Rich flammability limits of fuel mixtures involving hydrogen at elevated temperatures

Characterization of the effects of hydrogen addition in premixed methane/air flames

“…However, close to the lean flammability limits, the stability of the flame decreases and flame extinction phenomena may occur. A solution to increase the stability of the flame is to add small amounts of hydrogen into the mixture [1][2][3]. Several studies have been performed to estimate the impact of H 2 addition on the stability, on the reactivity and on the pollutant emissions of methane-air flames.…”

The upper flammability limit of methane/hydrogen/air mixtures at elevated pressures and temperatures

“…A comparison is made between the results obtained in this study using the tube method and those of Wierzba and Ale [6] and Van den Schoor et al [10], at atmospheric pressure and ambient temperature (Fig. 8).…”

“…At an initial pressure of 10 bar, however, a deviation from this linear dependence is found. Wierzba and Ale [6] have found similar deviations for the UFL of methane/hydrogen/air mixtures at atmospheric pressure at an initial temperature of 300 • C for a hydrogen fuel molar fraction of 50% and at 200 • C for pure hydrogen as fuel. They determined the flammability limits in a stainless steel cylindrical tube with an internal diameter of 51 mm and a length of 1 m. Ignition was initiated by an electric spark discharge.…”

“…To safely handle these mixtures knowledge of their flammability limits is indispensable. Inspection of the literature shows that Wierzba and Ale [6] have determined the upper flammability limit (UFL) of methane/hydrogen/air mixtures at atmospheric pressure and initial temperatures up to 350 • C, whereas Pahl [7,8] has determined the UFL of these mixtures at ambient temperature and initial pressures of 1, 10 and 100 bar. However, no data could be found in the open literature regarding the influence of both initial pressure and temperature on the flammability limits of methane/hydrogen/air mixtures.…”

Experimental study of flammability limits of natural gas?air mixture

“…As we know, a successful ignition would induce a rapid pressure increase and temperature rise within a short time, as well as produce a propagating flame front that could be readily observed. Previous gas flammability limit data were obtained mainly in flammability tubes, in those tests, a gas mixture in a vertical tube was ignited and flame propagation was inspected by a visual criterion [1,2]. The wall quenching has a significant effect on the flammability measurement in flammability tube.…”