N-Pentane Lab Report
As observed in both experiments and simulations, at 2 atm, DME can slightly inhibiting effect on n
pentane ignition, while at 10 and 20 atm, DME addition did not obvious influence n pentane ignition.
To further understand this phenomenon, reaction pathway analysis of DME, 50%DME/50% n pentane
and n pentane were conducted at 20% fuel consumption using NUI Galway pentane isomers model.
Fig 6 shows the reaction pathway of DME oxidation. At 2 atm and 1100 K, only 8% fuel is consumed
by unimolecular decomposition reaction, while most of the DME mainly undergoes H atom
abstraction by free radicals (ȮH (42.7%), ĊH3 (22.8%), Ḣ (13%) and HȮ2 (4.4%)) to form
methoxymethyl radical (CH3OĊH2). Subsequently, the methoxymethyl radicals (CH3OĊH2) readily
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7, at 2 atm, and 1100 K, n pentane is largely consumed through four channels: a) 44% of fuel
consumption undergo H atom abstraction from secondary C H bond by free radicals, Ḣ (22%), ȮH
(15.2%), ĊH3 (3.2%) and HȮ2 (1.1%), to yield sec pentyl radicals (Ċ5H11 2), following by C C beta
scission to readily form propylene (C3H6) and ethyl radical (Ċ2H5). b) 22.9% of fuel consumption
undergo H atom abstraction from primary C H bond by free radicals, ȮH (12%), Ḣ (9.4%) and Ö
(1.5%), to form n pentyl radicals (Ċ5H11 1), which will subsequently dissociated via either C C beta
scission (74.9%) forming n propyl (NĊ3H7) and ethylene (C2H4). More than 93% of the NĊ3H7
radicals can decompose directly to produce C2H4 and ĊH3 radicals. While 21.5% the n pentyl
radicals (Ċ5H11 1) undergoes isomerization reaction forming sec pentyl (Ċ5H11 2). c) 19.5% of fuel
consumption undergo H atom abstraction from tertiary C H bond by free radicals, Ḣ (11%), ȮH
(5.7%), ĊH3 (1.6%) and Ö (1.2%), to form 3 pentyl radicals (Ċ5H11 3), which is largely undergo C C
beta scission to produce 1 butene (C4H8 1) (99.8%). d) 10.9% of fuel undergo unimolecular
decomposition to yield Ċ2H5 radicals and NĊ3H7 radicals which can largely dissociate to C2H4. At 2
atm and 1600 K, the unimolecular decomposition of n pentane is the main pathway consuming
(59.7%) formed NĊ3H7 and Ċ2H5 radicals. Fuel molecule H atom abstraction only account for
30.8%, which can be observed from secondary C H (14.6%), primary C H (8.9%) and tertiary C H
(7.3%), respectively. Meanwhile, 6.5% of fuel also decomposed by ĊH3 radical elimination to
produce n butyl radicals (PĊ4H9). Therefore, at 2 atm and 1600 K, more pronounced unimolecular
decomposition pathway of n pentane will yield more NĊ3H7 and Ċ2H5 radicals, thus further generate
highly activated free radicals and promote the reactivity at high temperature[63,
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