Seasonal analysis of boil-off gas rates in liquid hydrogen storage tank using time-series analysis

Abstract

The storage of liquid hydrogen (LH₂) in stationary tanks poses significant challenges due to boil-off gas (BOG) losses caused by heat ingress from the external environment. This study aimed to analyze the boil-off rate (BoR) of an LH₂ tank across four different seasons summer, winter, autumn and spring using daily temperature profiles to examine seasonal variations in heat transfer and their impact on hydrogen losses. A stationary LH₂ tank with a volume of 5.6 m³ with multilayer insulation (MLI) and high vacuum conditions was modeled to simulate heat ingress and resulting BoR. Temperature data spanning 24 h of selective day for each season were collected and analyzed using time-series analysis, a statistical technique for examining and forecasting non-stationary data trends over time converted to a dataset. Historical temperature data were leveraged to predict seasonal variations in heat ingress and BOG generation. Additionally, the system was modeled and simulated using the software Ansys Twin Builder to accurately replicate the dynamic behavior of the tank under varying thermal conditions. An LH₂ tank is modeled using Python language and then interfaced with the twin builder and for the BOG collection tank the Modelica's vessel component is used.

The simulations demonstrated that the BoR exhibited significant fluctuations across the seasons, with the highest rates observed during summer due to increased ambient temperatures and reduced during winter due to lower thermal gradients. Spring and autumn(fall) showed intermediate BoR values, influenced by moderate temperature variations. The time-series analysis provided precise insights into the daily patterns of temperature-driven boil-off, validating the predictive capability of the model. The developed model successfully quantified the impact of seasonal temperature variations on LH₂ boil-off in stationary tanks, offering a robust tool for optimizing insulation strategies and BOG management. The findings underscored the importance of Thermal Management Systems (TMS) for minimizing hydrogen losses in the future, thereby enhancing the viability of LH₂ tanks in airport fuel for hydrogen-powered aircraft.