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A distributed avionics air architecture provides air cooling and air circulation in non-habitable Space Station zones utilizing dedicated hardware to support the zone-specific needs. That dedicated hardware, the Avionics Air Assembly (AAA), includes a selectable speed fan and heat exchanger used in racks for active avionics air cooling to reject the airborne heat load directly to the moderate temperature Internal Thermal Control System (ITCS). This paper addresses the design impacts resulting from the International Space Station Alpha (ISSA) restructure effort. It defines the service provided by the avionics air assembly, the design requirements and the integrated system performance. Detailed package configuration and interfaces, hardware design and off-design performance are included to define the full range of operating capability.

Shuttle Extravehicular Mobility Unit (EMU) studies have shown that the thermal interaction between the crewperson, liquid cooling garment and EMU thermal management system is highly transient in nature. Recent investigations of these phenomena provide a better understanding which have helped improve thermal comfort in the present system. Analyses show that the key to thermal comfort is understanding the interaction between physiological responses and EMU system thermal transients. A test program was conducted to evaluate the theorized causes of discomfort and proposed corrective actions. Several EMU thermal management related modifications were utilized in the Hubble Space Telescope repair mission where five, two crewperson ExtraVehicular Activities (EVAs) were conducted without any thermal discomfort in a mildly cold environment.

The Avionics Air Assembly Cooling Package which provides cooling for high heat load racks aboard the International Space Station has been designed and developed to balance challenging requirements for noise emissions, emitted vibrations, power usage, weight, and volume. The assembly consists of a high speed selectable flow fan, a compact air-to-water heat exchanger, noise attenuation components, motor controller electronics, and mounting structure. This paper addresses the final hardware configuration and performance characteristics and the successful development program that was required to create the first qualification/flight assembly. It describes the initial component development hardware performance, the initial package integration results, the completed optimization effort, and the final package performance. These optimization cycles, both to improve and reduce component performance, were necessary to attain the desired package results from this highly integrated assembly.

The TIMES is an evaporative water processor which has shown great theoretical potential for providing reliable and efficient production of high quality water. The test results of the system have however fallen short of the predicted performances. A thorough systems analysis has identified the condensing heat exchanger as a primary source of the shortcomings of the assembly. This condenser, along with three other heat exchangers in the system, have been redesigned and integrated into a new “Regenerator” that is predicted to significantly lower the power consumption and improve both the operating stability and product water quality.

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.