Flow patterns and heat transfer characterization during large aspect ratio hydrogen tank filling

Temperature management in high-pressure hydrogen tank filling is crucial, requiring detailed analysis of heat transfer physics. This study used 3D CFD simulations to examine how tank aspect ratio, filling time, and orientation affect heat transfer dynamics. Results show that turbulent jet flow extends approximately three tank diameters inward, creating a mixing zone between existing and incoming hydrogen. For tanks shorter than this mixing length, simplified thermodynamic models accurately predict temperature evolution due to uniform gas mixing. Longer tanks exhibit varied flow patterns requiring consideration of multiple heat transfer mechanisms. The present work reveals consistent flow and wall heat flux patterns across different aspect ratios, suggesting potential applications for extending thermodynamic models to diverse tank geometries. These findings contribute to understanding and optimizing high-pressure hydrogen filling processes, with implications for efficient tank design and operation. • Critical L=3D threshold separates jet-dominated and natural convection regimes. • Wall heat transfer follows distinct patterns in short and long tanks. • Flow and wall heat transfer characteristics in long tanks follow a consistent trend. • Enable simple thermodynamic models for optimizing tank designs and infrastructure.