Explosion hazards and mechanisms of hydrogen at elevated temperature and pressure

To ensure the safe utilization of hydrogen energy and promote the rapid development of the hydrogen industry, the explosive characteristics and reaction mechanisms of hydrogen at high temperatures and pressures have been studied through both experiments and simulations. The results indicate that the initial pressure is positively correlated with the lower flammability limit of H₂ but is insensitive to changes in initial temperature. Further investigation into the upper flammability limit reveals a significant nonlinear relationship with the initial pressure, following a power function increase. In contrast, the effect of initial temperature on the upper flammability limit shows a more straightforward linear characteristic. Explosion pressure increases proportionally with initial pressure and decreases linearly as the initial temperature rises. The laminar burning velocity of hydrogen at various temperatures and pressures is measured using the constant volume method and compared with simulation results. Sensitivity analysis is employed to identify the key controlling reactions of hydrogen explosions at different pressures and temperatures and to explore their synergistic effects. Finally, a predictive model for hydrogen explosion pressure at high temperatures and pressures is developed using the K-Nearest Neighbors (KNN) algorithm through machine learning.