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Technical Paper

Design Validation - via Parabolic Flight Tests - of a Condensate Buffer Equalizing a Discontinuous Gas / Water Flow between a Condensing Heat Exchanger and a Water Separator

EADS SPACE Transportation GmbH designed, built and tested a condensate buffer to be located between a Condensing Heat Exchanger (CHX) and a Condensate Water Separator Assembly (CWSA), as part of the ECLSS of the European Columbus Module. Under zero-g conditions, the separation of water from an air-water mixture is always difficult, especially if a passive device is to be used such as the low power consuming Columbus CWSA. The additional buffer volume reduces condensate water peaks reaching the CWSA to a level that excludes an overloading of the CWSA and a release of free water droplets into the air return to the cabin. In the CHX/CWSA system this may only be necessary under worst case operational conditions and with a failure of the qualified hydrophilic coating of the CHX. The buffer design principle was confirmed via prior analyses and on-ground testing. The performance of such a condensate buffer under micro-g conditions was verified during parabolic flights.
Technical Paper

Advanced Stainless Steel Condensing Heat Exchanger

Under an ESA Contract EADS SPACE Transportation GmbH has designed and built an advanced Stainless Steel Condensing Heat Exchanger (CHX) Spare as part of the Environmental Control and Life Support Subsystem (ECLSS) of the European Columbus Module that shall be docked to the ISS in early 2007. Lessons learnt from both, ground and space applications of condensing heat exchangers were to be considered, for risk mitigation, in a CHX alternative design. The slurper section is equipped with a sophisticated capillary suction feature that supports an adequate condensate removal and transport through the slurper holes to the water separator assembly even at low airflow condition. The air fin surface is covered with a hydrophilic coating that did pass qualification for 10 years' exposure to the various contaminants specified respectively determined in the ISS atmosphere so far. The biocidal additive of such coating is qualified for fungus growth prevention, accordingly.
Technical Paper

Improving the Columbus Integrated Overall Thermal Mathematical Model (IOTMM) Using Computational Fluid Dynamics (CFD)

The cabin space of the Columbus APM is well ventilated by air entering through multiple air diffusers and exiting via the return grid and hatch. Therefore, the heat transfers by bulk fluid motion and by convection to the walls need to be experimentally and/or numerically investigated and implemented in the thermal mathematical models (TMM) describing the cabin. CFD analysis provided key data on the thermal couplings due to convective heat transfer and bulk fluid motion for the thermal mathematical model, which in turn was used to correlate test data from an environmental control system test and to provide supplemental information on assumptions used in the lumped capacitance model. This paper presents the logic and results of the steady-state CFD analysis, the potential implementation of the results in a thermal mathematical model, and compares these results with test data obtained during a separate Columbus cabin ventilation qualification test.
Technical Paper

ECS Re-Test Analytical Evaluation

A final test activity was carried out to complete the verification of the Environmental Control System (ECS) performances by experimentally reproducing the thermal hydraulic behaviour of the Environmental Control & Life Support Subsystem (ECLSS) section integrated in the overall Module, expected on analytical basis. A previous test campaign (called Columbus ECS PFM Test) carried out in EADS-Bremen in spring 2003 and described in paper number 2004-01-2425 showed some contradictory data concerning the air loop behaviour. These incoherent test results were related to the environmental and geometrical cabin loop conditions during the on-ground 1g test and to improper position of the sensor measuring the cabin temperature. For this reason a partial repetition of the test has been performed. In particular, this experimental campaign was focused on the verification of the cabin air temperature control, as a consequence of the Temperature Control Valve (TCV) movement.
Technical Paper

Simulation Model of the Air Revitalization System for ISS

An air revitalization system is being designed for the ISS. The name of this system is ARES, which stands for Atmosphere Regeneration System. Its major functions in the Life Support System of the ISS would be to: - Generate breathable oxygen from water - Collect the produced CO2 from air cabin and to control cabin CO2-level as required - Convert CO2 into water and methane - Recover the produced water for use in the water management system. ARES is based on ESA ECLS Technology Program developments. The prototype, so-called ARES Elegant Breadboard, has been manufactured and has just been tested at EADS. In parallel to the design and manufacture activities of the ARES Elegant Breadboard, an EcosimPro simulation model of the overall hardware system has been developed. The simulation model has been used intensively in the design process and it is going to be correlated according to test data.
Technical Paper

The Columbus ECLSS First Year of Operations

The launch and activation of ESA's Columbus module in early 2008 marked the completion of more than 10 years of development. Since then the Columbus ECLS is operating, including its major European ECLSS assemblies such as Condensing Heat Exchanger (CHX), Condensate Water Separator, Cabin Fans and Sensors. The paper will report the experiences from the first year of operations in terms of events, failures and lessons learned. Examples of this is the description of some off-nominal situations (such as Condensate Removal and IMV Return Fan failure, and relevant troubleshooting), and the preparation to Columbus Reduced Condensation Mode, as requested by NASA in order to minimize the crew time needed to empty Condensate Water Tanks in US Lab.
Technical Paper

Columbus ECLS Activation and Initial Operations

European Space Agency's (ESA's) Columbus module was launched on February 7, 2008. This marks the completion of more than 10 years of development. It is a major step forward for Europe in the area of Environmental Control and Life Support (ECLS) as Columbus contains several major assemblies which have been developed in Europe. These include the Condensing Heat Exchanger, Condensate Water Separator and the Cabin Fans. The paper gives a short overview of the system and its features and it will report the experiences from the initial activation and operations phase.
Technical Paper

Columbus Integrated System Level ECS Test Correlation

The Columbus ECS PFM Test was intended as the final verification of the Module Thermal Design after a series of successful tests at subsystems level (e.g. the Active Thermal Control Subsystem and the Environmental Control and Life Support System) The test campaign has been articulated as a sequence of several test cases to investigate the main thermal aspects, to prove the Module thermal design in the extreme operative conditions and to correlate the thermal mathematical model (TMM). The interpretation of test results and the correlation confirmed that the thermal design of the module is adequate, but some areas of concern remain, mainly for the difficulty to translate to 0-g the results of a complex test in 1-g environment, and for some aspects of the air and cabin loops.
Technical Paper

Development of Sublimator Technology for the European EVA Space Suit

Temperature and Humidity Control are important functions for the astronaut's comfort and safety in an EVA Space Suit. Several sources within the suit, like electrically powered devices, the CO2 removal system and the astronaut himself are permanently producing heat and humidity. Both have to be removed in order to prevent visor fogging and overheating of the astronaut. Heat from the European Space Suit will be dissipated by the physical process of water sublimation. At pressures lower than 6 hPa water will directly transform from ice into vapor. In the Sublimator this process will take place within a porous plate and will remove heat from both the oxygen ventilation loop and the cooling water loop. The Sublimator thus consists of a porous plate with the feedwater distribution underneath and a liquid/gas heat exchanger part. A breadboard model has been fabricated from stainless steel and a new porous plate has been developed.