Modeling of hydrogen diffusion in a piezoceramic with temperature gradient

Clean fuels are increasingly used for transportation due to environmental concerns and limited supply of fossil fuels. Hydrogen is considered a clean fuel that is free from carbon dioxide and other greenhouse gas emissions. Fuel injectors are a key element in the development of hydrogen-based engine technology. Piezo actuator-based fuel injectors can provide superior injection accuracy and control. Basic understanding of hydrogen behavior in piezoelectrics is needed to improve the durability and performance of fuel injectors for use in hydrogen-based direct injection engines. In this paper, a preliminary study of hydrogen diffusion process in piezoceramics is presented. The Cahn-Hilliard equation which describes the process of hydrogen diffusion in a solid is used in the modeling. The temperature gradient is also taken into account in the present model as a driving force for diffusion. The non-linear diffusion and heat transfer equations are solved by the explicit Euler finite difference method. Selected numerical results of temperature and hydrogen concentration distribution for one-dimensional cases are presented to investigate the key features of the diffusion process.