| KEYWORD |
Hydrogen absorption in components of hydrogen-fueled internal combustion engines
Reference persons PAOLO MATTEIS
Description Recent developments in the field of electricity production with intermittent renewable sources and in public policies to reduce carbon dioxide emissions have led to a renewed interest in the use of hydrogen as an energy intermediate, in particular for applications in heavy and long-haul vehicles (heavy road vehicles, construction machinery, trains, ships) and/or electricity generation at construction sites or isolated locations. In this area, therefore, there is interest in the development of hydrogen-powered endothermic engines.
This also requires verification of the compatibility with hydrogen of the metallic materials used in engines, in particular with respect to the risks inherent in hydrogen embrittlement phenomena, not only of an environmental nature, i.e. determined by surface exposure to hydrogen, but also of the internal type, i.e. determined by the progressive absorption of hydrogen inside the metal during the engine life.
In the thesis work, therefore, we intend to develop a numerical model of the diffusion and accumulation of hydrogen in solid solution inside the metallic components which together constitute the combustion chamber. For this purpose we will first study numerically simplified cases, with constant pressure and temperature inside the combustion chamber and very simplified models of the hydrogen diffusion inside the metal, then gradually more realistic cases, with the aim of modeling both the cyclic variation of the temperature and partial pressures inside the combustion chamber during engine operation (known on the basis of prior studies), and the influence of traps and temperature and hydrostatic stress gradients in the diffusion of hydrogen within the metal. We will use very simple models from a geometric point of view and instead we will focus our attention on the modeling of the material (with particular reference to the interaction between the diffusion of hydrogen and the traps), the boundary condition (i.e. the exchange of hydrogen between metal and gas) and the long-term accumulation of hydrogen in the metal (after a very large number of cycles).
The numerical simulation work will be carried out using the calculation programs available in the teaching laboratories.
Deadline 21/04/2024
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