Combustion of n-C₃–C₆ Linear Alcohols: An Experimental and Kinetic Modeling Study. Part I: Reaction Classes, Rate Rules, Model Lumping, and Validation

Abstract

This work (and the companion paper, Part II) presents new experimental data for the combustion of n -C 3 –C 6 alcohols ( n -propanol, n -butanol, n -pentanol, n -hexanol) and a lumped kinetic model to describe their pyrolysis and oxidation. The kinetic subsets for alcohol pyrolysis and oxidation from the CRECK kinetic model have been systematically updated to describe the pyrolysis and high- and low-temperature oxidation of this series of fuels. Using the reaction class approach, the reference kinetic parameters have been determined based on experimental, theoretical, and kinetic modeling studies previously reported in the literature, providing a consistent set of rate rules that allow easy extension and good predictive capability. The modeling approach is based on the assumption of an alkane-like and alcohol-specific moiety for the alcohol fuel molecules. A thorough review and discussion of the information available in the literature supports the selection of the kinetic parameters that are then applied to the n -C 3 –C 6 alcohol series and extended for further proof to describe n -octanol oxidation. Because of space limitations, the large amount of information, and the comprehensive character of this study, the manuscript has been divided into two parts. Part I describes the kinetic model as well as the lumping techniques and provides a synoptic synthesis of its wide range validation made possible also by newly obtained experimental data. These include speciation measurements performed in a jet-stirred reactor ( p = 10 7 kPa, T = 550–1100 K, φ = 0.5, 1.0, 2.0) for n -butanol, n -pentanol, and n -hexanol and ignition delay times of ethanol, n -propanol, n -butanol, n -pentanol/air mixtures measured in a rapid compression machine at φ = 1.0, p = 10 and 30 bar, and T = 704–935 K. These data are presented and discussed in detail in Part II, together with detailed comparisons with model predictions and a deep kinetic discussion. This work provides new experimental targets that are useful for kinetic model development and validation (Part II), as well as an extensively validated kinetic model (Part I), which also contains subsets of other reference components for real fuels, thus allowing the assessment of combustion properties of new sustainable fuels and fuel mixtures.

Pyrolysis and Combustion Chemistry of Pyrrole, a Reference Component for Bio-oil Surrogates: Jet-Stirred Reactor Experiments and Kinetic Modeling

“… 11 Aldehyde chemistry has been recently discussed in refs ( 12 and 13 ), with the latter study specifically focusing on benzaldehyde, the simplest aromatic aldehyde. Alcohol chemistry has been systematically investigated in refs ( 14 and 15 ). Kinetic subsets for acetic, butanoic, and pentanoic acids have also been developed and validated.…”

Combustion of n-C3–C6 Linear Alcohols: An Experimental and Kinetic Modeling Study. Part II: Speciation Measurements in a Jet-Stirred Reactor, Ignition Delay Time Measurements in a Rapid Compression Machine, Model Validation, and Kinetic Analysis

“…As highlighted in Part I, alcohol are promising alternative fuels, as well as blending fuel components for internal combustion engines. , Alcohols thus constitute a valuable and viable solution to the negative impact of the transport sector on the environment and on human health. The development of detailed and predictive combustion kinetic models provides a very efficient tool for the synergistic design of fuels and engines, thus guiding the implementation of alternative routes for energy production and utilization.…”

“…The development of detailed and predictive combustion kinetic models provides a very efficient tool for the synergistic design of fuels and engines, thus guiding the implementation of alternative routes for energy production and utilization. This work completes Part I by describing in detail the experimental facilities and methods used for a systematic investigation of linear n -C 3 –C 6 alcohols. New ignition delay time (IDT) data for ethanol, n -propanol, n -butanol, and n -pentanol have been measured in a rapid compression machine (RCM).…”

An integrated protocol to study hydrogen abstraction reactions by atomic hydrogen in flexible molecules: application to butanol isomers

“…The rate constants employed in the combustion models of Cai et al 39 (based on the HA reactions of ref. 38) and Pelucchi et al 41 substantially underestimate the total HA from 1-butanol.…”

“…However, the approach is approximate in the sense that treats tunneling effects from a one-dimensional point of view and neglects the effect of multiple conformers, two aspects that are treated more rigorously in our protocol. From the experimental point of view, the data originate from kinetic model studies on combustion, 31,[37][38][39][40][41] and therefore they are also approximate.…”