Lightweight hydrogen storage cylinder for fuel cell propulsion systems to be applied in drones

A lightweight type-4 cylinder is developed using a polyethylene terephthalate (PET) liner for application in drones. We conducted a parametric study on the internal phenomena of the developed cylinder during the filling process to examine the applicability of the cylinder to drones. First, we fabricated a type-4 cylinder with a volume of 6.8 L. Then, variations in pressure and temperature inside the cylinder were examined during the filling test. At the end of the filling test, the internal pressure reached 450 bar, and the temperature reached 58 degrees C. The expansion of the cylinder at the center of the cylinder body was larger than that at the dome knuckle. Subsequently, the effect of the inlet gas temperature on the internal phenomena of the developed cylinder was examined. As the inlet gas temperature decreased, both the temperature of the stored gas and the expansion rate decreased. Finally, the storage density of the developed cylinder was compared with that of other types of vessels. The storage density of the developed cylinder was equal to 4.8 %, which higher than that of other types of cylinders. Through this study, the applicability of PET as a liner for a lightweight hydrogen storage cylinder was examined.