Propellant preservation using re-liquefiers Original Research Article

The long-term storage of cryogenic propellants in space requires the use of active cooling. Previous work has considered using closed cycle coolers to exactly balance the parasitic heat loads on the propellant. An alternative approach using a re-liquefier has been suggested. This paper considers some of the advantages and disadvantages of this approach. A re-liquefier uses the propellant vapor as the working fluid. This may eliminate the need for a mixer in the propellant tank; may reduce the effect of leaks in the cooler; and may allow a more graceful way to accommodate cooler failure. However, the re-liquefier is unlikely to be operating at its optimal operating point; and will require some means of controlling contamination.