Research Issues on Two-Phase Loops for Space Applications
5 ADVANTAGES OF TWO-PHASE LOOPS FOR SPACECRAFT THERMAL CONTROL 5 TWO SUCCESSFUL IN-ORBIT EXPERIMENTS: TPX I & LHPFX 7 ESA’s Two-Phase eXperiment TPX I 7 Loop Heat Pipe Flight eXperiment LHPFX 9 DESIGN SUPPORTING THEORETICAL WORK 10 Background of Thermal-Gravitational Modelling and Scaling 10 Dimension Analysis & Similarity Considerations 10 Pressure Drop & Heat Transfer Equations for Annular Flow 13 FLOW PATTERN ISSUES 15 Flow Pattern or Flow Regime Mapping 15 Flow Pattern Mapping for Anti-Super-Gravity 16 CURRENT LOOP-RELATED R&D ACTIVITIES AT NLR 17 AMS-2 Thermal Control 17 CIMEX-3: NLR’s Versatile Two-Phase Loop Experiment 18
Aerospace Heat and Mass Transfer Research for Spacecraft Thermal Control Systems Development
The paper focusses on heat and mass transfer research issues pertaining to the current development of, spacecraft active thermal control systems, i.e. the development of two-phase heat transport system technology. Topics (of paramount interest) discussed ar: the development and the inorbit demonstration of Capillary Pumped Loop and Loop Heat Pipe technology, the thermal/gravitational scaling of two-phase heat transport systems, including the aspects of two-phase flow pattern mapping, and the prediction of gravity level dependent condensation, plus the development of the various two-phase heat transport system components like vapour quality sensors, high efficiency low pressure drop condensers, and rotatable thermal joints.
Moveable thermal joints for deployable or steerable spacecraft radiator systems
A possible solution to handle the heat dissipated by the batteries of the Columbus Polar Platform is to equip each battery ORU (Orbital Replacement Unit) with a dedicated heat pipe radiator. Such a radiator, being stowed during launch, has to be deployed in orbit and might be chosen to be steerable to achieve maximum radiator performance, hence minimum radiator size. In such radiator systems the coupling between battery and deployable or steerable radiator has to Incorporate a rotatable or flexible thermal joint. Drivers for the design of such joints are a low thermal resistance, hence a limited temperature drop across the joint to optimize radiator size, and a small deployment/retraction torque or steering torque.