COF Thermal Control Development Tests 951703

During the Bridging Phase of the Columbus project, the Attached Pressurised Module has been subjected to a series of design changes to accommodate the new International Space Station interface requirements and to comply with the reduced budget allocated to the Columbus Orbiting Facility (COF) Programme. In parallel to the studies aimed to define the COF Configuration, tests have been performed on the Thermal Control Subsystem, in those areas not affected by redesign changes, to investigate some typical aspects in thermo-hydraulic mathematical simulation areas and in the passive design areas. For a better modelling of the water loop with ESATAN-FHTS, tests have been carried out on single items to verify the hydraulic characteristics of some components like hard pipe lines, flex pipe lines and bends that are already implemented in the simulation code, and to calculate the hydraulic characteristics of some new components, like on/off valves, three-way valves and flowmeters, that have never been simulated.

As a continuation of the hydraulic tests on components, a test on a simplified water loop dedicated to the development and the evaluation of the Pump control system philosophy has been performed. The purpose of the test was to correct the control parameters used in the mathematical models taking into account the effects of hydraulic inertia and data management system delay.

In parallel, a thermo-hydraulic test on a simple water loop provided with a heating source and a cooling system has been performed to evaluate the performances of the three-way valve control system. The purpose of this test was to verify the capabilities of mathematical models in the simulation of thermal effects such as thermal inertia and heat transfer delay time.

An upgrading of the water loop test set-up implementing heat sources and both three-way valve and pump control systems is planned to evaluate the interactions between the two control systems and the thermal and the hydraulic disturbances.

A second test campaign was related to the humidity condensation on cold surfaces, which could cause an uncontrolled growth of fungus and micro-organisms.

Anticondensation devices must be designed in such a way to achieve an insulation surface temperature higher than the dew point temperature of the spacecraft internal environment, for all the points of the “comfort box”.

Moreover, in long lasting missions, anticondensation materials are requested to maintain their features unchanged even after ten years of lifetime. Therefore the materials capability to pass depressurisation and repressurisation transients and its capability to provide a permanent barrier to the vapour diffusion have been tested.