Inherent irreversibility of channel and pipe flows for non-Newtonian fluids

We report, in terms of local and average entropy generation, the inherent irreversibility of fluid flow and heat transfer for non-Newtonian fluids in a pipe and a channel made of two parallel plates. Fully developed laminar flow is considered with uniform heat flux at the duet wall. Fluid is assumed to follow the power-law model of non-Newtonian fluids. Both the first and second laws of thermodynamics are applied to develop the expressions for dimensionless entropy generation number, irreversibility distribution ratio and Bejan number as a function of geometric, fluid and flow parameters. Average entropy generation number is presented graphically for both pipe flow and channel flow. (C) 2002 Elsevier Science Ltd.