Search Results

The ESTEC calorimeter was designed for heat transfer measurements on blankets of multi layered insulation (MLI). This work comprises a Finite Element thermal model based on the computer code ANSYS which is used for an interpretation of the experimental data gained during the 35 years of measurement. A parameter study of various test setup parameters was performed to find possible improvements for future calorimeter designs. Similar blanket lay-ups were used to test the influence of number of layers and material parameters on the analysis results. The influence of residual gas conduction in the MLI blankets was further studied and included in the numerical model. The results of the study form the basis of a further improvement of the measurement accuracy and of possible design improvements.

The ESTEC Calorimeter device was commissioned 1974 and during 35 years of operation, nearly 100 different samples were tested. The calorimeter was designed for heat transfer measurements on blankets of multi layered insulation (MLI). The measurement device is a flat circular double sided hot plate calorimeter with a sample diameter of 480 mm. In this work an excerpt of the most significant measurement results collected during the last 35 years are presented and some MLI lay-ups are compared. This comparison focuses on dependencies of achievable performance on lay-up parameters, for example used materials, surface properties and number of layers.

Verification of the Integrated Overall Thermal Mathematical Model (IOTMM) is one of the last tasks in the thermal and environmental control area of the Columbus module. For this purpose a specific test covering as well thermal-hydraulic performance tests as Environmental Control and Life Support (ECLS) cabin temperature control functions has been defined and performed on the european Columbus Protoflight Model (PFM) in Bremen in 2003. This Environmental Control System test was successful for all Active Thermal Control System (ATCS) related thermal-hydraulic functions and could provide sufficient data for a proper IOTMM correlation. However, it failed to verify the ECLS related functions as cabin temperature control and ventilation. Data, which have been generated during this first test, could not be used for a successful IOTMM correlation related to ECLS subsystem performance and modelling.

An approach to the creation of passive radiative cooling system ensuring temperature levels less than 220K for the optical sensor of scientific space equipment elements is considered. The system is intended for the arbitrary orientation-in-space function under solar radiation. Theoretical analysis of the application field of this system, using heat pipes with constant and variable thermal resistance in a range of solar constant variation (500…2700)W/m2 is given. Experimental results on system models, in which two engaged in parallel thermodiodes with freon-22 and ammonium were used, showed the possibility to attain device temperature levels less than 220 K at the solar constant magnitude 1400 W/m2 and device heat release under (1…2) W.