A shock tube laser schlieren study of cyclopentane pyrolysis

Abstract

The dissociation of cyclopentane has been investigated in a diaphragmless shock tube with laser schlieren densitometry at nominal post-shock pressures, P2, of 35, 70, 150, and 300Torr and temperatures, T2, of 1472–2074K. These are the first experimental data reported in the high temperature fall-off regime for cyclopentane. The experimental density gradients were simulated using a chemical-kinetic model with good agreement between simulations and experiments. Rate coefficients for dissociation of cyclopentane were obtained and mechanistic details were elucidated. An RRKM model was developed to best fit the experimental results, and the rate coefficients calculated are: k1(35Torr)=(7.93±3.96)×1084 T−19.815 exp(−64366/T) s−1, k1(70Torr)=(4.79±2.39)×1077 T−17.705 exp(−62316/T) s−1, k1(150Torr)=(2.42±1.21)×1069 T−15.295 exp(−59862/T) s−1, k1 (300Torr)=(4.66±2.33)×1061 T−13.065 exp(−57493/T) s−1, and k1∞=(1.69±0.85)×1016 T−0.005 exp(−42983/T). Results show that cyclopentane dissociation is similar to that of cyclohexane, and involves formation of a biradical intermediate. The high-pressure limit rates for cyclopentane dissociation are also compared with previous results in the literature and show good agreement with a study by Tsang (1978) [21].