Preliminary physical analysis of a single-bubble pool-boiling experiment in space: Effect of subcooling and possible non-condensable residuals

Abstract

The purpose of this work is to study the boiling heat transfer mechanisms in microgravity. Single bubbles growing without departure up to a centimetric size on a single artificial nucleation site are investigated under well-controlled pool-boiling conditions in the framework of the RUBI experiment on the International Space Station. Subcooling is one of the important parameters defining the bubble growth process. In this work, we conduct a first physical analysis of the experiment. The bubble diameter is evaluated in time using a developed algorithm. Several stages are highlighted. It is shown that subcooling has a significant effect on all stages of bubble life and can even lead to a partial collapse. A numerical model is developed to help a better understanding of the phenomenon. Some observations couldn't be explained without evoking the presence of non-condensable residuals. The amount of those is estimated.