 |
The Phases of Hydrogen Based on Vapor Pressure and Temperature [1] |
The concept of operations for a mobile application dictates the design of ground support and onboard LH2 systems. Typical key operations include conditioning, fueling, standby storage, pressure control, variable feed rates, refueling, defueling, purging, inerting, and various maintenance activities.
Cryogenic fluid management of the hydrogen temperature, pressure, and phase conditions are critical during all of these operations. Thermal environments imposed on a mobile LH2 system vary depending on the operations underway, system design, and local natural conditions.
Solar flux and surrounding air or water temperatures and velocities drive heat loads from the environment. Additional heat loads to onboard LH2 systems come from warmer structures and penetrations via thermal conduction, and surrounding temperature boundaries via noncontact thermal radiation.
Transient heat loads are also imposed by any internal heat exchangers and thermal soak back from operating fuel cells, engines, or other sources [2].