Thermodynamic Model of Storage and Discharge of Liquid Hydrogen and Oxygen in Pressure Vessels Under Cryogenic Conditions

A thermodynamic model is used to characterize cryogenic hydrogen and oxygen storage in adiabatic pressure vessels with operating pressures of 16 bar and 60 bar, respectively. Initially, the fluid is stored in the vessel at near atmospheric pressures as a liquid–vapor mixture. After absorbing heat from the surroundings the pressure increases and the entire volume is filled with subcooled liquid at first, and then supercritical fluid. During the next supercritical process, the stored material is still in a homogeneous single-phase fluid state, and fluid flow is achieved due to higher pressure. This supercritical pressure can be maintained by absorbing or giving heat to the stored fluid during fluid withdrawal. The actual operating temperature for the whole process is 20–110 K for hydrogen and 90–250 K for oxygen.