Radiation Transport Measurements in Methanol Pool Fires with Fourier Transform Infrared Spectroscopy

Abstract

Pool fires rely on radiation and conduction heat feedback from the combustion process to the liquid surface to vaporize the fuel. This coupled relationship determines the fuel burning rate and thus the fire structure and size. Radiative heat transfer is the dominant heat feedback in large pool fires. Species concentrations and temperatures have large influence on the radiative heat transfer in the fuel rich-core between the flame and the pool surface. To study radiative transport in the fuel-rich core, an experimental method was developed to measure radiative absorption through various pathlengths inside a 30 cm diameter methanol pool fire by using a Fourier Transform Infrared Spectrometer with N₂ purged optical probes. The measured spectra are used to estimate species concentration profiles of methanol, CO, and CO₂ in the fuel rich core by fitting predictions of a spectrally resolved radiation transport model to the measured spectra. Results show the importance of reliable temperature measurements for fitting the data and the need for further measurements to further understand the structure of fuel rich cores in pool fires.