Visualization of Microbubble Dynamics Behavior in Rectangular Capillary Microgrooves Under Spray Cooling Condition

Abstract

Visualization of microbubble dynamics behavior in rectangular capillary microgrooves under spray cooling condition was performed in an open chamber at a nozzle pressure of 0.51 MPa. Distilled water was used as working liquid in this experiment. A high-speed camera with the maximum speed of 100,000 frames per second and a micro lens were used with the combination of VERSION and MATLAB software. The process of microbubble growth was found to be divided into two stages, which are the growth of bubble as semispherical in the grooves, and the growth as semi-ellipsoidal along the groove when constrained by the groove's width until the bubble breaks. The results also show that the bubble life cycle and the bubble breakup equivalent diameter decrease considerably compared with those in rectangular capillary microgrooves without spray cooling, and that they fluctuate as the heat flux rises and are somewhat affected by the placements of the grooves.