Offset strip fin channels promote higher heat transfer rate than plain fins due to the periodic disruption of boundary layers in the offset channels and downstream flow mixing. The enhanced convection heat transfer in laminar air flows (50 < Re < 2000; Pr = 0.7) is computationally investigated. By considering the fin height h to be much larger than the inter-fin spacing s (or s/h <<1) which is representative of many practical applications, a two-dimensional flow channel is modeled. With thin fins (t/s) < 20%, the effect of fin offset length l (1 ≤ l/s ≤ 35) on the convective enhancement is explored. Higher heat transfer coefficients are found to be obtained with shorter fin lengths and higher flow Reynolds number Re. This effect, however, diminishes for low Re and very large fin offset length and performance asymptotically approaches that of plain rectangular fin channels. The frictional loss also increases correspondingly, and is primarily due to flow acceleration and boundary-layer disruption. This penalty is offset by a 2.5–3 times higher heat transfer rate capacity for fixed pressure drop condition relative to plain fins. For a fixed heat transfer rate application, offset-strip fins are shown to yield 40%–50% smaller surface area cores.
- Heat Transfer Division
Computational Study of Enhanced Convection and Effects of Geometrical Features in Offset Strip Fin Cores
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Bhave, CC, Manglik, RM, & Jog, M. "Computational Study of Enhanced Convection and Effects of Geometrical Features in Offset Strip Fin Cores." Proceedings of the ASME 2017 Heat Transfer Summer Conference. Volume 2: Heat Transfer Equipment; Heat Transfer in Multiphase Systems; Heat Transfer Under Extreme Conditions; Nanoscale Transport Phenomena; Theory and Fundamental Research in Heat Transfer; Thermophysical Properties; Transport Phenomena in Materials Processing and Manufacturing. Bellevue, Washington, USA. July 9–12, 2017. V002T10A001. ASME. https://doi.org/10.1115/HT2017-4754
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