A calibration and sampling technique for quantifying the chemical structure in fires using GC/MSD analysis

Abstract

This work presents an approach to measure, calibrate, and verify local concentrations of combustion products in pool fires steadily burning in a quiescent environment.This study describes a method that can be used to measure and verify the chemical species present in a fire. Such information is needed to assist in the development and validation of the chemistry subroutines in computational fluid dynamic fire models.Samples are extracted along the centerline of pool fires using a thermal quenching probe. Gas species volume fractions are analyzed using a custom Agilent 5977E Series gas chromatograph fitted with a permanent gas dual-column comprised of a Molsieve 5 Å and PoraBOND Q capillary columns in parallel flowing into mass selective and thermal conductivity detector. The system can identify and quantify a variety of stable reactant, intermediate, and product species collected from the fire, including several condensable species (eg, water, methanol, ethanol, and acetone).The time-weighted average soot mass fraction is determined using a gravimetric sampling method. In order to solidify the legitimacy of the measured gas composition, the results are verified by implementing different techniques, including the determination of the carbon to hydrogen ratio, calculating the argon to nitrogen ratio, and comparing the total moles estimated from the chromatogram peaks to the total moles of the injected sample.

The design and performance of a second-generation phi meter

“…The gas analyzer included two non-dispersive infrared sensors and a paramagnetic sensor to provide real-time CO 2 , CO, and O 2 concentration measurements, respectively. The grab sample container was used to collect well-mixed gas samples that would be analyzed via a gas chromatograph/mass spectrometer (GC/MS) system to estimate time-averaged gas species concentrations [9]. Grab samples were extracted for a 1 min period 70 sec prior to the door opening.…”

“…Applications of molecular spectroscopy, such as laser-induced fluorescence (LIF) and laser-induced breakdown spectroscopy (LIBS), are shown to measure the equivalence ratio using non-extractive techniques [1][2][3][4][5] and require extensive corrections to address low signal to noise ratios. Using an extractive sampling approach, gas chromotography with mass selectivity detectors can provide a time-averaged equivalence ratio [6][7][8][9]. For real-time applications, a phi meter, initially proposed by Babrauskas et al [10], has been utilized for several applications [11][12][13][14][15][16][17] to make in-situ global equivalence ratio measurements.…”