Detonation Wave Propagation and Interaction with Transportation Infrastructure

Propagation of the blast wave caused by hydrogen-air detonation, and the blast wave interaction with a transportation infrastructure are studied. A cylindrical blast wave and a planar blast wave are investigated. RHT-35MPA concrete is the material used for a wall to model the interaction. The blast wave-structure interaction shows that the structure can fail in different modes depending on the material properties. Concrete has failure features quite distinct from metals such as steel and aluminum. H YDROGEN has emerged as a prime candidate as an alternative fuel in the strategy to reduce dependence on fossil fuels. Hydrogen has advantages over hydrocarbon fuels because it doesn’t produce greenhouse gases such as CO2. Hydrogen can be produced from a wide range of feedstock such as natural gas, ethanol and brewery byproducts. While the economics are being debated, it is generally accepted that hydrogen is cost-competitive if factors such as global warming are included in the cost considerations. Associated with the increasing use of hydrogen are several issues that must be addressed. Safety is one such important issue. Safety considerations must be included in the planning and implementation of the hydrogen transportation infrastructure. Hydrogen for transportation use may take different forms depending on the technology being considered. These form include gaseous, liquid, slush, and hydrides. The hazard issues associated with each form must be assessed for a systematic evaluation of the various technologies. Gaseous hydrogen is much lighter than air, highly diffusive, conducive to flow-induced static charge generation, leak-prone, colorless and odorless. As it is a very light gas, it requires high pressure storage (5000-10,000 psi). High pressure rupture and flying debris are of greater concern. Pipe whip caused by leak events, oxygen displacement in confined spaces, and gas jet impingement damage can occur in accidents involving stored hydrogen. Hydrogen is flammable with no luminous flame and no toxic combustion products. It has a large flammability range—4%-74% by volume—and can deflagrate at low pressures and detonate at high pressures. It also has low ignition energy—0.02 mJ-1mJ spark to ignite a deflagration—and has a modest autoignition temperature of ~575 o C. Metals and plastics are prone to hydrogen embrittlement posing challenges to storage and piping. Boiloff losses from liquid hydrogen storage tanks are large and the gas quickly diffuses into the surroundings creating hazardous situations. Flow-induced static charge generation is high. Rapid phase change from liquid to vapor can lead to explosive pressure levels. Condensing gases from air contact cause easy contamination. Colorization and odorization to improve detection are difficult because additives freeze at cryogenic storage temperatures. Cryogenic burns, especially eyes, lung damage from cold vapor inhalation, and hypothermia are possible health hazards. Air condensation can result in oxygen-rich environment which may create favorable ignition scenarios. High thermal gradients from cryogenic to ambient temperature induce high thermal stresses on storage system components. Materials have low specific heats at low temperatures which reduce the time lag of events that follow an explosion. The safety aspects of slush hydrogen are very similar to those of liquid hydrogen. It can plug passageways and suddenly build up pressure. Slush can also be contaminated by condensing gases. There are additional flammability concerns associated with organic hydrides. Some have low autoignition temperatures. And some are also toxic. The main advantage of hydrides is that the operating pressures are low. However, hydrogen decomposition may require temperatures close to H2 autoignition temperature. The organics released during thermal decomposition may have health effects as well as the potential to foul components of the power