Optimization of a Low-Gravity Two-Phase System for Lunar Heat Rejection

A mathematical model of a low-gravity reflux boiler system for lunar-surface heat rejection, including the performance of a single tube and a linear array of tubes, is described. Model verification is demonstrated throughcorrelation with NASA vacuum chamber test data. Performance comparisons are made between three manufactured configurations of the tubes for similar environmental conditions and with the tube dimensions normalized with respect to one another. Finally, the optimization of a linear array of composite tubes for operation in a worstcase lunar surface thermal environment is presented. A pitch-to-diameter ratio of between 4 and 5 is recommended because that choice provides over 95% of the maximum heat transfer with a more logistically feasible array.