1117 Investigation on Limit of HCCI Combustion by Fuel Ignitability and Heterogeneous Mixture Formation

Homogeneous charge compression ignition (HCCI) is a promising concept for internal combustion engines that can considerably decrease NOx and soot emissions in part-load operations without penalizing fuel consumption. The HCCI combustion can be implemented in direct injection diesel engines without major modifications by introducing a specialized fuel injector in the intake port. This decouples the homogeneous mixture formation from the traditional in-cylinder injection, thus providing two fueling systems that can be used to optimize exhaust emissions and fuel consumption over the engine operating range. However, understanding and controlling the complex mechanisms and interactions driving the HCCI combustion process is still a difficult task. For this reason, it is essential to identify the most important control parameters and understand their influence on the auto-ignition process. The current work analyzes HCCI combustion with external mixture formation through experimental investigation and the definition of a control-oriented model. An extensive testing activity was performed on a passenger car diesel engine equipped with an external fuel atomizer to operate in HCCI mode. This provided an understanding of the process as well as experimental data to identify a mean value model of the system and its parameters. The model includes a thermodynamic combustion calculation that estimates the heat release, cylinder pressure, and the relevant variables for combustion control. The tool developed was then validated and used for analyzing the system behavior in steady state conditions. Finally, a description of the HCCI system behavior in transient operations is presented.

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Homogeneous Charge Compression Ignition (HCCI) Combustion of Diesel Fuel with External Mixture Formation

10.4271/2009-01-0924 ◽

2009 ◽

Cited By ~ 6

Author(s):

D. Ganesh ◽

G. Nagarajan

Keyword(s):

Diesel Fuel ◽

Homogeneous Charge Compression Ignition ◽

Compression Ignition ◽

Mixture Formation ◽

Hcci Combustion ◽

Homogeneous Charge

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A Control-Oriented Mean-Value Model of HCCI Diesel Engines With External Mixture Formation

Dynamic Systems and Control, Parts A and B ◽

10.1115/imece2005-79571 ◽

2005 ◽

Cited By ~ 10

Author(s):

Marcello Canova ◽

Luca Garzarella ◽

Marco Ghisolfi ◽

Shawn Midlam-Mohler ◽

Yann Guezennec ◽

...

Keyword(s):

Diesel Engines ◽

Combustion Process ◽

Mean Value ◽

Ignition Process ◽

Fuel Injector ◽

Mixture Formation ◽

Calculation Algorithm ◽

Hcci Combustion ◽

Mean Value Model ◽

Value Model

Homogeneous Charge Compression Ignition (HCCI) is considered a promising concepts to achieve low NOx and Particulate Matter emissions in traditional Spark Ignition and Diesel engines. However, understanding and controlling the complex mechanisms which govern the combustion process is still extremely difficult. A viable method to obtain HCCI combustion in DI Diesel engines consists of premixing the charge by applying an additional fuel injector in the intake port, thus decoupling the HCCI mixture formation from the traditional in-cylinder injection. The system allows high load operation in DI mode without compromising performance, low to mid-load operation in HCCI mode, and a region in between where both systems operate together. To manage HCCI combustion with external mixture formation it is essential to identify the most important control parameters and understand their influence on the auto-ignition process. The proposed paper deals with the analysis of HCCI combustion with external mixture formation through experimental investigation and a Control-Oriented mean-value model. The model provides the data required by a combustion calculation algorithm to perform a first-law analysis that estimates the in-cylinder heat release and pressure. The tool developed was then validated on data provided by an extensive experimental activity on a 4-cylinder Diesel engine equipped with an external fuel atomizer to operate in HCCI mode.

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

Dynamic Systems and Control, Parts A and B ◽

10.1115/imece2006-14110 ◽

2006 ◽

Cited By ~ 4

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.

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A Computational Study of HCCI Engine With External Mixture Formation Technique

Volume 8A: Heat Transfer and Thermal Engineering ◽

10.1115/imece2014-37211 ◽

2014 ◽

Author(s):

T. Karthikeya Sharma ◽

G. Amba Prasad Rao ◽

Madhu Murthy Kotha

Keyword(s):

Computational Study ◽

Nox Emissions ◽

Mixture Formation ◽

Gasoline Engines ◽

Hcci Engine ◽

Velocity Magnitude ◽

Hcci Combustion ◽

Numerical Studies ◽

Diesel Injection ◽

Formation Technique

HCCI combustion is gaining increased attention amongst the research community to make it viable in both diesel and gasoline engines. Of late, technique of External mixture formation is being adopted to avoid the problems associated with the early injection and late injections of the direct injected diesel HCCI engine. This paper reports the numerical studies on the effect of External mixture formation using three-zone extended coherent flame (ECFM-3Z) CFD model of the STAR - CD package. Firstly, the results obtained through package were validated with the results available in the literature. Trade-off between HC, CO and NOx was clearly observed through simulation. The simulation results revealed decrease in in-cylinder pressures and NOx emissions with increase in EGR concentration. There is an under prediction of NOx emissions when compared with the experimental results. However, a significant reduction in NOx emissions was observed with external mixture formation, usage compared to direct diesel injection. In case of HC and CO emissions increasing trend was observed with increase in EGR concentration. Increase in HC and CO emissions was observed with external mixture formation when compared with a direct diesel injection. Also, reduction in turbulent kinetic energy and velocity magnitude levels were observed with increase in EGR concentration. Improved piston work is resulted at lower EGR concentrations. Studies revealed that for a given combustion bowl geometry, It is concluded that external mixture formation technique could be adopted to achieve HCCI combustion.

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Improvements in Efficiency and Mixture Formation for an Innovative Diesel HCCI Concept

ASME 2009 Internal Combustion Engine Division Fall Technical Conference ◽

10.1115/icef2009-14046 ◽

2009 ◽

Cited By ~ 4

Author(s):

E. Musu ◽

R. Rossi ◽

R. Gentili

Keyword(s):

Combustion Process ◽

Pressure Rise ◽

Pollutant Emissions ◽

Spontaneous Ignition ◽

Exhaust Gas ◽

Mixture Formation ◽

Hcci Combustion ◽

Gas Recirculation ◽

Transfer Flow ◽

Homogeneous Charge

Homogeneous-charge, compression-ignition (HCCI) combustion is triggered by spontaneous ignition in dilute homogeneous mixtures. The combustion rate must be reduced by suitable solutions such as high rates of Exhaust Gas Recirculation (EGR) and/or lean mixtures. HCCI is considered to be a very effective way to reduce engine pollutant emissions, however only a few production engines have been built. HCCI combustion currently cannot be extended to the whole engine operating range, especially to high loads, since the use of EGR displaces air from the cylinder, limiting engine mean effective pressure, thus the engine must be able to operate also in conventional mode. This paper concerns a study of an innovative concept to control HCCI combustion in diesel-fueled engines. The concept consists in forming a pre-compressed homogeneous charge outside the cylinder and in gradually admitting it into the cylinder during the combustion process. In this way, combustion can be controlled by the transfer flow rate, and high pressure rise rates, typical of standard HCCI combustion, can be avoided. This new combustion concept has been called Homogenous Charge Progressive Combustion (HCPC). This paper concerns CFD analysis focused on improving efficiency and reducing pollutant emissions considering a new HCPC engine configuration. Results show an indicated efficiency around 45% and a consistent reduction of soot emission compared to conventional diesel engine.

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