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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

COMPUTATIONAL MODELING OF LOW REYNOLDS NUMBER AIR FLOWS IN WAVY-PLATE-FIN CHANNELS: CONTRIBUTION OF PRESSURE DRAG ON PERFORMANCE

Get access (open in a dialog) DOI: 10.1615/IHTC16.hte.024221
pages 5123-5130

Résumé

Wavy fins enhance heat transfer in plate-fin heat exchangers due to their larger surface area per unit volume and significantly enhanced convection. The convoluted flow geometry between the corrugated fin plates not only produces frictional drag (or shear drag) but pressure drag (or form drag) as well. This is unlike in a parallel plate channel where only the former is present. This has been a source of discrepancy in defining the friction factor in numerical studies. To highlight this, 3-D simulations are conducted for 100 ≤ Re ≤ 2000 with air (Pr = 0.71) as the working fluid to investigate the thermal-hydraulic behavior of wavy-plate-fin channel flows and ascertain the form drag contribution to the total pressure loss. Both friction factors and Colburn factors obtained from simulations are validated with two sets of experiments. Results show that for plate-fin channels with gentle waviness or at small Re, shear drag is the dominant component, whereas with increasing Re and fin waviness, the influence of pressure drag increases considerably. Particularly, at Re = 1000 and corrugation aspect ratio (2×amplitude/pitch) γ = 0.5, the form drag can be as much as 88% of the total drag force. The associated heat transfer results are also presented and analyzed.