How ozone affects the product distribution inside cool flames of diethyl ether

Abstract

Cool flames of diethyl ether were stabilized and extensively studied in a stagnation plate burner. Two conditions were selected, enabling the assessment of the impact of ozone-seeding on the cool flame: In the first case, ozone was seeded to stabilize a lean cool flame with an equivalence ratio of 0.5, and in a second case a stoichiometric flame was stabilized without O3 addition. Excited formaldehyde chemiluminescence (CH2O*) was used to measure the cool flame position in the burner. Detailed temperature and mole fraction profiles of stable intermediates of the oxidation of diethyl ether were measured for both conditions. Relevant detailed kinetic models issued from the literature, respectively developed by Tran et al. [Tran et al., Proc. Comb. Inst. 2019, 37, 511–519] and Serinyel et al. [Serinyel et al., Combust. Flame 2018, 193, 453–462] were used in order to improve the understanding of the low temperature kinetics of this ether, as well as the effect of ozone on the species distribution after the cool flame. The Tran et al. model is able to correctly predict the cool flame position as well as its heat release in the lean case, but shows high discrepancy in the prediction of products formation, while the Serinyel et al. model shows a fair prediction of the cool flame products distribution. A numerical comparison between a stoichiometric flame, with and without ozone-seeding, was also performed in order to gain some insight into the ozone influence on the low temperature products distribution. Main results show that the RO˙ radical decomposition is of particular importance in our conditions, which formation is directly linked to RO˙2 bimolecular reactions, reinforcing the link between atmospheric chemistry and low temperature combustion.