Friction factors of power-law fluids in chevron-type plate heat exchangers

In the present work laminar flows of Newtonian and power-law fluids through cross-corrugated chevron-type plate heat exchangers (PHEs) are numerically studied in terms of the geometry of the channels. The plates area enlargement factor was a typical one (1.17), the corrugation angle, beta, varied between 30 degrees and 60, and the flow index behaviour, n, between 0.25 and 1. Single friction curves fRe(g) = K for both Newtonian and non-Newtonian fluids are proposed for each beta by developing an adequate definition of the generalised Reynolds number, Re-g. The coefficient K compares well with experimental data, for all (seven) values of beta, and depends on the tortuosity coefficient, tau. It was found that, for each beta, tau decreases with the decrease of n. Food fluids are frequently processed in PHEs and usually behave as non-Newtonian fluids. This study can be useful in engineering applications as well as in the characterization of transport phenomena in PHEs. (C) 2008 Elsevier Ltd. All rights reserved.