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The Regenerable Carbon Dioxide Removal System (RCRS) has been flying on Extended Duration Orbiter (EDO) versions of Shuttle since 1992. Life characteristics of an enhanced sorbent were evaluated after five years of service life on two Orbiter vehicles. Performance data is presented showing excellent carbon dioxide removal. Limited data forces a range of life predictions for the useful life of the sorbent.

Hamilton Standard Space Systems International, Inc. is currently under contract to NASA for the development and certification of an advanced technology regenerable carbon dioxide removal system for the International Space Station Extravehicular Mobility Unit (EMU), or “space suit.” This new metal-oxide-based system (“Metox”) will replace the existing non-regenerable lithium hydroxide (LiOH) carbon dioxide (CO2) removal system located in the EMU's Primary Life Support System (PLSS). The Metox canister is designed to replace the current LiOH Contamination Control Canister (CCC) with no modification to existing EMU interfaces. The metal oxide sorbent is “regenerable” and can be restored to its original condition permitting the Metox canisters to be used over and over again on-orbit. Once a Metox canister becomes “loaded” with CO2, it will be placed in the “Regenerator,” where the system will circulate hot air through the canister to drive off, or desorb, the CO2.

Hamilton Standard Space Systems International, Inc. (HSSSI) has obtained and is currently testing a variety of Russian life support hardware. These units have been or are contemplated for use on Mir I and II space stations. This paper presents the current status of performance testing of a Sabatier Carbon Dioxide Processing Unit (CDPU) and components of a Potable Water Processing System (PWP). These systems were fabricated by NIICHIMMASH, the supplier of these units to the Russian space program. It is the intent of this testing program to obtain a data base for technology comparisons to support planned and future international missions. For the CDPU, reactant conversion efficiencies in excess of 99 percent have been noted for the variation in test conditions with 2 to 6 man processing (flows) tested. The CDPU's effluent water has been produced at anticipated rates and is relatively contaminant free.

In 1991, Hamilton Standard initiated an Independent Research and Development program to enhance the performance characteristics of solid amine based regenerative CO2 removal systems. A solid amine based system had been selected by NASA/JSC for Extended Duration Orbiter missions. As a result of this research effort, two promising new solid amine candidates, designated HSC+ and HSG, were identified. Bench scale testing indicated that these formulations provided 25% to 33% greater initial cyclic capacity when compared to the baseline HSC solid amine sorbent. This paper reports on comparative life testing of HSC, HSC+ and HSG. The solid amine sorbents were exposed to accelerated life testing with laboratory air under controlled temperature and flow conditions.

The generation (and recovery) of water, rather than the reduction of CO2, drives the requirements for the integration of a Sabatier CO2 Reduction Subsystem (SCRS) within an Air Revitalization Subsystem (ARS). It is important, therefore, to understand the system level decisions that impact the water production capability of the Sabatier CO2 Reduction Subsystem. This paper defines each of the operational parameters that affect water production and loss and explores the impact they each have on total water recovery. The particular subsystem parameters examined include hydrogen and carbon dioxide flow rates, feed gas composition, subsystem operating pressure, condensing heat exchanger performance, heat sink temperature, and phase separator performance. Each of these has a minor contribution to the amount of water lost from the system, but combined, their effect is substantial.

The International Space Station's primary external heat transport system is a single phase ammonia loop called the Active Thermal Control System (ATCS). ATCS loop heat is acquired from the station modules through interface heat exchangers (Internal Thermal Control System water to ATCS ammonia) and from external truss mounted electronics through cold plates. The heat exchangers are compact plate/fin counterflow type and the cold plates are a brazed and bonded construction using a radiation heat transfer interface to the electronics.