High-Temperature Carbon Particle Formation and Decay in Carbon Suboxide Pyrolysis behind Shock Waves

Abstract

The formation of carbon particles following the pyrolysis of C

Chemical Condensation Wave Initiating Oxygen-Free Combustion and Detonation

“…However, this behavior of the process is realized until the reverse reactions of the decomposition of clusters and nanoparticles come into play due to an increase in temperature. It was shown in [9,10] that as the temperature behind the shock wave increases to 2800-3000 K, the rate of particle formation slows down. At T = 3000 K, the total time of particle growth is more than 100 μs, and at T = 3400 K the rate of the decay (evaporation) of the particles is higher than the rate of their formation [10].…”

“…It was shown in [9,10] that as the temperature behind the shock wave increases to 2800-3000 K, the rate of particle formation slows down. At T = 3000 K, the total time of particle growth is more than 100 μs, and at T = 3400 K the rate of the decay (evaporation) of the particles is higher than the rate of their formation [10]. Consequently, it is obvious that, in contrast to the classical detonation, supported by combustion pro-cesses, this phenomenon should have an extremum in temperature, depending on the integral heat release, and the process should become self-decaying upon excessive overheating.…”

“…The reason for this nonmonotonic behav-ior of the detonation condensation wave with the increasing intensity of the initiating shock wave lies in the fundamental difference between the condensation kinetics and the kinetics of combustion processes. With an increase in temperature and as it approaches to the temperatures of the phase transition (sublimation) of the forming nanoparticles, the effective rate of their condensation inevitably decreases and at certain temperatures becomes lower than the rate of their decay (disintegration) [10,18].…”

“…tion of condensed carbon nanoparticles were studied in [7][8][9][10][11]. The integral heat balance of the conversion of carbon suboxide into condensed carbon and CO is also significantly positive, although somewhat lower than that of acetylene [8]:…”

Numerical study of carbonaceous nanoparticle formation behind shock waves

“…The measured particle yield did not depend on the C 3 O 2 mole fraction and had a maximum at approximately 1600 K for all mixtures. Recently, a series of measurements have been carried out to study the particle formation at a higher temperature range (from 2000 K to 3700 K) [6][7][8][9]. It was found that at the measured time of 1 ms after the reflected shock wave, the temperature dependence of the particle yield showed double bell-shaped curves with two local maxima at 1600 K and 3200 K. More recently, two studies [10,11] provided new explanations for the double bell-shaped optical densities measured in the previous experiments.…”