Effect of spark duration on explosion parameters of methane/air mixtures in closed vessels

The paper outlines an experimental study on influence of the spark duration and the vessel volume on explosion parameters of premixed methane–air mixtures in the closed explosion vessels. The main findings from these experiments are: For the weaker ignition the spark durations in the range from 6.5 μs to 40.6 μs had little impact on explosion parameters for premixed methane–air mixtures in the 5 L vessel or 20 L vessel; For the same ignitions and volume fractions of methane in air the explosion pressures and the flame temperatures in both vessels of 5 L and 20 L were approximately the same, but the rates of pressure rises in both vessels of 5 L and 20 L were different; The explosion indexes obtained from the measured pressure time histories for both vessels of 5 L and 20 L were approximately equal; For the weaker ignition with the fixed spark duration 45 μs the ignition energies in the range from 54 mJ to 430 mJ had little impact on the explosion parameters; For the same ignition and the volume fractions of methane in air, the vessel volumes had a significant impact on the flame temperatures near the vessel wall; The flame temperatures near the vessel wall decreased as the vessel volumes increased.

► Spark durations from 6.5 μs to 40.6 μs have little impact on explosion parameters of methane–air.
► Explosion pressure and flame temperature in 5 L vessel are approximately equal to those in 20 L vessel.
► Rates of pressure rises in both vessels of 5 L and 20 L are different.
► Ignition energies from 54 mJ to 430 mJ have little impact on explosion parameters in 5 L or 20 L vessel.
► Vessel volumes have a significant impact on the flame temperatures near the vessel wall.