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Heat Transfer Research
Импакт фактор: 0.404 5-летний Импакт фактор: 0.8 SJR: 0.264 SNIP: 0.504 CiteScore™: 0.88

ISSN Печать: 1064-2285
ISSN Онлайн: 2162-6561

Выпуски:
Том 50, 2019 Том 49, 2018 Том 48, 2017 Том 47, 2016 Том 46, 2015 Том 45, 2014 Том 44, 2013 Том 43, 2012 Том 42, 2011 Том 41, 2010 Том 40, 2009 Том 39, 2008 Том 38, 2007 Том 37, 2006 Том 36, 2005 Том 35, 2004 Том 34, 2003 Том 33, 2002 Том 32, 2001 Том 31, 2000 Том 30, 1999 Том 29, 1998 Том 28, 1997

Heat Transfer Research

DOI: 10.1615/HeatTransRes.2018020730
pages 1247-1273

THERMAL PERFORMANCE OF A PIN FIN WITH UNEQUAL CONVECTIVE COEFFICIENTS OVER ITS TIP AND SURFACE

Sunil S. Mehendale
Michigan Technological University, Houghton, Michigan 49931, USA

Краткое описание

It is generally understood that heat transfer of a fin increases with its length. In cases where the fin tip experiences significantly higher convective coefficients, a situation exists where the heat transfer decreases with its length. Applications of this situation may exist in air conditioning, refrigeration, and electronics cooling. Analytical results for one-dimensional temperature distribution and heat transfer rate are presented for such a pin fin. A critical tip-to-surface coefficient ratio h(= hcrit) depending only on the transverse Biot number Bi exists, for which the heat transfer is independent of length. For "subcritical" conditions (h < hcrit), fin heat transfer increases with length, as is commonly known. In this case, long fins will be necessary for maximizing heat transfer. For "supercritical" situations (h > hcrit), however, the heat transfer rate decreases with length, asymptotically approaching that for an infinitely long fin. Here, short fins will suffice to provide near-maximum heat duty. Compared to the unfinned base exposed to the tip coefficient, subcritical fins will enhance heat transfer; under supercritical situations, they will insulate the surface. However, compared to the finless base exposed to the surface coefficient, fins will always increase heat transfer. If the fin tip is employed to accurately measure the fluid temperature, the dimensionless fin length L must be no less than Lmin, which is a function only of Bi and h/hcrit . An analytical expression for Lmin necessary to keep the relative error within one percent has been developed. Whether the fin is used to enhance heat transfer or measure fluid temperature, the fin cross section should have as high surface area-to-volume ratio as possible.


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