An estimate of the correction applied to radiant flame measurements due to attenuation by atmospheric CO2 and H2O

A narrow band statistical model has been used to estimate the uncertainty introduced into radiative heat flux measurements from fires which is attributable to attenuation by atmospheric H2O and CO2. The flames were assumed to be soot-dominated with blackbody emission characteristics. The ambient surroundings near the flames were assumed to be homogeneous with the total pressure being fixed at one atmosphere. Atmospheric CO2 concentrations were held constant at 0.04 kPa and the water vapor concentrations varied between 0.55-5.63 kPa based on temperature and relative humidity. The remaining partial pressures were accounted for by O-2 and N-2. Correlations to estimate atmospheric attenuation are given over a range of conditions that include path length (10-200 m), ambient temperature (19-35degreesC), source temperature (1000-1600degreesC) and relative humidity (0.25-1.0) as parameters. The results of these calculations indicate that, over this range of conditions, the radiant flux can be attenuated by as much as 42%. (C) 2002 Elsevier Science Ltd. All rights reserved.