcci Combustion

Homogeneous Charge Compression Ignition (HCCI) is a combustion process based on a lean, homogeneous, premixed charge reacting and burning uniformly throughout the mixture volume. This principle leads to a consistent decrease in NOx and PM emissions, while the combustion efficiency remains comparable to traditional Compression Ignition Direct Injection (CIDI) engines at low and mid-load operations. However, understanding and controlling the combustion process is still extremely difficult, as well as finding a proper method for the fuel introduction. A viable method consists of premixing the charge by applying a proper fuel atomization device in the intake port, thus decoupling the HCCI mixture formation from the traditional in-cylinder injection. This avoids the traditional drawbacks associated to external Diesel mixture preparation, such as high intake heating, low compression ratio, wall wetting, and soot formation. The system, previously developed and tested on a single-cylinder engine, has been successfully applied to multi-cylinder Diesel engine for automotive applications. Building on previous modeling and experimental work, the paper reports a detailed experimental analysis of HCCI combustion with external mixture formation. In the considered testing setup, the fuel atomizer has been applied to a four-cylinder turbo-charged Common Rail Diesel engine equipped with a cooled EGR system. In order to extend the knowledge on the process and to provide a large base of data for the identification of Control-Oriented Models, Diesel-fueled HCCI combustion has been characterized over different values of loads, EGR dilution and boost pressures. The data collected were then used for the validation of a HCCI Diesel engine model that was previously built for steady state and transient simulation and for control purposes. The experimental results obtained, especially considering the emission levels and efficiency, suggest that the technology developed for external mixture formation is a feasible upgrade for automotive Diesel engines without introducing additional design efforts or constraints on the DI combustion and injection system.

Effect of altitude conditions on combustion and performance of a turbocharged direct-injection diesel engine

2021 ◽  
pp. 095440702110262
Author(s):  
Zhentao Liu ◽  
Jinlong Liu
Keyword(s):  
Diesel Engine ◽  
High Altitude ◽  
Diesel Engines ◽  
Direct Injection ◽  
Pressure Rise ◽  
Ambient Conditions ◽  
Allowable Limit ◽  
Spray Formation ◽  
Direct Injection Diesel Engine ◽  
And Performance

Market globalization necessitates the development of heavy duty diesel engines that can operate at altitudes up to 5000 m without significant performance deterioration. But the current scenario is that existing studies on high altitude effects are still not sufficient or detailed enough to take effective measures. This study applied a single cylinder direct injection diesel engine with simulated boosting pressure to investigate the performance degradation at high altitude, with the aim of adding more knowledge to the literature. Such a research engine was conducted at constant speed and injection strategy but different ambient conditions from sea level to 5000 m in altitude. The results indicated the effects of altitude on engine combustion and performance can be summarized as two aspects. First comes the extended ignition delay at high altitude, which would raise the rate of pressure rise to a point that can exceed the maximum allowable limit and therefore shorten the engine lifespan. The other disadvantage of high-altitude operation is the reduced excess air ratio and gas density inside cylinder. Worsened spray formation and mixture preparation, together with insufficient and late oxidation, would result in reduced engine efficiency, increased emissions, and power loss. The combustion and performance deteriorations were noticeable when the engine was operated above 4000 m in altitude. All these findings support the need for further fundamental investigations of in-cylinder activities of diesel engines working at plateau regions.

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