Onboard Compressed Hydrogen Storage: Fast Filling Experiments and Simulations

Technology safety represents a key enabling factor for the commercial use of hydrogen within the automotive industry. In the last years considerable pre-normative and normative research effort has produced regulations at national, European and global level, as well as international standards. Their validation is at the moment on going internationally. Additional research is required to improve this regulatory and standardization frame, which is also expected to have a beneficial effect on cost and product optimization. The present paper addresses results related to the experimental assessment and modeling of safety performance of high pressure onboard storage. To simulate the lifetime of onboard hydrogen tanks, commercial tanks have been subjected to filling-emptying cycles encompassing a fast-filling phase as prescribed by the European regulation on type-approval of hydrogen vehicles. The local temperature history inside the tanks has been measured and compared with the temperature outside at the tank metallic bosses, which is the measurement location identified by the regulation. Experimental activities are complemented by computational fluid-dynamics (CFD) modeling of the fast-filling process, by means of a numerical model previously validated. The outcome of these activities is a set of scientifically based data which will serve as input to future regulations and standards improvement.