injection of nucleate-boiling slug flows into a heat exchange chamber (Slug Boiling)

abstract

The purpose of the proposed research project is to take a step forward in the study of flow boiling in microgravity by combining our previous expertise in management of (non- thermal) two-phase flows, with the needs of a more basic understanding of the physical processes involved in flow boiling heat transfer in microgravity. The rationale is to focus on situations that are sufficiently simple and controllable so that one can get high quality data, which can be amenable to theoretical analysis and interpretation. The long-term goal is to search for fundamental insights that may eventually lead to innovative approaches and potential breakthrough in space technology. Within this spirit, the key innovation of the present project is to consider for the first time the induction of controlled nucleate boiling in a capillary tube, with the practical goal of achieving a periodic slug flow, and use it to create controlled environments to study the physics of boiling in optimal conditions. Bubbles will be nucleated at specific sites and detached by a laminar cross-flow to fill the entire diameter of the capillary, a situation that we term slug boiling. The combination for the first time of (i) controlled nucleation at boiling sites, (ii) flow boiling, and (iii) slug flow conditions, is proposed as a method to tame the nucleation process and produce bubbles with a regular pace and orderly transport for subsequent study in heat exchange chambers. In this way, we will generate novel configurations of bubble suspensions to study coalescence, phase change dynamics and heat exchange in general in a turbulent medium under controlled conditions.

experiment year: 2014
number of drops: 27
number of catapult launches: 5

experiment year: 2013
number of drops: 30