Injection of Nucleate-Boiling Slug Flows into a Heat Exchange Chamber in Microgravity

: This project has tested and optimized a method to produce controlled boiling through a localized nucleation cavity feeding a capillary crossflow forming regular trains of bubbles. The main objective was to achieve control of bubble size and bubble formation frequency, in order to generate regular slug flows in a capillary tube, and to show that the system performance was robust and independent of gravity. The periodic slug flows created by this method can then be potentially used for applications of heat transfer. The system was tested in a demonstrative setup in the form of a serpentine heat exchange device. This work achieved a full quantitative characterization of the capillary boiling system in a broad range of parameters, identifying the different regimes of operation, and showing that the results are indeed robust and independent of gravity. In addition, the investigators identified an idealized version of the problem to provide novel theoretical insights of fundamental interest, giving rise to exact analytical results that are relevant in the context of scaling and universality in kinetics of phase transitions.