Asian Journal of Engineering and Technology Innovation
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HCCI Engine as chemical reactor to produce fuel/chemicals: An exploring study of n-alkanes low-temperature chemistry in an HCCI Engine
Ahmad Saylam
Institute for Combustion and Gas Dynamics, University of Duisburg-Essen: Lotharstraße 1, Raum: MA 363 - 47057 Duisburg - Germany
Abstract
The species production (oxygenated hydrocarbons, hydrogen peroxide, formaldehyde, and alkenes) of low-intermediate temperature (LIT) chemistry of C1-C7methane, ethane, propane, n-butane, n-pentane, n-hexane and n-heptane fuelled a homogeneous charge compression ignition (HCCI) combustion process was explored via single-zone modeling. At fixed intake temperature and pressure of 400 K and 1 bar and in varying compression ratio from 3 to 19, engine speed from 100 to 2000 rpm and equivalence ratio of investigated n-alkanes/air mixtures from 0.05 to 1, the main production of target species is generated under portions of LIT region, which starts at near 680 K to around 1000 K depending of n-alkane. This maximum production is attended during the maximum mixture reactivity near to Top Dead Center (TDC) and survive the remaining cycle when auto-ignition is avoided. The engine speed of 400 rpm is the favourite for the studied C1-C7 n-alkanes. Maximum productivity from longer-chain n-alkanes is less sensible toward engine speed variation. A compression ratio of 5 is near optimal for the top conversion of C4-C7 n-alkanes, but higher values are needed for the lower-reactivity alkanes of C1-C3. The intermediate reactivity of n-butane leads to a wide range of productive equivalence ratio reaching stoichiometry. The lower and higher-reactivity of other n-alkanes oblige leaner productive conditions, less than 0.5. The synthesis process of chemicals/reactive fuels blend using an HCCI engine with yields up to 85% for n-heptane, as primary chemical/fuel, is now theoretically justified and necessities indeed to be validated experimentally.
