Intrinsic irreversibility of Al2O3-H2O nanofluid Poiseuille flow with variable viscosity and convective cooling

Purpose - This study aims to investigate the flow behavior of aluminum oxide-water nanofluid with variable viscosity flowing through the microchannel parallel with the ground, with low aspect ratio. The study focuses on the first and second law analyses of Poiseuille flow using water as the base fluid with alumina nanoparticles suspended in it. Combined effects of thermal radiation, viscous dissipation, variable viscosity, nanoparticle shape factor and volume fraction on the thermal performance are studied and the in-built irreversibility in the process is examined. Design/methodology/approach - The governing equations with dimensions are reduced to non-dimensional equations by using dimensionless quantities. Then, the Runge-Kutta-Fehlberg shooting scheme tackles the present non-linear equations. Findings - The outcomes of the present analysis reveal that the activation energy parameter with its increase, depletes the exergetic effectiveness of the system, thus defending the fact to keep the activation energy parameter the lowest as possible for the system efficiency. In addition, thermal radiation and Biot number enhance the release of heat energy, thereby cooling the system. Bejan number graph exhibits the decreasing behavior for the increased nanoparticle shape factor, whereas the temperature enhances with the rise in nanoparticle shape factor. Originality/value - The effects of nanoparticle shape factor in Poiseuille flow for alumina-water nanoliquid in low aspect ratio microchannel is inspected at the earliest. Exergetic effectiveness of the system is studied and heat transfer characteristics are explored for thermal radiation effect and activation energy parameter. Besides, Be(eta)(Sphere) > Be(eta)(Blades).