Analyzing Failure Behavior and Prediction Models for LH2 Fuel Tank

Kurzfassung

Great efforts have been made in the maritime industry to reduce its CO2 footprint by transitioning from fossil fuels to alternative fuels. Liquid hydrogen (LH2) has been identified as a promising alternative because of its high energy density, as well as zero emissions. Challenges in infrastructure and storage systems have been identified for this potential fuel. Currently, C-type tank designs are under research to store and ship this fluid. These storage units consist of a set of inner and outer tanks connected by structures such as I-beams or Bakelite supports. While these solutions are suitable for LNG storage, limitations in handling thermal and mechanical stresses emerge when this technology is adopted for LH2. This study aims to address the research gaps in this matter by proposing a spring arrangement connection between the tanks as one of the potentially feasible solutions. This novel supporting structure is designed to reduce the contact area with the inner tank, thereby decreasing the conduction heat transfer. Within this study, the vapor pressure and thermal stresses induced by the LH2 cryogenic temperature are considered. The evaluation of the connection systems consists of addressing the fatigue life of the storage tank by employing the stress-life method and the Finite Element Analysis (FEA) for structural stress determination. The methodology involves the evaluation of stress values generated by two loading scenarios, the bunkering process, and the ship’s movement. These stress values are then used to determine the fatigue life of the storage unit. Compliance of the results with the IGC code and DNV rules for strength and fatigue resistance is also presented. The research showed that the spring connection reduced the heat transfer from the outside to the inner tank which reduced thermal stresses induced by the temperature gradient. Moreover, stress limits and fatigue damage experienced by the inner and outer tanks complied with international regulations indicating the spring connection as a favorable alternative.