Laminar Flow and Heat Transfer in Periodic Serpentine Channels: Square, Circular and Semi-Circular Cross-Sections

Abstract

This paper presents studies into laminar flow in serpentine channels with periodically repeating elements analogous to those found in compact plate heat exchangers. Fully-developed flow and heat transfer behaviour in circular, semicircular and square cross-section passages are investigated using Computational Fluid Dynamics (CFD) for a constant wall heat flux (H2) boundary. Flow and heat transfer characteristics are reported for a fixed geometry over a range of Reynolds numbers (Re = 5−200). Pressure drop penalties and heat transfer enhancements within a single repeating module are calculated relative to the results obtained for fully-developed flows in a straight section of pipe of equal path length. Beyond Reynolds numbers of about 5, flow in these passages is increasingly dominated by Dean vortices that form after each bend in the passage. These vortices inhibit flow separation around bends and give rise to high rates of heat transfer with modest pressure-drop penalties. The number and pattern complexity of the Dean vortices is highly dependent on the passage cross-section, the mass flow rate and the geometric configuration.