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A very significant effort has been conducted in the 2007 to adequately prepare the off-site support to be provided by Thales Alenia Space Italia (TAS-I) to the Columbus Mission Stage 1.E. for Thermal Control aspects. The tasks have been conducted in the frame of the Engineering Support Team (EST) Off-Site responsibilities in response to the requests and in strict cooperation with the On-Site Support Team. The activities have considered all the constituents of the Thermal Control System (TCS) of Columbus including the Payloads to be utilized during the Stage 1.E and have covered the different stage phases since the Launch-to-Activation phase up to the Payloads activation and operation ones. A large slice of activities have concerned the simulation of the Active Thermal Control Subsystem (ATCS) and Passive Thermal Control Subsystem (PTCS) operations and resources to the equipment and Payloads in nominal, off-nominal and emergency conditions.

The Columbus water loop active thermal control system (ATCS) started its operations on early 2008 as main thermal bus for the internal equipments of the laboratory. From then on, several events occurred like internal payloads activations/deactivations, Condensing Heat eXchanger (CHX) dry-out, Intermediate Heat eXchangers (IHX) insertions, by-passes opening and so on. Even if the control system stability was beyond dispute, some of these events produced unexpected transients, posing some problems to the overall system operations. Scope of this paper is to provide a brief overview of the system alerts and describe the major events occurred, the use of mathematical modelling analysis and correlation for the engineering evaluations and finally the agreed actions applied in flight operations.

The Moderate Temperature (MT) Columbus Active Thermal Control Subsystem (ATCS) has been conceived to collect all the waste thermal loads generated in the various Columbus Module Subsystems and in the ISPR Payloads and reject them through the NODE 2 (Water/Ammonia) Inter-Loop Heat Exchangers providing a controlled and stable cooling resource to the experiments with the help of temperature and delta pressure control laws. The maximum amount of ATCS mass flow rate, actively modulated and shared among the different loop segments, depends on the total thermal head to be controlled and rejected. A deep and wide study - ATCS Re-Certification - was undertaken to increase the cooling resources offered to the ISPR Payloads. Starting from the already base lined total cooling mass flow rate of about 950 [kg/h], the capability to reach flow figure of 1050 [kg/h] was carefully investigated.

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.

The Columbus laboratory module for the International Space Station (ISS) uses active thermal control for cooling of avionics and payload in the pressurized compartment. The Active Thermal Control Subsystem (ATCS) is based on a water loop rejecting waste heat to the Medium Temperature Heat Exchanger and Low Temperature Heat Exchanger on Node 2, part of the US Segment of the ISS. Flow and temperature control in the ATCS is achieved by means of the Water Pump Assembly (WPA) and the 3-Way Modulating Valve (WTMO) units. For the flow control the WPA speed is commanded so that a fixed pressure drop is maintained over the plenum with the avionics and payload branches. Adjusting the WTMO internal flow split permit the two active units to perform the CHX and plenum inlet temperature control. The WPA includes a filter and an accumulator to control the pressure in the ATCS and to compensate for leakage and temperature-dependent volume variations.

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.