Modeling of the formation of short-chain acids in propane flames

TL;DR

This study develops a detailed kinetic model to simulate the formation of short-chain acids in propane flames, revealing key pathways and concentrations, and compares results with limited experimental data.

Contribution

It introduces a new kinetic mechanism for short-chain acids in propane flames and analyzes their formation pathways and concentrations.

Findings

Up to 25 ppm acetic acid and 15 ppm formic acid are formed in flames.

Propenic acid is the most abundant C3 acid produced.

Simulation results agree reasonably with scarce literature data.

Abstract

In order to better understand their potential formation in combustion systems, a detailed kinetic mechanism for the formation of short-chain monocarboxylic acids, formic (HCOOH), acetic (CH3COOH), propionic (C2H5COOH) and propenic (C2H3COOH)) acids, has been developed. Simulations of lean (equivalence ratios from 0.9 to 0.48) laminar premixed flames of propane stabilized at atmospheric pressure with nitrogen as diluent have been performed. It was found that amounts up to 25 ppm of acetic acid, 15 ppm of formic acid and 1 ppm of C3 acid can be formed for some positions in the flames. Simulations showed that the more abundant C3 acid formed is propenic acid. A quite acceptable agreement has been obtained with the scarce results from the literature concerning oxygenated compounds, including aldehydes (CH2O, CH3CHO) and acids. A reaction pathways analysis demonstrated that each acid is mainly derived from the aldehyde of similar structure.