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This paper determines the feasibility of potential Active Thermal Control System (ATCS) growth paths by assessing thermal, integration, and implementation impacts. TRASYS/IRTRAN models were used to evaluate the effects of increased radiator temperature, increased radiator area, and radiator wing addition on Space Station Freedom (SSF) elements, including energy reflected back to the ATCS. SINDA/FLUINT models were used to determine the heat rejection capability of an ATCS loop with an integrated heat pump that operates with Electrical Power System (EPS) peak power. The effects of upgrading the ATCS by advanced technology ORU implementation during maintenance replacements was also evaluated. The study results presented lead to conclusions on which paths are best suited for different growth scenarios.

The “restructured” baseline has eliminated many options for Active Thermal Control System (ATCS) growth for Space Station Freedom (SSF). Modular addition of baseline technology to increase heat rejection will be extremely difficult. The system design and the available real estate no longer accommodate this type of growth. As the station matures during its thirty years of operation, a demand of up to 165 kW of heat rejection can be expected. The baseline configuration will be able to provide 82.5 kW at Eight Manned Crew Capability (EMCC). A promising technology that could increase heat rejection by the necessary 82.5 kW is the heat pump. This paper provides a preliminary feasibility assessment of the application of a vapor compression heat pump to the ATCS.

A computer analysis program designed to predict and evaluate the steady state performance and size of integrated extravehicular mobility unit (EMU) life support systems has been developed for advanced missions. Trade study evaluations for various extravehicular activity (EVA) technologies can be accomplished using the Life Support Options Performance Program, version 2.0 (LSOPP II). LSOPP II is an interactive menu-driven program based upon a dual loop structure (vent loop - water loop). It solves for the outlet flow conditions of each component in a loop, given the associated heat loads and inlet flow conditions. System and component results of LSOPP II include heat load, flow rate, pressure, temperature, power, weight, and volume.