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
Numerical simulation of a condenser in two-phase heat transport systems a feasibility study
In this report the numerical simulation of a mathematical model of a condenser is discussed. This mathematical model of the NLR approach to model and scale two-phase heat transport systems. In this report the model of the condenser is reformulated to a model that is suitable for a numerical discussion. The results is a model that is represented by an implicit non-linear Differential/Algebraic Equation. One nximerical solution procedure is discussed. Test cases are defined and simulation studies are conducted with several working fluids and under varying gravity conditions. The simulation results show that the approach taken is suitable to obtain the behaviour of a condenser.
A new mechanism for pool boiling crisis, recoil instability and contact angle influence
Abstract In this paper a new mechanism is proposed to explain the occurrence of boiling crisis. Indeed differing theories as to the effective cause of the critical heat flux (CHF) have been proposed by researchers in this field. Wide experimental data reveal numerous influencing parameters which are not included in any of the theoretical models proposed so far. The dry out mechanism observed for CHF is the clue of the analysis. The proposed mechanism is then valid for all boiling categories, to our mind the crisis is the same and caused by the below described mechanism. The role of the contact angle is revealed to be determining which is in good agreement with experimental data.