Effects of hydrogen peroxide on the low-temperature ignition delay times of ethylene/air/Ar mixtures in an RCM

Hydrogen peroxide with strong oxidative activity has received increasing attention in the field of ignition and combustion enhancement. To further seek out its potential benefits in ignition, the effects of hydrogen peroxide on the ignition delay times of ethylene were experimentally investigated using a rapid compression machine and numerically analyzed via the AramcoMech 3.0. The experiments with different levels of hydrogen peroxide (0 - 7000 ppm) were performed at Pc = 3.33 MPa, Tc = 817.9 - 921.0 K, phi = 0.5 - 1.5, and a dilution of 45 mol% Ar. Experimental results showed that adding hydrogen peroxide can effectively shorten the ignition delay times, and extend the low-temperature limitations. The improving effect was proceeded by three stages (0 - 1000 ppm, 1000 - 4000 ppm, and 4000 - 7000 ppm) of different decreasing rates. Kinetic analyses revealed that adding hydrogen peroxide promoted the production of OH radical to highlight the H-abstraction reaction of ethylene, further accelerating the oxidation of vinyl to vinyloxy and then to formaldehyde. Moreover, higher heat release rates were obtained with the addition of hydrogen peroxide for its exothermic character. By the kinetic effects of hydrogen peroxide addition, the ignition delay times of ethylene/air/Ar mixtures were significantly decreased. However, with the increase of additive fraction, the growth rate of both heat release rate and rate of production of OH radical were slowed down, lessening the enhancement effect on the ignition delay times.