Review of the Influence of Oxygenated Additives on the Combustion Chemistry of Hydrocarbons

Abstract

This review summarizes the chemical impact of oxygenated additives on the combustion chemistry of hydrocarbons. Experimental studies in shock tubes, rapid compression machines, jet-stirred reactors, flow reactors, and premixed flames are summarized for additions of ethers, alcohols, esters, and other oxygenates to hydrocarbon fuels. Special emphasis is on the ignition behavior at low and high temperatures and on how molecule-specific intermediate chemistry impacts pollutant emissions by the addition of oxygenated components to hydrocarbon fuels. The literature work indicates that at high temperatures, i.e., in flames, the combustion chemistry of the oxygenate/hydrocarbon can be accurately modeled by merging the individual's submechanisms, excluding cross reactions. The observed trend in the intermediate species pool is largely due to a replacement effect, which describes a linear dependence of the intermediate concentration on the mixture composition. At low-temperatures, the chemistry is slightly more complex because of the fuel-specific reactivity in this temperature range. It was shown that unreactive fuels can undergo low-temperature oxidation processes when a highly reactive fuel component is present. As such, the sensitivities of specific reactions on ignition delay times varies.

Experimental and Modeling Evaluation of Dimethoxymethane as an Additive for High-Pressure Acetylene Oxidation

“…The addition of ethanol has almost no effect on the oxidation of C 2 H 2 , the predicted C 2 H 2 concentration profile remains almost the same as without any additive, while the presence of an ether, DME or DMM, shifts the conversion of C 2 H 2 to lower temperatures. The chemical structure, and the favorable formation of QOOH radicals, clearly influences the reactivity at low temperatures (550−750 K) as stated by Yang et al 41 in a recent review on the interaction of oxygenates on hydrocarbon combustion when comparing studies of the isomers DME and ethanol.…”

High-Temperature Pyrolysis and Combustion of C5–C19 Fatty Acid Methyl Esters (FAMEs): A Lumped Kinetic Modeling Study

“…Blending oxygenated fuels with fossil fuels can mitigate the energy depletion and emissions. Therefore, many studies focused on the blending effects . In addition to pure FAME fuels, experimental data of diesel/biodiesel surrogate fuels were also selected to validate the present model.…”

“…Therefore, many studies focused on the blending effects. 63 In addition to pure FAME fuels, experimental data of diesel/biodiesel surrogate fuels were also selected to validate the present model. Table 3 summarizes the validation data from six biodiesel surrogates, incorporating the experimental types and conditions.…”

Virtual Special Issue of Recent Advances in Fundamentals of Biomass and Biofuel Combustion

“…Three review papers describe the progress in the research on the chemical kinetics of biofuel combustion. Yang et al 2 reviewed recent experimental studies to understand how adding oxygenated additives, such as dimethyl ether, ethanol, or dimethyl carbonate, influences the formation of oxidation intermediates and the ignition behavior for hydrocarbons. Westbrook et al 3 provided an overview of detailed kinetic models, explaining how the combustion chemistry of biofuels (alcohols, aromatic oxygenates, alkyl esters, and cyclic ethers) differs from that of alkanes.…”