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Formulating a quaternary gasoline surrogate (MTRF-87) using laminar burning velocity measurements
Journal
Fuel
ISSN
00162361
Date Issued
2022-12-01
Author(s)
Kumar, Rohit
Priyadarshani Padhi, Upasana
Kumar, Sudarshan
Abstract
This work reports the formulating of a new quaternary gasoline surrogate (MTRF-87) model utilizing the measured burning velocities of methylcyclohexane (MCH), toluene (TL), n-heptane (nC7) and iso-octane (iC8) in a mixing rule (energy-fraction based). The laminar burning velocity (LBV) measurements are performed using an externally heated diverging channel (EHDC) method. The LBV measurements are reported for an equivalence ratio range, ϕ = 0.7–1.4 for different mixture temperatures (≤600 K) at atmospheric pressure to develop this model. The final MTRF-87 composition is governed by the octane number comparison with commercial gasolines, and constitutes 0.2, 0.2, 0.1 and 0.5 mol fractions of MCH, TL, nC7 and iC8 respectively. The MTRF-87 predictions exhibit excellent consistency with a Ranzi model (2014) and other commercially available gasolines at all mixture conditions, whereas a significant over-prediction (up to 16 %) by KAUST correlation is observed for ϕ > 1 at elevated temperatures. Experimental measurements of the formulated surrogate, MTRF-87 at ϕ = 1 showed that the LBV variation with the temperature ratio agrees well with the measured burning velocities of gasoline, as well as the predictions of various models. From sensitivity analysis, the reaction, H2 + OH = H + H2O tends to increase the LBV of lean-to stoichiometric conditions and decrease for ultra-rich mixtures (ϕ = 1.4). The temperature exponent (α) variation at different mixture conditions of toluene + air and gasoline + air mixtures follow a downward parabolic trend with minimal value at ϕ = 1.1, and shows parity with the predictions of distinct detailed kinetic model predictions.
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