Visualization of bubble mechanism of pulsating heat pipe with conventional working fluids and surfactant solution
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Visualization experiment is a must in realizing functional characteristics of an operational pulsating heat pipe (PHP). So far there is no general formulation which can foretell the complex and chaotic flow nature for every working fluid. Different response of working fluids and their distinct flow nature as well as their behavior can be visualized which thereby helps to understand the operational mechanism of the PHP. In this experiment, tests were conducted in a transparent PHP with 3 conventional working fluids, viz. de-ionized (DI) water, methanol, ethanol, and 300 ppm cetyltrimethyl ammonium chloride (CTAC) solution, each with fill ratio (FR) of 50%. With the help of high speed camera, flow characteristics at different operational stages for each working fluid are captured. Difference in the generation, growth, movement, and flow direction of bubbles are observed and the consequence of combined effects of various thermal properties of the fluid rather than a dominating single property. Start-up characteristics and dominating flow pattern for each fluid are reported in this paper. Moreover, peculiar flow characteristics with 300 ppm CTAC like bubble detachment, movement of cluster of micro-bubbles, and swirling are also presented.
Keywordspulsating heat pipe (PHP) aqueous surfactant solution flow pattern visualization
This paper is supported by the National Natural Science Foundation of China (Grant Nos. 51576051, 51606054, and 51776057). Zhang would like to thank the financial support of “Key Laboratory of Advanced Reactor Engineering and Safety, Ministry of Education (ARES-2018-01)”.
- Akachi, H. 1990. Structure of a heat pipe. U.S. Patent No. 4,921,041. Washington, DC: U.S. Patent and Trademark Office.Google Scholar
- Bergles, A. E. 1985. Techniques to augment heat transfer. In: Handbook of Heat Transfer Application. Rohsenow, W. M., Hartnett, J. P., Ganie, E. Eds. New York: McGraw-Hill.Google Scholar
- Fumoto, K., Ishida, T., Kawanami, T., Inamura, T. 2016. Effect of working fluid in heat transport characteristics of pulsating heat pipe. Trans JSME, 82: 15–00529.Google Scholar
- Liang, Q., Hao, T., Wang, K., Ma, X., Lan, Z., Wang, Y. 2016. Effect of ionic liquid on the startup and operation performance of the pulsating heat pipe. Journal of Engineering Thermophysics, 37: 2680–2683. (in Chinese)Google Scholar
- Mangini, D., Ilinca, A. I., Mameli, M., Fioriti, D., Filippeschi, S., Araneo, L., Marengo, M. 2017. Single loop pulsating heat pipe with non-uniform heating patterns: Fluid infrared visualization and pressure measurements. In: Proceedings of the 9th World Conference on Experimental Heat Transfer, Fluid Mechanics and Thermodynamics.Google Scholar
- Wu, W. T., Yang, Y. M. 1992. Enhanced boiling heat transfer by surfactant additives. In: Proceedings of the Engineering Foundation Conference on Pool and External Flow Boiling, 361–366.Google Scholar