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

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 experi-mentally 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. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The lower flammability limits (LFL) of H2/CO/air mixtures with N2 and CO2 dilutions were systematically studied at various initial pressures using an 8L cylindrical vessel and metal wire fusing as an ignition source. The results showed that LFL decreased with increasing H2 fractions, and CO2 had a stronger dilution effect than N2. The LFL of diluted syngas slightly decreased with increasing initial pressures. Kondo's extended Le Chatelier's Rule provided a satisfactory estimation of LFL, and Zabetakis' logarithmic function expression showed better accuracy in predicting LFL at different initial pressures than linear regression.