A kinetic investigation on the synergistic low-temperature reactivity, antagonistic RON blending of high-octane fuels: Diisobutylene and cyclopentane

Abstract

A synergistic effect on low-temperature autoignition reactivity of blending two high-octane compounds, i.e. cyclopentane and diisobutylene, was observed in engine experiments and ignition delay time measurements at 700-880 K and up to 25 bar with a rapid compression machine. Results show that the low-temperature ignition delay and RON of a cyclopentane-diisobutylene blend are inferior to those of its isolated blendstocks, therefore exhibiting an increased reactivity towards ignition at the tested conditions. Sampling and speciation of the reacting mixture during the ignition delay of pure compounds and the most reactive blend was conducted to support discussions focused on the kinetic perspective to this phenomena, which suggest that the separate chain initiation pathways of these potential high-octane blendstocks can interact with each other to help the radical pool growth at the beginning stage of the autoignition chemistry, and finally accelerate the propagation and branching pathways to promote the global reactivity. This result in significant two-stage ignition behavior for the blend, which is not observed at this temperature for both isolated blendstocks. These findings are especially meaningful for designing and blending suitable high-octane fuels for advanced combustion mode engines.

Is ortho-Cresol a Viable Lignocellulosic Blendstock? A Kinetic Study of Its Co-Oxidation within a Surrogate Fuel

“…The ULille RCM was used to measure the ignition delays of stoichiometric isooctane/ortho-cresol blends at several blending ratios between 0 and 40% mol. ortho-cresol in the fuel blend, and at pressures between 14 and 20 bar, and temperatures between 688 and 850 K. Because this experimental setup has been described extensively in the literature before [11][12][13], a schematic being given in [14], only the features relevant to this work will be described here. Mixtures of iso-octane, ortho-cresol, dioxygen, and inert gases were prepared using the partial pressure method inside a heated mixture preparation facility, whose temperature was fixed as superior to the one necessary for a vapor pressure of all compounds superior to twice the required one.…”

“…Energies 2021, 14, x FOR PEER REVIEW 2 of 10 in order to include all the necessary pathways into kinetic models, as demonstrated in the past [4,[10][11][12]. To serve that purpose, because of its two-stage ignition features and relevance to spark-ignition engine fuels, iso-octane was used as a co-oxidant in this study.…”

“…Especially, in the case of automotive fuels, species that are often considered unreactive can undergo co-oxidation because of the presence of a more reactive compound inside the fuel blend. Studying co-oxidation conditions is therefore of crucial importance in order to include all the necessary pathways into kinetic models, as demonstrated in the past [4,[10][11][12]. To serve that purpose, because of its two-stage ignition features and relevance to sparkignition engine fuels, iso-octane was used as a co-oxidant in this study.…”

Insight into the Ozone-Assisted Low-Temperature Combustion of Dimethyl Ether by Means of Stabilized Cool Flames

“…Facilities in which the study of the LTC of fuels can be operated in a permanent, non-diluted regime, such as burner-stabilized cool flames, are therefore useful to quantify the heat release of cool flames, which is in turn correlated with second-stage ignition in RCMs. 13 First observations of cool flames were achieved 2 centuries ago 15 by igniting gaseous diethyl ether over a heated platinum wire. Few studies on stabilized double flames of n-butane were realized some decades ago, 16,17 but this research field gained renewed interest in the context of plasma-assisted ignition 18 and ozone-assisted ignition.…”

“…However, quantification of the heat release is typically difficult using such devices, as JSRs operate in highly diluted and isothermal conditions, and RCMs use creviced pistons to mitigate fluid motion after compression, allowing part of the mixture to transfer to the crevice during the first-stage ignition and therefore reducing the relevant pressure increase. Facilities in which the study of the LTC of fuels can be operated in a permanent, non-diluted regime, such as burner-stabilized cool flames, are therefore useful to quantify the heat release of cool flames, which is in turn correlated with second-stage ignition in RCMs. , …”