Study On Spontaneous Ignition Of High-pressure Hydrogen Leak From A Pipe

Hydrogen has the advantages of renewable,clean and pollution-free,and has higher energy efficiency.Hydrogen storage technology is an important part of the hydrogen development process.High-pressure hydrogen storage has proven to be one of the most economical hydrogen storage methods.However,the leakage of high-pressure hydrogen will spontaneously ignite,which will cause fires and explosions,restricting the promotion of hydrogen energy.The phenomenon of spontaneous ignition of high-pressure hydrogen leakage is a complex physico-chemical process.At present,people know very little about it.In this context,a combination of experiments and numerical simulations is used in this thesis to study the spontaneous combustion of high-pressure hydrogen leaks.1)The occurrence of spontaneous combustion in the tube and the critical regulation of spontaneous ignition is studied in the thesis with the help of pressure and light record systems.The influence of factors such as the initial release pressure,tube length,tube diameter,and the shape of the pre-cracks on the occurrence of spontaneous combustion were mainly analyzed.It was found that when the length of the tube is less than 1100 mm,the critical ignition pressure decreases with the increase of the tube length.After the tube length increases to 1500 mm,the critical ignition pressure increases instead.Under the condition of "Y" pre-crack,10 mm diameter and 1100 mm tube length,the critical pressure of spontaneous ignition can be even lower than 4.1MPa.The shape of the pre-crack also has a certain effect on the spontaneous combustion of hydrogen.Compared with the "Y" and "+" two pre-cracks,the critical ignition pressure corresponding to the "-" crack is higher under the same tube size.2)Open Foam is used in this thesis to numerically simulate the spontaneous ignition of high-pressure hydrogen leakage in the shock tube according to the relevant parameters of the experiment.The correctness of the results of numerical simulation is proved.The results show that the increase of the initial hydrogen pressure will greatly increase the temperature of the hydrogen-air mixture after the shock,generate lots of free radicals at the front of the hydrogen-air mixture,and promote the occurrence of hydrogen self-ignition.The length of the tube hardly affects the development of shock and the change of composition.Longer the tube,longer the time of the hydrogen-air mixture remain in the tube,which promote the occurrence of hydrogen self-ignition.Through experiments and simulation studies,some relevant laws of the phenomenon of spontaneous ignition of high-pressure hydrogen leakage are drawn,a theoretical basis is provided for the development and safe use of hydrogen storage equipment,and a foundation is laid for further understanding of the process of spontaneous ignition of high-pressure hydrogen leakage.