Physicists have found that if you burn a mixture of hydrogen and air in the gap thickness, the combustion front can propagate in a highly unusual fractal trajectories. This behavior is caused by the high diffusion rate of hydrogen molecules and is not typical of other combustible gases, write scientists in Physical Review Letters. The results obtained have not only aesthetic value, but also crucial for the development of regulations for hydrogen storage and work with him in a small confined space, in particular in fuel cells.
As safe for the environment electroenceph and mobile energy sources are increasingly adopting hydrogen fuel cell: these elements are used to power spacecraft, many countries are testing hydrogen passenger aircraft specifically for hydrogen technology create field hydrogen generators. Read more about the principles of operation of fuel cells you can read in our article “Chemistry and Tok”. However, with all the advantages of hydrogen fuel cells with them rather unsafe to work: the hydrogen molecule is very small and is able to seep including through solid walls, which can lead to a gas leak and subsequent fire or explosion.
However, if the hydrogen in the gas mixture is small, then such mixtures are not dangerous. At atmospheric pressure the minimum content of hydrogen in which a mixture of oxygen may catch fire — about 4 percent. In addition, the combustion reaction is much worse than going to a limited extent: it is believed that the resulting flame is very quickly extinguished due to the limited diffusion. However, the features of the processes of ignition and combustion of hydrogen in mixtures with air in confined spaces and with a small content of the fuel is practically not been studied, and it is such a situation very likely in fuel cells as a result of the leaks.
Physicists from Spain and Germany under the leadership of Mario Sanchez-Saens (Mario Sánchez-Sanz) from the Complutense University of Madrid Carlos III decided to find out how quickly it can actually spread the flames, resulting in the ignition of the mixture of hydrogen and air, wedged in a narrow crack. To do this, scientists conducted an experiment: in a small gap between two flat transparent plates (gap width from 1 to 6 mm) was fed a mixture of hydrogen and air with varying hydrogen content (15 percent) and set fire to it. Then use high-speed cameras recorded the trajectory of the flame propagation between the plates — the easiest way to do trail of condensed water that formed in the reaction between hydrogen and oxygen.