Calculated adiabatic flame temperature – a tool for ascertaining the minimum inert concentraction of fuel-nitrous oxide-inert gaseous mixtures

Abstract

A previous correlation of CAFT (Calculated Adiabatic Flame Temperature) found for limit fuel-air and inert-diluted fuel-air gaseous mixtures is revisited, aiming to test its validity for mixtures where air is replaced by nitrous oxide. The flammability of these mixtures is less studied when compared to fuel-air, especially in respect to the influence of inert additives on flammability limits. The paper examines several data sets reported in literature and outlines the good correlation found between the CAFT at the lower flammability limit of fuel-nitrous oxide (CAFTLIE) and the CAFT at the extreme point of flammability range, i.e. EIP, the extreme inertization point (CAFTEIP) of fuel-nitrous oxide-nitrogen gaseous mixtures. The correlation can be further used to predict the MIC (Minimum Inert Concentration) for nitrogen-diluted fuel-nitrous oxide gaseous mixtures, using only the lower flammability limit (LIE) of fuel-nitrous oxide and the corresponding adiabatic flame temperature (CAFTLIE).