ON THE IMPACT OF THE O-ATOM ON THE IGNITION OF A 5-MEMBERED RING: A COMPARATIVE STUDY BETWEEN CYCLOPENTANE AND TETRAHYDROFURAN
Résumé
Cyclopentane (CPT) is one of the simplest cycloalkanes with five membered carbon ring, which has high-octane and knock-resistant characteristics, and it is commonly found in commercial gasoline. Tetrahydrofuran (THF) is a saturated cyclic ether compound, and has been shown to be as a promising bio-fuel for internal combustion engines. The molecular structure of CPT and THF is similar excluding the oxygen heteroatom in THF ring which induces lower bond dissociation energies of the C-H bonds on the α-sites, but higher BEDs on the β-sites. This work aims at comparing the auto-ignition delay times of CPT and THF measured in shock tube, and explain the differences and similarities observed with the help of a unique detailed kinetic mechanism. The ignition delay times have been measured in a high-pressure shock tube over a wide temperature range for various mixture compositions. The kinetic model used in the simulations was developed by introducing a sub-mechanism for CPT from Lokhachari et al. (2021) into the THF mechanism from Fenard et al. (2018). The present mechanism contains 1322 species and 6709 reactions. It was observed that despite differences in terms of bond dissociation energies, CPT and THF have very similar ignition delay times at the same equivalence ratio. However, when XFuel/XO2 is kept constant, it turns out that a discrepancy appears between CPT and THF when the mole fraction of O2 decreases, CPT becoming longer than THF to ignite. This observation indicates that CPT is more sensitive to the O2 content than THF.