Numerical assestments of maximum depressurisation rate for polymer materials under high-pressure hydrogen

Abstract

Hydrogen containers type IV should stand for severe operational conditions, such as temperature variations from −40 °C to 85 °C, and depressurisation from high-pressure above 95 MPa to near atmospheric pressure. There are experimental studies showing that container's liner, usually a thermoplastic material, can suffer blistering and buckling during depressurisation process. It has also been proved that elastomers under high-pressure conditions, which are submitted to a rapid depressurisation, can suffer the formation of cavities because of the dissolved gas. The formation of microscopic defects in thermoplastic materials because of rapid depressurisation is less common in scientific literature.In this paper, we evaluate by numerical means the maximum depressurisation rate a polymer sample can stand before cavitation occurs. By studying the influence of geometrical and pressure conditions, so as material's properties, we obtain algebraic equations that define maximal depressurisation rate. Results of present work serve to estimate performance of liner materials, with the scope of safe and fast container discharge.