Experimental study on explosion characteristics of ethanol gasoline–air mixture and its mitigation using heptafluoropropane

Highlights: • FM-200 is proved to be effective in mitigating ethanol gasoline explosion. • Blue, yellow to purple of the flame mitigated by FM-200 are observed. • The effect of initial volume on flame speed and overpressure is examined. • Products of explosion and its mitigation are analyzed and compared via GC–MS data. -- Abstract: Ethanol gasoline is being widely used as a new environmentally friendly and energy-saving alternative energy, and the control/reduction of its fire/explosion risk has become an important aspect, not only for its production and storage, but also for its transport and application. This study aims to investigate the explosion characteristics of ethanol gasoline and its mitigation using heptafluoropropane in a restricted vessel. The flame propagation was visualized using a Phantom high-speed camera at 3000 fps, the explosion overpressure was measured using PCB pressure sensors, and the gas released from the vent was collected and analyzed using a gas chromatography-mass spectrometer. The results indicate that heptafluoropropane has a good suppression effect on the flame propagation speed and the explosion overpressure. The maximum overpressure of an ethanol gasoline explosion is approximately 456 kPa, and the overpressure reduction exceeds 60% when the concentration of heptafluoropropane addition is 10%, whereas an explosion is completely mitigated when the concentration of heptafluoropropane continuously increases. In addition, different flame colors during the mitigation process, such as blue, yellow, and purple, were observed and analyzed. The results of this study will be valuable for further understanding ethanol gasoline explosion mitigation and designing optimum heptafluoropropane explosion mitigation systems.