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Experimental Investigation of Impinging Diesel Sprays for HCCI Combustion
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Engine research and development is to a large extent driven by the quest of lowering exhaust emissions and fuel consumption. The combination of low emissions and low fuel consumption is not the simultaneous characteristic of the world’s primary engine concepts, the diesel and the spark-ignited (SI) engine. However, such a concept do exist, it is commonly called Homogeneous Charge Compression Ignition (HCCI).

The HCCI combustion concept is when a premixed air and fuel mixture is ignited by the heat of compression. The operation is unthrottled, like the diesel engine, which is advantageous for its efficiency. The premixed air / fuel mixture preclude soot formation, like the SI engine. An exclusive feature of HCCI combustion is extremely low NOX production due to low-temperature combustion.

The mixture preparation of the typical gasoline HCCI engine is similar to the SI engine, via port-injection, which results in a well homogenized mixture. Port injection of diesel fuel is however very difficult since the environment is too cold for the fuel to vaporise. A better alternative is therefore direct-injection. However, injection must occur in a way where a homogeneous mixture is formed, while contact of the liquid fuel with cold walls is avoided.

There are many approaches to direct-injected mixture formation. This thesis focuses on exploring the concept of impinging sprays; its characteristics and its impact on combustion and emissions. The work comprises unique information regarding impinging sprays, as well as results regarding engine performance. It is concluded that impinging sprays are well suited for early direct-injection.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , viii, 70 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2006:17
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-4276OAI: oai:DiVA.org:kth-4276DiVA: diva2:11583
Public defence
2007-02-21, Sal F3, KTH, Lindstedtsvägen 26, Stockholm, 14:00
Opponent
Supervisors
Note
QC 20100824Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2010-08-24Bibliographically approved
List of papers
1. Fuel Sprays for Premixed Compression Ignited Combustion: Characteristics of Impinging Sprays
Open this publication in new window or tab >>Fuel Sprays for Premixed Compression Ignited Combustion: Characteristics of Impinging Sprays
2004 (English)In: SAE 2004 World Congress & Exhibition Technical Papers: Diesel Fuel Injection & Sprays (Part 3 & 4), 2004, Vol. 01-1776, 2004-01-1776- p.Conference paper, Published paper (Refereed)
Abstract [en]

For homogeneous charge compression ignition (HCCI) engines with direct-injected fuel (also called PCI, Pre-mixed Compression Ignition), it is important to achieve a lean and homogeneous mixture before ignition. For this purpose, impinging diesel sprays have proven to be useful. In this study, an evaluation of the overall air/fuel ratio of such sprays was made in a test rig. The test rig consists of a pressurized vessel with optical access and a Common Rail (CR) fuel injection system. The investigation was made for impinging spray nozzles with different impingement angles and orifice diameters. Three gas back pressures and three injection pressures were evaluated. The evaluation was based on images of the fuel sprays taken in the test rig. The fuel spray images were automatically processed using in-house developed software. The results of the investigation points out some important factors to obtain a lean spray, (a high air/fuel ratio). The investigation also points out some factors that give a low spray penetration for a certain injected mass of fuel.

National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-6773 (URN)10.4271/2004-01-1776 (DOI)
Conference
SAE 2004 World Congress & Exhibition, March 2004, Detroit, MI, USA, Session: Diesel Fuel Injection & Sprays
Note
QC 20100825Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2010-08-25Bibliographically approved
2. Segmentation Algorithm for Diesel Spray Image Analysis
Open this publication in new window or tab >>Segmentation Algorithm for Diesel Spray Image Analysis
2004 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 43, no 32, 5971-5980 p.Article in journal (Refereed) Published
Abstract [en]

An algorithm for segmentation of diesel spray images has been developed. Its most important feature is robustness against experimental setups that fail to guarantee images whose histograms show two distinct peaks. According to the approach presented, only the peak from the background is used, and it is assumed that the background peak is narrow enough not to include too much of the spray. The algorithm has proved successful for evaluation of images from a pressurized vessel as well as from an engine with optical access, with no need for adjusting the tuning parameters. By adjusting them, one may tune the noise sensitivity.

