Numerical Study On Spontaneous Ignition Process Of Pressurized Hydrogen Release

In the situation of global energy shortage and the increasingly serious problem ofenvironment, new energy has been recognized as the engine to boost the next round ofworld economic growth. As a large country with major power generation andconsumption of coal, developing new energy plays an important role in the sustainablestrategy of China. Among the many new energy resources, hydrogen has beenwidespread concern around the world due to its high efficiency and no pollution. Thestorage methods of hydrogen plays a vital role in the production, transportation and use.Pressurized hydrogen storage has been proven to be the best economic way among allthe storage methods of hydrogen, but the leak of pressurized hydrogen has always beena great security problem in the hydrogen energy promotion. The spontaneous ignition ofpressurized hydrogen leak is a very complex physical and chemical processes so thatpeople know little about it. In this situation, this thesis carried out the followingresearch work and has achieved some results.This thesis focuses on the leaks of pressurized hydrogen with typical horizontalshock-tube as research object. Based on the open code CFD package OpenFOAM, thesonicFoam solver is used to simulate the characteristics of the leak of pressurizedhydrogen. Finite volume method, Euler discrete method, Discrete Gaussian linearinterpolation method, and PISO method are used to simulate the pressure and velocityfield.The simulation for the spontaneous ignition of the pressurized hydrogen leak iscarried out and the simulation results are compared with the experiment results to proveits effectiveness. By comparing different initial pressures and temperatures of hydrogen,different diameters and lengths of the downstream tubes and different amount of DMEadded to hydrogen, the numerical study reveals that all those aspects mentioned aboveare essential to leading the spontaneous ignition in the shock-tubes. The results showthat with higher initial pressure and temperature, the shock wave gains moretemperature which leads to a more intense ignition. The reducing of the tube diameterwill increase the mix of the shock wave which promotes the combustion. However, ifthe diameter of the tube is too small, there won’t be sufficient mixed gas for thecombustion which leads to a less intense combustion. The increase of the length of thetube will promote the mix of hydrogen and air so that the combustion can be much more intense. But if the length of the tube is too large, the hydrogen will take away too muchheat during its diffusive process and the combustion will be suppressed. With more andmore DME added to the hydrogen, the combustion will be promoted in the first placeand then suppressed. In general, the combustion characteristics of the mixed gas areconsistent with hydrogen.This thesis reveals some characteristics about the spontaneous ignition of thepressurized hydrogen leak, makes contributions to the design, produce and use of thehydrogen storage devices and can be the foundation of deeper understanding of thespontaneous ignition of pressurized hydrogen leak.