TY - JOUR
T1 - An experimental and mechanistic study on the laminar flame speed, Markstein length and flame chemistry of the butanol isomers
AU - Wu, Fujia
AU - Law, Chung K.
N1 - Funding Information:
This work was supported by the Combustion Energy Frontier Research Center, an Energy Frontier Research Center funded by the US Department of Energy, Office of Basic Energy Sciences under Award Number DESC0001198. The authors thank Professor Mani Sarathy for his help in using the S-mechanism, Professor Alessio Frassoldati his help in using the R-mechanism and the OpenSMOKE code, and Professor Yiguang Ju and Roe Burrell for their help in the use of the PLOG Chemkin code.
PY - 2013/12
Y1 - 2013/12
N2 - Laminar flame speeds and Markstein lengths for n-butanol, s-butanol, i-butanol and t-butanol at pressures from 1 to 5. atm were experimentally measured in a heated, dual-chamber vessel. Results at all pressures show that n-butanol has the highest flame speeds, followed by s-butanol and i-butanol, and then t-butanol. Results further show that the reduced Markstein length measured for n-butanol as compared to other isomers is a flame thickness effect, and that all four isomers have similar Markstein numbers, which is the appropriate nondimensional parameter to quantify flame stretch. Computation and flame chemistry analysis were performed using two recently published kinetic models on butanol isomers by Sarathy et al. and Ranzi et al., respectively. Comparison shows the former model satisfactorily agrees with the present results while agreement of the latter is less satisfactory. Based on reaction path analysis the major differences of the two models on fuel cracking pathway were identified. It is concluded that the primary reason for the lowered flame speed of s-butanol, i-butanol and t-butanol is that they crack into more branched intermediate species which are relatively stable, such as iso-butene, iso-propenol and acetone. This indicates that the general rule that fuel branching reduces flame speed for hydrocarbons can also be applied to alcohols, and that the fundamental reason for this generality is that in alcohols C. O has similar bond energy to the C. C bond while O. H has similar bond energy to the C. H bond.
AB - Laminar flame speeds and Markstein lengths for n-butanol, s-butanol, i-butanol and t-butanol at pressures from 1 to 5. atm were experimentally measured in a heated, dual-chamber vessel. Results at all pressures show that n-butanol has the highest flame speeds, followed by s-butanol and i-butanol, and then t-butanol. Results further show that the reduced Markstein length measured for n-butanol as compared to other isomers is a flame thickness effect, and that all four isomers have similar Markstein numbers, which is the appropriate nondimensional parameter to quantify flame stretch. Computation and flame chemistry analysis were performed using two recently published kinetic models on butanol isomers by Sarathy et al. and Ranzi et al., respectively. Comparison shows the former model satisfactorily agrees with the present results while agreement of the latter is less satisfactory. Based on reaction path analysis the major differences of the two models on fuel cracking pathway were identified. It is concluded that the primary reason for the lowered flame speed of s-butanol, i-butanol and t-butanol is that they crack into more branched intermediate species which are relatively stable, such as iso-butene, iso-propenol and acetone. This indicates that the general rule that fuel branching reduces flame speed for hydrocarbons can also be applied to alcohols, and that the fundamental reason for this generality is that in alcohols C. O has similar bond energy to the C. C bond while O. H has similar bond energy to the C. H bond.
KW - Butanol isomers
KW - Flame chemistry
KW - Laminar flame speeds
KW - Markstein lengths
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U2 - 10.1016/j.combustflame.2013.06.015
DO - 10.1016/j.combustflame.2013.06.015
M3 - Article
AN - SCOPUS:84885294008
SN - 0010-2180
VL - 160
SP - 2744
EP - 2756
JO - Combustion and Flame
JF - Combustion and Flame
IS - 12
ER -