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, P 2 , of 35, 70, 150, and 300 Torr and temperatures, T 2 , of 1472-2074 K. 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: k 1(35Torr) = (7.93 ± 3.96) × 10 84 T -19.815 exp(-64366/T) s -1 , k 1(70Torr) = (4.79 ± 2.39) × 10 77 T -17.705 exp(-62316/T) s -1 , k 1(150Torr) = (2.42 ± 1.21) × 10 69 T -15.295 exp(-59862/T) s -1 , k 1 (300Torr) = (4.66 ± 2.33) × 10 61 T -13.065 exp(-57493/T) s -1 , and k 1∞ = (1.69 ± 0.85) × 10 16 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 [Int. J. Chem. Kinet. 10 (1978) 599-617].

Measurements and interpretation of shock tube ignition delay times in highly CO2 diluted mixtures using multiple diagnostics

“…Absorption-based diagnostic studies are non-intrusive, provide in-situ measurements (e.g., concentration of individual species including trace species, temperature) and have fast-time response. The combination of shock-heating and non-intrusive laser detection provides a state-of-the-art test platform for high-temperature kinetics of various hydrocarbons and oxygenates [32,[37][38][39][40].…”

Low temperature autoignition of 5-membered ring naphthenes: Effects of substitution

“…A combination of innate temperature inhomogeneities within the adiabatic core [71,72], e.g., due to complex gas dynamic processes that could occur during the piston seating process [73], and the propensity of CPT to form resonantly stabilized radicals such as cyclopentenyl, allyl, etc. [10,74] could create an environment in which thermal non-uniformities cannot be homogenized and thus flame kernels have sufficient time to develop and propagate before the onset of chemical ignition. Cyclopentane's unique chemistry, which may facilitate this, is discussed further in Section 4.2.…”

“…The reactivity of cyclopentane was suppressed in the JSR at fuel rich conditions and intermediate temperatures (900-1100 K), as evidenced by decreased consumption of the fuel. Allyl radicals can form more directly from the ring opening of cylcopentane [74], though this is likely to only be an important pathway at high temperatures.…”