Control of CAI Combustion Through Injection Timing in a GDI Engine With an Air- Assisted Injector

Leach, Ben; Zhao, Hua; Li, Y.; Ma, Tom

doi:10.4271/2005-01-0134

Cited by 18 publications

(15 citation statements)

References 9 publications

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“…An air-assisted injector with individual adjustable air and fuel quantities and timing was fitted in the center of the cylinder head provided by Orbital Engine Corporation Ltd. Detailed specifications of the engine are shown in Table 1 and previous papers [2,20].…”

Section: Enginementioning

confidence: 99%

“…However, developments to the process have continued in order to address the major drawbacks of CAI -the limited operating range and relatively high HC emission. Therefore, as a method of extending the operating regime, many investigations, including the current study, apply spark-assisted combustion and in-cylinder fuel injection strategies to control combustion phasing [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

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Combustion Characteristics of CAI Combustion with Alcohol Fuels

Tongroon

Zhao

2010

SAE Technical Paper Series

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Due to its potential for simultaneous improvement in fuel consumption and exhaust emissions, controlled autoignition (CAI) combustion has been subject to continuous research in the last several years. At the same time, there has been a lot of interest in the use of alternative fuels in order to reduce reliance on conventional fossil fuels. Therefore, this experimental study has been carried out to investigate the effect of alcohol fuels on the CAI combustion process and on the resulting engine performance.The experimental work was conducted on an optical single cylinder engine with an air-assisted injector. To achieve controlled autoignition, residual gas was trapped in the cylinder by using negative valve overlap and an intake air heater was used to ensure stable CAI combustion in the optical engine. Methanol, ethanol and blended fuels were tested and compared with the results of gasoline. The combustion processes were analysed through total chemiluminescence images captured with a high speed camera equipped with an intensifier. In addition, the effect of spark discharge was investigated.The images show that CAI combustion of alcohol fuels was characterized with fast and early autoignition combustion compared with pure gasoline. Chemiluminescence of the gasoline fuel was most visible and it decreased with increasing percentage of oxygenated fuels. During the re-compression stroke, chemiluminescence images of the gasoline engine indicated the presence of oxidation reactions. In the presence of spark discharge, the location of charge ignition was dominated by spark discharge at the center of cylinder while simultaneous autoignition sites were found around the periphery of the combustion chamber for nonspark-assisted ignition.

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Section: Enginementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Combustion Characteristics of CAI Combustion with Alcohol Fuels

Tongroon

Zhao

2010

SAE Technical Paper Series

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“…Subsequent studies on single and multi-cylinder direct injection gasoline engines [8][9][10] have also shown that the presence of spark discharge hardly affected CAI engine operation when the engine was operating well within the CAI operational range. However, as attempts were made to extend the low load limit of CAI combustion, the effect of spark discharge became noticeable and in some cases the presence of spark was crucial to get CAI combustion going.…”

Section: Effect Of Spark Ignition On Cai Combustion In the Four-strokmentioning

confidence: 94%

“…Therefore, it will be desirable and necessary to find other means capable of more independent control over the combustion phasing from the engine load, in order to improve the CAI combustion and its operational range. Research done at the author's laboratory [8][9][10] and others [11][12][13] has shown that direct fuel injection into the cylinder can be used as one of the most effective means of controlling the combustion phasing for optimised engine performance and emissions. This section will present some of the main findings from such studies.…”

Section: Effect Of Direct Injection On Cai Combustion In the Four-strmentioning

confidence: 99%

Four-stroke CAI engines with residual gas trapping

Zhao

2007

HCCI and CAI Engines for the Automotive Industry

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“…They visualized the formation of formaldehyde during NVO using planar laser-induced fluorescence, and argued that its persistence through to the main compression stroke affected combustion phasing [13]. Leach et al [14] also investigated injection timing variations in a direct-injection, retention-mode HCCI engine, but found increased pumping work due to vaporization of the pilot-injected liquid fuel which negatively affected the overall fuel economy.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of recompression reaction for low-load operation in direct-injection homogeneous charge compression ignition engines with n-heptane and i-octane fuels

Song

Padmanabhan

Kaahaaina

et al. 2009

International Journal of Engine Research

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Experiments have been reported in the literature in which the low-load limit of a retention-mode HCCI engine operating on gasoline has been significantly extended by preprocessing of the fuel during negative valve overlap. This paper presents experimental studies in which this low-load-limit extension is demonstrated and characterized using simple, singlecomponent hydrocarbon fuels with relatively well-known chemical kinetics. The model fuels were n-heptane and i-octane and this choice was made both because of the extensive work that has been undertaken to develop their chemical kinetic mechanisms and because these fuels span the range of ignitability that is likely to be of interest for HCCI engines.The experimental results reported here show that both fuels exhibit load extension to as low as 1 bar net indicated mean effective pressure when operated at high residual mass fractions, low equivalence ratios, and an appropriate choice of compression ratio (13 for n-heptane, 18 for i-octane). Near the low-load limit, combustion is stable, exhibits slightly advanced timing, has relatively low unburned hydrocarbon emissions, negligible (, 5 ppm) NO emissions, and slightly increased CO emissions (compared to higher load conditions). The indicated efficiency of low-load operation with recompression reaction is somewhat reduced, mainly due to increased heat transfer and decreased combustion efficiency.

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Control of CAI Combustion Through Injection Timing in a GDI Engine With an Air- Assisted Injector

Cited by 18 publications

References 9 publications

Combustion Characteristics of CAI Combustion with Alcohol Fuels

Combustion Characteristics of CAI Combustion with Alcohol Fuels

Four-stroke CAI engines with residual gas trapping

Experimental study of recompression reaction for low-load operation in direct-injection homogeneous charge compression ignition engines with n-heptane and i-octane fuels

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