Naslov
Heat Transfer and Fluid Flow in Rectangular Offset Strip-Fin Heat Exchanger

Autori
Blecich, Paolo ; Trp, Anica ; Lenić, Kristian

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Proceedings of the International Congress Energy and the Environment 2010, Engineering for a Low-Carbon Future, Vol. II / Andre Manificat, Bernard Thonon - Rijeka : Association GRETh i Hrvatski savez za sunčevu energiju, 2010, 187-198

ISBN
978-953-6886-16-6

Skup
Energy and the Environment 2010

Mjesto i datum
Opatija, Hrvatska, 18.10.2010. - 22.10.2010

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
offset strip-fin; numerical analysis; unstable laminar flow; heat transfer; pressure drop

Sažetak
Numerical analysis of heat transfer and fluid flow in a rectangular offset strip-fin heat exchanger has been carried out. The chosen offset strip fin geometry is defined with a fin space of 1.7 mm, fin height of 2.2 mm, fin thickness of 0.3 mm and strip length of 6 mm. The commercial CFD package FLUENT 6 has been used for the numerical analysis. The SIMPLE algorithm has been used for velocity and pressure coupling in momentum equations. Both conduction in the solid sub-domain (separating plates and fins) as well as convection in the air sub-domain are considered. A constant temperature of 315 K is prescribed on the separating plates. The steady-state laminar and turbulent flow models have been chosen for Reynolds numbers, ranging from 100 to 4000. The resulting heat transfer and pressure drop numbers are compared with results of empirical correlations as well as results of experimental and numerical studies of different authors. The computed Nusselt numbers and pressure drops are over-estimated by an average of 20% with regard to the Manglik-Bergles correlation model. The discrepancy is even smaller when the results of the numerical analysis are compared against a numerical model. It has been concluded that the flow in the offset strip-fin is pure laminar only in the region of Reynolds numbers below 400. It becomes unstable laminar for Re > 400, when self-sustained unsteadiness is established from the interrupted fin surface. Recirculation zones or separation bubbles at fin leading edges and wake regions at fin trailing edges are visible at Reynolds numbers above 400. A change in the Fanning f-factor curve slope testifies that the flow becomes transitional at Re = 1000. The London goodness factor j/f has been used to evaluate the performance of the selected offset strip-fin geometry.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne tehničke znanosti

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