An experimental investigation of the explosion characteristics of dimethyl ether-air mixtures

• Explosion characteristics of DME (dimethyl ether) -air mixtures are systematically investigated.
• The effect of initial pressure on the flammability limits is quantitatively investigated.
• Laminar burning velocity is estimated by using both a theoretical model and PREMIX simulation.
• Dimensionless radius of the flame for DME-air at different initial pressure is analyzed.

In this work, experiments are performed to study the explosion characteristics of DME (dimethyl ether) -air mixtures using a standard 20-L spherical explosion test apparatus. The experimental data reported in this paper includes: the maximum explosion pressure (pmax), flammability limits, maximum rate of pressure rise (dp/dt)max, and combustion properties (i.e., laminar burning velocity, flame radius) of DME-air mixtures at different initial conditions. The experimental results indicate that the variation between pmax and DME concentration (CDME) exhibits a typical inverse “U” shaped behavior, with the peak pmax at slightly larger than the stoichiometric concentration. pmax is also found to decrease as the initial pressure goes down. As the initial pressure decreases from 100 kPa to 40 kPa, the LFL (lower flammability limit) is observed to vary slightly, while the UFL (upper flammability limit) is found to have a more significant drop. The relation between (dp/dt)max and CDME behaves similarly as that of pmax as a function of CDME, and the explosion pressure rises more abruptly at higher initial pressure. A satisfactory agreement is also found between the laminar burning velocity determined experimentally from the pressure measurement and that computed by PREMIX simulations. The present experimental results also show that the increase of the dimensionless radius of the flame is slower at higher initial pressure.