Influence of Initial Pressure and Vessel’s Geometry on Deflagration of Stoichiometric Methane–Air Mixture in Small-Scale Closed Vessels

Abstract

In the present work, experimental data on closed vessel explosions of stoichiometric methane–air mixture are reported for mixtures at ambient initial temperature and various initial pressures between 0.2 and 1.2 bar for small-scale closed vessels. The data are collected as pressure–time records in a spherical vessel and two cylindrical vessels with central ignition. The influence of initial pressure and vessel size and shape on maximum rates of pressure rise and deflagration (severity) indices is examined. In each explosion vessel, a linear correlation of the maximum rate of pressure rise with the initial pressure is found. At all pressures, the rates of pressure rise and the severity factors reached in the spherical vessel exceed those reached in cylindrical vessels as a result of differences in heat losses within these enclosures. The experimental deflagration indices are compared with the adiabatic deflagration indices, calculated by means of peak explosion pressures and laminar burning velocities; the heat losses in various enclosures explain the observed differences. The peak explosion pressures and laminar burning velocities are also used to calculate the dimensionless deflagration indices, found to be less influenced by vessel’s size and shape.

Propagation of CH4-N2O-N2 Flames in a Closed Spherical Vessel

“…For all examined N 2 -diluted CH 4 -N 2 O mixtures the laminar combustion velocities decrease with initial pressure, within the examined range of initial conditions. A decrease of the laminar combustion velocity at initial pressure increase was already reported in the literature for other flammable gaseous mixtures, under various initial conditions [25,37,[39][40][41]43,44,53].…”

“…The dependence of laminar combustion velocities on the initial pressure was analyzed using an empirical power law [38,[43][44][45][46][47]56]:…”

“…The runs were performed for stoichiometric and lean (ϕ = 0.8) CH 4 -N 2 O flames in the presence of N 2 at room temperature and various initial pressures (0.5-2.0 bar). Other details can be found in previous papers [43,44].…”

Effect of Inert Gas CO2 on Deflagration Pressure of CH4/CO

“…Mitu et al 33 studied the effect of inert gas on a methane–air deflagration propagation index and the effect of initial pressure on the deflagration of methane–air in a small airtight container. 34 In addition, in the aspect of LPG, Razus et al. 35 , 36 studied the deflagration characteristics of LPG.…”

Effects of Initial Temperature on the Deflagration Characteristics and Flame Propagation Behaviors of CH4 and Its Blends with C2H6, C2H4, CO, and H2

“…To date, extensive research has been conducted on the deflagration characteristics of methane − and suppression techniques. , The deflagration characteristics of other single gases, such as ethylene, propane, and hydrogen, have been extensively studied in the literature, − and the deflagration characteristics of mixtures of these gases have also been considered. − The explosive characteristics of flammable gas mixtures (explosion pressure ( P )/peak explosion pressure ( P max ) and pressure rise rate (d p /d t )/maximum pressure rise rate (d p /d t ) max )) are determined under various conditions (pressures and/or temperatures, concentration, humidity, explosive vessels of various volumes, and ignited by sources with various energies). The data refer to an individual fuel, such as hydrogen and gaseous alkane fuels, or a composite fuel (liquefied petroleum gas, gasoline, and ethanol). − For example, Razus experimentally measured the deflagration parameters of propane-air mixtures (2.50–6.20 %) in vessels of different shapes at various initial temperatures (298–423 K) and pressures (0.3–1.2 bar) .…”