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A method of defining the auto-ignition quality of gasoline-like fuels in HCCI engines
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).ORCID iD: 0000-0002-4243-7134
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Place, publisher, year, edition, pages
Stockholm: KTH , 2005. , 74 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2005:10
Keyword [en]
Engineering design, auto-ignition quality, HCCI, CAI and fuels
Keyword [sv]
Konstruktionsteknik
National Category
Reliability and Maintenance
Identifiers
URN: urn:nbn:se:kth:diva-343OAI: oai:DiVA.org:kth-343DiVA: diva2:9228
Presentation
2005-04-29, M3, Brinellv 64, Stockholm, 10:00
Supervisors
Note
QC 20101220Available from: 2005-08-01 Created: 2005-08-01 Last updated: 2010-12-20Bibliographically approved
List of papers
1. A Method of Defining Ignition Quality of Fuels in HCCI Engines
Open this publication in new window or tab >>A Method of Defining Ignition Quality of Fuels in HCCI Engines
2003 (English)Conference paper, Published paper (Refereed)
Abstract [en]

A homogeneous charge compression ignition (HCCI) engine has been run at different operating conditions with fuels of different RON and MON and different chemistries. The ignition quality of the fuel at a given operating condition is characterized by CA50, the crank angle at which the cumulative heat released reaches 50% of the maximum value for the cycle. It is found that CA50 might show no correlation with either RON or MON but correlates very well with the Octane Index, OI defined as OI = (1-K)RON + KMON = RON - KS, where K is a constant depending on the engine operating condition and S is the fuel sensitivity, (RON - MON). The higher the OI, the more the resistance to autoignition and the later is the heat release in the HCCI engine at a given condition. When the engine is run with a boost pressure of 1 bar and with the intake air temperature maintained at 40° C, K is highly negative and fuels of low MON, such as those containing aromatics, olefins or ethanol, have a higher OI and ignite later than paraffinic fuels of comparable RON. When the engine is run with no intake boost and the intake air is heated to 120° C, the value of K becomes slightly greater than zero so that the autoignition quality of the fuel is determined mostly by its RON. Thus K decreases as the engine is run relatively cooler and at higher pressures and MON contributes less to the measure of resistance to autoignition. This trend is in line with earlier studies of autoignition in knocking engines.

National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-5657 (URN)10.4271/2003-01-1816 (DOI)
Conference
Presented at the SAE Fuels & Lubricants Meeting, held May 19-22, 2003, in Yokohama, Japan, SAE 2003-01-1816
Note
QC 20100917 Available from: 2006-05-08 Created: 2006-05-08 Last updated: 2010-12-20Bibliographically approved
2. Auto-ignition quality of gasoline-like fuels in HCCI engines
Open this publication in new window or tab >>Auto-ignition quality of gasoline-like fuels in HCCI engines
2003 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The auto-ignition quality of a fuel of any chemistry at a given engine condition is described by an octane index defined as, OI = (1-K) RON + K MON, where RON and MON are the Research and Motor Octane numbers respectively and K depends only on the engine design and operating conditions. The higher the OI value, the greater is the resistance to auto-ignition. A single cylinder homogeneous charge compression ignition (HCCI) engine has been run at thirty seven different operating conditions using fuels of different chemistries and different known RON and MON values. At each operating condition CA50, the crank angle for 50% of the total heat release, is established for different fuels and from this the value of K is determined. We take T comp15 , the temperature when the pressure reaches 15 bar during the compression stroke, as a generic engine parameter. K is strongly dependent on and increases with T comp15 and is less strongly dependent on the mixture strength. Surprisingly, there was no significant effect of engine speed on K. A predictive equation for K as a function of T comp15 and the normalized air/fuel ratio, λ is found. At each operating condition there is an ideal fuel with OI = OI 0 such that heat release occurs at top dead center (TDC). OI 0 increases with increasing P maxcomp and T maxcomp the compression pressure and temperature at TDC, and decreases with increasing λ and engine speed. An empirical equation relating OI 0 to these generic engine parameters is found. These predictive equations could also be used to explore control strategies for an HCCI engine running on a fuel of known RON and MON.

