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
Feasibility Demonstration of a Mechanically Pumped Two-Phase CO2 Cooling Loop for the AMS-2 Tracker Experiment
The Alpha Magnetic Spectrometer AMS-2, planned for a five years mission as attached payload
on the International Space Station ISS, is an international experiment searching for anti-matter,
dark matter, and missing matter. AMS-2, an improved version of AMS-1 flown on STS 91,
consists of various particle detector systems, one of these being the (Silicon) Tracker. The tradeoff
based choice and the experimental feasibility demonstration of a mechanically pumped twophase
CO2 cooling loop for the Tracker is discussed in detail. Ongoing and planned development
activities are indicated.
Venus: Evolution of the Upper Atmospheric Clouds
Abstract The large number of UV photographs taken by different observatories throughout the world are grouped for analysis at the IAU Planetary Photograph Center of Meudon Observatory. Three horizontal V, Y, or psi-shaped dark-hued cloud features are usually aligned along the equator and move 110 m s−1 westward in a planetary-wide rotation. The more intense and distinctly V-Shaped features last several weeks. The smaller scale cloud structures usually show significant changes after each successive rotation in 4 days around the planet. The average UV contrast is 32% but can fluctuate from disappearance to 37%. For periods of several years, the polar areas are sometimes covered by a white cloud. According to a set of photographs taken at Pic-du-Midi, this never occurred between 1962 and 1966 but has happened during 25% of the time for at least one pole since 1967, and only when the planet was in a given half of its orbit. These polar clouds are ephemeral and usually last several weeks or months; they evolve...