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A study of in-cylinder fuel spray formation and its influence on exhaust emissions using an optical diesel engine
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
2010 (English)In: SAE Technical Papers, 2010, no 01-1498Conference paper (Refereed)
Abstract [en]

Increasingly stringent emission legislation as well as increased demand on fuel efficiency calls for further research and development in the diesel engine field. Spray formation, evaporation and ignition delay are important factors that influence the combustion and emission formation processes in a diesel engine. Increased understanding of the mixture formation process is valuable in the development of low emission, high efficiency diesel engines. In this paper spray formation and ignition under real engine conditions have been studied in an optical engine capable of running close to full load for a real HD diesel engine. Powerful external lights were used to provide the required light intensity for high speed camera images in the combustion chamber prior to ignition. A specially developed software was used for spray edge detection and tracking. The software provides crank angle resolved spray penetration data. The images also provide data of ignition delay, ignition location and premixed flame propagation. The evaluation was made for an array of engine operation points with variations in fuel rail pressure, injection timing, boost pressure and charge air temperature. The influence of using pilot injections has also been investigated. This set of experiments makes it possible to analyze the impact of the various engine parameters on the spray formation and ignition processes. Some of the results are compared with the exhaust emission measurements in order to provide an insight into how the emission formation process is influenced by the spray formation and ignition processes.

Place, publisher, year, edition, pages
2010. no 01-1498
, SAE Technical Papers, ISSN 0148-7191
National Category
Mechanical Engineering
URN: urn:nbn:se:kth:diva-34254DOI: 10.4271/2010-01-1498ScopusID: 2-s2.0-84877187746OAI: diva2:419863
International Powertrains, Fuels and Lubricants Meeting; Rio De Janeiro; Brazil; 5 May 2010 through 5 May 2010

QC 20110530

Available from: 2011-05-30 Created: 2011-05-30 Last updated: 2014-08-19Bibliographically approved
In thesis
1. Methods for Characterization of the Diesel Combustion and Emission Formation Processes
Open this publication in new window or tab >>Methods for Characterization of the Diesel Combustion and Emission Formation Processes
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis various aspects of the diesel engine fuel injection, combustion and emission formation processes have been evaluated. Several types of evaluation tools and methods have been applied. Fuel spray momentum was used to characterize injection rate and hole-to-hole variations in fuel injectors. Using both instantaneous fuel impulse rates and instantaneous mass flow measurements, spray velocity and nozzle flow parameters were evaluated. Several other hole-to-hole resolved injector characterization methods were used to characterize a set of fuel injectors subjected to long term testing. Fuel injector nozzle hole-to-hole variations were found to have a large influence on engine efficiency and emissions. The degree of hole-to-hole variations for an injector has been shown to correlate well with the performance deterioration of that injector. The formation and atomization of fuel sprays, ignition onset and the development of diffusion flames were studied using an optical engine. Flame temperature evaluations have been made using two different methods. NO-formation depends strongly on flame temperature. By applying a NO-formation evaluation method based on both heat release rate and flame and gas temperature it was possible to achieve a reasonable degree of correlation with measured exhaust emissions for very varying operating conditions. The prediction capability of the NO-formation evaluation method was utilized to evaluate spatially and temporally resolved NO-formation from flame temperature distributions. This made it possible to pinpoint areas with a high degree of NO-formation. It was found that small hot zones in the flames can be responsible for a large part of the total amount of NO that is produced, especially in combustion cases where no EGR is used to lower the flame temperature. By applying optical diagnostics methods the combustion and emission formation phenomena encountered during production engine transients were evaluated. The transient strategy of the engine involved reducing the EGR-rate to zero during the initial parts of the transient. Increased general flame temperature and the occurrence of small hot zones were found to explain the increase in NO-emissions during these transients.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. 111 p.
Trita-MMK, ISSN 1400-1179 ; 2011:10
diesel engine emissions
National Category
Vehicle Engineering
Research subject
SRA - Energy
urn:nbn:se:kth:diva-34140 (URN)978-91-7501-037-3 (ISBN)
Public defence
2011-06-08, Sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
QC 20110530Available from: 2011-05-30 Created: 2011-05-26 Last updated: 2011-09-13Bibliographically approved

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Lindström, MikaelÅngström, Hans-Erik
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