A numerical study of heat transfer and entropy generation in Powell-Eyring nanofluid flows.

Abstract

The heat transfer in non-Newtonian nanofluid flow through different geometries is an important research area due to the wide application of these fluids in biomedical, chemical and thermal engineering processes. The continuous generation of entropy leads to exergy loss which reduces the performance and efficiency of any physical system, therefore, the minimization of entropy generation becomes necessary. In this thesis, we present a numerical study of heat transfer and entropy generation in non-Newtonian nanofluid flows. We study the flow of a Powell-Eyring nanofluid, using models developed from experimental data. The equations that model the flow are, in each case, reduced to systems of nonlinear differential equations using Lie group theory scaling transformations. Accurate, efficient and rapidly converging spectral numerical techniques including the spectral quasilinearizzation, spectral local linearization and bivariate spectral quasilinearization methods are used to find the numerical solutions. The results show, among other findings, that increasing either the nanoparticle volume fraction or thermal radiation parameter enhances the nanofluid temperature, entropy generation and the Bejan number. In addition, we find that the Nusselt number increases with the temperature ratio parameter and thermal radiation. The results from this study may find use in the design of cooling devices to enhance and optimize the performance of thermal systems.