Laminar Flow in a Periodic Serpentine Channel

This paper presents a study of laminar flow in serpentine channels with periodically repeating elements, with application to heat transfer passages within complex compact heat exchangers. A methodology has been developed to determine the fullydeveloped flow and heat transfer behaviour in such channels with a constant wall heat flux using Computational Fluid Dynamics (CFD). Utilising this approach, flow characteristics are investigated for a fixed geometry, with L/d = 4.5 and Rc/d = 1, for a range of Reynolds numbers up to 200. Pressure loss and heat transfer within a repeating module is compared with that expected from fully-developed flow in a straight pipe of equivalent path length. Dean vortices are generated in the flow and their rotation sense and intensity are dependent on the bend direction and Reynolds number. They are shown to suppress recirculation around bends and to be responsible for the high heat transfer rate with a relatively low pressure drop. The effect of the length to diameter ratio (L/d) on pressure loss and heat transfer performance is also reported for a Reynolds number of 110, with Rc/d = 1.