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    A fundamental investigation into the relationship between lubricant composition and fuel ignition quality

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    Type
    Article
    Authors
    Kuti, Olawole Abiola
    Yang, Seung Yeon
    Hourani, Nadim
    Naser, Nimal
    Roberts, William L.
    Chung, Suk Ho
    Sarathy, S. Mani
    KAUST Department
    Chemical Engineering Program
    Clean Combustion Research Center
    Combustion and Laser Diagnostics Laboratory
    Combustion and Pyrolysis Chemistry (CPC) Group
    Mechanical Engineering Program
    Physical Science and Engineering (PSE) Division
    high-pressure combustion (HPC) Research Group
    Date
    2015-11
    Permanent link to this record
    http://hdl.handle.net/10754/594070
    
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    Abstract
    A fundamental experiment involving the use of an ignition quality tester (IQT) was carried out to elucidate the effects of lubricant oil composition which could lead to low speed pre-ignition (LSPI) processes in direct injection spark ignition (DISI) engines. Prior to the IQT tests, lubricant base oils were analyzed using ultra-high resolution mass spectrometry to reveal their molecular composition. High molecular-weight hydrocarbons such as nC<inf>16</inf>H<inf>34</inf>, nC<inf>17</inf>H<inf>36</inf>, and nC<inf>18</inf>H<inf>38</inf> were selected as surrogates of lubricant base oil constituents, and then mixed with iso-octane (iC<inf>8</inf>H<inf>18</inf>-gasoline surrogate) in proportions of 1 vol.% (iC<inf>8</inf>H<inf>18</inf> = 99 vol.%) and 10 vol.% (iC<inf>8</inf>H<inf>18</inf> = 90 vol.%) for the IQT experiments. In addition, lubricant base oils such as SN100 (Group I) and HC4 and HC6 (Group III) and a fully formulated lubricant (SAE 20W50) were mixed with iso-octane in the same proportions. The IQT results were conducted at an ambient pressure of 15 bar and a temperature range of 680-873 K. In the temperature range of 710-850 K, the addition of 10 vol.% base oils surrogates, base oils, and lubricating oil to the 90 vol.% iC<inf>8</inf>H<inf>18</inf> reduces the average total ignition delay time by up to 54% for all mixtures, while the addition of 1 vol.% to 99 vol.% iC<inf>8</inf>H<inf>18</inf> yielded a 7% reduction within the same temperature range. The shorter total ignition delay was attributed to the higher reactivity of the lubricant base oil constituents in the fuel mixtures. A correlation between reactivity of base oils and their molecular composition was tentatively established. These results suggest that the lubricants have the propensity of initiating LSPI in DISI engines. Furthermore, similar results for n-alkanes, lubricant base oils, and fully formulated commercial lubricants suggest that it is the hydrocarbon fraction that contributes primarily to enhanced reactivity, and not the inorganic or organometallic additives.
    Citation
    Kuti, O. A., Yang, S. Y., Hourani, N., Naser, N., Roberts, W. L., Chung, S. H., & Sarathy, S. M. (2015). A fundamental investigation into the relationship between lubricant composition and fuel ignition quality. Fuel, 160, 605–613. doi:10.1016/j.fuel.2015.08.026
    Publisher
    Elsevier BV
    Journal
    Fuel
    DOI
    10.1016/j.fuel.2015.08.026
    Additional Links
    https://linkinghub.elsevier.com/retrieve/pii/S0016236115008340
    https://e-space.mmu.ac.uk/617199/1/MANUSCRIPT%20REVISED%20BASE%20ON%20REVIEWER%233%20COMMENTS.pdf
    ae974a485f413a2113503eed53cd6c53
    10.1016/j.fuel.2015.08.026
    Scopus Count
    Collections
    Articles; Physical Science and Engineering (PSE) Division; Chemical Engineering Program; Mechanical Engineering Program; Clean Combustion Research Center

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