Convective heat transfer of non-Newtonian power-law slip flows and plug flows with variable thermophysical properties in parallel-plate and circular microchannels

In this study, the perturbation method was implemented to analytically solve the governing equations relevant to both hydrodynamically and thermally fully developed power-law fluid and plug flows through parallel-plates and circular microchannels under constant isoflux thermal and slip boundary condition. The temperature-dependent properties, being viscosity and thermal conductivity, were considered along with non-linear slip condition in the analysis in addition to viscous dissipation. The velocity, temperature and constant property Nusselt number closed form expressions were derived. Then, Nusselt number corresponding to temperature-dependent thermophysical properties was numerically obtained due to their complexity nature. Numerical simulations were also performed for verifying the analytical results. The results indicated that the property variations and slip condition significantly affected thermo-fluid characteristics, and these parameters should be included to achieve a better thermal design for microdevices.