Explosion mechanisms of nano- and micro-sized dust in interconnected vessels

The overpressure characteristics and explosion mechanism of micron and nano polymethyl methacrylate (PMMA) dust in interconnected vessels were studied with different pipe diameters, pipe lengths and volume ratios. The results show that 150 nm PMMA dust exhibits more intense explosion intensity. Relative to 30 mu m PMMA particles, the explosion overpressure is more significantly affected by the pipe diameter due to the faster combustion rate for 150 nm PMMA particles. The increase in volume ratio positively affects the increase of explosion overpressure, and the highest increase is 463 % for 30 mu m PMMA. Due to the change in the relative relationship between energy loss and combustion heat release in the pipe, the explosion intensity of 150 nm PMMA with different pipe diameters increases to a certain extent with the increase of pipe length, while the explosion intensity of 30 mu m PMMA decreases. Under identical circumstances, the 150 nm PMMA dust cloud inside the second vessel failed to ignite, while the 30 mu m explosion successfully diffused into the second vessel. The explosion in the second vessel is mainly due to the different flame energy entering the second vessel. The heat transfer rate between the single 30 mu m PMMA particle and the external environment is significantly higher than 150 nm, resulting in an instantaneous quenching of the 30 mu m PMMA flame front at the initial entry stage into the pipe.