Experimental study on the lower flammability limit of N2 and CO2 diluted H2/CO/air mixtures at high initial pressure

Abstract

The lower flammability limits (LFL) of H2/CO/air mixtures over a wide range of H2 fractions (0–100 vol%) with N2 (0–67 vol%) and CO2 (0–67 vol%) dilutions were systematic experimentally studied at various initial pressures (100 kPa–500 kPa) via an 8L cylindrical vessel and using the metal wire fusing as ignition source. The results showed that LFL decreased with the growth of H2 fractions under all measured initial pressures. Due to the larger heat capacity and chemical kinetic effect, CO2 presented a stronger dilution effect on LFL than N2. LFL of diluted syngas slightly decreased with the increase of initial pressures. Kondo's extended Le Chatelier's Rule presented satisfactorily application on estimating LFL of diluted mixtures based on accurate measurements. Moreover, a simple expression of logarithmic function proposed by Zabetakis provided the better accurate prediction on LFL of syngas at different initial pressures than linear regression.