Efficient Models for Film Condensation in Cryogenic Tank Applications

NASA’s long duration human space exploration plans to the moon, and later mars, require the design and maturation of hardware for propellant replenishment technologies such as in-space tank-to-tank transfer from a fuel depot and liquid propellant production through In-Situ Resource Utilization (ISRU). Currently CFD tools required to support the design of these systems, with complex condensation phase change features, are not sufficiently mature either in their accuracy or numerical efficiency to be useful within design cycle timelines. The innovation proposed here is the development of accurate sub-grid CFD models for modeling condensation in cryogens, on coarse grids, that provide condensate estimates of film thickness within 25% accuracy and with numerical speed-up of an order of magnitude. The framework proposed captures growth and transport of liquid layer along wall boundary while conserving mass, momentum and energy as part of continuum numerical framework. The model was validated for condensation on a vertical flat plate for three cryogenic fluid including methane, nitrogen and oxygen. Test data for oxygen condensation with enhanced experimental techniques and additional instrumentation was obtained as part of this effort. The proposed effort will extend the database for oxygen condensation by conducting parametric studies over a broad range of temperatures and pressures, as well as orientations of the plate to vary the effect of gravity. Test data for oxygen condensation in a sub-scale tank will be obtained and used for validating the model for complex three-dimensional configurations. The well validated CFD framework can be used for design support and optimization of hardware for in-space tank-to-tank transfer in NASA’s Artemis program. as well as liquid propellant production through In-Situ Resource Utilization (ISRU) for future Mars missions.