Hydrogen dispersion

Furthermore, even if no ignition takes place, escaping hydrogen may accumulate into closed spaces adjacent to the source posing asphyxiation hazard for the people being there. Hydrogen dispersion may be considered safe only when no ignition occurs and no space confinement exists. 

The loop reactor provides very efficient hydrogen dispersion, with the heat exchanger surface being almost unlimited. It is especially useful when the space-time yield is very high (fast reaction, high substrate concentration) or when a low reaction temperature is required. 

Figure 14.12 shows the shares of the various hydrogen transport and distribution means for the above scenarios. It can be stated that liquid hydrogen is a preferred option for medium amounts of hydrogen dispersed over a large area, which is mainly... 

Hydrogen has very high diffusivity. This ability to disperse in air is considerably greater than gasoline and is advantageous for two main reasons. Firstly, it facilitates the formation of a uniform mixture of fuel and air. Secondly, if a hydrogen leak develops, the hydrogen disperses rapidly. Thus, unsafe conditions can either be avoided or minimized. 

Of all the approaches, the k-6 model offers the highest relative independence of empirical relations. It appears to be the only one to allow a proper simulation of hydrogen dispersion, because it meets the requirements of describing effects such as turbulence energy in the gas cloud, interaction of the cloud with the atmospheric wind field, the characteristic positive buoyancy, transient sources with initial momentum, and last but not least, gas flow in a complex geometry (buildings, terrain). K-e modeling has been realized in a variety of... 

The 3D finite volume code ADREA-HF was developed for the computation of the atmospheric dispersion of heavy gas clouds in complex terrain. It contains a one-equation turbulence submodel taking account of two-phase processes [3]. The code has been applied to ammonia, propane, chlorine, and also buoyant releases. It has recently been tested against the BAM hydrogen release experiments. The calculational results for one of the trials are given in Fig. 8-8 showing the hydrogen dispersion near buildings [111]. 

A k-e atmospheric dispersion model POLLUT was developed at the TU Munchen [93] to describe hot gas plumes escaping from stacks of power plants. The code was used in a DLR study [45] to investigate hydrogen dispersion upon accidents with LH2 powered cars releasing their tank contents both in open terrain and in a road tuimel. 

The Battelle k-c model BASSIM originally designed for hydrogen combustion in nuclear containments (see section 3.4.5.) was also applied to the above mentioned LH2 spill experiments conducted by the BAM, Berlin, for predictive calculations providing reasonable qualitative results for 3D effects of hydrogen dispersion behavior [94]. 

Accidents If large amounts of hydrogen are inhaled, move the person to fresh air and seek medical attention at once. In the event of a leak, remove all ignition sources and allow the hydrogen to disperse with increased ventilation. Hydrogen disperses rapidly in normal open environments. Respiratory protection may he necessary in the event of a release in a confined area. 

Blister formation or raised areas in the cladding of spent nuclear fuel can lead to breach of the aluminium cladding and subsequent corrosion of the fuel core. This blistering is a manifestation of internal gas pressurization and/or internal oxide formation. Blistering is facilitated under coatings and oxides because hydrogen has low diffusion rates in aluminium, so trapped hydrogen disperses slowly. Blisters can be formed by several mechanisms. 

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