Evaluation of cold filling processes for 70MPa storage systems in vehicles

The potential of hydrogen gas pre-cooling for fast refueling of 70MPa storage systems is exp lored in this paper. Both energy cost and impact on vessel materials have been assessed. For a given hydrogen mass transferred into the vessel the gas cooling energy was compared to the compression energy gained from operating at a lower gas temperature. Results show that the energy consumption increases dramatically for filling gas temperature lower than –75°C, but some advantages are expected for a filling gas temperature around –40°C, and even more if investment cost are taken into account. Cold filling tests were performed on a type III composite tank with filling gas temperatures as low as –85°C. As expected, the gas quickly heats up in the vessel but the vessel inlet (neck and shoulder) can be exposed to quite lower temperatures than the average gas temperature. This work has been performed within the European funded project STORHy which objective is to develop storage systems for automotive application.