Shock Tube Investigation and Modeling of Dicyclopentadiene: Fundamental to Application

Abstract

Dicyclopentadiene (DCPD), a homodimer of cyclopentadiene (C5H6) was chosen for the present study. DCPD can be obtained by dehydrogenation of JP-10 (jet propellant C10H16) which is currently used as aviation fuel. The combustion chemistry for JP-10 is well established. Very few studies are present in the literature on the thermal decomposition of dicyclopentadiene. Hence, to begin with, the thermal decomposition of DCPD was carried out in a single pulse shock tube. The shock tube is incorporated with the step size driver insert to correct the non-ideal pressure rise due to non-ideal effects. Hence it facilitates the near-ideal behavior behind the reflected shock wave region. The experiments were performed behind the reflected shock wave in the temperature range of 1250-1550 K and pressure range of 13-16 atm. Also, Ab-initio calculations were carried out to find the minimum energy pathway that can lead to the formation of observed products. Thereupon the detailed kinetic modeling was carried out to simulate the concentration profile of different observed products. Ab-initio calculations were carried for the dissociation reaction of dicyclopentadiene to cyclopentadiene conversion. Quantum theory of atoms in molecule (QTAIM) which is based upon electron density topology provides insight into the reaction. AIM analysis along the reaction coordinate was carried out which provides information about bond breaking and bond making phenomenon occurring during chemical transformation. In addition, AIM analysis was used to identify the various types of non-covalent interactions present in the structures along the reaction coordinate from reactant to product. Ignition delays were measured for DCPD using the modified chemical shock tube (CST3) to characterize it as a fuel. The measurement of ignition delay times were performed for three different equivalent ratios 0.5, 1, and 1.5. A comparison of ignition delay times between JP-10 and DCPD has been made. Furthermore, a detailed kinetic mechanism was developed for a better understanding. In addition, a comparison was made between the calculated and experimental observed ignition delay times.