Faculty of Engineering and Natural Sciences
Heat and Fluid Flow in Micro Pin Fin Heat Sinks
Ali Koşar, Rensselaer Polytechnic Institute
Rapid progress in compact micro heat exchanger technology has stimulated the design of microchannel type micro heat exchangers in various engineering applications. Heat transfer in microchannels has received significant amount of attention and many studies have been conducted to unveil their heat transfer performance. However, enhancing the surface of microchannels to mitigate boiling heat transfer and improving their thermal-hydraulic performance have not extensively been applied in micro scale yet. This might be due to the limitation imposed by micromachining surfaces in micro scale and the still existing ambiguity and lack of theory in micro scale heat transfer in plain microchannels. The research work has been directed towards proposing micro pin fin heat sinks as an alternative of plain microchannels and conducting experiments on micro pin fin devices. A pioneering investigation on micro pin fin devices has been conducted to present them as an alternative type of second generation micro heat sinks and obtain their thermal-hydraulic and boiling heat transfer performance.
In single-phase flow studies, it has been found that existing conventional scale correlations were not able to predict the friction factors and Nusselt number accurately particularly for low Reynolds numbers due to the endwall effects and the effect of the delay in flow separation and provided fair agreement at high Reynolds numbers. The performance of the micro pin fin device is dependent on the performance evaluation criterion used, as well as on the hydrodynamic conditions.
In boiling studies, it has been found that existing large scale correlations provided large scatter and inability to predict the heat transfer coefficients. More research should be conducted to develop better prediction tools.
Bio: Ali Koşar received his B.S. degree in Mechanical Engineering from Boğaziçi University, Istanbul, in 2001. He pursued his graduate study in the Department of Mechanical Engineering at the Rensselaer Polytechnic Institute between 2001 and 2006. He completed his M.S. and Ph.D. degrees in 2003 and 2006, respectively. He is recently working in Rensselaer Polytechnic Institute as a post doctoral research associate and adjunct professor.
His research interests lie in heat and fluid flow in micro heat sinks. He has been conducting pioneering research on single-phase and boiling heat transfer, single-phase and two-phase pressure drop, critical heat flux (CHF), and cavitation in MEMS-based pin fin and second generation microchannel heat sinks. The results of his research have generated papers on micro heat sinks, 13 of which have been accepted for publication in some prestigious journals like Journal of Heat Transfer and International Journal of Heat Transfer, while the others are still in review. He also has conference papers in the 3rd International Conference on Minichannels and Microchannels, 9th AIAA/ASME Joint Thermophysics and Heat Transfer Conference, 2005 ASME International Mechanical Engineering Congress and Exposition, and 2006 ASME International Mechanical Engineering Congress and Exposition. Moreover he is serving in Journal of Heat Transfer as a reviewer.
January 10, 2007, 15:40, FENS L056