Session: HT-07-02: Design and Analysis of High Pressure Hydrogen Equipment - 2

Paper Number: 84904

84904 - Hydrogen Diffusion Analysis in Non-Isothermal Axisymmetric Bodies 

Hydrogen usage as an energy carrier and storage medium is increasingly regarded as an essential factor for a zero-emission global energy economy. Still, its widespread application is delayed by several technical problems that remain to be solved. Among those is the phenomenon known as Hydrogen Embrittlement (HE), defined as the increasingly significant reduction of strength and ductility properties of metals in the presence of increasing hydrogen concentration diffused in the metal matrix. Therefore, predicting the concentration field in a component is crucial for assessing the risk of damage due to HE. The distribution of hydrogen in the metal matrix is determined by many factors: such as microstructural factors, plasticity or inclusions, geometrical features (like notches or grooves), and temperature field.

 

In the literature, many models and methods have been proposed to study hydrogen diffusion problems. Many works have focused on the formulation of the diffusion problem by the Finite Element Method (FEM) due to its ability to easily comprise complex geometries and boundary conditions. The most widespread implementation of diffusion models exploits the analogy with the heat equations or already implemented coupled stress-diffusion models. Due to the lack of trapping implemented in commercial FEM software, this phenomenon can be modeled only by exploiting the temperature DOF, with the drawback that temperature effects cannot be included. However, both stress gradients and temperature gradients are present and significant in common industrial applications such as low or high-temperature pipelines .

 

This work aims to present a methodology to simulate hydrogen diffusion phenomena using the FEM, including trapping, structural and thermal effects. For this purpose, a custom FORTRAN script, able to perform diffusive FEM analysis on mono- and bi-dimensional meshes, is employed along with a model implemented in Ansys Mechanical. Case studies, focused on problems of interest in the piping field, are used to validate the procedure and to compare results from different known diffusion models.

Presenting Author: Carlo Maria Belardini Department of Civil and Industrial Engineering, University of Pisa

Presenting Author Biography: PhD student in Industrial Engineering, University of Pisa

Authors:

GIUSEPPE MACORETTA DICI - UNIVERSITY OF PISA
Bernardo Disma Monelli Department of Civil and Industrial Engineering, University of Pisa
Carlo Maria Belardini Department of Civil and Industrial Engineering, University of Pisa
Leonardo Bertini Department of Civil and Industrial Engineering, University of Pisa
Renzo Valentini Department of Civil and Industrial Engineering, University of Pisa