Flow characteristics and thermal performance in chevron type plate heat exchangers

We report an unsteady numerical analysis using large-eddy simulation (LES) to investigate the fluid flow in chevron-type plate heat exchangers. The flow in the heat exchanger consisted of a streamwise direction component and furrow direction components, and this complex flow structure induced turbulence, even at low Reynolds numbers. In the turbulent regime, the flow periodically oscillated, inducing a secondary flow and a vortex pair. The friction factor f and Colburn factor j were investigated for various geometrical parameters, i.e., 30 degrees <= beta <= 60 degrees and 2.0 <= p/h <= 4.4. The results showed that both f and j increased with increasing chevron angle beta, and both increased as the ratio of the chevron pitch to the chevron height p/h decreased. We found that to achieve optimum performance, the following parameters should be used: beta = 30 degrees with laminar flow and beta = 60 degrees with turbulent flow; furthermore, p/h = 2.0 should be used in both laminar and turbulent flows. (C) 2014 Elsevier Ltd. All rights reserved.