Keyword
Automated segmentation; Diesel spray images; Histograms; Tuning parameters; Algorithms; Diesel fuels; Image segmentation; Lighting; Nozzles; Pressure vessels; Spraying; Image analysis
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-6774 (URN)10.1364/AO.43.005971 (DOI)000225144000008 ()
Note
QC 20100825Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2017-12-14Bibliographically approved
3. Effect of Injection Pressure and Engine Speed on Air/Fuel Mixing and Emissions in a Pre-Mixed Compression Ignited (PCI) Engine using Diesel Fuel
Open this publication in new window or tab >>Effect of Injection Pressure and Engine Speed on Air/Fuel Mixing and Emissions in a Pre-Mixed Compression Ignited (PCI) Engine using Diesel Fuel
2004 (English)In: 2004 Powertrain & Fluid Systems Conference & Exhibition Technical Papers, 2004, Vol. 01-2989, 2004-01-2989- p.Conference paper, Published paper (Refereed)
Abstract [en]

PCI combustion of diesel fuel was accomplished in a direct-injected heavy-duty single-cylinder research engine. An impinging spray nozzle combined with a shallow bowl piston design offered a short air/fuel mixing time. Low HC and CO emissions were observed compared to fully premixed operation using n-heptane. A method for evaluating the air/fuel mixing process has been established by quantifying the in-cylinder air/fuel heterogeneity with the NOx emission. The results indicate that high injection pressure and engine speed are favorable for a fast mixing process. The injection pressure had a small impact on HC and CO emissions, while the engine speed had a larger impact. There were no correlation between air/fuel mixing time and HC and CO emissions.

National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-6775 (URN)10.4271/2004-01-2989 (DOI)2-s2.0-84877237526 (Scopus ID)
Conference
2004 Powertrain & Fluid Systems Conference & Exhibition, October 2004, Tampa, FL, USA, Session: Homogeneous Charge Compression Ignition (Part C&D)
Note
QC 20100825Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2010-08-25Bibliographically approved
4. Impinging Diesel Sprays
Open this publication in new window or tab >>Impinging Diesel Sprays
2008 (English)In: Atomization and sprays, ISSN 1044-5110, E-ISSN 1936-2684, Vol. 18, no 2, 97-127 p.Article in journal (Refereed) Published
Abstract [en]

Diesel fuel sprays from a common-rail injector have been optically investigated with respect to their macroscale characteristics. The tested nozzle designs were of standard plain orifice type, as well as the impinging-spray type, in which two orifices intersect at a specific angle at the exit. Testing was conducted using a pressurized vessel at room temperature. The impinging sprays were found to be low penetrating and widely dispersed compared to the nonimpinging sprays. The shape of the impinging sprays was as one homogeneous spray with no trace of individual sprays. It was found that impinging diesel sprays can be predicted in a manner similar to standard nonimpinging sprays, using a dimensionless penetration correlation. The cone angle of the impinging sprays increases with the impingement angle, and in contrast to nonimpinging sprays, appears insensitive to ambient density. The results indicate that the impinging spray has a larger spray volume at lower ambient densities. However, at higher ambient densities, the volume of the nonimpinging sprays is larger.

Keyword
Correlation methods; Fuel injection; Pressure vessels; Spraying; Impinging sprays; Room temperature; Diesel fuels; Correlation methods; Diesel fuels; Fuel injection; Pressure vessels; Spraying
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-6776 (URN)000248847200001 ()
Note
QC 20100825. Uppdaterad från Accepted till Published 20100825.Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2017-12-14Bibliographically approved
5. HCCI Combustion with Impinging Diesel Sprays
Open this publication in new window or tab >>HCCI Combustion with Impinging Diesel Sprays
(English)Article in journal (Other academic) Submitted
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-6777 (URN)
Note
QS 20120328Available from: 2007-02-14 Created: 2007-02-14 Last updated: 2012-03-28Bibliographically approved

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