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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

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

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.