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Computational Fluid Dynamics airflow models for the Waste and Hygiene Compartment (WHC) in the U.S. Laboratory module and Node 3 were developed and examined. The International Space Station (ISS) currently provides human waste collection and hygiene facilities in the Russian Segment Service Module (SM) which supports a three person crew. An additional set of Russian hardware, known as the system, is planned for the United States Operational Segment (USOS) to support expansion of the crew to six persons. Integration of the Russian system into the USOS incorporates direct Environmental Control and Life Support System (ECLSS) interfaces to allow more autonomous operation. A preliminary design concept was used to create a geometry model to evaluate the air interaction with the module cabin at varied locations and performance of the avionics fan placed in WHC. The Russian and the privacy protection bump-outs (Kabin) were included into the present modeling.

This paper presents an assessment of test data for the Sabatier CO2 Reduction Subsystem which has been selected for the Environmental Control and Life Support System (ECLSS) for Space Station Freedom (SSF). The assessment is facilitated through the application of a developed mathematical model for the subsystem. The Sabatier CO2 Reduction Subsystem is one of several subsystems included in the regenerative portion of the overall ECLSS for SSF. It provides the important function of reducing collected metabolic CO2 from the crew with H2 generated by the water electrolysis unit. (Water electrolysis primarily generates makeup O2 for the crew and for space cabin leakage.) The product water resulting from the CO2 reduction is supplied to a water recovery subsystem for further processing. The test data for the Sabatier subsystem were obtained from the comparative test (CT) program performed by the Boeing Missiles & Space Division at Huntsville, Alabama.

During a recent International Space Station (ISS) flight (Flight 2A.1), an improper ventilation event might have occurred and resulted in stuffy air, as reported by the crew. Even though no air samples were analyzed, the accumulation of metabolic CO2 in the ISS was suspected as the cause of the crew sickness. With no possibility of conducting an on-orbit test of this kind, it was decided to utilize Computational Fluid Dynamics (CFD) analysis to investigate this problem. Based on the Flight 2A.1 and 2A.2a configurations, a CFD model of the air distribution system was built to characterize airflow between the ISS elements. This model consists of Inter-module Ventilation (IMV) covering the Functional Cargo Block (FGB), two Pressurized Mating Adapters (PMA-1 and PMA-2), the Node-1, and portions of the Orbiter volume.