Zero-Dimensional Heat Release Modeling Framework for Gasoline Compression-Ignition Engines with Multiple Injection Events

A compound diesel homogeneous charge compression ignition (HCCI) combustion system has been developed based on the combined combustion strategies of multiple injection strategy and a mixing enhanced combustion chamber design. In this work, a STAR-CD based, multidimensional modeling is conducted to understand and optimize the multiple injection processes. The parameters explored included injection timing, dwell time, and pulse width. Insight generated from this study provides guidelines on designing the multipulse injection rate pattern for optimization of fuel-air mixing. Various heat release modes created by different injection strategies are investigated by experimental comparison of combustion efficiency, heat loss, and thermal efficiency. It is demonstrated that the process of fuel evaporation and mixing are strongly influenced by pulse injection parameters. Through control of the parameters, the stratification and autoignition of the premixed mixture, and the heat release mode can be controlled. The dispersed mode of heat release created only by the compound diesel HCCI combustion is a flexible mode in combustion control. The thermal efficiency with this mode can reach approximately to as high as that of conventional diesel combustion, while the NOx and smoke emissions can be reduced simultaneously and remarkably.

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Combustion and Emissions of Biodiesel and Diesel Fuels in Direct Injection Compression Ignition Engines using Multiple Injection Strategies

10.4271/2008-01-1388 ◽

2008 ◽

Cited By ~ 15

Author(s):

Valerie L. Stringer ◽

Way Lee Cheng ◽

Chia-fon F. Lee ◽

Alan C. Hansen

Keyword(s):

Direct Injection ◽

Compression Ignition ◽

Multiple Injection ◽

Diesel Fuels ◽

Compression Ignition Engines ◽

Injection Strategies

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Using the Ideal Gas Law and Heat Release Models to Demonstrate Timing in Spark and Compression Ignition Engines

International Journal of Mechanical Engineering Education ◽

10.7227/ijmee.28.4.1 ◽

2000 ◽

Vol 28 (4) ◽

pp. 279-296 ◽

Cited By ~ 2

Author(s):

G. David Huffman

Keyword(s):

Heat Release ◽

Ideal Gas ◽

Compression Ignition ◽

Compression Ignition Engines ◽

Ideal Gas Law ◽

The Ideal

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Investigation of thermal stratification in premixed homogeneous charge compression ignition engines: A Large Eddy Simulation study

International Journal of Engine Research ◽

10.1177/1468087418795525 ◽

2018 ◽

Vol 20 (8-9) ◽

pp. 931-944

Author(s):

Aimilios Sofianopoulos ◽

Mozhgan Rahimi Boldaji ◽

Benjamin Lawler ◽

Sotirios Mamalis

Keyword(s):

Heat Release ◽

Thermal Stratification ◽

Homogeneous Charge Compression Ignition ◽

Working Fluid ◽

Compression Ignition ◽

Modeling Framework ◽

Cyclic Variability ◽

Large Eddy ◽

Hcci Engines ◽

Homogeneous Charge

The operating range of Homogeneous Charge Compression Ignition (HCCI) engines is limited to low and medium loads by high heat release rates. Negative valve overlap can be used to control ignition timing and heat release by diluting the mixture with residual gas and introducing thermal stratification. Cyclic variability in HCCI engines with NVO can result in reduced efficiency, unstable operation, and excessive pressure rise rates. Contrary to spark-ignition engines, where the sources of cyclic variability are well understood, there is a lack of understanding of the effects of turbulence on cyclic variability in HCCI engines and the dependence of cyclic variability on thermal stratification. A three-dimensional computational fluid dynamics (CFD) model of a 2.0L GM Ecotec engine cylinder, modified for HCCI combustion, was developed using Converge. Large Eddy Simulations (LES) were combined with detailed chemical kinetics for simulating the combustion process. Twenty consecutive cycles were simulated and the results were compared with individual cycle data of 300 consecutive experimental cycles. A verification approach based on the LES quality index indicated that this modeling framework can resolve more than 80% of the kinetic energy of the working fluid in the combustion chamber at the pre-ignition region. Lower cyclic variability was predicted by the LES model compared to the experiments. This difference is attributed to the resolution of the sub-grid velocity field, time averaging of the intake manifold pressure boundary conditions, and different variability in the equivalence ratio compared to the experimental data. Combustion phasing of each cycle was found to depend primarily on the bulk cylinder temperature, which agrees with established findings in the literature. Large cyclic variability of turbulent mixing and spatial distribution of temperature was predicted. However, both of these parameters were found to have a small effect on the cyclic variability of combustion phasing.

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Understanding partial fuel stratification for low temperature gasoline combustion using large eddy simulations

International Journal of Engine Research ◽

10.1177/1468087420921042 ◽

2020 ◽

pp. 146808742092104

Author(s):

Priya Priyadarshini ◽

Aimilios Sofianopoulos ◽

Sotirios Mamalis ◽

Benjamin Lawler ◽

Dario Lopez-Pintor ◽

...

Keyword(s):

Low Temperature ◽

Heat Release ◽

Direct Injection ◽

Large Eddy Simulations ◽

Compression Ignition ◽

Load Range ◽

Injection Strategy ◽

Compression Ignition Engines ◽

Fuel Stratification ◽

Large Eddy

The development of gasoline compression ignition engines operating in a low temperature combustion mode depends heavily on robust control of the heat release profile. Partial fuel stratification is an effective method for controlling the heat release by creating a stratified mixture prior to autoignition, which can be beneficial for operation across a wide load range. In this study, three-dimensional large eddy simulations were used to model a double direct injection strategy for which 80% of the fuel was injected during the intake stroke, and 20% of the fuel was injected at varying timing during the compression stroke. The simulations replicated a set of experiments performed at Sandia National Laboratories on a 1-L single-cylinder research engine using E10 gasoline (gasoline fuel containing 10% vol. ethanol). The objective of this study is to analyze the effects of the double direct injection strategy on the compositional and thermal stratification of the mixture, and understand the best use of this operating strategy. The modeling results indicated that by retarding the start of the second injection, the mixture stratification increases, which can be used to control the autoignition timing and the combustion phasing. Ignition and CA50 (crank angle of 50% mass fraction burned) are dictated by the mass concentration of the richest zones in the combustion chamber, as well as their location. The richer zones have the lowest temperatures before ignition primarily due to evaporative cooling from direct fuel injection. Overall, this study enhances the understanding of partial fuel stratification that can be used for controlling the heat release in gasoline compression ignition engines.

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