National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-5658 (URN)10.4271/2003-01-3215 (DOI)
Conference
Presented at the SAE Powertrain & Fluid Systems Conference & Exhibition,held October 2003, in Pittsburgh, PA, USA. SAE 2003-01-3215
Note
QC 20100917Available from: 2006-05-08 Created: 2006-05-08 Last updated: 2010-12-20Bibliographically approved
3. The influence of EGR on auto-ignition quality of gasoline-like fuels in HCCI engines
Open this publication in new window or tab >>The influence of EGR on auto-ignition quality of gasoline-like fuels in HCCI engines
2004 (English)In: SP-1896, 2004Conference paper, Published paper (Refereed)
Abstract [en]

In previous studies it has been shown that the auto-ignition quality of a fuel at a given engine condition can be described by an octane index defined as, OI=(1-K) RON + K MON, where RON and MON characterize the fuel and the K-value depends only on the engine design and operating conditions. It has been shown that the K-value is highly dependent on the pressure and temperature history. Another important parameter is OI 0 , the OI of the fuel which gives heat release centred at top dead center; OI 0 can be considered to be the requirement of the engine. In previous work, empirical relations for both K and OI 0 in terms of in-cylinder pressure and temperature and engine speed and mixture strength were found but the influence of EGR was not considered. Therefore experiments have been done in a single cylinder engine, working in HCCI mode, at different operating conditions including various internal and external EGR rates, using fuels of different chemistries and different known RON and MON values.

National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-5659 (URN)10.4271/2004-01-2952 (DOI)
Conference
Presented at SAE Powertrain & Fluid Systems Conference & Exhibition, heldOctober 2004, in Tampa, FL, USA. SAE 2004-01-2952, SAE Transactions
Note
QC 20100917Available from: 2006-05-08 Created: 2006-05-08 Last updated: 2010-12-20Bibliographically approved
4. Cooxidation in the auto-ignition of primary reference fuels and n-heptane/toluene blends
Open this publication in new window or tab >>Cooxidation in the auto-ignition of primary reference fuels and n-heptane/toluene blends
Show others...
2005 (English)In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 140, no 4, 267-286 p.Article in journal (Refereed) Published
Abstract [en]

Auto-ignition of fuel mixtures was investigated both theoretically and experimentally to gain further understanding of the fuel chemistry. A homogeneous charge compression ignition (HCCI) engine was run under different operating conditions with fuels of different RON and MON and different chemistries. Fuels considered were primary reference fuels and toluene/n-heptane blends. The experiments were modeled with a single-zone adiabatic model together with detailed chemical kinetic models. In the model validation, co-oxidation reactions between the individual fuel components were found to be important in order to predict HCCI experiments, shock-tube ignition delay time data, and ignition delay times in rapid compression machines. The kinetic models with added co-oxidation reactions further predicted that an n-heptane/toluene fuel with the same RON as the corresponding primary reference fuel had higher resistance to auto-ignition in HCCI combustion for lower intake temperatures and higher intake pressures. However, for higher intake temperatures and lower intake pressures the n-heptane/toluene fuel and the PRF fuel had similar combustion phasing.

Keyword
HCCI, homogeneous charge compression ignition, auto-ignition, fuel chemistry, primary reference fuels, n-heptane, toluene, co-oxidation, CHEMKIN
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-7570 (URN)10.1016/j.combustflame.2004.11.009 (DOI)000227865300003 ()2-s2.0-14744268733 (Scopus ID)
Note
QC 20101109Available from: 2007-11-06 Created: 2007-11-06 Last updated: 2010-12-20Bibliographically approved

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Citation style
  • apa
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