Lower flammability limit of hydrogen/air mixture under different electrode parameters, initial pressure and diluent gas

Abstract

The investigation of the lower flammability limit (LFL) is essential to the security application of hydrogen. In the present work, the LFL of hydrogen under a variety of conditions is systematically measured. The effect of electrode gap length (2–4 mm), electrode shape (30°, 90°, and spherical) and initial pressure (40–200 kPa) on the LFL of hydrogen/air mixture are analyzed. It shows that the LFL of hydrogen/air mixture increases with the increase of initial pressure and decreases with the increase of electrode gap length. The LFL of 30° electrodes is higher than that of 90° and spherical electrodes at the initial pressure higher than 80 kPa. Besides, the LFL of hydrogen/air mixture diluted with inert gas (CO2 and N2) at different initial pressure (50 kPa, 100 kPa, and 150 kPa) is investigated. The LFL of H2/air/CO2 mixture increases with increasing CO2 concentration, while the LFL of H2/air/N2 mixture is almost unchanged under different N2 concentration.