Extinction of hydrogen enriched methane and propane flames through perforated plates flame arrester elements with varying thickness

This study investigated the extinction of premixed flames involving methane, propane, hydrogen and air by using a flame arrester element composed of multiple perforated plates. Six stoichiometric mixtures were considered in the experiments, namely, [100%CH4]/air, [25%C3H8+75%H2]/5%He/air, [100%CH4]/10%He/air, [40%C3H8+60%H2]/10%He/air, [75%CH4+25%H2]/air and [10%C3H8+90%H2]/air. Helium was added to three of the mixtures to increase the thermal conductivity and produce different Lewis (Le = 0.72 to 1.36) and Zeldovich numbers (Ze = 4.98 to 8.45). Experiments were performed in a closed duct at 40 kPa and 295 K using flame arrester elements with varying thickness (δplates = 18 to 150 mm) and with orifice diameters of 1.0 and 2.0 mm. The mixtures and arrester configurations were tested at least three times, totaling 240 experiments. A one-dimensional heat-transfer model was also employed to strengthen the interpretation of the experimental observations. The results indicated that mixtures with similar Le and high Ze were successfully extinguished once a sufficiently thick perforated plates assembly was used.