The auto-ignition of propane at intermediate temperatures and high pressures

Abstract

The results of a new experimental programme to measure auto-ignition delay times in mainly lean (/ \ 0.5) propaneÈair mixtures at intermediate temperatures in the range 850 K upwards and pressures 5È40 bar are described. The delays are compared to predictions obtained by the integration of two detailed chemical kinetic reaction schemes. Experimentally, a decrease in activation energy was observed at around 1000 K. The work shows that extrapolation of ignition delays obtained at high temperatures T [ 1000 K can lead to signiÐcant overestimation of the actual delay times at lower temperatures. Despite the introduction of additional key reactions the kinetic schemes used could not fully reproduce the delay times observed experimentally at temperature below ca. 1000 K. Previous studies Ignition delay measurementsPrevious experimental studies of the oxidation and autoignition of propane, as with other hydrocarbons, fall into

Chemical‐kinetic modeling of ignition delay: Considerations in interpreting shock tube data

“…Further evidence of similar disparities can be found in the study of Cadman et al [27]. They reported a distinct decrease in the activation energy of propane-air ignition data for ignition times longer than approximately 1 ms.…”

“…Such behavior could not be reproduced using available chemical-kinetic models. Cadman et al [27] identified the importance to their observations of hydroperoxyl, propyl, and methyl radical chemistry, which they then considerably modified; the updated chemical-kinetic scheme, however, still could not reconcile the observed model-experiment differences. Furutani et al [23,24] reported similar changes in the activation energy of methane as well as isooctane ignition delays as those shown by Cadman et al [27].…”

“…Cadman et al [27] identified the importance to their observations of hydroperoxyl, propyl, and methyl radical chemistry, which they then considerably modified; the updated chemical-kinetic scheme, however, still could not reconcile the observed model-experiment differences. Furutani et al [23,24] reported similar changes in the activation energy of methane as well as isooctane ignition delays as those shown by Cadman et al [27]. Based on the results of Furutani et al, however, it is clearly evident that the change in the activation energy of the data at lower temperatures and longer ignition times is solely due to the nonidealities discussed above rather than being dependent on chemical processes.…”

Effect of Materials on the Autoignition of Cyclopentane

“…In this intermediate temperature region, IDT decreases with decreasing temperature. This behavior, wherein a negative temperature coefficient is displayed at intermediate temperatures, has been observed for various hydrocarbons (Minetti et al, 1994;Cadman et al, 2000). This phenomenon is attributed to the transition from a low-to high-temperature kinetic mechanism.…”

Some observations on the initiation and onset of detonation

“…Results by Cadman et al [60] indicate a decrease in activation energies in propane mixtures at temperatures in the region of 850-1000 K and show clearly that the use of hightemperature chemical kinetics data can lead to an over prediction by nearly an order of magnitude in the ignition delay times at these temperatures. A similar study with methane was reported by Goy et al [61], although the discrepancies observed were not as extreme as with propane.…”