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.

Acknowledgments

The authors acknowledge the financial support provided by the National Natural Science Foundation of China (grant 50776088).

Ningning Xie is a Ph.D. student in the Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, China, under the supervision of Professors Tang and Hu. He obtained his bachelor's degree in 2006 from Shandong University, Jinan, China. He is currently working on spray cooling and the combination of spray cooling and capillary microgrooves.

Xuegong Hu is an associate professor at the Center for Heat and Mass Transfer at the Institute of Engineering Thermophysics, Chinese Academy of Sciences. He received his Ph.D. from the Graduate School of the Chinese Academy of Sciences in 2005. His research interests include microscale flow and phase-change heat transfer, rapid transient heat transfer, advanced thermal management for high-power electronic and photoelectronic parts and systems, micro heat exchangers and cooling systems, and new high-efficiency drying fundamentals and technology. He has co-authored more than 70 scientific papers in referred journals and conference proceedings, and obtained 11 Chinese national patents.

DaWei Tang is a professor at the Institute of Engineering Thermophysics, Chinese Academy of Sciences. He received his Ph.D. in engineering from the Graduate School of Science & Technology, Shizuoka University, Japan. From 1993 through 2003, he was an assistant professor in the Faculty of Engineering and Graduate School of Electronic Science and Technology, Shizuoka University, Japan. His current research interests include microscale thermophysics, and advanced thermal management technology in electric, electronic, and optical–electronic systems. He has co-authored more than 80 journal papers.