refrigeration plant and increased solar array area to provide power to that plant. For an orbital application, the refrigeration plant and additional solar array would outweigh any resulting savings in tankage. However, since the tankage for a lunar application is such a large portion of the overall system mass, the savings realized by cryogenic storage might easily pay for the added components and complexity. To determine if a net advantage does exist, two ‘lunar base' PV/RFC conceptual designs were generated and characterized as follows: a baseline case using conventional (gaseous reactant) storage, similar to the lunar base solar-power plant design developed by Eagle Engineering [1], was established using a well-known modeling code [2]. This baseline was then modified to reflect the implementation of cryogenic storage. The cryogenic system was defined, and the mass of each component determined, for both a 20 kWe and a 250 kWe output power level. The resultant total power system mass was compared to the mass of the baseline system. System Modeling A conventional RFC was modeled as a baseline system. For this system, the reactant gases were assumed to be stored at the electrolyzer operating pressure of 2.2 MPa (315 psia) in tanks made from filament-wound Kevlar 49/epoxy matrix. Based on data from the Lawrence Livermore Laboratory [3], the rupture stress of this type of material is approximately 931 MPa (135 000 psi). The working stress used for modeling the tanks was 233 MPa (33 750 psi). A 10 mm titanium liner was included in each tank to
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