Explosion risk assessment of a liquid organic hydrogen carrier system by using toluene–methylcyclohexane on varying hydrogen storage scenarios

The effects of phase state, delayed ignition time, mixing ratio, addition of hydrogen, and stoichiometric ratio on the explosion risk of toluene–methylcyclohexane (MCH) mixtures was investigated. Our findings indicated that the addition of 10% hydrogen to the toluene–MCH mixture exhibited a highest explosion risk, compared to other operating conditions. Gaseous toluene–MCH mixtures had a higher explosion risk than did liquid droplets of these mixtures. Of the toluene–MCH mixtures prepared in this study, that with a mass ratio of 7:3 had the highest explosion risk. Although the explosion intensities of the toluene–MCH mixtures were higher than those of their individual components, their explosion sensitivity was lower than that of MCH alone. Toluene had the lowest explosion risk. Toluene or MCH droplets can produce high-intensity explosions even in an oxygen-lean environment. These results indicate that the physical and chemical properties (and thus the combustion performance) of toluene–MCH mixtures are substantially affected by the mixing ratio and operating conditions. Overall, explosion prevention and control measures must be carefully considered when handling toluene–MCH mixtures for various hydrogen storage scenario, such as heating, mixture, or hydrogenation.