Researchers in Korea have launched the primary complete security evaluation framework for liquid hydrogen storage techniques in UAVs, in a seemingly essential contribution to efforts to deploy the putative inexperienced gas on this space of aviation. It was revealed within the Worldwide Journal of Hydrogen Vitality in July (phrases: Seoul Nationwide College of Science and Know-how).
Hydrogen propulsion techniques have arguably emerged as a sustainable and eco-friendly various for unmanned aerial autos (UAVs). Regardless of intensive analysis, earlier research targeted on standalone efficiency evaluations for liquid hydrogen storage techniques in UAVs. In a brand new examine, researchers have developed an built-in analytical framework for evaluating thermal efficiency and structural integrity of liquid hydrogen storage techniques, tailor-made to UAV-specific operation circumstances. This examine may function reference for establishing design standards for hydrogen-powered UAVs.
Aviation accounts for about 12% of world carbon dioxide emissions. With intensifying local weather change and environmental points, the aviation business is looking for greener propulsion techniques. For unmanned aerial autos (UAVs), which have extensive functions in army, logistics, and agriculture, analysis has turned in direction of hydrogen propulsion techniques. Hydrogen is a clear gas that produces solely water throughout combustion, representing a promising various to standard fossil fuels.
Nonetheless, hydrogen has low volumetric power density, which means bigger volumes are required to provide the identical power as standard fuels. One answer is liquid hydrogen storage techniques, the place hydrogen is saved at cryogenic temperatures in liquid kind. Whereas this reduces storage dimension and weight, it additionally presents varied challenges, together with vessel deformation as a result of thermal stresses in cryogenic temperatures and fatigue failure. That is significantly dangerous in UAV operation circumstances, which contain multi-directional acceleration masses. A complete evaluation of thermal efficiency and structural integrity in UAV operation circumstances is, due to this fact, essential. Nonetheless, regardless of intensive analysis, an analytical framework for evaluation of liquid storage techniques in UAVs continues to be missing.
To deal with this hole, a analysis staff led by Assistant Professor Nak-Kyun Cho and Mr. Jinmyeong Heo from the Division of Manufacturing Methods and Design Engineering (MSDE) at Seoul Nationwide College of Science and Know-how, Korea, in collaboration with Professor Nam-Su Huh from the Division of Mechanical System Design Engineering on the identical college, developed the primary built-in analytical framework for evaluating the efficiency and structural integrity of liquid hydrogen storage tanks in UAVs. “Not like current research that principally had been restricted to remoted thermal insulation efficiency or structural analyses, we have now developed the primary holistic system integrating thermal, structural, fatigue, and impression analyses, particularly tailor-made for UAV operations,” explains Dr. Cho. Their examine was made accessible on-line on June 09, 2025, and revealed in Quantity 145 of the Worldwide Journal of Hydrogen Vitality on July 07, 2025.
Particulars of the examine (click on picture to enlarge)
The staff started by acquiring cryogenic properties of the supplies used within the storage techniques with the assist of analysis funding and materials testing and verification of the Hydrogen Supplies Analysis Middle at Korea Institute of Supplies Science (KIMS). They thought of a normal liquid hydrogen storage tank, consisting of interior and outer vessels, pipes, and supporters, made utilizing SUS316L metal. Moreover, the vessel included vapor-cooled protect (VCS) that scale back the entry of warmth into the system, produced from Al6061-T6 aluminium. Temperature-dependent properties of those supplies had been measured utilizing a 100 kN tensile-fatigue testing system. These properties had been then included into finite aspect analyses of the vessel, overlaying thermal, structural, fatigue, and drop impression assessments.
Thermal evaluation revealed that the VCS implementation diminished the boil-off charge (BOR) by 30%. BOR is a key efficiency indicator that represents the speed at which saved liquid hydrogen is transformed to gasoline as a result of unavoidable entry of warmth into the storage system. In experiments, the BOR was diminished by 15%, a distinction attributed to simplifications within the mannequin. Structural evaluation revealed pipes and supporters because the weak factors beneath UAV-specific operational circumstances, highlighting the necessity for structural modifications. Fatigue evaluation confirmed that the vessel far exceeded the ten,000 cycle requirement laid out in ISO 21029-1 requirements, with an successfully limitless fatigue life.
For drop impression testing, the staff developed a brand new pc simulation technique utilizing a VUSDFLD subroutine-based aspect deletion strategy to foretell how tanks behave when dropped from a top. This evaluation recognized connecting pipes and supporters as susceptible areas, whereas demonstrating the power of the strategy to foretell failure behaviour of multi-material element techniques.
“Our findings set up new requirements for complete security evaluation of liquid hydrogen storage tanks in UAV functions,” notes Mr. Heo. “Furthermore, our established cryogenic materials database will even be an essential reference for future designs in aerospace discipline. Finally, this framework will function a priceless reference for establishing design requirements or standards for hydrogen-powered UAVs, enabling longer flight durations, speedy supply companies, and extra sustainable operation.”
