Modeling and Analysis of Effect of Various Tank Geometries and Relief Pressure on Liquid Hydrogen (LH2) Boil-Off Losses

Abstract

This research investigates the effect of various storage tank geometries and relief pressure on boil-off losses for liquid hydrogen (LH2). The effect of storage volume of LH2 in the tanks for the various geometries is analyzed as well. The model takes into consideration the heat transfer between the liquid and vapor phases, integrates actual heat transfer mechanisms, and employs variety equations of state to estimate evaporative losses. For this, a software package BoilFAST has been used to investigate the boil-off losses. The model was validated against experimental data available in open literature from NASA. Results showed that the effect of relief pressure on the evaporation of LH2 is very high. The LH2 volume is reduced by 34% in the case of cuboid shape and 22% the for spherical shape of the tank from relief pressure of 111 to 10 kPa. However, the effect of the filled volume of LH2 in the storage tank on the evaporation of LH2 is minimal as the volume is reduced only by less than 5% for all tank shapes. Overall, for various tank geometries, spherical shape showed minimum evaporation losses compared to other tank geometries.