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Proceedings of CHT-17 ICHMT International Symposium on Advances in Computational Heat Transfer
May 28 - June 1, 2017, Napoli, Italy

DOI: 10.1615/ICHMT.2017.CHT-7


ISBN Print: 9781-56700-4618

ISSN: 2578-5486

HEAT TRANSFER IN COMBINED MICROCHANNEL WITH CONE-SHAPED MICRO PIN FINS BASED ON ENTROPY GENERATION ANALYSIS

pages 1711-1730
DOI: 10.1615/ICHMT.2017.CHT-7.1790
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Краткое описание

This study focus on the heat transfer enhancement and fluid flow characteristics of combined microchannel with cone-shaped micro pin fins (MCPF for short) for Re ranging from 140 to 650. The numerical simulations are conducted to investigate the overall performance of micro pin fins located in the upstream (case1), middle (case2), downstream (case3) and distributed throughout of the channel (case4) in a fixed number of pin fins. The rectangle smooth microchannel (case0) is the reference channel. A three-dimensional laminar flow model is performed and Navier-Stokes equations and energy equation are solved by computational fluid dynamics. The variations of apparent friction factor ƒapp,ave and average Nusselt number Nuave with inlet Re number are derived and the thermal enhancement factor (η) is applied to select the best comprehensive performance of MCPF. Furthermore, the entropy generation analysis is proposed to evaluate the heat transfer and flow friction irreversibility loss. The results show that the microchannel inserted cone-shaped micro pin fins improves the heat transfer accompanied with a higher pressure drop as compared with the smooth rectangular microchannel. Microchannel with uniform fins distribution (case4) has the largest η and the bottom wall temperature is the lowest and well-distributed among all cases. The entropy generation analysis demonstrates that the heat transfer irreversibility loss is larger than the irreversibility loss caused by flow friction. The total entropy generation of MCPF is lower than smooth rectangular microchannel. The augmentation entropy generation number of case4 is the smallest and case2 is next among all the cases. When Re<500, the Ns value of case3 is less than casel and when Re>500, the tendency is adverse.

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