# Investigating the Influence of Alcohols (Ethanol and Iso-butanol) on TRF Flame Chemistry

Doha Kdouh, Sylvie Gosselin, Nathalie Lamoureux, Kanika Sood, Laurent Gasnot, Luc-Sy Tran

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Doha Kdouh, Sylvie Gosselin, Nathalie Lamoureux, Kanika Sood, Laurent Gasnot, et al.. Investigating the Influence of Alcohols (Ethanol and Iso-butanol) on TRF Flame Chemistry. 27th Journées d'études of the Belgian Section of the Combustion Institute, Belgian Section of the Combustion Institute, Apr 2024, Bruxelles, Belgium. hal-05248540

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Submitted on 10 Sep 2025

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Investigating the Influence of Alcohols (Ethanol and Iso-butanol) on TRF
Flame Chemistry

D. Kdouh¹, S. Gosselin¹, N. Lamoureux¹, K. Sood¹, L. Gasnot*¹, L.-S. Tran*¹

¹Univ. Lille, CNRS, UMR 8522 - PC2A - Physicochimie des Processus de Combustion et de l'Atmosphère, F-59000 Lille, France.

* Corresponding authors: laurent.gasnot@univ-lille.fr ; luc-sy.tran@univ-lille.fr

There's growing interest in oxygenated biofuels as an alternative to fossil fuels to reduce CO2 emissions from spark-ignition engines. However, their complex interaction with pollutants like PAHs and soot particles, as well as their higher formaldehyde and aldehyde levels compared to traditional fuels, pose challenges. This study aimed to understand these issues by experimenting with oxygenated biofuels, ethanol, and iso-butanol, in premixed laminar flames generated from a toluene reference fuel (TRF). While there have been some studies investigating the combustion chemistry of toluene reference fuel (TRF) [1][2][3], and a few focusing on TRF/alcohol mixtures [4][5], research featuring quantitative analysis of chemical species under flame conditions remains limited. This work seeks to contribute to this field by presenting preliminary findings from our study, which aim to advance our understanding of the combustion behavior of oxygenated biofuels (ethanol and iso-butanol).

Three flames were studied in this work: TRF Φ= 1.82, TRF-E (with ethanol) Φ= 1.82, TRF-B (with iso-butanol) Φ= 1.82. These flames were subjected to gas chromatography analysis to measure the mole fractions of various saturated and unsaturated aliphatic compounds, aldehydes, ketones, and aromatic species using 3 GCs. The first GC (GC-1) was used to measure O₂, N₂, CO, hydrocarbon species from C₁ (methane) to C₇ (toluene). The second GC (GC-2) was used to measure and analyze small oxygenated C₁-C₈ species (alcohols, aldehydes, and ketones) and the last GC (GC-MS), was used for the identification of species. Two temperature measurement techniques were used for identifying flame temperatures: NO-LIF (Laser Induced Fluorescence) thermometry [6] and thermocouple-based technique [7].

Various species were detected and measured in this study. The impact of adding ethanol and iso-butanol to the TRF flame species was examined and illustrated in Figure 1. C₂H₂ exhibited similar behavior when mixed with either ethanol or iso-butanol, whereas other hydrocarbons showed lower mole fractions as shown in Figure 1a. Oxygenated species showed different behavior depending on the alcohol added, as depicted in Figure 1b. The maximum temperature of the three flames did not change, we noticed a little shift of about 0.5mm upon the addition of ethanol and 0.25mm shift upon the addition of iso-butanol as presented in Figure 2.

[1] E. Hu, Z. Xu, Z. Gao, J. Xu, and Z. Huang, "Experimental and numerical study on laminar burning velocity of gasoline and gasoline surrogates," *Fuel*, vol. 256, p. 115933, Nov. 2019, doi: 10.1016/j.fuel.2019.115933.

[2] C. Shao, G. Kukkadapu, S. W. Wagnon, W. J. Pitz, and S. M. Sarathy, "PAH formation from jet stirred reactor pyrolysis of gasoline surrogates," *Combustion and Flame*, vol. 219, pp. 312–326, Sep. 2020, doi: 10.1016/j.combustflame.2020.06.001.

[3] S. Park, Y. Wang, S. H. Chung, and S. M. Sarathy, "Compositional effects on PAH and soot formation in counterflow diffusion flames of gasoline surrogate fuels," *Combustion and Flame*, vol. 178, pp. 46–60, Apr. 2017, doi: 10.1016/j.combustflame.2017.01.001.

[4] A. Khosousi et al., "Experimental and numerical study of soot formation in laminar coflow diffusion flames of gasoline/ethanol blends," *Combustion and Flame*, vol. 162, no. 10, pp. 3925–3933, Oct. 2015, doi: 10.1016/j.combustflame.2015.07.029.

[5] P. Dirrenberger et al., "Laminar burning velocity of gasolines with addition of ethanol," *Fuel*, vol. 115, pp. 162–169, Jan. 2014, doi: 10.1016/j.fuel.2013.07.015.
[6] K. K. F. Pascale Desgroux, "The accuracy and precision of multi-line NO-LIF thermometry in a wide range of pressures and temperatures, J. Quant. Spectrosc. Radiat. Transfer.".

[7] J. E. Xavier Mercier, "Thermocouple-based thermometry for laminar sooting flames: Implementation of a fast and simple methodology," *International Journal of Thermal Sciences*.

<figure><img src="image_2.png" /><figcaption>Figure 1: Fig. 4. Mole fraction profiles of selected soot precursors and oxygenated intermediates measured in the three flames</figcaption></figure>

<figure><img src="image_3.png" /><figcaption>Figure 2: The temperature profiles for the three flames.</figcaption></figure>
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