Limiting oxygen concentration and minimum inert concentration of fuel-air-inert gaseous mixtures evaluation by means of adiabatic flame temperatures and measured fuel-air lower flammability limits
- The present paper aims to re-examine the validity of the linear correlation found between AFTLOC, the adiabatic flame temperature at the apex of the flammability range of fuel-air-inert mixtures (where LOC, the Limiting Oxygen Concentration, is measured) and AFTLFL, the adiabatic flame temperature at the lower flammability limit of fuel-air mixtures (LFL). New sets of experimental measurements of LFL and LOC referring to fuel-air mixtures diluted with N2, CO2 and H2O(vap) from trusted literature sources form a comprehensive database for such evaluation. Both the slope and intercept of correlations AFTLOC = a + b*AFTLFL are dependent on the nature of inert gas and on initial temperature. Based on the linear correlation between AFTLOC and AFTLFL, a procedure for calculation of LOC and MIC (Minimum Inert Concentration) of fuel-air-inert mixtures is presented, using measured or calculated LFL of fuel-air mixtures and their corresponding AFT. The method predicts with reasonable accuracy LOCThe present paper aims to re-examine the validity of the linear correlation found between AFTLOC, the adiabatic flame temperature at the apex of the flammability range of fuel-air-inert mixtures (where LOC, the Limiting Oxygen Concentration, is measured) and AFTLFL, the adiabatic flame temperature at the lower flammability limit of fuel-air mixtures (LFL). New sets of experimental measurements of LFL and LOC referring to fuel-air mixtures diluted with N2, CO2 and H2O(vap) from trusted literature sources form a comprehensive database for such evaluation. Both the slope and intercept of correlations AFTLOC = a + b*AFTLFL are dependent on the nature of inert gas and on initial temperature. Based on the linear correlation between AFTLOC and AFTLFL, a procedure for calculation of LOC and MIC (Minimum Inert Concentration) of fuel-air-inert mixtures is presented, using measured or calculated LFL of fuel-air mixtures and their corresponding AFT. The method predicts with reasonable accuracy LOC and MIC of fuel-air-inert mixtures (relative deviations ranging between -14 and +17% when calculated and measured LOC and MIC for fuelair-nitrogen and fuel-air-carbon dioxide at ambient initial conditions are examined).…