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A Study of Hole Properties in Diesel Fuel Injection Nozzles and its Influence on Smoke Emissions
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.), Machine Design (Div.).
2008 (English)In: Proceedings Conference on Thermo- and Fluid Dynamic Processes in Diesel Engines, 2008Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
2008.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-25553ISBN: 978-84-8363-313-7 (print)OAI: oai:DiVA.org:kth-25553DiVA: diva2:359214
Conference
Thiesel 2008 Conference on Thermo- and Dynamic Processes in Diesel Engines,Conferences & symposia, Valencia, Spain
Note
QC 20101027Available from: 2010-10-27 Created: 2010-10-27 Last updated: 2011-05-30Bibliographically approved
In thesis
1. Injector Nozzle Hole Parameters and their Influence on Real DI Diesel Performance
Open this publication in new window or tab >>Injector Nozzle Hole Parameters and their Influence on Real DI Diesel Performance
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

A modern diesel engine is capable of running efficiently with low exhaust gas emissions over a wide operating range. This is thanks to techniques such as turbocharging, EGR, charge air cooling and an advanced fuel injection process. The fuel injection process is important for the combustion and emission formation in the diesel engine. The fuel injector has to atomize and vaporize the fuel as it is injected. During the combustion the emission formation has to be kept to a minimum. Very strong pressure gradients are present in a modern diesel injection nozzle, this causes cavitation to occur in the nozzle holes. The influence of cavitation on flow parameters such as the various discharge coefficients is discussed. The occurrence of cavitation helps the spray break up and it can keep the nozzle holes free from deposits. Excessive amounts of cavitation can lead to hole erosion and thus impact the long term operation of the nozzle in a negative way. Hole erosion as well as other mechanisms can cause hole to hole variations in fuel spray impulse, mass flow, penetration etc. This is a very important issue in any low emission diesel engine, especially during transients, as less than optimal conditions have to be handled. The influence of hole to hole variation on fuel consumption and emissions is not very well known and this thesis contributes to the field. As a part of this work a fuel spray momentum measurement device was developed and tested. Any automotive engine needs to be able to perform quick transitions between different loads and speeds, so called transients. In a turbocharged diesel engine with EGR issues related to the turbocharger and the EGR-circuit arise. A diesel engine has to run with a certain air excess in order to achieve complete combustion with low emissions of soot. When turbocharging is used the turbocharger turbine uses some of the exhaust enthalpy to drive the turbo compressor, in this way the engine is provided with boost pressure. In order for the engine and turbocharger to function at the higher load and thus higher mass flow rate the turbocharger has to increase its rotational speed and the surface temperatures have to settle at a new thermodynamic state. Both of these processes take time and during this time the combustion process may have to proceed under less than optimum circumstances due to the low boost pressure.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 48 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2009:01
Identifiers
urn:nbn:se:kth:diva-9929 (URN)
Presentation
2009-01-26, Rum M36, KTH, Brinellvägen 64, Stockholm, 14:00 (English)
Opponent
Supervisors
Available from: 2009-02-09 Created: 2009-02-09 Last updated: 2010-10-27Bibliographically approved
2. 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.
Series
Trita-MMK, ISSN 1400-1179 ; 2011:10
Keyword
diesel engine emissions
National Category
Vehicle Engineering
Research subject
SRA - Energy
Identifiers
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)
Opponent
Supervisors
Funder
StandUp
Note
QC 20110530Available from: 2011-05-30 Created: 2011-05-26 Last updated: 2011-09-13Bibliographically approved

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