Hydrogen cyanide (HCN) is a major source of prompt-NOx formation especially in fuel-bound nitrogen systems. To date, there is still a significant disagreement between experimental data and theoretical predic- tions of the rate coefficients of combustion reactions involving HCN as a prompt-NOx precursor. Accurate modeling of NOx formation would greatly benefit from a diagnostic capable of performing high-fidelity measurements of HCN formation/consumption time-histories. In this study, a laser diagnostic is developed for sensitive and selective HCN sensing by probing its most intense absorption feature in the mid-infrared (MIR). The diagnostic is based on difference-frequency generation (DFG) between a CO2 gas laser and an external-cavity quantum cascade laser in a nonlinear orientation-patterned gallium arsenide crystal which results in a DFG laser tunable over 11.56 − 15 μm. HCN measurements were carried out at the peak of the Q-branch of its strong ν2 vibrational band near 14 μm. Pressure dependence of the absorption cross-section was investigated at room temperature over the pressure range of 0.07 − 1.07 bar. Temperature-dependent absorption cross-section measurements were conducted behind reflected shock waves over the temperature range of 850 − 3000 K. The diagnostic was demonstrated in reactive experiments in a shock tube where HCN mole fraction time-histories were measured during the thermal decomposition of isoxazole (C3H3NO) and the first-order rate coefficients of C3H3NO → HCN + CH2CO reaction were determined.

A mid-IR laser diagnostic for HCN detection

Marangoni, Marco;
2022-01-01

Abstract

Hydrogen cyanide (HCN) is a major source of prompt-NOx formation especially in fuel-bound nitrogen systems. To date, there is still a significant disagreement between experimental data and theoretical predic- tions of the rate coefficients of combustion reactions involving HCN as a prompt-NOx precursor. Accurate modeling of NOx formation would greatly benefit from a diagnostic capable of performing high-fidelity measurements of HCN formation/consumption time-histories. In this study, a laser diagnostic is developed for sensitive and selective HCN sensing by probing its most intense absorption feature in the mid-infrared (MIR). The diagnostic is based on difference-frequency generation (DFG) between a CO2 gas laser and an external-cavity quantum cascade laser in a nonlinear orientation-patterned gallium arsenide crystal which results in a DFG laser tunable over 11.56 − 15 μm. HCN measurements were carried out at the peak of the Q-branch of its strong ν2 vibrational band near 14 μm. Pressure dependence of the absorption cross-section was investigated at room temperature over the pressure range of 0.07 − 1.07 bar. Temperature-dependent absorption cross-section measurements were conducted behind reflected shock waves over the temperature range of 850 − 3000 K. The diagnostic was demonstrated in reactive experiments in a shock tube where HCN mole fraction time-histories were measured during the thermal decomposition of isoxazole (C3H3NO) and the first-order rate coefficients of C3H3NO → HCN + CH2CO reaction were determined.
2022
HCN, Isoxazole decomposition; Absorption cross-section; Shock tube; Difference-frequency generation
File in questo prodotto:
File Dimensione Formato  
1-s2.0-S1540748922004485-main Proc Comb Institute _ 60.pdf

Accesso riservato

: Post-Print (DRAFT o Author’s Accepted Manuscript-AAM)
Dimensione 1.54 MB
Formato Adobe PDF
1.54 MB Adobe PDF   Visualizza/Apri
Proc Comb Inst _ accepted _ 60 _ Re Public embargo 24.pdf

embargo fino al 28/02/2025

: Post-Print (DRAFT o Author’s Accepted Manuscript-AAM)
Dimensione 842.84 kB
Formato Adobe PDF
842.84 kB Adobe PDF   Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1227394
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 4
  • ???jsp.display-item.citation.isi??? 6
social impact