Optimization of a low-gravity reflux boiler system for lunar surface thermal control

A key element for space missions and outposts such as a lunar base is a well-designed thermal control system which provides an adequate thermal environment for both crew and equipment. One concept for accomplishing this is a reflux boiler device which operates like a heat pipe, transferring waste heat from the habitat module via a thermal bus to vertical tubes radiating to space. A previous paper by these authors describes a mathematical model of several lightweight tube configurations which had been built and tested by various manufacturers. Following model verification through correlation with NASA vacuum chamber test data, the model was used to simulate both single tubes and a linear array of tubes for lunar surface operation. After comparing the heat rejection capability of three pf the manufactured tubes under similar conditions with normalized tube dimensions, performance predictions for a linear array of tubes operating in the lunar surface environment were then developed. The subject of this paper is an extension of the simulation effort for one of these tube types, which includes the optimization of a linear array of composite tubes for operation in a worst-case lunar surface thermal environment.